Deep vee hull design and an economic financial model for production

2

ARCHEÍ

Wa

Deepvee huU dsgn nd an

eccnomfc-flnancai model

for production

Since the Tiirbinia, designed b Sir Chades Parsons, surpas-sed 35 knots in 1S96 ", there have been notable advances in

the technologies of propulsion. building materials. and

construction methods. and since the early Thirties, in Planing

HuH Design . The work by Lindsay Lord in the thirties and forties, and later by C. Raymond Hunt , on deep-vee hulls. had been preceded in the twenties and thirties by extensive research in the USA. the UK. France, Grrnany and Italy, on the design of flying boat hulls and seaplane floats '.

The Huckin's quadraconic t.ull concept has been in use since 1932. During \Vorld War II, and since then, consider-able research, model testing, and actual full size construction

of liard chine planing hulls has taken place under the

direction of Clement, Murray. Savitsky, du Cane, Baader, Hacker and Cooper

Today. fast compact naval vessels with deep-vee planing hulls desiened by Sterner move at less resistance per tonne than dis2lacement hulls, particularly at speeds less titan

Vk!VtWL = 3. The main limitation

is the relationship AP/1-DELTA that relates the ship's weight with the area of the planing surface. This limitation appears as finite because area increases with the square of the ships dimensions, while weight or displacement increases with the cube pover of the dimen;ions '.

As demonstrated by full size sea trials performance, up to the dimensionless ratio Vk1VLV\L 2.0. a narrow round-bilge hull is a hcuer performer, but only in calm waters '. The decp-vee planing hull. v,ith ts wider beam. greater volumetric space. extensive deck area, and the ioson of the longitudinal centre of huovanc (LCB) and the coincidental

centre of gravity (LCG) at

rest, aft of amidships. can accommodate the varied requirements of large and heay p!easur'craft, commercial, and naval vessels.

The ability to maintain speed in rough seas, with Sea State above 3-4. the equiva'ent seakcepine qualities, the stability both at rest and while planing at full speed. the anti-roll characteristics of the hard chine hull, its ¡nanouvreahilitv at both low and high speeds. and the overall performance of the deep-vec hull, is considerably superior to either the warped bottoni planing hulls, or the round bilge hulls.

Furthermore, a deep-vee hull is ideally suited

to be

equipped with water jet propulsion, allowing military and para-rni!itary vessels

to operate at very high speeds in

extremely shallow waters, with a significant tactical edge when persecuting law violators in deltas and archipielagos, over sand bars and mud flats.

Hull bottom

Deep-vee hulls nia or may not be monohedron The term means "one sin dihedral angle" in the main part of the planing hull bottom. This is IÌOt the common characteristic of most pl.mnin hull bottoms s Itich are of a variable deadrise angle or warped bottom design that starts vitIi BETA less

titan IO denrcs at the transom (this may be even zero or negative) incrcaing to 16 to 0 degrees at the niidshipsection and quite higher further fotvard.

The mottoliedron maintains the same BETA antie of deadrise from the transom to about the midship section and in

a deep-vec monohedrori the BEl A deadrise angie is of 23 to 26 degrees. The determinant of this angle is a function of the displacement required witinn a certain chine beam (Bl'N),

y.

Scheepsbouwkunu

Technische Hogeschoo

fl.ranw

Niels E. Sorensen-Viale

the chine beam itself being the dependable of the bottom aspect ratio defined by the quotient of the chine projected length by the maximum chine breadth (LPí'BPX). a value itself related to the maximum design speed . The other ven

important relationship is that of the weight of the vessel to the

bottom projected planing surface area as in the dimensionless ratio AP/1-DELTA. Finally, what makes the craft do what it is meant to do is the colocation between the longitudinal centre of gravity (LCG) and the variable centre of dynamic planing lift (LCLft),

By varying the width of the planing surface at the transom (BPX) and its relationship to the maximum width of the bottom (BPT/BPX) and tite length, shape, and dihedral BETA of the forehody, the non-nionohedron part of the hull, tite dynamic lift component (LCLft) is always ahead of the LCG and a 10W speed causes a pronounced trimli atmee that lifts the foref6ot to water surface level.

Then, as the speed increases, the centre cf dvnarttic lift (LC'Lft) moves aft and its com;caent incrc:'cs, and the aft part of the hull is lifted while :he forefoot renìair.s at' he earlier attained level at the surface cf the water. Titus. at true planing speed. the whole hull is partially lifird out of the

vater while the trim angle declines to a moderate angle. Another important characteristic in the design of dep-ree hulls is the flatness, er cur,ature. cf the cross sections cf the

bottoai surface. Lindsay Lord. the master of the

monohedron, advocated flat straicht sections 's'. Itt earI' monohedrons, the deadrise I3ETA was small cad the '.vi.:h of the chine at the transom vas markJlv reduced.

PL

L /E RFC M'yZ!'v'C t? ¼ Q. '

(

G'

---i

f

i,i

,.'-- . ,-._-

.,t,'",

-_,.. g ,.

--- »,

' tç_.p.t.

ç

m.,i '

___

Q H-'1Tij LQ1 _

,'

I

I/

p4

I I

_...--'.'ì

i

.---"

I --'

I._!_

1._

-s t:.

scaE.Sru-I"-':'

_{-j ï_}

_I

¿ 1,5 ¿'s

DEEP-VEE HULLS

Monohedrori huUs

Deep-vec monohedron hulls. as iii thc Iatcst fast attack craft (lo, in the planing notor yachts and gunboats from my own drawing board. and in the notable designs by Shezid,

I Iarraucr, Levi. Cnstauta and I hint, have the chine breadth at the transom virtually as wide as the maxirawn chine breadth aniid:hips. the cross sections are convex and the chine high at the forward end of the esseIs.

Also quite important, is where the monohedron part of the bottom starts tengtllwise. The basic Lord monohedron established this position as exactl' midlengLh of the design waterline, but this location is altered to satisfy balance requirements. usually moving aft with very high speed craft and moving forward at the high ratios of weight to planing surface area (AP/1-DELTA3).

The transverse shape of the sections of the bottom is what separates some designs frein the others ". Not less than seven distinct configurations may be identified:

Monohedron with parallel body

Monohedron with variable depth, resulting in curved aft buttocks

Monohedron with variable width(3)

Variable deadrise BETA deep-vee hull

\Varped bottom, changing angle and section throughout the length

Concave or convex cross sections of the bottom Inverted bell, or combination of convex and cocave sections.

The deep-vee high deadrise constant section monobedron

hull form, :ossesses besides other advantages, that of

combining both displacement and planing features.

Be-haviour of the monoliedron at lo'v.speeds (below the sueed when planing starts) is displacement hull behaviour. As the

speed increases, the hull rises bodily, the bow more than the Stern. At the maxirrum trim angle. planing has begun with a lift component approximately ecual to 50% of the static displacement weight.

Planing begins when the water flows clear at tue stern, the wake does not tumble forward towards the transom. and the

\vater also separates cleanly along the chines. ehmmnatiii the

wetting of the sides. The ratio of speed to beam of VkIBPX = 2 24. as determined by both Lord and Murray a and (7), appears to be the lower limit of olaning speed. Since the centre of gravity (LCG and VCG) remains tixed during a short sea trials run, except for the fuel consumption, as the speed is increased the trim aiielo adjusts itself to attain equilibrium between the vectors of the component forces.

Equilibrium is attained when the sum of the vertical forces due to weight-gravity and the opposite buoyancy and/or dynamic lift, and the vertical and horizontal force vectors of dynamic lift, propeller thrust, and resistance, is equal to zero. Trini angle may he predicted, controlled and modified by the colocation of the longitudinal centre of gravity and buoyancy (LCG and LCB). the vector location of dynamic lift (LCLft)

(this is dependent on the shape of the bottom) and the

propeller thrust vector.

Expe ri in e n ts

An interesting series of experiments were conducted by the Stevens Institute of Technology with a family of 20 planing hulls '. The same parent lines provided models with four distinct displacement and five length beam relationships applied to each of the four displacements. resulting in the 20 models. These were first tested at the design displacement and then with 20% overload and 10% underload, iesulting in 60 different configurations. Furthermore, these sixty models or configurations were each tested at three distinct trim angles corresponding to three longitudinal locations of the CG. In total, 1St) planing hull configurations.

The overall results ir.dicated that overloading had variable effects. At the designed trim, at rest, at slow and medium speed and at less than VkI\/[VL = 355 (or 20 knots for our

24 High-Speed Surface Craft August 1984

N otatlo n AP EFTA B PX B PT LP LWL LCB LCG LCLft DELTA 1-DELTA VCG Vk

Projected bottom planing area Deadrise angle ¡n degrees Maximum breadth over chines Breadth over chines at the transom Projected chine length

Load waterline at resi

Longitudinal centre of buoyancy at rest Longitudinal centre of gravity

Longitudinal centre of dynamic lift l)isplacement in weight

Displacement in volume Vertical centre of gravity Speed in knots

example), the increase in resistance was negligible while at higher speeds it was quite significant. Inversely, if tile vessel was trimmed aft by four degrees at rest, the disadvantage was marked at 10W speeds and insignificant at the higher speeds

Over 20 knots.

The overall conclusion vas, and is,

that the losses in

performance duc to overload arc much less than those caused by trim which is a direct dependent on the colocation of LCG and LCLft. The resistance increased markedly when at the design trm the speed exceeded 22 knots, at two degrees of trim aft when the speed exceeded 16.2 knots and at four degrees of trim aft vhen the speed reached 13 knots.

At tIle design trim. there was no porpoising at any speed but at 2 2nd 4 degrees trim aft, porpoising started at 32.4 and 22 knots respectivel'. Interestinciv for the designer, the wened surface area of the majority of the models at 20 knots

'vas 60 of the wetted surface area at rest.

\Vith model testing series, particularly when the results are presented as irr reference ° by Clement, the scope of the significance of the term 'model testing' may be expanded to unsuspected dimensions when the designer recognizes that, "A 'model' need not be smaller than the full size yacht or ship.. .'. A 'fu!l' size yacht or ship. when sea trial perform-noce llave been iricasured and recorded with precision, may

itself he used as the 'model' for another hull, larger or

smaller, tIS long as the Law of Mechancal and Geometrical Sinilitucle is fully understood and coraplied with. Once we consider evers' one of our own designs, and those published by other Naval Architects, as each boing a model, we shall

greatly çnrich the technical data base provided by the

published towing basin model series.

Comparison s

The curves presented in the graph are for a 4.5 tonne planing

hull of identical parameters except for the shape of the

bottom. The three examples, a deep-vee monohedron, a shallow monohedron and a warped bottom hull, arc the reflection of data from my own designs, from the designs published by distinguished colleagues, and from the data published by several towing tanks

"'

and ".

The three examples are:

a deep-vee moriohedron with the constant deadrise BETA between 23 to 26 degrees

a shallow nionohedron hull with the constant BETA deadrise angle between 12 and 16 degrees

a shallow warped bottom hull with dihedral angles varying from zero degrees at the Iransom to 10 to 16 degrees at midships.

Our experience concludes quite convincingly that the deep-vee. either monohedron or variable deadrise, need not be any less efficient than the flatter warped bottom hulls. What we find is that:

1) The longitudinal shape of the bottom. and the resulting colocation of the LCG and the LCLft is much more important than the absolute deadrise BETA angle.

The shape of the planing sustaining surface is most important since it influences directly the longitudinal location of the centre of dynamic lift (LCLft) and of the consequent dependable derivative, the trim angle TAU.

Bottom loading as is defined by the relationship

AP/1-DELTA is critical. Excessive loading will preclude

planing.

A generous deadrise angle BETA as in the deep-vee, makes the vessel very comfortable at both displacement and planing speeds, and uni4uely seaworthy at high speed in waves.

The deep-vee without vertical keel or skeg, is direc-tionally stable at any speed, and much easier to manoeuvre

than a flatter bottom or warped bottom hull with an

appendage keel.

The constant deadrise monohedron deep vee hull at very low speeds makes a deep upsurging frothy wake which is proven excellent to raise game fish.

References

R. 'W. L. Gawn, "Historical Notes on Investigations at the Admiralty Experimental \Vorks, Toraquny", RiNA, 1941.

12I W. Sotiorf, "Experiments \Vith Planing Sw faces", 1934.

pl L. Lord, "The Naval Architecture of Planing Hulls",

1949.

1'1 Eugene F. Clement, "Resistance Test of a Systematic

Series of Plining Hull Forms", SNAME, 1963.

Pl Eugene F. Clement, "How to use the SNAME Small Craft Data Sheets", SNAME, 1963.

II _{L. Prarìdtl, "Vier Abhandlungen zur Hvdrodynaniik und}

Acrodynamik", Goettingen, 1927.

fil _{A. B. Murray, "EMB-50 Test Series", Stevens institute of} Technology, 1941, compieted 1949.

Daniel Savitsky, "Wetted Area and Centre of pressure of Planing Surfaces", 1949.

(I _{A. B. Murray, "The Hvdrodinamics of Planing Hulls",}

SNAME, New York, 1950.

Marran índ Shaw, "Speed and Power", The Rudder,

1950.

Borner and Witte, "Some Test with Models of Small Vessels", Schiff und Haffen, 1950.

Hans Baader, "Cruceros y Lanchas Veloces", Buenos Aires 1951.

Peter du Cane. "High Speed Small Craft", Cambridge. 1952.

E. H. Sterner. "Hull Forms, a Comparative Study of two

Dif;er'nt Concepts".

lirternational Defense Review. 1981.

J. G. Kocihel, Jr., "Better Performance for Planing

Hulls", Motorboating. June-July, 1959.

1161 H. F. Norclstrorn, "Speed and Power", SSPA 1951.

(17) _{E. F. Clement, "Analyzing the Stepless Planing 1JulI",}

David Taylor Model Basin. 1956.

1181 E. F. Clement, "Comparative Resistance Data for Four Planing Boat Designs", David Taylor Model Basin, 1957.

An economc-flnancia modet for yacht production

Manufacturers of production yachts have until now produced sail and power yachts that appear to be, in general, viable competitors in the field of read made. off-the-shelf mass-marketed yachts. But until now nianufacwrers, production investors, and distributors have not had sufficient definitive information to make sound discussions concerning a produc-tion programme for their particular acht and condiproduc-tions.

That is, the general information level

has not been

sufficient foi tiir' prospectie VC1)lilfC investors to accurately assess the probable economic result; and financial demands of a j'roJuetioit rul1 No profit oriented venture could ever consider ilivesting hundreds of thousands of dollars without having a pretty good idea of the operating capital needed and of the potential net revenues.

At the time when the sales of production yachts is at an all tiifle low and many production builders have been forced to close their doors, the phenomena has a clear and logical explanation that carries a forceful management lesson. The yacht-building industry has had. no doubt at all. a couple of horrible devastating years, with artificially high interest rates depressing theirsales. Most builders have found themselves starved of orders - some sunk, others survived. But in the final count, the main culprit has been a total absence of economic and financial analysis of the production program-me, of the investment risks, and of the opportunity costs.

The objective pursued in the development of the yacht production econo-financial model, was to ascertain:

\\That amount of cost improvement can be expected with yacht production runs of varying quantities and time span duration?

how many units must be produced within a specified pioduction programme time duration, to reach a specific average cost per unit?

How much a given yacht must he sold for to recover a specified capital investment in facilities, tooling, design, market research and development.

Can the pioduction yacht unit in fact he built for a cost

that is the base for a selling price that tile existing market shall accept?

Is the selling price that the market will accept a figure that provides an acceptable rate of return on the invested funds, acceptable in terms of investment risk and opportunity

Cost?

Da;kg l'OLtfl d

The model stacted to take shape 38 years ago at a time when the author had his first experience as a shipyard manager. Since 1946, the model has grown. expanded and improved at a steady pace with both computer technology developments and the author's experience.

lii 196 the yard managed by the author von a competition

for the production of 128 fast patrol motor boats to be

delivered within a period of 18 nionths.

A vers' simple economic model was developed and used for the specific purpose of justifying the investment in test prototype toolings, j ig, and engine-compartment mockup against savings in overall programme duration. direct and indirect labour and attaining a 70% learning rurve.

_nhisvas followed by a taste of sensitivity analysis in a cost

benefit study that considered the cost of duplicate and

triplicate assembly tooling against additional savings in

delivery time, facility occupancy and the cost of money invested.

1'v'o years later, the author, by then an independent naval architect. consulted and supervised the assembly and welding of the pre-fabricated sections of 162 river barges of 800 ton capacity within 36 months. Again, the model v.as used to determine the level of investment needed in facilities, tooling and ti aining to achieve the fast t urn around , substantial learning curve and resulting considerably lower unit cost. once more, in 1950. the iìodcl was used to determine the Optinlum investment in tooling and jkts for the fabrication of hulk load (grain) bodies for a fleet of heavy trucks.

By 1965, it had progressed further and was programmed into a digital computer and an analog Computer, and used a

plotter to provide graphic outputs. There followed the

development of three aspects of a prodi.ielion programme of commercial hydrofoils; (a) the return on the invçstinent by the manufacturer in research and development, facilities, and tooling -by virtue of the learning curve and of other savings

obtained

only by the use of productioì tooling and the

ceononhics of volunic, (h) the engineering economieS to guide and limit the cne,inccriiig dcsh'n will!!!) ec000nhic parameters

Ici ensure the cconoinic success of the hydrofoil and (e) the customers economic utility model that defined the price tIle client could afford to pay for the hydrofoil based on the economics of his operation.

DEEP-VEE HULLS

The model was expanded in 197() and programmed on a n:tin frame computer to stimulate the economics of the operations of comnicicial airlines and the performance of competing airplane models.

Modorn computers

There are no perfect models of real life situations. But if the model is realistic enouth. modern up to date fast computers can handle and process large numbers of facts or bits of knowledge, representing alternative scenarios and yield workable results which will allow vell informed and sound decisions to be made.

The yacht production ëcono-financial model expresses a fundamental relationship:

The sum of discounted profits must equal the sum of discounted expenditures over the length of the production programme. The profits and expenditures considered are those involving actual cash flows. Annual profit is defined as the difference between the area under the revenue curve and

the ccst improvement curve for a given year. This

is

illustrated in Fig i and 2 where the horizontal axis represents the number of units and the vertical axis represents the dollars per unit. Different number of units for different years are caused by a typically monotonical increasing production and sales curve.

L?''0_cr'Ta AYD PRCC.F' p7cr:T3

-t.cSS

TITE (YEATS)

Fig 2

To implement this model we need information and the information gathering process is aided by questionnairelike forms which request inputs in the form and units as required by the model.

UNIT COST

CURVE

B

26 _{Hi'h-Speed Surface Craft August 1984}

tE VE NUE CURVE

V_________

UNIT COST C U V E 10 20 30 40 0 63 70 to UNITS ¡ -.+- -'-'-2 3 T(ME (YE.&?5) Fig i

T TYT-CCî ?ATIO

'D 5rLLTT

Â'S T-S T'TR ETN ftTT 15U::Tt ?BYTS

REVENUE CUTVE PROFIT -y I Ii 35 d 50 65 70 ¿3 UNITS -J C TSJN -1 MON

The input required is of the following basic types: I) Information about the 'acht in question

Unitary cost to produce one unit

Cost of production facilities, tooling, the design and the continuous product improvement programme

Ail the costs and variables associated with the

produc-IJOTi run.

Input needs are set by the output required. Whatever has to be combined for presentation as output will have to be put in at sonic preceding time. Thus the input form design will be determined by tise desired output structure. The output was the first consideration in the development of this econo-financial model. The primary questions.seeking answers were

identified as follows:

1) \Vhat answers are generally required to make a decision?

2)1 low sensitive are these answers to changes in the input values or to modifications of the relationships v,ithin the model?

Considerations of the above led to the adoption of straight forward sequential form and the inco'poration of sensitivity

analysis. PLCAT IC N kSJLE_ Nt,.Li.4'rTCN

t4rIy4

LS AC-4 k T'/, FTJNI SHEN.V C L

-4

I-'5 o (J F Jcr ON

IT

t, Pio du ctio n

The model has been intentionally limited to (he high lev& elements of a yacht production programme, work breakdowo

structure and to its principal cost elements (Fig 3). To

illustrate its application a sensitivity analysis exercise was run

through a short model in which a programme of the following characteristics was computed.

Production programme length in years K = lo. Cost improvement curve number XN = 95%. Rate of return RR = 15%.

Working capital percentage PCT = 25%.

A hypothetical number-one-unit-cost of production of USS 200,000 for a run of 50 units was considered.

Number of units produced and sold T = 10, 25, 50, 75, 100,

and 200.

Ratio of Unit-one-cost to Sales price R = 0.50, 0.75, 1.00, 1.25, and 1.50.

The sum of expenditures for FAC + XRD = 1.0 million and

2.5 million.

The results of these two 6 x 5 = 30 matrices are presented in Fig 4 and 5 and provide information that may guide to ranges of variables and limiting parameters. lt may be noted that for programmes including less than 100 units, ratios R of 1.25 or more are unrealistic. This is due to the fact that the average selling price X grows asimptoticaily as the ratio approximates 1 .25 and thus becomes uncompetitive.

350 2O 1O'5 500 150 100 FAC .D 1.0 )1LLCN tS$

FAC flD estet 5r FaeSiOtlez, ThcUre, Design,

Y.odtl stirg an.i Market Research.

l.ATiO

AVERAGE SELLING PflCE VS RATIO OF IL't.BER-ONE-UNIT COST

TO AVERAGE SELL UsG PRICE

Fig 5

As shown in Fig 4. the average selline. price for a run of 50 units would he USS 180,000 cc 90% of the cost of the numhr one unit. It is of uti1ost impol tance to notice that if the initial investment in facilities, tooling, design, model testing and market research increased freni USSI million to USS2.5 million,

the average selling

price would jump up to

USS300,000 or 66% higher, for the saille yacht whose first production unit is costing US$200.000. It is quite evident, and well supported by Lictual numerical values, that the initial investment is a number that can make or kill a production programme. Furthermore, it is also evident in FigS that if the production run was doubled within the sanie ten ears, to 100

units, then the selling price of the average unit would return to the earlier figure of US$180,000. And if the production run was increased to 200 units within the ten years. tue price would be reduced to USSI3O.000 hut do not forget that if investment had been held at tile USS I million level, the price for selling the average unit would OOiV he US$1 10,01K) or a

little over half uf the cost of producing the first unit. Figure 4 also shows that reducing the production run to only 25 units in ten years would n'-.0 linIe sense since tite price would jump to US$305,000. And that runs of only ten

tillits in it'll icars arc totally senseless unless the cost of the first unii vas held at 75% or less of the average selling price.

The main reason for the attractiveness of large numbers of units versus small numbers is the impact of tite production cost improvement or learning curve, which may have little effect in short runs of less than 50 units over the duration of the programme.

Mathematical model

The usc of a mathematical model sucht as the one we are describing, when applied to alternative scenarios and various production locations, will show, by numerical and factual output, the significant differences and consequences of the alternative choices. For example: the impact of using old and maybe imccrfect facilities that are fully amortized versus the investment cost in new and fully environmentally controlled facilities; the low factors' wages offered in one location. hut tied to uncomfortably low productivity per labour hour versus a higher cost of the labour hour, hut much higher skills and experience, resulting in productivity per hour exceedingly higher; the use of existing tooling versus the fabrication of new multi-pleLise moulds for accelerated production; and the commissioning of a totally new design. fully tank tested, professionally developed for production and tooling with dutifully calculated and designed structures of advanced and/or composite alloys or man-made fibres (GRP, Kevlar. Carbon, etc) versus the continued production of an existing

design. fuhi owned and amortized.

The frial ulility of the yacht production econo-financial iiiodei depends not only on the total number of actual maulS hut on tile actuality anti reliability assined to each of these

inputs, For example. if the market size (the numbes of

production 'aciit units sold) could he determined for the duration of the production nm. then the ranges of average Unit selling prices versus the ratio of price between the first unit cost and the average cost of the production run, taking into consideration a realistic production cost improvement learning curve, necessary for the desired return on investment could he obtained. Thus, if the average unit selling price. and the number of units to be sold. has been determined br' reliable maiket research. the ratio of that average selling price to the first unit cost could he determined.

The product of this ratio and the average selling price Wotlld then determine the target cost of the first unit for the production 'uri of the specified number of unts to provide the desired return on investment on a given initial investment. If all variables arc to remain constant with the exception of total

investment 110(1 total sales. the effect of varying the level of

total investment will he shown on the varying sales price per Liait and through it, the dependable variable sales will show how investment affects salts.

The output provided by the titodel is quantitati\'e in natuR'.

willi numerical measures of the success of the venture. The

ritodel does not make decisions but rather represents the investor with clear results of the alternative scenarios. lt may he used for various purposes and to satisfy different degrees of interest.

A naval architect might use the model to evaluate how the

change of some of the physical characteristics of the yacht vill

influence the cost and change the overall outlook of a

production programme.

A builder may use tite model to evaluate how the cost of the first unit compares with the overall programme average ex-yard saies price, or the impact of using existing facilities rather than acquiring a new environmentally, controlled building or a new design requiring new tooling.

The distributor may get an accurate picture of the

advantages and disadvantages of contiliuiig the production of an existing design or taking on a new, ad'. ;u'ced. state-of-the-art design that by being responsive to the clitngine market requirements could double or ti iple sales and tiwrchv c.i'dr absorb (hie design royalty costs.

The investor may use it to compare the feasibility of incrementing production as related to the extra investment

Auqust 1984 High'Speed Surface Cia ft 21

'4

w

L

L

V,.

DEEP-VEE HULLS

t' o o t,_o 350 X 300 z t. 250 200 0.50 0.75 LOO 1.25 .50 gAlIO

AVFAGE SELLING PRICE VS RATIO OF NUMBER-ONE-UNIT COST TO AVERAGE SELLING PRICE

Fig 4

FAC + X 2. VThLÖ1r tOS

FAC X?.O = nvct ir. FacilitIes, Tholin, Ceign,

DEEP-VEE HULLS

reqwrcd in additional duplicate or trip!icate tooling. And when to shut down a production run that is getting extremely

slow, dividing the fixed recurring costs_{over a smaller number}

of units and thus pricing these few units r)ut of the market.

The model is intended for thouhtfiil and judicious usc. It

can

not he any better

than

the accurate data inputs.

Furthermore, incorrect judgernentd assertions can only lead to invalid results.

Thus, people (one of the many variables) may affect the outcome. Some of the input variables are tangibly factual and numerical. Others arc intangible and difticult to quantify. Therefore the quantitative result of these models shouldhe

viewed and used with discretion. In any case, the model will always yield results that shall help the user make proper decisions.

Production

Two of Nids E. Sorensen-Vial&s deep-vee hull high-speed motor yachts are about to go into production. The Monarch 78 is to be built as a semi-customised series 24m boat in Seattle. Two versions are currently being offered, the Sedan with engine options for a maxinium speed range of 20-39 knots and the Sports Coupe. Fitted with two MTU 12V 396 TB93s developing 4,000bhp through Arneson drives and surface piercing propellers, this will have a top speed of 45 knots. Ferry, workhoat and patrol versions of the _Monarch design, some capable of speeds of up to 49 knots, _{are also} possibilities. The price of the standard boat is USSI.2 million. The second design, the Principessa 42, is a luxury custom desined 42m boat scheduled for sea trials from a European vari in the late summer of 1985. Three MTU 16V 396 TB93s delivering 7,830bhp are expected to give ita maximum speed

of up to 32 knots in waves of up to 1.8w without slamming. Range at a continuous half-load cruising speed of 25 knots vill be 1,500 nautical miles or 2,500 nautical miles

_{at a}

maximum endurance speed of IS knots.

Both designs are being tested in the model towing basin of the British Columbia Research Council in Vancouver. Two models of each in three configurations will be evaluated, giving a planned series of 20 models.

20 High-Speed Surface Craft August 1984

4Ti/2VS7?3

_i

----...

-

n

-EOÔ.

r

ITJ -

:-:==è?,:I.' ;,g.j7_..__

:::::Qt'

::::::::.:,.

Below, the Monarch 78 Sedan, Monarch 78 Spors Coupe, a,zd Principessa 42

/':tV

rt

...

r e7g/ 11.-g

gJ'7t7

T

21 -fA,cL

-:r

7:

f- rT

i.jI

.-..--..

-'

/

__L_iJ ...I _r_T= .

I

:-''

-7

Monarch Principessa 78 42

LOA (length overall) _{2388m 42.25m} DWL (½ load design waterline) _{19.611m 3700m} LP (projected chine length) 21.lOrn 39.110m

BMX (maximum beam) _{594m 8.20w}

BPX (maximum beam over chine) 5.46m 7.56w Bl'A (nican chine breadth) 4.96m 6.211w

BPT (chine beam at transom) _{537m 744m} LCB (long, centre of buoyancy) 1169m 2123m LAP (long, planning area centre) _{1098m 18.36w} LCF (long, centre of flotation) 11.40w 2049m PAP (projected planing area) 90.02 sq.m 238.14 sq.m AF (flotation surface arca) 85.52 sq.ni 230.58 rq.m 01-iF (overhang forward) _{3.22w 3.5Dm}

OHA (overhang aft) _{106m 1.20}

FJ3F (freeboard forward) 2.55w 2.SOm

FHA (freeboard aft) _{195m 255m}

DFFI (draught of hull, bare) 1.211m 1.60m

DPi' (depth of hull) _{3.20m 4.35m}

DELTA OEW

(empty operating weight) _{37,495kg 116,000kg} DELTA 50%

(½ fuel and water load) 41,657kg 141,000kg DELTA 100%

(full fuel and water load) _{45,820kg 173,000kg} DELTA sca trial (25% load) 39,574kg

-Immersion _{2,l33kct25mnt 2.3ùticrn}

Fuel _7,5701