Heer, P.W. de, Editor
Report 1239-P November 2000
TU Deift
Faculty of Design, Engineering and Productiony Department of Marine Technology"Yacht Design and Yacht Construction"
Amsterdam, 13 November 2000
PROCEEDINGS
Edited by P.W. de Heer
October 2000
Organized by HIS WA - National Association of Watersport in The Netherlands, the International Trade Show for Marine Equipment METS 2000
and the Deift University of Technology
Deift University of Technology Ship Hydromechanics Laboratory
DocVision BV Leeghwaterstraat 42 2628 CA Deift The Netherlands
CIP-DATA KONINKLIJKE BIBLIOTHEEK, DEN HAAG
16th International Symposium on "Yacht Design and Yacht Construction": proceedings of the 16th International Symposium on "Yacht Design and Yacht Construction", Amsterdam 13
November 2000/P.W. de Fleer
(editor), - Deift University of Technology, ShipHydromechanics Laboratory, The Netherlands. ISBN: 90 - 370 - 0185 - 8
Subject headings: Yacht Design, Yacht Construction Telefoon: +31 15 2784642
THE INFLUENCE OF BOW SHAPE ON THE PERFORMANCE OF SAILING YACHTS
J.A. Keuning, R. Onnink, A. Damman, Ship Hydromechanics Laboratory,
DeIft University of Technology, Deift, The Netherlands 107
PROGRAMME 5
INTRODUCTION 7
THE VERIFICATION OF MAST AND RIGGING OF LARGE SAILING VESSELS
Michael J. Gudmunsen, Lloyd's Register, London, England 9
PRACTICAL EXPERIENCE ON REDUCING MOTIONS AND IMPROVING COMFORT ON BOARD LARGE MOTOR YACHTS
H.M. van Wieringen, F.A. Gumbs, F. De Voogt, International Ship Design and Engineering, Bloemendaal, The Netherlands
R. Dallinga, MARiN, Wagenin gen, The Netherlands 51
SOME CRITICAL NOTES ON DESIGNING WITH COMPOSITES
Jons Degrieck, Ghent University, Ghent, Belgium 65
ALL ELECTRIC YACHT - ELECTRIFYING OR TERRIFYING? U. Nienhuis, Netherlands Institute for Maritime Research, The Hague,
The Netherlands 77
PERFORMANCE PREDICTION OF SCHOONERS USING WINDTUNNEL DATA IN VPP CALCULATIONS
I.M. C. C'ampbell. Wofson Uiit MTL4, Southampton, U'?ited Kingdom
16th International HISWA Symposium on "Yacht Design and Yacht Construction". Monday, 13 November 2000
JADE LOUNGE
08:00 - 10:00 Registration and information
ROOM RIS
10:00 - 10:15 Moderator Jack A. Somer
Word of welcome by Jack A. Somer
10:15 - 11.00 Michael J. Guthnunsen, Lloyd's Register, London, England
THE VERJFICA T1ON OF MAST AND RIGGING OF LARGE SAILING VESSELS
11.00-11.30
Break11:30 - 12:15 H.M. van Wieringen, F.A. Gumbs, F. De Voogt, International Ship Design and Engineering, Bloemendaal, The Netherlands
R. Dallinga, MARIN, Wageningen, The Netherlands
PRA CTI CAL EXPERIENCE ON RED UCING MOTIONS AND iMPROVING COMFORT ON BOARD LARGE MOTOR YACHTS
12:15 - 13:00 Jons Degrieck, Ghent University, Ghent, Belgium
SOME CRITICAL NOTES ON DESIGNING WiTH COMPOSITES
13.00 - 14.00 Lunch in Parkrestaurant?
14.45 - 15.30
ALL ELECTRIC YACHT- ELECTRIFYING OR ThRRIFYING?
I.M.C. Campbell, Wolfson Unit MTIA, Southampton, United
Kingdom
G. Dijkstra, Gerard Dijkstra and Partners, Amsterdam, The
Netherlands
PERFORMANCE PREDICTION OF SCHOONERS USING
WIND TUNNEL DATA IN VPP CALCULATIONS
15.30 - 16.00 Break
16.00 - 16.45
J.A. Keuning, R. Onnink, A. Damman, Ship Hydromechanics
Laboratory, Deift University of Technology, Delft, The Netherlands
THE INFLUENCE OF BOW SHAPE ON THE PERFORMANCE OF
SAILING YACHTS
16.45 - 17.00 Closing
JADE LOUNGE
17.00 - 18.00 Reception
On behalf of the Organizing Committee ot the 16th International HISWA Symposium on Yacht Design and Yacht Construction I have the pleasure of inviting you to participate in the forthcoming Symposium.
The Organizing Committee believes that it succeeded in getting together an interesting set of papers presented by well-known experts in their fields. This year, the design and construction of large custom-built yachts is emphasised. The construction of large custom-built yachts, both motor yachts and sailing yachts, is an ever-increasing market, in particular over the last decades, and an area in which high-tech developments play an important role both in realising these projects as well as in acquiring them.
This year, the set-up of the Symposium is slightly changed to allow for more time in-between the sessions, so that ample time is available for informal contacts between the delegates and/or the presenters of the various papers. Since yacht designers and researchers from allover the world attend the Symposium it never fails to be an interesting day for all ofyou.
We hope to have the pleasure of welcoming you at the 16th Symposium.
Alexander Keuning
THE VERIFICATION OF MASTS AND
RIGGING OF LARGE SAILING VESSELS
By M. J. Gudmunsen Principal Surveyor
Lloyd's Register Marine Division
The Verification of Masts and Rigging
of Large Sailing Vessels
by M. J. Gudniunsen Senior Surveyor
Lloyd's Register Marine Division
SYNOPSIS
This paper presents the formal classification approach used in the appraisal and verification of the masts and standing rigging of large sailing passenger vessels. Comparison is made between the tabular scanthngs for masts and rigging in Lloyds Register's rules and regulations of 1922, and the direct calculation techniques currently employed by Lloyds Register.
The calculation methods and assumptions are described with illustrations from analyses of the rigs of both newbuilding vessels and vessels currently in service.
Amongst the number of large sailing vessels rigs referenced, examples from the "STAD AMSTERDAM" rig have been presented, as it represents the visual
replication of a traditional 19th century sailing ship but employs a range of modern 20th century hi-tech materials.
The criteria for rig design, verification and acceptance into class is presented
together with details on the build quality, materials, survey, testing and certification requirements.
Designers, tasked with meeting dassification or flag administration requirements for large sailing vessels have foand the criteria presentedinthis paper useful with regard to setting a standard for both design and acceptance of the masts and standing rigging.
-INTRODUCFION
During the second half of the 1980's interest was developing with owners and operators in passenger ships propelled by wind power. The concept was to provide a high standard of accommodation and services combined with the unique experience of tall ship sailing for normal fare paying passengers.
figure 1
The first vessel, "Star Dipper" leaving Flushing for her sea trials is shown in figure 1. The vessels were submitted for formal classification with Lloyds Register with a contemplated hull notation of 100A1 Sailing Passenger Ship.
Verification of and acceptance into class of the all-welded steel hull of the vessels was facilitated through the application of the Rules and Regulations for the classification of Steel Ships with some minor amendments.
The verification of the masts and rigging, however, presented a more complex structural problem. Lloyd's Register's Rules for masts and standing rigging of sailing vessels had been discontinued in the mid 1920's. These Rules had provided scantlings and dimensions of masts, yards and wire rope standing rigging in tabular form. Mast scantlings being based upon mast length and rigging dimensions being based upon a numeral using the ship's principal dimensions.
These early rules were developed and maintained mainly through service
experience. Théicantlings of masts and wire ropes were based upon the material performance available at that time and the construction methods employed such practices as riveting of curved shells to form tubular mast structures. From the
2-At this time, the Langebrugge
shipyard in Belgium had received an order from White Star Clippers of Brussels to build two barquentines, suitable for up to 194 passengers with a crew of 59. The ships were to
measure 111.57m over the bowsprit, have a loaded displacement of 2556 tonnes and carry 3365 m2 of sail area on four steel masts.
Initially intended for operation in the Caribbean the first ships would operate out of Miami on a pattern of one or two-week cruises. Research conducted by White Star suggested that their guests would be
predominantly European, with a knowledge and interest in sailing The rig would require to be designed in order to permit some participation on the part of the passengers but with a high degree of confidence in the safety of the rigging and sail systems.
tabulated scantling method, it is clearly not possible to determine the margins of safety inherent in the final design, nor establish the limiting environmental conditions for the rig.
The tabular scantling approach provides no flexibility regarding design change or novel design features and would appear to be adequate solely for a traditional mast/rigging configuration.
figure 2
Interestingly, in parallel with the appraisal of the Langebrugge
barquentmes, another large LR classed sailing passenger ship, "Le Ponant" was under development at the French shipyard of SCNF.
This aluminium hulled vessel was proposed with high strength oval section aluminium grooved masts, stainless steel rod rigging1 hydraulic
mast jacking and hydraulic sail systems. The arrangements would permit most sailing operations to be conducted solely by the helmsman
from the central steering position. The design employed over 2000m2 of
sail area, fore and aft rigged on the 3 masts.
Clearly, from the diverse nature of the mast and rig designs being contemplated, a more direct calculation approach was demanded in order to verify the structural adequacy of the arrangements and to provide a satisfactory procedure for formal classification.
The mast and rigging scanthng tables from Section 37 of the 1922 Rules and
reproduced in Appendix 1. In order to
LiLILaLt LULLLj)CU1J1L YVIUL ilLU.Lt11L
"b t.ULUuìb, ut
LaL)1c) 1Lac LCtflau..uuunaky produced in metric format and are annotated with the table reference number and 'Imperial' or 'Metric' as appropriate.Many terms stated in the rules and in the tables may be unfamiliar to today's Naval Architects, namely, mast partners, hounds, futtocks, chainpiates, topgallants, royals, shrouds etc. It is however anticipated that the reader will consult the many
reference books available on this topic in order to develop familiarity with these traditional nautical terms.
ACCEPTANCE CRITERIA
From a Classification Society perspective, the structural verification of the masts and rigging is carried out in order to establish the level of safety and reliability of the structures and the supporting rigging components. Many large sailing ships are used for training purposes as well as those dedicated to providing a "tall ships" experience for physically disabled people. At the other end of the client spectrum, we have those sailing ships that are dedicated passenger ships, carrying significant numbers of people who range in age from children to the very senior age groups.
For all these vessels, failure of the rig, masts or supporting structures could have far reaching consequences. Recently built sailing ships generally have an auxiliary engine which is used to power the vessel in rivers, harbours and estuaries, or in wind conditions where the sails cannot often be utilised. When utilising wind
power, the sail system must be considered as the "engine" of such ships and loss of this prime mover may endanger the survivability of the complete vessel. Failure of individual rigging components or masts would endanger the lives of crew and passengers and it is not possible to provide any real physical separation between the personnel and the location of the risk.
figure 3
In order to establish suitable factors of safety for rigging, standards used in the marine industry for lifting appliances were examined. Stayed derrick posts are similar in configuration and response to stayed masts and it was considered that the
The proximity of booms, blocks and other rigging to passengers and crew is clearly illustrated in figure 3 which shows Star Clipper underway.
As previously mentioned, the tabular methods of mast and rigging scantling selection provide the designer with no indication of the inherent factors of safety against failure.
Where rigs are proposed with modified, hybrid or indeed novel arrangements, empirical derivation of scantlings would be highly unreliable.
accepted safety criteria for sailing vessel masts and rigging should, at the very least, comply with these criteria.
Since the prime purpose of the standing rigging is to provide support to the mast and bowsprit structures, it would be reasonable to ensure that the standing rigging had a moderate to high factor of safety against failure. With this rationale, stresses in the mast structures could be allowed up to a level normally accepted by
classification for integral components of the ship's structure. Any selected factor of safety must be commensurate with the probability of design load exceedence and hence the following safety factors against failure of the standing rigging were established;
All sailing conditions F.O.S=3.5
Survival, bore poles condition F.O.S= 2.0
The masts and bowsprit are subject to a combination of both axial compressive and bending loads. Factors of safety must therefore be related to the critical axial failure load (stress) and also the bending failure load (stress). Hence, the mast acceptance criteria are based upon a combined safety index:
All sailing conditions [ab!
a
+aa/ a]
0.67Survival, bare poles condition [ab /
a
+ aal (Ycrit] 0.85Where :- abis the derived bending stress in the mast.
aa is the derived axial stress in the mast.
a is the material yield stress.
aaitis the critical elastic buckling stress.
I--MATHEMATICAL IDEALISATION
With the complex interaction between mast and rigging stiffness and the mteraction between successive masts due to their connection via longitudinal stays, it is
considered that any simplistic analytical calculation would be both maccurate and unsuitable.
The verification process requires calculation of the component tensile loads for the rigging and the axial force and bending moment results for every section of the masts and bowsprit. The analysis technique employs a large displacement non-linear finite element code which satisfies both the response and output result requirements.
The mast and bowsprit structures essentially perform as axially loaded compression columns. Due to the load contribution of the running and standing rigging at
various points on the masts, each different section of mast between rigging attachment points has its own unique set of axial and bending loads. Hence, the masts and bowsprit are represented mathematically by line beam elements, each with its commensurate axial, bending, shear and torsional geometric properties. The standing rigging is represented by one-dimensional line elements attached to
the masts and to the deck or chainpiates as defined on the rigging plan. Since rigging is unable to provide compressive stiffness, the associated material is provided with a non-linear response capability, representing the normal load-extension response in the tensile domain but a zero load-load-extension response in the compression domain.
The axial stiffness of the rigging components depends upon the basic Young's Modulus of the material of construction, the effective cross section and the efficiency of the geometric section to resist strain. With steel wire rope, around 20% of the axial stiffness is lost due to the lay of the rope and further losses are incurred due to
the difference between net cross section and gross idealised cross section.
In consideration of these effects, the following list indicates acceptable Young's Modulus values for a range of rigging materials based upon nominal diameter for the derivation of cross sectional area:
Component material Young's modulus
(N/mm2)
Area based upon
(mm2)
MP 35N 2.32E5 Nominal dia
Stainless steel (22-13-5) 1.92E5 Nominal dia
Titanium (6AL-4V) 1.10E5 Nominal dia
Aluminium (6061-T6) 0.72E5 Nominal dia
G.S.W.R 1.09E5 Nominal dia
S.S.W.R 1.21E5 Nominal dia
Alpha & Gamma rods 1.93E5 Nominal dia
A 3-Dimensional model of the masts and rigging for the Stad Amsterdam is shown in figure 4. The lower masts are of steel, whereas the topmasts and topgallant masts are of high strength aluminium ahoy. The steel bowsprit has additionally a jib-boom, again fabricated from high strength aluminium alloy. The analysis model shown has 189 nodes, 92 axial/bending mast elements and 154 axial rigging elements.
figure 4
LOADING DETERMiNATION
Other than motion induced loads, the significant loading on the masts and rigging results directly from the wind speed and direction. In order to take dueaccount of the relative velocity between the ship and the wind, the sail loads are based upon an apparent wind velocity (Va). Clearly, there is no effective means of controlling Va and adjustment to sail area is the logical reaction to increasing values of apparent wind speed. In very severe wind and sea conditions the masts and rigging must be capable of survival without sustaining excessive loading. Hence, a "bare poles" condition with a hurricane wind speed of 122 knots from any direction is considered as a survival load case. With only "bare poles and furled sails, the vessel will also be subject to wave induced ship motions, particularly roll which will induce lateral acceleration forces into the masts. Three clearly defined limiting conditions result from the anticipated operational modes of large sailing vessels;
Normal operation with a full press of sails. Storm conditions with reduced sail.
Survival condition with all sails furled.
Depending upon the rig configuration, fore and aft sails or square sails, the design will have a stated apparent wind speed in association with sailing condition 1). Usually this is defined by the Beaufort wind scale and for classification purposes is not taken as less than 25 knots,
The storm condition wind speed is largely dictated by the size and number of sails which can be effectively used in high wind conditions. Of the vessels analysed to date, this storm wind speed is generally between 40 and 50 knots. Again, for classification purposes the storm apparent wind speed is not taken as less than 40 knots.
In addition to the wind generated loads in the survival condition, long term values of ship motion are used as
follows:-Ø=3O
= l2exp (Lbp/ 300)
Lbp/80
Tr = 0.7B/(GM)
0.3T = 0.5 (Lbp)°.S
Th = 0.5 (Lbp)0.5 t3
Ship Motions
Motion
I\Iaxinìum Single
Period ìn
Amplitude
Seconds
k(oU
Pitch
Heave
Where: Lbp = Length of ship between perpendiculars, in metres,
B = moulded breadth of ship, in metres,
GM = transverse metacentric height of loaded ship, in metres
= is to be taken as not greater than 80.
Wind generated loads carried by the masts from the sails or to staysail stays may be evaluated using typical expressions for the lift on aerofoil sections:
F5 = P/2.AS.VA2.0
Where: = p the density of air. = A5 sail area.
= VA Apparent wind speed. CL or CD as appropriate.
The mean lift coefficient (CL) from sails assuming the optimum angle of attack are generally taken to be:
1.1 for staysails
1.2 for fore and aft sails on masts with booms 1.4 for square sails
The drag coefficient for masts, standing rigging and yards with furled sails is taken to be 1.2. Application of drag is generally only required for the survival condition with bare poles and a very high wind speed.
Staysail loads induce catenary response into the stays and equilibrium between the stay sag, applied sail luff load and stay tension has to be maintained. There clearly is a practical limit as to how much sag can be removed from a staysail stay before abnormally high stay tensions are induced. Over the years there has been much argument and debate over a suitable value of stay sag and it is suggested that the likely value lies somewhere between 3% and 6% of the stay length. For the purposes of calculation, an assumed stay sag within these boundaries is used to develop staysail stay tensions. Hence, staysail stay tension is approximated to:
T9= 3.75 X F
The vectorial components of the stay tensions are added to the loading in the analysis model at the mast and bowsprit attachment points. For analysis of the loads in the staysail stays, the tension induced by the staysail however, must be added to the F.E. analysis result in order to obtain the total stay tension.
Although running rigging is not included in the classification process, significant additional loads are generated on the masts and bowsprit at running rigging attachment points. The mass of the yards and sails also contribute to the axial
loading in the masts and more importantly, to the lateral forces applied to the masts as a result of ship motion induced acceleration.
The detailed methods of load application to the finite element model are not presented in this paper as it is considered that experienced analysts would apply suitable techniques which would generally be discussed and agreed with the certifying authority.
MSC'PATRAN Vercion 9.0 28Jun-86 15:25:38
Vector: SC1:2BKNOTS RUNNING. A1:Nonlinear- 188. ' of Load. Applied Loads, Translational, a
I
22
figure 6
226851 218647 1 94444 170240 162036 145033 129629 I 13425 97222 81810 64814 401311 32407 16203 O default_Vector Ma, 243055 Nd 614 O Nd 106ANALYSIS
The rig analysis forms the basis for ail subsequent appraisal of the masts and standing rigging. The results provide evidence that the acceptance criteria have been satisfied and permit detailed strength assessments to be carried out for complex structures and attachments. The deformed shape of the rig is shown in Figure 7 and represents the loading case of wind from abaft at 28 knots (relative).
NSC/PflTRHN Vcron 9.6 26-Jun-66 15:26:22
DeÇorn,: SCI:28KNOTS PUNNING, R1:Non-11r,r: 166. of Lo8d, T-s1at1ona1, CNONI-LRYI
defau1t_Uefornaton
t1 3.19+62 Nd 617
figure 7
The analysis is carried out without the effects of pre-tension in order to consider the likely scenano of a rig in service prior to a scheduled maintenance period. With square rigged ships, the vector of the applied loads is along the ships fore and aft axis, which produces deformations in the x-z plane.
With longitudinally rigged vessels such as schooners and barquentines, significant deflection of the masts occurs additionally at 90° to the wind direction. The
deformation characteristics are controlled by the relationship between mast and rigging stiffeness. For Stad Amsterdam the topmasts and topgallant masts are of aluminium and due to its low Young's Modulus, relative to steel, the topgallant
-22-backstays provide high restraining forces which effectively pull the mast heads aft and result in forward curvature of the mast.
The deflected shape of the bowsprit and jib-boom are reproduced in figure 8, for a condition where all the forward staysails are employed. The upward bending of the structure due to the significant stay tensions is apparent. The need for high stiffness in the stays of the bowsprit and jib-boom is clear from this plot in order to reduce bending in the structure. Pre-tensioning of the bobstay and martingales in order to induce downward bending of the bowsprit and jib-boom may be applied in order to attempt to reduce the bending response when under load.
9.0 20
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2L
£1.,. 3.29.02 SNd SI?
figure 8
Typical mainmast scantlings are shown in figure 9. For comparison, the scantling requirements of the 1922 Rules have been indicated and for the steel masts the comparison is favourable. For the topmasts and topgallant masts however, the dimensional comparison between the steel requirements and the alununium scantlings fitted is invalid.
The axial fuie. in the masts ùbtairied for a typical 2 knot wind speed sailing condition for the sailing ship 'Stad Amsterdam' are shown in Figure 10.
In addition to the verification of the mast scantlings and its ability to efficiently sustain this column load, the supporting ship structure requires to be examined in way of the mast heel support and also in way of the attachments for rigging.
Based upon the calculation of the safety indices described in the section on acceptance criteria, the values obtained for the masts of the example vessel, Stad
Amsterdam are reproduced in figure 10, for a typical 28 knot wind speed sailing condition. 11.3 m 420x12 Alu fitted .5?,4x9(l922Rijlps' 569x10 fitted 576x9 (1922 660x9.5 fitted 694x11 (1922
-25-Axial force 711 kN. Axial force 909 kN. 0.34 360x10 Alu fitted 229x5 (1922 Rules) 416x12 Alu fitted 533x8 (1922 Rules) Safety Index 0.33 (FOS 2.O Safety Index 0.48 (FOS1.4) 290x8 Alu. Fitted 203x5 (1922 Rules) Axial force 13.Om QL11cM Safety Indexli
13.0MAST CONSTRUCTION
Based upon the most severe axial and bending loads obtained from the finite element analysis, the mast sections are verified for compliance with the safety indices set out in the section on acceptance criteria. Generally, tubular masts of circular cross section should have wall thicknesses of greater than D/80. This will ensure that local instability of the mast wall is not a likely premature failure mode.
figure 11
The shells of circular section masts are generally rolled from plate and one longitudinal seam weld is made to complete each mast section.
Successive mast sections should have seams displaced circuferentially by
120°.
By comparison with 19th century construction methods, typically the mast sections would have been formed from three curved plates, each
completing a 120° arc, overlapped and double riveted. Successive mast
sections were likewise double riveted butin way of the partners and other critical sections, triple riveting was
applied. Internal stiffening was provided by angle bars with their flanges riveted through the mast walls. Figure 11 shows a mast constructed in this way.
Modern masts are generally of the single pole type, tapered over their entire length. The taper is achieved by either manufacturing mast sections of conical form or connecting constant diameter sections via conical reducers as is the method used for
the masts of Royal Clipper.
At the mast heel, suitable arrangements are required to prevent rotation around the mast's own axis and diaphragms or other stiffening are required to stabilise the mast wall in way of the reaction at the mast heel. In view of the high mast heel
reaction force, almost all masts are carried through the decks and are supported at
the ship's keel.
-As the mast sections between decks are short in length and have small end bending moments there is good technical justification for a reduced geometric section in these locations. On the Star Clipper/Star Flyer a reverse conical taper was arranged
below the weather deck and a pifiar from the lower deck to the keel. This
mininilsed the width requirements for the central passageway in way of the masts. At deck levels where lateral support is provided, the
structural arrangements must be such as to prevent localised loads on the mast wall which could lead to
deformation of the section. Where the mast is not jointed above the deck a substantial deck insert with spigot is arranged in way of an increased mast wall section to provide an annulus for wooden or plastic wedges. In order to avoid this feature, Royal Clipper has a flanged and bolted connection
immediately above the weather deck as indicated in figure 12. Hence the lower section of mast can be fully welded into the hull. Un-stepping the masts for inspection or repair is made easier by this flanged arrangement.
figure 13
Most modem sailing vessels employ eyeplates welded to the mast wall in order to allow direct connection of the standing rigging rope terminal or shackle. The capability of the eyeplate should be in excess of the breaking strength of the rope and requires to be of sufficient thickness to provide adequate bearing length for the terminal/shackle pin and to ensure that the pin is not subject to significant bending.
27
figure 12
On traditional tall ships, the standing rigging was passed around the masts and small pegs or "thumb cleats" were arranged to locate the upper ioop of the wire stay or shroud.
With this arrangement, the
shroud/stay loading applied to the mast results in a circumferential compressive hoop stress in the mast wall. This principle is visible in figure
The angularity of the shrouds/ stays and the geometry of the eyeplate will result in punching shear loads in the mast walls at the extremities of the eyeplates.
Therefore, in way of shroud and stay attachment points it is required that the mast should be protected by one of the following options:
Internal diaphragms at the upper and lower boundaries of the eyeplates.
External mast rings in way of the upper and lower boundaries of the eyeplates. (see figure 14).
A mast section of 2 x the basic mast wall thickness over a length of 3 x depth of eyeplates.
figure 14
-29-In all cases, full or partial penetration welds with appropriate preparations are required in order to achieve sufficient shear area for eyeplate attachments. The choice of the most appropriate option depends upon many factors, including mast diameter and aesthetic considerations. The moulded dimension of masts is conventionally the internal surface and hence any steps in mast wall thickness will be external. Where the thickness differential between
successive sections exceeds 4mm the thicker part is to be tapered with a 1:3 ratio in order to avoid abrupt
discontinuity in the section.
The attachment of isolated eyeplates using, doubling plates is permitted provided the eyeplates are first welded to the mast wall and the doubler is slotted over the eyeplate and fully welded to both eyeplate and mast.
From a purely engineering point of view, the application of higher strength steels for masts appears initially not to provide significant structural advantage since the elastic buckling response of mild and higher tensile steels are similar. However, since modern all welded mast structures have significant bending stiffness, the chosen mast material must have adequate tolerance to bending induced direct stress. For steel masts, material with a yield stress in excess of 280N/mm2 is frequently selected, with higher tensile steel of 355N/ mm2 yield strength being employed in several designs.
STANDING RIGGING
figure 15
The majority of sailing ships dealt with recently, employ galvanised steel wire rope for the standing rigging although stainless steel is being increasingly used in view of its good corrosion resistance.
As there is usually no requirement for standing rigging wires to pass through blocks or sheaves, the make up of the
rope section often consists of small numbers of individual wires.
A typical lower shroud arrangement during assembly is indicated in figure
15.
The Jubilee Sailing Trust vessel, "TENACIOUS" uses a316S31 fully austenitic stainless steel wire of i x 19 construction for all standing parts of the rig.
On occasions where running backstays or forestays are arranged, the selected rope is required to provide a degree of flexibility and both "STAD AMSTERDAM" and
"CISNE BRANCO" utilise a 6 x 36 construction in these locations and for the majority of the remaining standing rigging.
It is widely accepted that fibre cored rope is not suitable for standing rigging and hence is not permitted by many classification authorities and flag administrations. Also, some aspects of the material strength used in the construction of the rope wire appear to be of concern to someadministrations and builders. Although stainless steel wire rope offers acceptable strength characteristics coupled with generally good corrosion resistance, some grades are prone to fatigue cracking caused by stress corrosion. The onset of failure of stainless steel wire ropes is often not readily
observed and this has been clearly demonstrated byinstantaneous failure during the break tests of completed ropes and terminal end connections.
Galvartised steel wire rope (GSWR) is available with wire strands of three material strengths, 1420N/mm2, 1570N/mm2 and 1770N/mm2. Owner or designer
Young's Modulus is the same for each strength, larger diameter, low strength wires will provide greater axial stiffness and will in turn provide greater restraint to mast deflection. The non-availability of higher strength GSWR in the specific areas of the world where the vessel is intended to operate may also limit the choice of wire material strength. The use of low strength wire material should ensure that the fatigue failure of terminal end connections and of loose gear is reduced due to the lower operational stress levels.
figure 16
Invariably, these are often of solid round bar section of significant diameter or short link steel chain. Figure 17 shows a typical rod
arrangement and figure 16 a short link chain arrangement. Figure 18 shows the stem connection of a wire rope bobstay.
figure 18
-
30-The bowsprit and jib-boom, where fitted, are subject to significant loading. The fore royal, topgallant topmast and jibstays are attached to these structures or pass over built in sheaves. These stays are heavily tensioned due to the catenary loading induced by the staysails. The
mechanical advantage obtained by the angularity of the bowsprit supporting stays is usually not optimal and results in high tensions in the bobstay and martingale stays.
TESTING, SURVEY AND CERTiFICATION
Any formal design appraisal is required to be complimented by a suitable regime of testing and survey in order to certify the structural components of the rig as 'fit for purpose.'
figure 19
-:2t-The masts and bowsprit may be fabricated from tubular steel or aluminium. The mast sections may employ classic yacht oval aluminium extrusions or alternatively may be more complex space frames or assemblies employing hi-tech materials.
For the large passenger sailing ships classed by LR over the last 10 years the vast majority employ seam welded, tapered, tubular sections.
Figure 19 shows the assembled
sections of the topmast and topgallant masts being positioned on the lower mast section.
The rolling process limits the
individual mast section lengths which can be accommodated and this results in a large number of circumferential butt welds.
In order for the masts to be structurally efficient some degree of control is required over the dimensional accuracy and build quality. Manufacturing tubular section from rolled plate and subsequent seam welding generally results in dimensional variation from the design values and the following criteria are recommended:
Nlì\iflhIifl1 variahofl Ifl diameter
Ma'imum ovalitv
-0.6t
Where:- t = local mast wall thickness
dx = outside diameter in the fore and aft direction dy = outside diameter in the transverse direction
Assembly of the individual rolled mast sections into complete mast assemblies requires control to ensure that successive sections have satisfactory alignment and that overall straightness of the mast is achieved. The recommended limits on these build parameters are:
t/ 4
5mm in a 4m length with a maximum of 20mm for the complete mast length.
lc1\lfltUtfl Eflts-dligflhìient between SUCCeSSLVC sections
Niaximurn overall mast eccentricity from mast centreline
The completed mast butt and seam welds are required to be examined using an approved non-destructive test method. All butt and seam welds in masts are classed as 'critical welds' and the survey procedures of LR demand that the following non-destructive examination is carried out:
At the time of the design appraisal of the masts and standing parts of the rigging, the locations and attachments of running rigging to the masts are generally not well defined. In many instances running rigging attachments are decided at ship once the masts, spars and standing rigging are installed.
-2-\Veki Category Critical welds Butt Welds MPI US Fillet welds MPI 100% 100% 100% Primary welds 100% 20% 100%Hence, as provision for these
attachment points is carried out aloft, the primary method of attachment is by drilling and tapping the mast wall
to accept bolted pad-eyes. Care has to be taken to ensure that large numbers of holes are not arranged in close proximity thereby locally reducing the structural integrity of the mast section.
figure 20
Unlike the traditional sailing ships of the19thcentury, modern vessels utilise the internal mast cavity for the lead of electrical wiring to navigational aids and lights, hydraulic lines for the yard arm motors and in some cases for the running rigging. The exhaust piping and silencer from the auxiliary engine or generating set are often arranged inside mrzzen or jigger masts.
The masts also provide a convenient route for the air pipes of sewage tanks thus ensuring that venting is remote from the passengers and crew irrespective of wind direction.
All components of the standing rigging are required to meet the following criteria: Steel wire ropes used for the standing rigging are to be manufactured at an approved works and are to have manufacturers test certificates.
Loose gear items such as shackles, bottle screws etc. are to be from approved manufactures and are to have certificates of proof testing.
Generally the shipbuilder will obtain the services of experienced rigging specialists for the preparation of the steel wire ropes with their terminal end connections. The proof testing of completed ropes depends entirely upon the type of end connections. Poured zinc or resin approved terminal end connections do not
, 4, ho ii4hor rt,-rC fo4oA for
I L'L $&I Li [L] t'1 LL,J Lt]4At%.,1
completion. Experience in the extensive use of this connection for lifting appliances has indicated that a high degree of security and reliability can be obtained with this type of terminal end connection.
figure 21
Testing of completed ropes is a time consuming and expensive undertaking and where it is found that testing machines are unable to accommodate the long lengths of completed rope, methods of doubling ropes over large sheaves or clamping the rope have to be employed.
figure 23
-a-For swaged or talurit clamping terminal end connections the proof testing of the completed assembly has to date been carried out for each component. The proof test is not to be less than 40% of the nominal breaking strength of the rope. For traditional rope termination's such as clamping and seizing the termination can often only be completed at the ship with the rope in situ. Any prior testing of the
termination only demonstrates the acceptability of the methodology rather than as an indication of the quality and overall reliability of the connection.
The vast majority of large sailing ships employ bottle screws to tension the standing rigging. The 'Stad
Amsterdam' however, uses traditional deadeyes and lanyards for all shrouds. In place of hemp, the lanyards are of Dyneema and the dead eyes are of a high density polymer. The testing of the 'wall knot' is shown in figure 21 and the break testing of the completed assembly is shown in figure 22.
The pre-tension is required to guard against loss of tension in the leeward shrouds which in turn will subject the rigging to shock loads which will result in wear and fatigue damage to the components. With the vast number of lower shrouds, often 12 per mast, it is important that excessive pre-tension does not lead to load criticality
for the mast column. The normal working load in the shrouds should not exceed 29% of the breaking strength of the rope (F.O.S3.5). Based upon the calculated shortening of the leeward shrouds from the finite element analyses undertaken, a
pre.tension of no more than 15% of the breaking strength of the rope would appear to be sufficient to ensure positive tension at all times.
Typically for a large barquentine with lower shrouds of 22mm diameter (6 x 36 GSWR) the pre-tension should not exceed about 4OkN. Tests with bottle screws and a suitable able bodied seaman would indicate that the maximum axial force which can in fact be generated is probably no more than 20 kN.
As part of the classification process, the scheme of pre-tension is required to be submitted and proposals are to be made regarding the methods of measuring and establishing that the intended pre-tension has been achieved.
All adjustable, demountable or removable rigging components or parts of
components are to have mechanical securing methods to ensure that the effects of vibration, motion or load cycling will not result in loss of connection integrity.
A detailed rigging plan indicating the dimensions and construction of all standing rigging ropes together with a list of loose gear forms a very important reference document. As the rigging is surveyed, usually at annual intervals, correct
identification and replacement of worn or corroded parts is essential for maintaining the safety and integrity of the rigging and more importantly the mast structures.
SURVEY AND SERVICE EXPERIENCE
An integral part of classification is the periodical surveys undertaken to ensure that the masts and standing rigging fulfil their function without compromise on safety. For LR classed sailing ships the schedule of periodical survey falls into two distinct categories;
The annual survey The quadrennial survey.
Due to the nature of the surveys, specialist rigging companies are employed to carry out the inspection, examination and reporting.
The content and level of survey is set out in the document
"Preliminary guidance information for the testing, marking, survey and certification requirements for masts and standing rigging."
The annual survey is concerned with the rigging arrangement, mast and rigging condition and the functionality and efficiency of all associated loose gear items. The annual survey is carried out with the masts and rigging in situ and in addition to a visual observation of the condition of the wires and fittings, the structural condition of the masts and bowsprit are reported upon.
fic!ure 24
-36-The quadrennial survey is a more rigorous examination of the masts and rigging and normally requires
elements of the standing rigging to be removed in order to gauge the amount of diminution or wear down of
shackle and devis pins. Where masts exhibit corrosion or damage they are required to be un-shipped and thickness determination carried out using ultrasonic gauging techniques. At the time of preparation of this paper, the barquentines, Star Gipper and Star Flyer have been in service for almost 10 years and these ships have now undergone two quadrennial surveys.
figure 25
Examples of items observed and noted during annual surveys of the standing rigging are shown in figures 24 and 25. Note, the mis-match between devis pin diameter and eyeplate hole in figure 25.
A heavily corroded stay wire is shown in figure 27 and fouling of the running rigging may have been responsible for the loss of paint and galvanising from the wire in way of the terminal end in figure 28.
3 7
The surveys and corresponding reports form a unique basis for verification of the adequacy of the initial criteria used in the design and verification process of the masts and rigging.
The most commonly reported items in annual surveys are that the pre-tensioning of shrouds is not maintained or stays are too slack. Sailing ships used for commercial enterprises such as passenger vessels may employ crews who are unable to maintain the rig or are not afforded the time or facilities to do so.
In contrast to this, sail training ships would be expected to be maintained to a satisfactory standard as this function is an integral part of the vessel's purpose.
Table 49 Mastb of Sailing Vessels
1922
Rules
ImperialLength
Fore and aft rig
of mast Diameter and thickness of mast Sizes of angle Cheeks
Square rig Partners Heel Hounds Head Bars In mast Thickness of plate Sizes of angle bar feet feet inches inches inches inches inches inches inches inches inches inches inches
36 30 16 0.30 13 0.26 131/2 0.26 11 0.24 0.40 31/2 X 21/2 X 0.34 37 31 17 0.30 131/2 0.26 14 0.26 111/2 0.24 0.40 3 1/2 X 3 X 0.36 38 32 i8 0.30 14 0.26 15 0.26 12 0.26 0.40 31/2 X 3 X 0.36 39 33 19 0.34 15 0.30 151/2 0.30 12 1/2 0.26 0.44 4 X 3 X 0.40 41 34 20 0.34 16 0.30 16 1/2 0.30 131/2 0.30 0.44 4 X 3 X 0.40 43 35 21 0.34 i6 1/2 0.30 171/2 0.30 14 0.30 0.44 4 X 3 X 0.40 45 36 22 0.36 17 0.30 i8 1/2 0.30 14 1/2 0.30 0.46 41/2 X 3 X 0.40 47 37 23 0.36 18 0.30 19 0.30 15 1/2 0.30 0.46 41/2 X 3 X 0.44 49 38 24 0.36 19 0.30 20 0.30 i6 0.30 0.46 4 1/2 X 3 X 0.44 51 39 25 040 191/2 0.34 21 0.34 161/2 0.34 0.50 5 X 3 X 0.46 53 40 26 040 20 0.34 211/2 0.34 17 1/2 0.34 0.50 5 X 3 X 0.50 55 42 27 0.44 21 0.34 221/2 0.34 i8 0.34 0.50 5 X 31/2 X 0.50 57 44 28 0.44 22 0.36 23 0.36 i8 1/2 0.36 31/2 X 3 X 0.40 0.54 5 X 31/2 X 0.50 59 46 29 0.46 221/2 0.36 24 0.36 191/2 0.36 4 X 3 X 040 0.54 51/2 X 4 X 0.54 62 48 30 0.46 23 0.40 25 0.40 20 0.36 4 X 3 X 0.44 0.56 6 x 4 X 0.54 6 50 31 0.50 24 0.40 26 0.40 201/2 0.36 41/2 X 3 X 0.44 o.6o 6 x 4 X 0.56 68 52 32 0.50 25 0.40 261/2 0.40 21 0.36 5 X 3 X 0.46 0.60 6 X 4 X 0.56 71 54 33 0.50 z6 0.40 27 0.40 211/2 0.36 5 X 3 X 0.48 0.60 6 x 4 X 0.56
Table 49 Steel Bowsprits continued
1922 Rules
ImperialLength outside bed Bed Heel Cap Sizes of angle bars
Diameter Thickness Diameter Thickness Diameter Thickness
feet inches inches inches inches inches inches inches
14 161/2 0.30 14 0.30 12 21/2 X 2 X 0.30 15 171/2 0.30 15 0.30 121/2 0.30 21/2 X 2 X 0.30 16 19 0.30 i6 0.30 13 0.30 3 X 2 X 0.30 17 20 0.34 17 0.34 14 0.30 3 X 2 X 0.30 18 21 1/2 0.36 18 0.34 15 0.30 3 X 2 1/2 X 0.30 19 28 0.36 19 0.34 16 0.30 3 X 3 X 0.32 20 24 1/2 0.40 20 0.36 16 1/2 0.32 3 1/2 X 3 X 0.34 21 25 1/2 0.40 21 0.36 171/2 0.32 3 1/2 X 3 X 0.36 22 261/2 0.40 22 0.36 18 1/2 0.32 4 X 3 X 0.40 23 28 0.44 23 0.40 19 0.34 4 X 3 1/2 X 0.40 24 29 0.44 24 0.40 20 0.34 4 X 3 1/2 X 0.40 25 30 0.46 25 0.40 21 0.36 41/2 X 3 1/2 X 0.42 26 31 1/2 0.46 26 0.40 21 1/2 0.36 4 1/2 X 3 1/2 X 0.44 27 33 0.46 27 0.40 22 0.36 4 1/2 X 3 1/2 X 0.46
Table 49 Masts of Sailing Vessels
1922
Rules
MetricLength of maat Diameter and t.hlckneaa of mast Sizes of angle Bara in mast
Cheeks
Fore and aft rig Square rig Partners Heel Hounds Head Thickness of plate Sizes of angle bar
m m mm mm mm mm mm mm mm mm mm mm mm 10.97 9.14 406 8 330 7 343 7 279 6 io 8g x 64 X 9 11.28 945 432 8 343 7 356 7 292 6 10 89 X 76 X 9 11.58 9.75 457 8 356 7 381 7 305 7 10 89 X 76 z 9 11.89 io.o6 483 9 381 8 394 8 318 7 11 102 X 76 x io 12.50 10.36 508 9 406 8 419 8 343 8 11 102 X 76 X 10 13.11 10.67 53.3 9 419 8 445 8 356 8 11 102 X 76 X 10 13.72 10.97 559 9 432 8 470 8 368 8 12 114 X 76 z lo 14.33 11.28 584 9 457 8 483 8 394 8 12 114 X 76 X 11 14.94 ii.8 6io 9 483 8 508 8 406 8 12 114 X 76 X 11 15.54 11.89 635 10 495 9 533 9 419 9 13 127 X 76 x 12 1615 12.19 660 10 508 9 546 9 445 9 13 127 X 76 X 13 16.76 12.80 686 11 533 9 572 9 457 9 13 127 X 8g X 1.3 17.37 13.41 711 11 559 9 584 9 470 9 89 X 76 X 10 14 127 X 89 X 13 17.98 14.02 737 12 572 9 6io 9 495 9 102 X 76 X 10 14 140 X 102 X 14 18.90 14.63 762 12 584 10 635 10 508 9 102 X 76 X 11 14 152 X 102 X 14 19.81 15.24 787 13 610 10 660 10 521 9 114 X 76 X 11 15 152 X 102 X 14 20.73 813 13 635 10 6'3 10 533 9 127 X 76 X 12 15 152 X 102 X 14 21.64 16.46 838 13 660 10 686 10 546 9 127 X 76 X 12 15 152 X 102 X 14
Length outside bed Bed Heel Cap Sizes of angle bars
Diameter Thickness Diameter Thickness Diameter Thickness
m mm mm mm mm mm mm mm 4.27 419 8 356 8 305 64 X 51 X 8 4.57 445 8 381 8 318 8 64 X 51 X 8 4.88 483 8 406 8 330 8 76 X 51 X 8 5.18 508 9 432 9 356 8 76 X 51 X 8 4.49 546 9 457 9 381 8 76 X 64 X 8 5.79 711 9 483 9 406 8 76 X 76 x 8 6.io 622 10 508 9 419 8 89 X 76 X 9 6.40 648 10 533 9 445 8 89 X 76 X 9 6.71 673 10 559 9 470 8 102 X 76 x 10 7.01 711 11 584 10 483 9 102 X 89 X 10 7.32 737 11 610 10 508 9 102 X 8g x 10 7.62 762 12 635 10 533 9 114 X 89 X 11 7.92 800 12 66o 10 546 9 114 X 89 X 11 8.23 838 12 686 10 559 9 114 X 89 X 12
Table 50 Yards and topmasta of sailing vessels
1922
Rules
ImperialYards Topmasta
Length Cleated Centre First quarter Second quarter Third quarter Ends at cleat Length Heel Lower part of head Head
Diameter Thickn sa Diameter Thickness Diameter Thickness Diameter Thickness Diameter Thickness Diameter Thickness Diameter ThIckness Diameter Thickness
feet juches jnchni inches inches inches inches inches Inches inches inches feet Inches inches inches inches inches Inches
32 8 0.18 77/8 o.i8 71/4 0.18 6 0.18 4 0.12 12 12 0.24 101/2 0.24 9 o.i8 36 9 o.i8 83/4 o.i8 81/8 0.18 63/4 0.18 4 1/2 0.12 13 1/2 121/2 0.24 11 0.24 91/2 0.18 40 10 0.20 93/4 0.20 9 0.18 71/2 0.18 5 0.12 15 13 0.24 111/2 0.24 10 o.i8 44 11 0.21c 103/4 0,22 10 o.i8 8 1/4 o.i8 51/2 0.12 16 1/2 4 0.26 121/2 0.24 10 1/2 0,20 48 12 0.24 113/4 0.24 103/4 0.20 9 0.18 6 0.4 18 141/2 0.26 13 0.24 11 0.22 52 13 0.24 125/8 0.24 113/4 0.22 93/4 0.18 61/2 0.14 191/2 15 0.30 131/2 0.26 111/2 0.24 56 14 0,2f 13 /8 0.26 125/8 0.24 10 1/2 0.20 7 0.16 21 16 0.30 14 0.26 12 0.24 6o 15 0.20 14 /8 0.26 131/2 0.26 111/4 0.22 71/2 oiS 221/2 i6 1/2 0.30 141/2 0.26 121/2 0.26 64 16 0.30 155/8 0.30 143/8 0.30 12 0.24 8 o.i8 24 17 0.34 15 0.30 13 0.30 68 17 0.30 161/2 0.30 151/4 0.30 123/4 0.24 81/2 o.i8 251/2 18 0.34 16 0.30 13 1/2 0.30 72 18 0.30 171/2 0.30 161/4 0.30 131/2 0.26 9 0.18 27 i8 1/2 0.34 161/2 0.30 4 0.30 76 19 0.32 iB 1/2 0.30 171/8 0.30 141/4 0.26 9 1/2 0.20 281/2 19 0.34 17 0.30 141/2 0.30 80 20 0.36 191/2 0.30 18 0.30 15 0.26 10 0.22 30 20 0.34 iB 0.30 15 0.30 84 21 040 201/2 0.34 19 0.30 153/4 0.30 10 1/2 0.24 311/2 201/2 0.32 181/2 0.30 151/2 0.30 88 22 040 211/2 0.34 193/4 0.30 16 1/2 0.30 11 0.24 33 21 0.36 19 0.30 16 0.30 92 23 040 22 1/2 0.36 203/4 0.34 171/4 0.30 111/2 0.26 35 22 0.36 20 0.30 161/2 0.30 96 24 041 223/8 0.36 215/8 0.34 i8 0.30 12 0.26 37 23 0.36 21 0.30 17 0.30
Table 50 Yards and topmasta of sailing vessels
1922
Rules
MetricYarda Topmasts
Length Cleated Centre First quarter Second quarter Third quarter Ends at cleat Length Heel Lower part of head Head Diameter Thicknss Diameter Thickness Diameter Thickness Diameter Thickness Diameter Thickness Diameter Thickness Diameter Thickness Diameter Thickness
ro mm mm mm mm mm mm mm mm mm mm m mm mm mm min mm mm 9.75 203 5 200 5 184 5 152 5 102 3 3.66 305 6 267 6 229 5 1097 229 5 222 5 206 5 171 5 114 3 4.11 318 6 279 6 241 5 12.19 254 5 248 5 229 5 191 5 127 3 4.57 330 6 292 6 254 5 13.41 279 6 273 6 254 5 210 5 140 3 5.03 356 7 318 6 267 5 14.63 305 6 298 6 273 5 229 5 152 4 5.49 368 7 330 6 279 6 15.85 330 6 321 6 298 6 248 5 165 4 5.94 381 8 343 7 292 6 17.07 356 7 346 7 321 6 267 5 178 4 6.40 406 8 356 7 305 6 18.29 381 371 7 286 6 191 4 6.86 419 8 368 7 318 7 19.51 406 8 397 8 365 8 305 6 203 5 7.32 432 9 381 8 330 8 20.73 432 8 419 8 387 8 324 6 216 5 7.77 457 9 406 8 343 8 21.95 457 8 445 8 413 8 343 7 29 5 8.23 470 9 419 8 356 8 23.16 483 8 7o 8 435 8 362 7 241 5 8.69 483 9 432 8 368 8 24.38 508 9 495 8 457 8 381 7 254 6 9.14 508 9 457 8 381 8 25.60 533 10 521 9 483 8 400 8 267 6 9.60 521 9 470 8 394 8 26.82 559 10 546 9 502 8 419 8 279 6 io.o6 533 9 483 8 406 8 28.04 584 10 572 9 527 9 438 8 292 7 10.67 559 9 508 8 419 8 29.26 6io 10 568 9 549 9 457 8 305 7 ji.28 584 9 533 8 432 8
Table 51 Standing iilng of sailing vessels
1922
Rules
Imperial SecondlongltiidlnalnumeralLx( Il + D)
6200 7100 8000 9000 10000 11400 12800 14200
No Size No. Size No. Size No, Size No. Size No. Size No. Size No Size
inch inchea inchea inches inches inchee minea inches
Fore and main shrouds dr 4 of 2 1/2 4 of 2 3/4 5 of 5 of 3 1/4 5 of 3 1/2 5 of 3 3/4 6 of4 6 of 4 1/8
t i 1/4 1 1/4 1 3/8 end can 1 5/8 and cao 1 3/4 and cap i 3/4 end cao 1 7/8 and can 1 7/8 cham platea
dead eyes dia xt 7 X 4 i/a 7112 X 4 1/2 8 o 5 81/2 X 5 9 0 5 1/2 91/2 X 5 1/2 io x 6 101/2 X
lanyardo (hemp or 3 1/2 3 3/4 4 4 1/4 4 i/a 4 3/4 5 5 1/4
rigging screwa, diameter at bottom of thread cha i s/S 1 i/S 1 1/4 1 3/8 1 1/2 1 1/2 i 5/8 1 5/8
rigging acrews diameter of pino dia 1 1 1 i/8 1 1/4 1 5/8 1 3/8 s /8 1 3/8
topmestbksti,ya dr 2 of 2 1/2 0 of 2 3/4 2 of 3 1 of 3 5/4 a of 3 1/2 2 of 3 3/4 of4 of4 i/8
top-gallant baci otays dr 1 /4 2 2 1/8 2 i/4 2 3/8 a a s/a 2 2 5/8 2 2 3/4
lower stays or 2 of 2 1/2 2 of 2 3/4 2 of 3 2 of 3 1/4 1 aS 3 1/a 2 3 3/4 2 4 2 4 1/8
topmaßt stays nr 2 1/2 2 3/4 3 3 1/4 2 3 1/2 2 3 3/4 2 4 2 - 4 1/8
top-gallant sta3ii dr 1 3/4 2 a 1/8 2 1/4 2 3/8 2 1/a 2 5/8 2 3/4
Mimen shrouds dr of 2 1/4 3 of 2 3/8 4 of a s/a 4 of a 5/8 5 of 2 3/4 5 of 2 7/8 5 Xi 3 5 of
cori rar,
topmast bachstays dr a 1/4 2 3/8 a o/a a - a 5/8 2 2 3/4 2 - 2 7/8 3 3 3 /4
top-gallant beckstays or 1 1/4 1 3/8 i 1/2 i 5/8 1 3/4 1 7/8 a a a 2 1/8
lower stays or 2 1/4 2 J8 2 s/s a 5/8 2 3/4 2 7/8 2 3 2 3 1/4
topmast stays dr 2 1/4 2 3/8 2 1/2 2 5/8 2 3/4 2 7/8 3 2 3 5/4
top-gallant stays dr s 1/4 i 3/8 1 1/2 1 5/8 i 3/4 1 7/8 2 2 5/8
Bobstay bar dia 2 2 2 2 2 1/4 a o/a 3 1/4
pin die 1 1/2 1 1/2 1 i/s 1 1/2 1 5/8 0 7/8 2 1/8 2 1/4
chain dia i 3/16 1 1/4 1 1/4 i 1/4 1 5/16 i 3/8 1 1/2 1 5/8
Table 51 Stan.ling rigging of sailing vessels continued
1922
Rules
ImperialSecon.I longitudinal numerai
Lx( B + D)
15600 17000 18400 20000 21900 24200 27200
No. Size No, Size No, Size No. Size No. Size No. Size Ño. Size
inches Inches inches inches lochai Inchei inches
Fore and main shrouda tir of 4 1/4 6 of 4 1/2 6 of 4 3/4 6 Of 7/8 6 of 5 6 Of 5 1/4 6 of 5 i/a
t a end cao a i/S and ceo 2 1/4 and cao a 3/8 end Cao 2 i/a and can a 5/8 aniS Cal) 2 3/ champisses
deed e es dia xi ii X 6 n i/o X 6 1/2 12 X 7 - - -
-lanyard s (hemp) nr i/a 5 3/4 6 - - -
-riggln screws diametor at botthm of thread dia 1 3/4 1 3/4 1 7/8 1 7/8 1 2 i/B 2 1/4 ri.ggin screws diameter of pins dia 1 1/2 1 1/2 1 5/8 1 /8 1 3/4 1 7/8 a
topmeotbackstays tir of 4 1/4 3 of 4 i/a 3 of 4 3/4 3 Of 4 7/8 3 of 5 3 Of 5 i/. 3 of 5 i/a
top-ga iantbackstays tir a 3 2 3 1/4 2 3 1/2 a 3 3/4 2 3 7/8 2 4 i/S 2 4 1/4
lower .ays tir 2 4 1/4 4 1/2 2 4 3/4 2 4 7/8 2 5 a 5 1/4 1 5 1/2 topmat stays tir a 4 1/4 2 4 1/2 2 4 3/4 2 4 7/8 2 5 a 5 1/4 2 5 1/2
top-gallant stays tir 3 3 1/4 3 1/2 3 3/4 3 7/8 4 1/8 4 i/.
Mizzen shrouds cii 5 of 3 1/2 5 of 3 5/4 5 of 4 5 Of 4 1/8 5 of 4 1/4 5 of 4 /8 5 of 4 1/2
endran endren endran sudran andren andres endest
topmast backainys dr 3 3 i/a 3 3 3/4 3 4 3 - 4 1/8 3 4 1/4 3 4 /8 3 4 1/2
top-gallant backstaya tir 2 2 1/4 2 - a i/a z a /4 2 2 7/8 2 3 a 3 i/B a
lower stsys nr a 3 1/2 2 3 3/4 2 - 4 2 4 1/8 2 - 4 1/4 2 4 /8 2 4 1/2
topmast stays tir a - 3 i/a a - 3 3/4 2 - 4 2 4 o/8 a 4 1/4 2 4 3/8 2 4 1/2
top-gallant atayo tir 2 1/4 2 i/a 2 3/4 2 7/8 3 i/B 3 1/4
Bobstay bar dii 3 1/a 3 3/4 3 3/4 5 7/8 4 4 1/8 4 1/8
pin dia 2 i/a a 5/8 2 3/4 2 7/8 3 5 1/8 3 1/8
chain dia 1 3/4 in/io i 7/8 1 1.5/16 a a i/iS 2 1/16
Table 51 Standing rigging of sailing vessels
1922
Rules
MetricSecond IongItidina numer& Lx(l3+D)
576 66o 744 837 930 io6o 1190 1320
No. Size No. Size No. Size No. Size No Size No. Size No. Size No. Size
mm mm mm min mm mm mitI mm
Fore and main ahroudg dia 4 of oo 4 of 22 5 of 24 5 cl 26
ad cat) 5 of 28 artd 5 of 30 andjj 6 of 32 an. COIl 6 of 31 chain plateo t 32 32 15 41 44 44 48 48
dead eyes dia X t 178 11 U4 191 X 124 203 X 127 216 X 127 229 X 140 241 5 140 254 X 152 267 a 152
lanyarda (hemp) dia 28 30 32 14 36 38 40 42
rig1ingacrewedthineteratbottomofthread dia 29 29 32 35 38 38 41 41
rigginI screws, .iiaineter of pins dia 25 25 29 32 41 35 35 35
topmast backstt'a dia 2 of 20 2 of 22 2 of 24 2 of 26 2 of 28 2 of 30 3 of 32 3 of 33
top-gailantbacktays dia 14 16 17 1.8 19 2 20 2 - 21 2 22
lower stays die 2 of 20 2 of 22 3 of 24 2 of 26 2 of 28 2 30 2 32 2 33
topmast stays dIa 20 22 24 26 2 28 2 30 2 - 32 2 33
top-gllantstas dio 14 1 17 i8 19 20 21 22
Miueñ shrouds dia 3 of i8 of 19 4 of 20 4 it 21 5 of 22 5 of 23 5 of 24 5 3
of 26
end rar
26 3 - 24
topmast bacistays dia 18 19 20 2 21 2 22 2 23
top-gallant backotays dia 10 11 12 13 14 15 2 i6 2 17
lower aleya dia i8 19 20 21 22 23 2 24 2 26
topmast otaya dia 18 19 20 21 22 23 24 2 26
top-gallant stays dia io u 12 13 14 15 16 17
Bobatey bar dia 51 51 51 51 57 64 76 83
pin dis 38 38 38 38 41 48 54 57
chain dia 30 32 32 32 33 35 38 41
Table 51 Stan cling rigging of sailing vessels continued
1922
Rules
MetricSecor IongtudInaI numeral
Lx(B+D)
8450 1580 1710 1859 2036 2249 2528
No. Size No. Size No. Size No. Size No. Size No. Size No. Size
mm mm mm mm mm mm mm
Fore and main ahroud dia 6 of
end 34 6 of 96 aod 6 of 38 and caz 6 of 3 and ran 6 of 40 andi 8 of 42 nd 6 of 44 chain platea t 51 54 57 60 64 67 70
dead .,'ee dia xi 279 X 152 292 X 165 305 X 178 - - -
-lanyaili (hemp) dia 44 46 49 - - -
-rigginscrewa,diameterotbottomofthread dia 44 44 48 48 52 54 57
rigsiri screws, diameter of puis dia 38 38 41 41 44 48 51
topmitbackatays dia 3 of 34 3 Of 36 3 of 38 3 of 39 3 of 40 3 of 42 3 of 44
top-gi!lantbackstaya dia 2 24 2 26 2 28 2 30 2 31 2 33 2 34
lowec itaya dia 2 34 2 6 2 38 2 39 2 40 2 42 2 44
topm.lit atays dia 3 34 2 36 2 38 2 - 39 2 40 2 42 3 44
top-gillant stays dia 24 36 28 30 31 33 34
Minen shrouda dia s of a8 5 Of 30 5 of 33 5 rif 33 s Of 34 5 of 35 5 of 36
-Ial. .1.110.I .01* . . . .
topmastbkiisya dia 3 - 28 3 30 3 32 3 33 3 34 3 - 35 3 36
top-gallantbakataya dia 2 i8 2 - 20 2 22 2 23 2 - 24 2 25 2 26
lower stays dia 2 28 2 30 2 " 32 2 33 3 34 2 35 2 96
topmast staya dia 2 28 2 30 2 - 32 2 - 33 2 34 2 - 35 2 36
top-gallant sta dia 18 20 22 23 24 25 26
Bobatay bar dia 89 95 95 98 ins 105 105
pin dia 54 67 70 73 76 79 79
chain dIa 44 46 48 49 51 52 53
References
Thi s per s p epar ed w t h t he hd p and assi st ance of a nuiter of i nc vi dual s and
Organi sat i ons. FE an ysi s exarç4 es and dat a on nany sai li ng shi vere ol ai ned
f r orn depar nent s of LI 's' d Rçj st er' s I-adquar t er s i n Lancbn. flcÍ o ai c nat er i al and report s on sur veis ver e p ovi dad bj IR s su veyor s and t o a I ar ext ant, f r orn
the specialist rigng organisations viio in nariy cases, desigi, erect, survey aid nai ntain large sailing ships vcrldÑde.
Part i cul ar nrit i on i s nade of t hose desi glers, U c'cf s Fèçj st er has vorked wt h over
t he I ast decade vJio have vil I i nç y sha-ed t hei r kncwk edge and pert i se on t hi s
sped alised topC.
Ust of contributors:
(rard Djkstra &Ftriers
val Pr chit ed s and F'k i ne Bi neer s
Ctean i i ng Evel openent I-bl I and Bi
\i I3er I e I raat 10 Pnst er dam 1071 4W
vccn. naval consul t i ng Gt,t-j \M gast
Esi gaers, surveyors, consLi tangs and riggers of tal I ships Bienstrasse 58
D22765 l-biturg
thoren Cèsi & nsuI t i ng
Moindsena r. SA
R. 80-250 )*9<44
PO Bx31,
R1W
60-Ir. H.M. van Wieringen De Voogt Ship Design B.V.
Ing. F.A. Gumbs De Voogt Ship Design B.V.
Ir. R.P. Dallinga MARiN
INTRODUCTION
In the course of 1996 a very detailed investigation was carried out in order to improve the passenger comfort on board large motoryachts.
The l4' symposium on "Yacht Design and Yacht Construction" in 1996 contains the paper on this subject.
Also at Project '98 a paper has been presented on "Improving Motion Comfort on Motor Yachts".
For all these investigations and studies it is imperative to have a set of 'comfort criteria' to judge against.
As literature provided only limited data on criteria applicable for motoryachts, two methods were explored to improve on the knowledge on comfort.
First a set of tests was performed in a motion simulator at TNO Zeist, involving many test-persons to judge on the comfort or dis-comfort of various type of motions.
Second a long-term measurement program was organised and performed by MARIN, comprising actual motion measurements on board two motoryachts and the
simultaneously gathered comfort ratings of the crew and passengers on board. SH[P AND SH[P MOTION CHARACTERISTICS
For each yacht a small-scale body plan is attached in figure 1 and figure 2 The figures show, from a hydrodynamic perspective, two very similar ships. The 40.92 m Carmac VII has a displacement of 436 Tf. The 0.85 m GM yields in combinations with the initially adopted transverse radius of inertia of 2.8 m (32.4% B) a natural period of roll of around 6.7 s. The 41.0 mEnterprise V has a displacement of 465 Tf. The slightly higher 1.03 m GM yields in combination with the initially
adopted transverse radius of inertia of 2.8 m (32.4 % B) a slightly lower natural period of roll around 6.1 s.
For both vessels the rolling characteristics are very similar. The response is characterised by a sharp resonance peak around the natural frequency of roll. Noteworthy is the fact that the highest response is obtained in bow- and stern-quartering waves. A consequence is that the vessel requires a very careful alignment with the wave direction to reduce the roll motions: a heading 22.5 degrees off head
exceeding 4 deg!m.
The yaw response is the lowest of the three angular motions; it ranges around 2 deglm in bow- and stem-quartering waves.
Considering the vertical accelerations it is observed that at the bow and the stem the pitch response may be recognised to some extent. In beam seas heave dominates the vertical motions and accelerations.
Considering a reference point at 30 m from the stem as typical for the motions in the forward half of the vessel, the results show that the vertical accelerations are not very susceptible to the wave direction. The results in head seas are only marginally lower than in quartering and beam waves.
Contrary to the vertical accelerations the effect of the longitudinal position on the transverse accelerations is rather small. This may be understood by considering the dominant contribution of the roll in the transverse acceleration levels, a value, which is the same over the length of the vessel (at the same height).
COMFORT CRITERIA
Because MARIN is trying to predict a complete picture of the performance of ships and structures under operational conditions, literature describing ship-motion related human performance reductions is followed with interest. Considering in-house information in the light of the above comfort concept it must be concluded that the existing literature focuses primarily on discomfort and task related biomechanical problems.
An aspect which is not covered by the above is the functionality of the ship as an 'entertainment platform'. These aspects are highly dependent on the anticipated human activity. They range from the feasibility of transfer of guests to smaller boats,
feasibility of activities in and around the water and the feasibility of delicate on-board activities like formal dinners.
The most frequently discussed discomfort issues are the incidence of seasicimess and human mobility (standing, walking). Intellectual performance in a complex technical environment under the influence of motion induced fatigue seems an emerging area. Motion Sickness Incidence (MSI) due to single narrow banded vertical motions is a relatively well-developed area. Important uncertainties within the present contect are the effect of combined motions and habituation in a varying environment. Also it is not clear up to which extent the MSI estimate is a relevant measure for passenger discomfort.
Noteworthy is the fact that the range of accelerations in which MSI is low resides around 0.2
TNO simulator experiments
The motion simulator offered the opportunity to perform experiments in which the relative magnitude of various motion components could be varied systematically. Experiments during which typical "yacht activities" take place give insight in the
52-The simulator experiments focussed on intellectual tasks (memorising numbers, reading and memorising letters while being subjected to considerable head
movements), maintaining balance (walking a straight line and building a cube tower) and a game (throwing darts). These experiments were performed with 8 subject couples under 4 levels of roll (corresponding with 0, 0.05, 0.10 and 0.15 mIs2 transverse accelerations) with and without a 0.05 mIs2 rms heave motion. In all conditions a pitch motion with and rms of 0.5 degrees was added.
In addition coffee, lunch and tea breaks were spent on board the simulator with slowly increasing motion amplitude.
The quantitative scores as well s the task related and general personal impressions of the participants were subjected to a statistical analysis to identify the significance of the various effects.
RESULTS
A very clear result from the simulator experiments is the fact that the transverse accelerations have a significant effect on the perceived effort and on the related scores. A transverse acceleration level of 0.1 mIs2 rms proved to be half way on the 5 point scale between 'not at all' and 'extreme' influence of the motions on the effort to complete the task. Roughly the same result is obtained from the general questionaire when considering a point halfway acceptable and unacceptable on a 5 point scale. The number of MLI's during walking yielded a very straightforward relation with the rms transverse accelerations; it increased from O per 6 minutes for the case without transverse accelerations to i per minute at 0.15 mIs2 rrns.
Another very clear result is the fact that the presence of the 0.05 mIs2 rms vertical accelerations is of very little influence on the foregoing results.
Timing the events during the lunch and coffee breaks showed that around 50% of the subjects started commenting on the motions at an rms level of around 0.1 mIs2 at 0.14 mIs2 50% were of the opinion that the motions were unacceptable.
RESULTS OF THE ON-BOARD MEASUREMENTS Data
The records cover in total two three-month periods on board the two yachts. Figure 3 shows a sample time history of the data statistics. From each "reported" comfort rating (Figure 4) statistics are available of the roll response and the vertical and transverse accelerations at key locations. The volume of the data in the various categories is indicated in Figure 5.
Figure 6 indicates the correlation between the recorded roll motion and the recorded transverse acceleration. A very good coherence is obtained; indicating that roll is a prime factor in the transverse accelerations. The lower values in the cloud correspond closely with the inevitable gravity component along the deck.
reduced as well.
Figures 7 and 8 indicate the trend of the vertical and transverse accelerations with the comfort ratings. It shows that in the case of the vertical accelerations there is no clear relations between the comfort rating and the roll motion a very clear and similar trend is obtained. These values are summarised in the following table.
Taking the median value as the most robust estimate the transition between bad and good is around 0.08 mIs2. A value, which is quite close to the 0.1 mIs2 suggested by the motion simulator trials. The value for very bad (0.19 mIs2 rms) is close to the 0.14 mis2 suggested by the coffee-break and lunch trials on board the motion simulator. One obvious characteristic of the present data is that the rms values can not take
negative values. The fact that the Rayleigh distibution reflects this characteristic and the reasonable fit with the measured data motivated its use to predict 10% and 90% exceedance values.
Comparing the median values from the fitted Rayleigh distribution with the median value from the data a reasonable agreement is obtained.
DISCOMFORT CRITERIA AND DESIGN IMPLICATIONS Discomfort criteria
The reported comfort ratings correspond with a volume of accelerations statistics. These statistics show a considerable scatter, which indicates that the issue of discomfort is only partly understood.
Despite the scatter, the correlation between the median values and the comfort ratings suggest strongly that the transverse accelerations are a prime indicator for passenger discomfort. These median values, which correspond with a 50% score, suggest that an rms transverse acceleration around 0.1 mIs2 is the level in which in 50% of the
reported cased the motions are characterised as "bad".
lt is encouraging to note that the on board measurements and the Motion Simulator Trials in schematised conditions yield very similar levels.
Failed Very bad Bad Good Very good
Rms Tr.Acc. mis2 Mean 0.24 0.20 0.13 0.09 0.09
Median 0.26 0.19 0.09 0.07 0.06
Rms Roll deg Mean 1.10 0.95 0.56 0.38 0.28
Median 1.48 0.91 0.44 0.26 0.14
Ragin level Very Bad & Failed Bad Good Very Good Rms Tr. Acc. mIs2 10% 0.065 0.051 0.035 0.038 50% 0.167 0.131 0.090 0.096 90% 0.304 0.240 0.164 0.175 Rms Roll deg 10% 0.34 0.23 0.17 0.16 50% 0.88 0.59 0.44 0.42 90% 1.60 1.07 0.80 0.76
