ND LLOYD
E. VO 5SN AC K AO COLLEAGUES 3rd October 1985 TECHNISCHE UNIVERSITEJT Laboratorium voor Scheepshydromechanlca Archief Mekelweg 2, 2628 CD De!ft TeL;015-786873-Fax: 015-781838_1
-YNOP5I5
Future of our Seafarinq Nation:
- Bulktrade: Dry - wet - chemicals.
Activities in relation to oil.
- Liner trade:
Activities in "door to door" transportation - terminals - loadcentres
infrastructure - airfreight.
- Activities in recreation: freewheeling on the past?
Developments in the container trade: Neo Bulk Commodity Trade.
Competition - overcapacity.
Running of ships will become of less importance.
Marketing and financing are deciding the position of the company in the
market.
Concentration of European Liner Companies.
The existence of European Shipping is at stake.
Large containervessels serving East-West "Trunk"routes.
Medium sized and smaller containerships serving the less developed countries.
Feeder services.
Features of the large container vessels size speed propulsion vibrations
-tonnage.
Features of the Univerdsal Containership "UNCO".
Features of the small containership "KLECO".
Ro/RO-Container vessels.
Heavy Lift vessel: "Happy Buccaneer".
Container feeder.
Characteristics in general.
- Speed - manoeuvring - mooring - hullform - stability - transomstern.
- Rolling - distribution of weights - trim problems.
- Cells - breakbulk - hatchcovers - lashings - cargogear.
- Multipurpose as alternative.
- Reefers "integrals" versus ducted porthole boxes.
- Corrosion - fouling - smoothness - propeller roughness.
- Corrosion - maintenance - simplicity.
- Generation of electricity.
- Energy saving (Hansen).
- Workload on board: Operations - trouble shooting.
- Workload - crew.
- Orosstonnage - crew
9000 CT vessel: forced dimensions
- reduced safety.
Conclusion:
The cellular container vessel is serving as a link in the transportation-chain.
- Compatitive only in case of utmost efficiency in every aspect.
- Saving time in port, faster manoeuvring - less shifting.
- Ship to be designed for optimal cargo handling - ample stability and
manageable trim and sailing at minimum fuel consumption.
- Single screw to be preferred - vibration troubles can be solved.
- Economical speed should be possible without combustion problems followed
by wear down.
- Simplicity and high quality of materials and corrosion protection will result in
reliability and less maintenance, only then a small crew is justified.
- Lower depth - lower tonnage dues - extra tier on covers - extra lashings.
- Fuel costs are dominating on the large fast vessels.
- Crew cost are dominating on the small vessels.
-2-THE FU11JRE OF OUR SEAFARING NATION
The merchant fleet of the Netherlands is nowadays number 21 on the worldscale behind Denmark, Brasil and Malaysia.
In the shipbuilding periodicals Holland is mentioned as being capable to build small size specialized vessels only.
Indeed, after the reorganization of Van der Giessen de Noord our country has lost the possibility to build medium size vessels in future and consequently these vessels are to be ordered in Japan, Korea, Taiwan, Brasil, Germany, Denmark, Finland,
etc.
Considering the Dutch peaople's inclination to the sea, which is rooted in the past when the voyages of discovery started, the scalding question turns up, of how to employ the young generation in relation to trading at sea.
Many schools to educate seafaring people are staffed by motivated teachers and events like the rowing-race Harlingen-Terschelling show an enthusiasm of the participants by which you get really impressed.
The port-day in Hook of Holland presenting tugs, pilot vessels and lifeboats
attracted the attention of all kinds of people.
A newbuilding, ready for delivery at the quay in Rotterdam is bombarded by a rush
of families which feel related to this piece of work.
Are we doomed to "freewheel on the past" only? as is demonstrated during Sail 85
Amsterdam - or the "Prince Willim", the famous Indonesion trader, of which the
repliqua has been built at Amels in Makkum.
Are we doomed to earn our living by activitIes in the field of recreation? It can be stated that the Dutch are enterprising people which can offer reliable
services and for this reason a few possibilities of jobs for the youngsters are proposed.
Acit ivit les in relation to:
a few large container vessels, sailing on fixed routes, between main ports,
punctually to time schedule in an international consortium.
container feeders and short-distance Ro-Ro vessels, transporting the cargo to the main ports.
heavy lifts and special transports "World-wide".
reefer transport, whether by reefer vessels or by container vessels.
transportation of products or chemicals by specialised tankers, asking thorough knowledge of crew members and shorestaff.
offshore activities by crane-ships, pipelaying barges, accessory suppliers and diving support vessels - repair vessels.
planning and construction of ports, including terminals in developing countries connected with advisory services on buoying, piloting and port development. ferry service and cruiseline service + development of small cruise ships.
air freight.
inland water transportation
At all events it is most important that the scrapping program for obsolete vessels
is accelerated in order to overcome the depression in less than 10 years.
Too many bulkers and large tankers spoil the freightlevel in such a way, that no normal bulkcarrier can make money unless she is of modern design, sails
economically and offers flexibility in relation to a variety of commodities.
(dry bulk/containers/pipes/plates) ("open" vessel-geared) being the most suitable Columbus type, Götawerken, Woensdrecht type.
-3-The very large bulkcarrier, sailing on a fixed contract for transportation of ore or coal, surely has a realistic viability; however, only a few of them are needed.
The LNC transportation is waiting for land based terminals which most probably will not be ready in the near future, and meanwhile the japanese are intending to
build and run theìr own vessels in order to fulfill their requirements on energy.
Young people might be brought-in at freight forwarding load centres and load
transportation in order to offer an integrated door-to-door service world-wide.
The freight stations should be developed and customs problems minimized.
It also should be realised that Holland is a transhipment-country which is proved by
the fact that more than 50% of the imported materials are exported again.
Conta inerisation is nowadays generally accepted because of the pure fact that the
customer is requiring it.
Door to door transportation is faster, more reliable and punctionally on time, being
a great achievement against 30 years ago; it is not cheaper, however, in relation to palletised-unitised systems.
The container is providing many invisible advantages, which are difficult to
estimate in moneyseving.
In the coming 10 years a fundamental change is expected to take place in the equilibrium of forces between liner companies:
It has been supposed that conta inerisation, because of the huge investments involved, should be left to a few operators.
However, it turns out now, that a NEO-BULK-COMMODITY-TRADE is developed
with many outsiders participating, because of the fact that the application of the
universal box system is open to anybody and the containervessel is a simple
bulkcarrier for boxes.
Owing to the past, still a great number of people are involved in "container
loading" and these wages are burdoning the freight level.
After all, the container will be carried by the service, offering the lowest freight-rate in the shortest transit time which is of primary importance to valuable goods. A high frequency and reliability in departure and arrival are also of great
importance.
The United Nations Conference on trade and developments-shipping committee has
now developed "Basic-Tariff-Rules" in the multimodal containerfield in order to simplify the tariffs and stimulate "world-trade".
The opinion of Nediloyd in relation to this, is that "freight-all-kind" tariffs are not in the interest to the trade, nor the shipowner, because of the fact that such standardized tariffs expel a lot of cargo and for that reason delay the tendency to
economy of scale on the trunklines.
Nevertheless it is obvious that simplification of tariffs, clearness in the market and a longer lasting validity are generally required.
-4-The following forecast is realistic:
less influential conferences a stronger position by shippers
increasing amount of new containership-operators
diversification of the traditional shipowners
less bureaucracy - increased computer-control - better identification of
containers.
A bad functioning system of information and documentation at custom offices
are hampering these developments and ¡CHA should try to improve on the situation.
cost cutting: It is almost impossible for elder vessels to compete with the new
ones being fitted with the high stroke longitudinal scavenging supercharged diesels and slow-turning propeller because of the 30-40% lower fuel
consumption of the latter.
- under certain flags it is allowed to sail with a crew of 18-16 even 12 people
if all requirements in regard to safety and operation are fulfilled. A crew of
COMPETITION
During the foregoing years the transportaton activity in the Pacific Basin increased
enormously, due to the large imports of the USA which, however at this time are
shrinking considerably.
Conta inership operators between Japan/Korea/China/hongkongfSingapore and the
USA Westcoast and Eastcoast are competing heavily.
Meanwhile a few shipowners started a "Round-the-World" service:
Evergreen (Taiwan based) will at short notice sail Round-the-World with 22
vessels of 2728 TEU each, offering a weekly service Westbound and Eastbound,
77 days roundtrip - 18 kn - 6 RLB 90 - 14 - 16 crew.
11 vessel are rotating "with the sun"
Japan-Busan-Keelung-Kaohsiung-Singapore-Valencia-N.W.Europe
(R'dam)-US Eastcoast-Japan.
11 vessels are rotating "against the sun"
P.Klang-Sing apore-Hongkong-Kaohsiung-Keelung-Busan-Japan-US
Eastc oast-Valencia-Japan.
Contrarotating services allow well-filled-boxes.
Ever-C vessels originally have been designed with a length suitable for 2240
TEU, however, during the building period the ships were lengthened by two
hatches (1 hold, and still the design was kept sound).
The latest 4 ships of 24 in total will be fitted by RTA longitudinal scavenging
diesels which are distinctly better in fuel consumption and linerwear in
comparison to the RLB loop scavenging diesels on the foregoing sisterships.
In August 1985 Evergreen has ordered 4 large conta inervessels of 3428 TEU
each, for delivery in 1987 and by that time 34 modern vessels larger than 1800
teu will be available to them, which is about 5 % of the world container
tonnage.
IJSL will very soon sail in one rotation around the world by 12 large vessels of
4200 TEU max., also offering a weekly service Eastbount.
84 days roundtrip - 18 Kn - 7 RLB 90 - 24 crew.
US Eastcoast-R'dam-Marseilles-Jeddah-Khor
Fakkan-Singapore-Hongkong-Keelung-Pusan-Japan-US Eastcoast.
China and Taiwan cargo will be feedered as well as European cargo,
Arabian-Cull cargo and India-Pakistan cargo.
The "American-New York" type vessels are rather full-bodied, causing speedloss
or extra fuelconsumption when sailing against heavy seas.
Also problems with stability will arise caused by the fat underwaterbody, which
are to be solved by large amounts of waterballast in the double bottom.
Because at the fact that the main engine is located rather far aft, the hull is
"open" over a rather long percentage of the hull length without any connecting
"Dam" between. This will result in a rather "flexible" hull against torsion and
might give troubles with hatchcoaming structure guides.
These vessels are fitted with RLB loop scavenging diesels.
6
00CL (Orient Overseas ContainerLine of Island Navigation Hongkong)
Has ordered 6 container ships at 2800 Teu at MHI in Japan (4) and in Taiwan (2).
18 Kn - 9 RTA 76
- .. crew, delivery 85/86.
NOL (Neptune Orient Line - Singapore)
Has ordered 4 container vessels at 2970 TEU at Hyundai in Korea.
18 Kn - 7 RTA 84 -
.. crew, delivery 1986.
YAN MINC
Has ordered 4 container ships at 3050/3200 Teu at China Shipbuilding in Taiwan,
designed by "Blohm + Voss".
21,5 Kn on trials - 8 RTA 76, delivery May, July, Sept., Oct. 1986.
C+D. Nol and 00CL intend to start a weekly Round the World service between the
Far East and USA Atlantic Ports.
63 Days roundtrip, 22 Kn on trials - 7 RTA 84.
A+C. In case Evergreen is going to combine service with the Yamashita Shinnon Line
of Japan Line it might come to a co-operation in future with the round the
world service of 00CL and NOL.
The decreasing volume of cargo on the Pacific is forcing shipowners to speed up
the erection of a new superconference for the Far East-USA Trade.
Sea Land and Am.President Lines are stimulating this superconference and it is
expected that Maersk-OOCL-Korean Lines and NYK will support also.
It is unclear whether USL and Evergreen will join.
Rootliep:
Shippers in Singapore were encouraged to use non conference lines in order to keep
the freight level low and it is to be expected that this trend will continue.
Cosco (China), Evergreen, Yang Ming and Soviet Shipping Company are offering
15-20% lower freightrates in comparison to the conference.
The Far Eastern Freight Conference is considered to be sluggish, negotiating is
rather academic.
Besides this there exists the danger of protectionism.
The UNCTAD code (40-40-20%) for liner shipping is now accepted being a fair
sharing between developed and undeveloped countries.
Protectionism would mean a great step backward.
It is obvious that only a few shippers prefer their cargo, destined for many ports, to
be transported by one vessel only; on the contrary, it is much more likely that
weekly trunkservices, sailing punctly to schedule between main ports will have
preference after which feeder services will complete the door-to-door-transport.
A low freight rate however, is of primary importance.
Terminals and infrastructure.
lt is Nediloyd's opinion that developing countries should concentrate on connections
with the country-behind, instead of starting sophisticated container-terminals.
The fact is that the transfer of cargo is always the bottleneck and in case of
cargohandling being inefficient, the cargo flow will be delayed in total.
-7-Therefore the transfer points in or near ports are playing an important role in the chain of transportation.
Not only the shipowner, having invested money in expensive equipment will loose money in case of delay - also the shipper will suffer and might even loose his market.
Loadcentres-inland and at seaports are signs of sound development.
Lines, acting as through transport operator could take profit of these loadcentres, because of the possibility of optimalisation by comparing different possibilities. From the "Loadcentre" it is only a small step to "airfreight" and it might well be that the aircraft is offering an attrative complement to the intermodal transport; in particular where other ways of transportation to the inland are unreliable.
There is a steep increase in transportation by air during the last years, especially in the Asia-Pacific Region.
It is most remarkable that the interest in the ship, carrying cargo is diminishing
with regard to the other shackles in the chain container allocation and inland transport.
The transit time door-to-door is the important factor!
The container should not be delayed. "Empties" should not wait either.
W i lhe Im se n
The liner division is looking for the most profitable way, and many times the
chartered vessel is preferred to the owners ship, which is often burdoned by a huge 0V erhead.
Running of ships will become of less importance to the management;
Much more marketing and financing will decide the position of the company in the market.
8
How Nediloyd Management is looking onto the coming competition.
B.E.Ruys:
We have always tried to put sufficient ships on a certain trade.
-
in first, by employing multipurpose vessels and after a certain period when the
trade was ripe for containerisation we changed the MPS against pure cellular
vessels in conformity to our tradeshare.
-
Nedlloyd always tried to prevent overcapacity but then you get some very
expensive people coming along spoiling the whole business for a long period of
time and we have to defend our market share and try to make the best of it.
It is all very well to say that big ships are more economical than small ships,
which of course they are, but only if you fill them; empty: they are more
expensive.
-
No newbuildings at the moment but research for further improvements.
Croenendijk:
The European owners of the future will be smaller in number giving more scope for
the concentration into specialist fields.
These European consortia will be lined up against new regional consortia by the
developing countries and it is to be expected that this will turn up within the next 5
years.
European operators must be able to progress to a new phase in co-ordination by
consortia before the year 2000.
THE SHIPS
From this point of view it should be stressed that ships in this fleet are to be highly
efficient:
- simple design
- sailing at a low fuel rate
- appropriately crewed
- high quality materials and well "painted"
- no "tooters and bells" MULTIPURPOSE
The M.P.vessels of the fleet, characterized by a rather long portstay : 3 - 5 days, will become obsolete within a few years : containers and breakbulk are conflicting - the container carrying capacity will be too small, lack of space inside holds - lack
of stability
- hatchcover too weak for containerload - lacking deckspace - cargo gear having too small lifting capacity - heavy derrick being an obstackle.All these items will result in a rather low productivity; a long turnaround. The pure cellularvessel
The economy-of-scale effect can be applied, without increase of portstay, because of the large unitload, which can be handled very quickly.
A larger vessel can be served by more container cranes simultaneously and therefore no extra hours for cargo handling are required.
In case of a good planning there is rather no delay by waiting.
The final result is a portstay of i day maximum, resulting ina fast turnaround and
a high productivity of the ship.
The driver keeps his motor "warm".
The shipping company consequently will have to replace a large number of small size conventional vessels by only a few large containerships (as the tradeshare has to remain the same).
With this small number of vessels it is impossible for a single shipowner to offer a high-frequency-container service, and therefore co-operation is a "must".
From a marketing point of view a weekly frequency (or even shorter) means: turnaround time
-
70 daysnumber of vessel - 10 ships required
In case Nedlloyd is allowed to bring 2 ships into the consortium then 4 partners 2
ships are needed giving a total of 10. Main routes - sub routes - feeder
It is the opinion of planning/marketing/operations, that transportation of
containers by ships-world-wide will develop as follows: East-West traffic by large vessels: trunk routes.
Specific North-South routes to less developed countries by medium size
(Universal type "UNCO") and smaller size ships (klein container type "KLECO")
- Development of feeder services to trunkline ports.
- Fast turnaround.
- One day per port maximum.
lo
-The larqe container vessel for the East-West "Trunkroutes".
In case of entering the "round the world" trade the dimensions of the Panama Canal
locks are to be kept.
(The influence of only one channel on world shipping has become rather great).
Loa 290 m, B = 32,3 m, H = Max. 13,0 m, 3600 Teu à 12,7 Ton homogeneous.
Wider vessels should be more economical, because they need less waterballast to
sail upright, however, limitation in trading area, and the fact that almost all shore
container cranes are limited to Panama beam in their outreach and height has
brought us the conclusion that a wider vessel is unwise.
The depth to be constructed for 8 tiers in hull + 4 tiers on deck, instead of the
depth of many well-bred-existing vessels having 9 tiers + 3 tiers.
Moreover, lashing costs and lashing problems will be increased.
In general terms speed should not exceed 18 knots in view of fuel costs.
However, "too slow" will cause a conflict with the transit-time which is required by
marketing.
To be compared: 18 kn - rountrip 77 days = 58 at sea and 19 in port
-frequency 7 days - 11 ships required.
20
kn - roundtrip 70 days
51 at sea and 19 in port
-frequency 7 days - 10 ships required.
Fuel costs - capital costs
- daily running costs to be calculated.
The consortium, consisting of a large number of vessels can keep a moderate speed
and still maintain a high frequency in the service.
It is very important that the vessel has the potential of extra speed, in order to
bring a delayed vessel back on schedule.
(Missing a Suez convoi for 24 hrs will require 2 knot extra to arrive in Singapore
ontime.)
Keeping schedule is an important selling point.
The single screw propulsion is to be preferred in comparison to the twin screw - in
regard to following points:
Less expensive vessel.
-
Simpler installation - smaller amount of "bolts and nuts" to maintain.
-
Less auxiliary power.
-
Smaller crew.
-
Hydrodynamically, however, the highly powered single screw vessel is not
superior to the twin screw one
This conclusion was derived from intensive research at NSMB is in contradiction
to many assertions in the International Literatures. The main point is that the
scale effect of tankresuits should be taken into account properly.
Vibration by propeller.
The twin screw vessel, if properly designed is favoured by having no vibration
troubles, because of the fact that propellers are turning in a flow of water
which is only slightly disturbed by slender bossing and brackets, resulting in
a wakepeak of less than 30%.
Vibration troubles by propeller mainly occur on highly powered vessels turning
at high rpm in a "bad" wakefield, which is caused mainly by a disturbed flow
along the afterbody and huge appendages for shafting (in case of twin
screwAt the single-screw ship the flow of water towards the top quadrant of the
propeller disc is slowed down to more than 50%. Wakepeak normally is 60-70%. This slackening occurs at short bends in the flowlines along the hull and
paint-flow tests show this to happen mainly in the hard "upturn of the bilge".
Moreover a "duck-like" shaped stern will cause separation of flow.
The inhomogeneous inflow makes it almost impossible to design a propeller
which is free from cavitation over the full evolution (360°).
In the upperpart of the disc, the propeller meets a turbulating-rotating and contra rotating flow of water, which will create an instantaneous
cavitation-bubble on the propeller bladetip, causing strong fluctuations in the pressure on
the surface of the hull, which is rather flat in case of container and ro-ro
vessels.
Consequently the vessel will suffer from vibrations in the afterbody.
Remedy: - A finer hull around engine foundation, which means that the engine should be mounted in a slender gondola.
It is always advisible to apply the largest possible propeller at lowest rpm and minimum blade area.
- The propeller should have pitch reduction at the tip and be
designed as (highly or moderately skewed), resulting in a smaller tipload and a smooth passage of the turbulating wake peak.
- All these features will result in - higher efficiency.
lower tipspeed.
less tipload - smaller cavitation
less pressure fluctuations. Accommodation should not be at the aft end of the vessel but preferably at 2/3 L
to minimize vibration hindrance and
to reduce trimproblems (shifting/ballasting) and
- to maintain a proper sighting over a high pile of containers on the forepart of
the ship.
Vibrations by enqine.
During the last years vibration hindrance caused by the propeller was reduced mainly by the lower speed level - less horsepower - lower rpm and improved propeller design.
On the contrary now the main engine is a newcomer as a vibration-exciter. As long as the 6 cylinder engine is applied, fitted with the second order balancers (Lancaster gear) nothing happens.
However, nowadays the 5 and 4 cylinder engines are appearing, because of the increased horsepower per cylinder attained by the longstroke supercharging. The attraction to the reduced number of cylinders is based on expectations regarding:
shorter engineroom, less maintenance and lower engine cost.
Helas, the 5 cylinder engine might raise transverse vibrations in the
superstructure, 5 x rpm, excited by the relatively large variations in torque.
The 4 cylinder engine might raise a ship-bending-vibration of (5-6 nodes) under
a certain loading condition, excited by a free longitudinal moment of 4 x rpm
which cannot be compensated.
In case of resonance at service rpm, no remedy is available.
There is a rather high risk to run into this situation and the naval architects
12
-Loop scavenging turbocharged diesels are lacking air at reduced horsepowr
resulting in bad combustion, piston and liner wear and soot problems in the
exhausts and on deck. The highly superchargd RLB has lost against the LMC and
the RTA.
Longitudinal scavenging diesels are much better in this respect combined with
the lower specific fuel consumption which is achieved by the long-stroke highly
supercharged version.
It should be strongly emphasized that improvement of combustion at reduced
horsepower by diesel engine makers is barely necessary.
(i.e. electronic fuel injection - auxiliary blowers).
Coastal trips at economical speed (14-15 knots) should be possible without
getting into troubles.
The Universal Containership ("IJNCO") - Nediloyd Clarence/Clement.
The lengt overall in accordance with almost all ports worldwide.
Loa = 210 m, B = 32,3 m, H = 18,8 m, T.max = 12,0 m.
2224 Teu à 12,7 Ton homogeneous at 10,2 m draft.
Cargo weight at 30 ft draft to be at least 20.000 Ton.
Spacewise: 7 tiers in hold + 4 tiers on deck.
Service speed: 18 Kn - 52 Ton/day at 10,2 m (excl. shaftgenerator.
The vessel to have maximum flexibility to cope with the requirements of most of
the trades.
This means:
- Convertibility of holds from 20' to 40' cells and vice versa
(except hold no. 1).
Breakbulk to be carried on tanktop of 2 or 3 holds, this can be
achieved by the installation of collapsable bolts in the cell guides
at the 3rd tier level.
-
Possibilty of the carriage of integral reefer containers under deck
and on-deck in order to avoid shifting as far as possible.
Possibility of inserting "plug-in-cranes" into the cells in case some
ports on the route lack a shore container.
- Bowthruster and sternthruster -
high lift Becker / Hinze rudder to
be installed in order to be independant - save time - save crew
and save tugs.
- Electrical energy from main engine by power-take of on engine or
shaft generator.
Propulsion installation to consist of a direct driven supercharged
-longstroke - longitudinal scavenging dieselengine at low RPM and
large propeller diameter.
Orignally: 6L90 CBE-97 rpm, new: 6L9OLMC - 90 rpm.
- Lengthening of this vessel by 2 hatches (2 x 40' or 4 x 20' bays) is
possible which will increase carrying capacity from 2220 + 480 =
The small containership ("Kieco") - Nediloyd Van Neck/Van Noort/Van Diemen The length overall in view of calling ports of less developed countries
(Africa Westcoast - South America - India - Mediteranean). Loa 182,7 m, B 30,5 m, H = 16,2 ni, T.max = 11,2 m. 1606-1636 Teu 12,7 Ton homogeneous at 10,5 m.
Maximum cargo weight at 25 ft draft.
Spacewise 6 tiers in hull + tiers on covers.
Service speed : 17 kn - 43 ton/day at 10,2 m excl. shaftgenerator.
Because of the relatively large beam, this compact vessel can carry a large amount
of boxes relatively to her length. Most ships of this length overall are having a beam of 28,4 m and it is true that they sail at a lower fuel consumption, however,
the container capacity (homogeneously loaded) is much smaller.
Remarks in relation to the "UNCO" vessel are also applicable to this "Kieco" vessel.
In case of a newbuilding this vessel should have a six cylinder RTA, respectively LMC, engine (longitud scavenging) working at 92 rpm.
The application of a5 cylinder engine: 5 RLB9O (loopscavenging) is not a succes with regard to bad combustion - pistonring and linerwear and a small transverse vibration in top of deckhouse by the torque vibration of 5 x rpm which cannot be counterbalanced (N.B. The vessel is fitted with a 4 bladed propeller)
The RoRo Containervessels
Nedlloyd "Rotterdam-Rochester" (4-deckers, also suitable for trailers)
Loa = 196,5 m, B = 32,3 m, H = 23,25 m, T.max = 10,7 m.
In service T.serv. = 10,2 m - 68 T/d (trials + 12%) - 68 T/d normal ati. Nedlloyd Rouen-Rosario (3-deckers Scandinavian type).
Loa = 212.1 m, B = 32,3 m, H = 20,40 m, T.max = 10,7 m. T.serv. = 10,2 m - 71 T/d (trials + 12% - 71 T/d norm. ati.
These vessels were required for transportation of goods to the Arabian Cuif in the
period of development in this area 1974 (first oil crisis).
Because of the port congestion at that time, the Ro-Ro principle was in preference because of the fact that these vessels got priority.
For the USA-Middle East Service the 2 vessels should have capacity for trailers in particular besides cargo as "caterpillars" draglines, cranes, etc. and for that special reason the two uppermost decks were designed at trailer height (4,4 m).
In total 4 RoRo levels are applied in the ships hull under the upperdeck. The upperdeck to be loaded with containers by two methods:
By forklifts rolling via the quarterramp - upwards over the top of the main
engine to the upper deck.
by shorecrane directly loading on the upperdeck.
Length overall should not exceed 196 m in view of the portlimitation in Kuwait at
that time. Consequently the first 2 vessels resulted to be rather high and compact. The second 2 vessels, destined for the Europe-Middle East vessels should be
suitable for RoRo cargo and breakvulk in general and therefore the Scandinavian RoRo concept was adopted: Decks at twice container height (6.3 m).
In total 3 RoRo levels are applied in the ships hull under the upperdeck. Later it turned out that this concept was the most suitable.
14
-A few months after ordering the first 2 vessels it became clear that the length
restriction in Kuwait was not that hard and we were very happy as Naval
Architects that the second 2 vessels could be one pillar distance longer (abt 16 m). During the first years of development around the Arabian Gulf a huge amount of RoRo cargo was carried in this area and a lot of money was earned by the 4 vessels.
During the foregoing years the developing stage changed into one of consolidation: Less caterpillars, less dragline's, but more luxury goods to be imported.
At this moment the percentage of RoRo cargo has declined substantially and the amount of cargo suitable for stowage into containers has increased in accordanc e. Therefore a cellular vessel is now more suitable and economical in this trade (the torment of 40 ft containers in RoRo tween decks is very expensive).
Meanwhile all ports were developed into ultra modern container termincals equipped with shore container cranes.
Consequently loading the upperdeck by forklifts is out of date now. The "ski-slope" on NL Rotterdam/Rochester could be taken off.
Worldwide there still is a lot of cargo, which is not suitable for carrying in boxes,
for example: ingots, pipe, plate, lumber, paper, tractors, prefab houses and here the Scandinavian RoRo concept is justified.
(copper ingots: Chili-Europe) (paper: New Zealand-Singapore)
A new RoRo-container design should have cells in the forepart of the vessel by
which is obtained: better-faster stowage of containers, more weight in the forebody resulting in more stability and better trim.
Safety of the ship is considerably improved by addition of transverse bulkheads. An interesting experience was gained by comparing the consumptions of the shorter and longer sisterships at same service speed on the North Atlantic route.
According to tanktests, carried out in smooth water, the longer ships should burn 4% more fuel: 68 - 71 Ton/day to perform 19 kn in service.
Results in practice are showing the opposite, which only can be explained by
pitching resonance of the shorter vessels together with the larger trim by stern
and consequently non optimal interference by the bulb.
In general terms one might state that interest in RoRo transportation for the long
routes has been declined and the LoLo-container transportation has won. "The pencil case" (RoRo) is inferior to the "open bakers hand-craft" as far as loading/unloading is concerned.
Much work, improvisation and lashing, results in a low production and high
stevedoring costs. Moreover, much noise and exhaust gases is expelled into the air;
necessary hold ventilation will cost extra fuel.
On the contrary, the RoRo concept for private cars and trailer transportation on the short routes is very profitable,
Fast turnaround - wheels are kept turning - cargohandling by the drivers themselves occurs in most cases.
15
-Heavy Lift Vessel "Happy Buccaneer" of Mammoet Shipping
This type of vessel is suitable for transportation of whether voluminous or heavy
-or large and delicate cargo , in other w-ords unsuitable f-or cellular vessels bound to
the container terminals.
The concept was raised at Mammoet Amsterdam together with "Hytrack" of
Rodenburg and further developed by Nedlloyd in combination with Van der Giessen, Verolme Heusden and Hitachi.
Aim of the design is flexibility and fast dispatch which is not in line with the
merits of many heavy lifters elsewhere, which have their special features elsewhere.
The ship is characterized by a long uninterrupted hold extending from f'ostcle to transom.
The lower hold allows for two tiers of containers and is covered by very strong pontoons.
The tweendeck space also allows for two tiers of containers and is covered by almost the same type of pontoons, 6.7 m x 21 m.
Hatchcover pontoons are interchangeable per deck are handled by the mastcranes and might be used as floating lighters.
At 7 m draft, 7,8 m freeboard the vessel is allowed to sail without upperdeck
hatchcovers.
The transom is closed by a large door, functioning as RoRo sternramp.
lt must be clear that this robust vessel will consequently have quite a moderate deadweight.
Space-wise she can carry about 1100 Teu, these containers however, are limited in weight.
During repositioning-trips it might be economical to transport empties on behalf of the liner services.
Two heavy mastcranes are capable of lifting 550 ton each, 1100 ton in
conjunction. They0are rooted in the SB shipside (which has a width of 5 meter) and allow for 360 slewingangle.
Accommodation is arranged on the f'ocstle, which is prefered by Mammoet because of the protection of cargo and better judgement of weather conditions
in order to slow down at the right moment.
The view from the wheelhouse is undisturbed by cargo and gear.
Moreover, no vibration hindrance, although sometimes "whipping" may occur. The propulsion installation is arranged in the aft part underneath the tweendeck and consists of two mediumspeed 6 cyl L40 Sulzer engines each geared to a c.p.propeller.
The twin screw installation was selected in view of the small draft and wide
beam.
Two semi balance rudders and one bow thruster allow for good manoeuvring. However, here some interesting notes should be made:
Crabbing ability of the vessel (fitted with inward turning propellers) working with one proeller ahead (9 pitch) and one propeller astern (15 pitch) with
rudders at O - 35 angle, was not impressive.
The vessel would obey the rudder immediately, however, she immediately jumped ahead!
The astern propeller could not cope with the ahead thrust. We tried to find the reason:
CP propeller moderately skewed is working underneath the ship (at zero speed), at negative pitch in a strongly cavitating condition;
Recently held cavitation tests in the circulating tunnel at NSMB showed that asternthrust in this condition is reduced by more than 50% in
comparison to computer calculations without cavitation.
Propeller shafts, (although they are parallel to the centreline) which are
rather near to eachother, do not allow for a large turning moment because
16
-3. Pram-type hull form, having flat sections in the sternpart do not react on a propellerwash, which is flowing in forward direction and excited by the
astern propeller.
On the other hand, more common V-type afterboclies will react on a propeller wash by moving sideways.
In order to improve the situation on the Mammoet we might improve by:
-
increasing the rudder angle.- fitting a wedge type strip to the trailing edge.
- fitting horizontal endplates to top and bottom of the rudder.
However, in case of new design we would do the following: - Propeller shafts to be moved outward as far as possible.
- Rudders in line of the propeller shafts (and not next to the shaft in view of
shaft removal).
High lift rudders: flap type (Becker or Hinze) at 500 angle in order to bend the race of the aheadpropeller in an almost athwartship-direction.
By doing this, the astern thrust, required by the astern propeller needs to be
smaller than in the original situation.
Improvement of the bollard pull-astern of CP propellers should be studied. It seems that highly skewed propellers are even worse in this respect (tests did show a very severe thrust reduction by cavitation)
A fixed pitch propeller turning in opposite direction will excite a larger thrust
astern.
CP propellers in general
For manoeuvring on the spot the CP propeller is fully justified, it is the right type of propeller for ferries, suppliers, tugs, fighting craft and ships to that are be
dynamically positioned.
The propeller is turning in one direction only and allows for a highly-skewed design. Pressure fluctuations on the hull are reduced to a great extent.
RPM should be kept less than "optimal" in view of the possible propeller diameter to achieve the lowest possible tipspeed.
However, in view of saving fuel consumption, following facts should be realised:
By sailing at full power and original nominal rpm at reduced pitch, the efficiency is substantially reduced.
Simple shaftgenerators asking for the constant nominal rpm are causing an extra fuel consumption of 15% to 30% at reduced power.
In other words the vessel lost about one knot when not under the sam power. Tests on the Mammoet vessel showed that the ship made 12 knots when sailing at reduced power with 150 rpm nominal rpm at reduced pitch in comparison to 13 knots at constant pitch (with 122 rpm).
A power-take-off-generator should be connected to the main engine via the
rpm-variator, or alternatively as shaftgenerator, which is supplemented by a thyristor in
order to keep the required 60 cycles alternating current over a large range of engine rpm.
An other aspect of importance is the number of rpm during "idling" at zero pitch,
- at nominal rpm (for example 150) the propeller suffers from face cavitation and idling condition and meanwhile the fast spinning water brake will cost a lot of fuel oil.
Therefore it is strongit advisable on OP installations to lower the rpm when idling (for example from 150 to 125 rpm) (60 cycles - 50 cycles)
17
-Cenerai remarks in relation to the containervessel Speed
In future the service speed will vary between 17 and 20 knots which is mainly determined by the fuel costs.
Moreover the vessel should be able to make 14-15 knots "economical speed" without having combustion troubles with the dieselengine.
Manoeuvring and Mooring
A high productivity of the ship can only be realized by a fast turnaround. Therefore
the time for manoeuvring and mooring should be minimized, which can be achieved by bow and stern thrusters, making the ship handy and independent.
(Application of high-lift-flap rudder (Becker, Hinze) is also advisable).
The mooring gear should consist of 4 constant tension winches forward- and 4 -aft.
All wires are to be fitted on independent driven drums; mooring by ropes around the wharping head and bollards should be used in emergency case only.
This arrangement allows for quick mooring by 2 men fwd and 2 aft. The above mentioned measures will result in:
-
faster turnaround-
less dependence less towing dues smaller crewHuliform
The hullform is to have a blockcoêfficient between 0,62 and 0,68.
A fine hull will burn less fuel, but at a small draft lacks cargo deadweight and is
more critical to hogging stresses.
-
A full body hull will burn far more fuel and might come into minimum stabilityproblems, which can only be solved by huge amounts of waterballast in the double bottom.
"It is more economical to keep the water outside the hullplating".
Stability of container vessels is of optimal importance with regard to her maximum
carrying capacity (more than 50% of the cargo is located above the upperdeck). For this reason the hull form is growing anually to a wider beam and to a pram type
shape resulting in a large "stability of form" (the L/B coefficient might be lowered
from 7 to 5).
Sailinq-Yacht-Transom Stern
The sailing yacht stern, characterized by straight buttock lines and a wide transom is almost generally adopted.
The flat stern will sometime produce "slamming" but at normal seaspeed this never
happens.
In heavy weather under "heave-to" conditions, or waiting for a pilot outside in a long swell, a heavy blow might occur.
No indents or cracks developed on any of our ships so far and the crew is getting accustomed to this so called "Blow-aft".
Moreover, many small fishing craft, shaped with a wide transom stern have proven their seaworthiness during ages.
18
-Rolling
The application of stabilizer fins on containerships has almost come to a standstill,
mainly because of the fact of being hardly effective at the lower speed level.
Considerations in regard to extra cost, extra fuel and maintenance made
shipowners decide to omit the fins.
-
the beamy vessels, partly loaded and carrying only a little weight on the
hatchcovers will have a large metacentric height in this conition, which
maysometimes result in heavy rolling in a beam swell. (35
- 35 within 8-9 seconds)Reduction of stability by relocation of cargo is theoretical in many cases but
should be kept in mind by shipsplanners.
-
Heavy rolling creates great problems in regard to damage of
cargo insidecontainers, lashing of containers and workload on the crew, who are trying to do
their work properly (mind repairs in engine room).
Waterballast tanks located in the upper sides could ease this problem a and
should be incorporated in the design.
Distribution of weights - trim problems
The wide swept transomstern is fine lined underwater and does not provide
much boyancy. Moreover, there is a lot of weight above the water:
steelstructure and containers.
Consequently the ship will tend to trim by stern.
The location of the centre of boyancy of the underwater hull is restricted
to0,20 - 0,25% L behind
L for reasons of minimum resistance.
Therefore it should be clear, that proper balance can be achieved only by
moving fuel oil tanks and waterballast tanks towards the forepart of the vessel
(around hold no. 2).
Locating heavy weights even more foreward will result in higher still water
bending moments (hogging) in the structure.
A large distance between fuel tanks and engine room might raise transportation
problems by pumping in case of high viscosity heavy fuel oil. This problem
canbe solved by adequately heating the fuel oil and/or installing
a deepwell oiltransferpump in the foremost f.o.tank.
How to prevent a large trim by stern when the ship has a small amount of
cargo onboard.The location of the engineroom and accommodation should not be "too-far-afttt:
which makes it possible to keep the gondola ahead of the propeller rather
slender.
Stern trim and consequently a small draft forward has
a detrimental effect on
fuel consumption because of the "braking function" of the partly immersed bulb.
From this point of view also waterballast tanks in the upperpart of the forebody
are desirable. However, the stiliwater bending moment should not be exceeded
when using them.
Quite another important aspect is the unobstructed view from the wheelhouse
over a deckload of 2-4-5 container tiers.
An extra tier in height added to the deckhouse will increase hindrance by
vibrations.
A good longitudinal distribution of container weights during the whole roundtrip is
essential.
-
If the bulb can be kept below the waterline by a minimum of W.B. and
a19
-Therefore it is of utmost importance that ships planners ashore and shipsstaff on board are kept in operation.
- Masterplanning to be carried out ashore.
- Detailed planning by ships staf on board.
In first place, however, the shipdesign should be sound with regard to cargo and tank arrangement for F.O. and W.B.
It should always be possible to observe buoys or small craft at 1,5 L ahead. By this
law, you might loose top tiers top tiers of containers at the forepart, when the
wheelhouse is located far aft.
Cells
A flexible ship should have the possibility of 20 ft and 40 ft cells in all holds
(except the foremost hold which is only suitable for stowage by 20' oxes) Normally the percentage of 40 ft containers below deck varies from 20% to 50% Teu.
Too many 40 ft cells in the middle part of the ship with 20 ft cells in the ends
will cause large still water bending moments (hogging) and should be prevented. (The fact is that generally 2 x 20 ft boxes are having far more weight than one 40 ft box).
Heavy 20 ft containers on the stern of the vessel are also detrimential with
regard to bending moment and trim by stern, causing extra fuel by w.b. alternatively by extra resistance caused by a partly immersed bulb.
In these days it is quite common that a container vessel has to switch from one service into another which normally involves the changing of 20' cells into 40' cells or vice versa.
It is a challenge to the naval architect to find a practical robust construction
which allows for a simple conversion to be carried out within a few days (bolted connect ions).
Turnable guide structures might give troubles with jamming containers.
We have had a case where a container, jammed at halfheight in the guides was loaded on top with 2 extra ones because of the fact that the crane operator did
not notice the jamming.
After adding the third box the complete pile landed on the tanktop with a heavy
"bang", followed by the collapse of the boxes. Breakbulk
In the smaller vessels, serving less developed countries there is still a need for breakbulk transportation.
Following a German idea we installed collapsable bolts in the cell guides at the 3rd
tier level.
The pile of containers will rest on these bolts and breakbulk could be stowed underneath on the tanktop.
At this moment this system is applied on the South Africa-Europe service northbound, where copper ingots are to be carried in bulk underneath the containers in the cells.
In principle this method should be avoided because of the effect that turnaround time of the ship is increased (mind extra berth for copper discharge).
There is also the fact that the containerguides in the hold will be damaged by forklifts, manoeuvring around on the tanktop.
However, the "freight" level of the copper makes it impossible to carry the ingots
inside a container, On the other hand the use of special flattracks for
coppertransport is regarded as being too expensive, because this equipment goes for "deadheading".
20
-Hatchcover Lashings
Construction of covers and appendages is to be light and simple.
The 20 ft and 40 ft containers should be fastened "all around" by twistlocks. "Blockstowage" is unsafe because because of the fact that it is impossible to lash properly two blocks 20' boxes which are "back to back".
Connecting the block over the top of the container pile by bridgefittings is rather
theoretical, sometimes even impossible (mind 8 and 8-' box height).
The loss of a small containervessl might be caused by the above mentioned lashing problem.
Lashing by twistlocks is simple and practible and sailing three to four tiers
"high" with twistlock lashing only is now "common use".
However it should be kept in mind that the container in the lowest tier might
collapse by excessive side forces on the endframes during rolling. Therefore the
weight on top of the lowest tier should be limited to 30 ton.
In case of larger loads it is necessary to fit diagonal rods + turnbuckles at the endframes and the shIp should be provided adequately.
During foregoing years the lashings were sometimes overdone. Nowadays we
continue on "twistlock-lashing-only" up to the moment of collapse. Practical
research and information about this towards the ship staff is necessary. Many times a compromise has to be made between costs and safety.
There is a general tendency of increasing the deckload. More than 50% of the cargo is resting on the covers.
Competitors are sailing up to 5 tiers-"high" with the containers commonly asked by steelwire, (which might "slacken" on the long run).
Moreover, not much care is taken with regard to proper sighting from the
wheelhouse.
We are convinced that in future lashing by manpower ought to be minimized.
Walking over the 4th tier and throwing down twistlocks should belong to the past as
soon as possible.
The container handling costs are presenting a major part (about ) of the total
transportation costs door to door, and as far as the ship is concerned, a major part is caused by shifting containers and lashing.
Ships planners are already doing their best to minimize on necessary shifting but here improvement also in regard to cell- and hatchcover arrangement should be achieved.
The requirement by the terminal to keep hatchcovers on board instead of giving permission to drop them ashore below the rear end of the shoke container will
increase the number of shiftings and will increase the time-in-port of the ship.
On vessels having 7 or more container tiers in the hull and consequently a
freeboard of more than abt 7 m, the hartchcovers need not to be watertight by rubber packing.
Cleating of covers is also not required, which is easing the removal ofcovers by shore crane. As an exception, however, the cover on foremost hold should be cleated.
Cargo Gear
A number of less developed countries are lacking container terminals and shore cranes: Africa - East and Westcoast, South America - East and Westcoast Meditteranean - India Pakistan.
21
-Two solutions are possible:
40 tons gantry crane, travelling from focstle to deckhouse.
- Nediloyd van Neck (originally for Europe - W.Africa) -
Nedlloyd Clarence (destined for Eurosal - Europe - Chili)
- Nedlloyd Hollandia (sailing in Carol: Europe - W.Indies)
-
Nediloyd Zeelandia (destined for Carol service).
The gantry is very complicated, and costly. However, she can be taken off
overnight in case of the vessel has to change her service (Van Neck, Zeelandia).
2 x 40 tons luffing cranes, just simply fitted into the cells of the gearless vessel.
- Nedlloyd Van Noort - Nediloyd Van Diemen.
This solution is far cheaper, however, results in a loss of some containers and is
not optimal in cargo handling, because the shiperanes are hampering the
shore crane.
In case of conversion: "Cranes off" - more days are needed. (conversion of
covers has to be carried out).
Experience showed, that the second solution is more practible, because the vessel
itself is pure and modern in het basic design features.
Multi Purpose as an alternative.
It is our philosophy to built a simple modern vessel which temporarily could be
fitted with cranes and breakbulk facilities underneath the containers.
This way seems to be a better approach than taking as starting point the
conventional multipurpose ship, where tweendecks are incorporated and cargo
gear is fitted between the hatchopenings.
The conventional multipurpose vessel is more expensive (mind tweendecks fitted
with hatchcovers) and will have a container carrying capacity which wuill turn out
to be too small within a few years.
It should be stated, that the Newbuilding Department should look ahead over a
longer perod of time, than what the liner department wants instantly.
Integral reefers
These reeferboxes are of increasing mportance and for the newbuilding
deptartment it seems to be wise to install sufficient electric power and plugs for
reefers into the vessel.
Experience tells that the demand for integral reefers is increasing constantly:
during the period of newbuilding and afterwards during the period of service.
Normally integral reefers are carried upon the hatchcovers, however, it has
operational advantages to carry a number of them below "deck", in order to reduce
the shifting of deck stowed reefer-container in intermediate ports.
It is very well possible to provide these under-deck-integrals with sufficient air for
cooling (1 m3/sec per box).
However, this is rather expensive in regard to fuel consumption because of the
hugh energy need for ventilation.
It is more economical to cool the underdeck integrals by fresh water via a simple
"rubber garden hose", however, the integral reefer should be equipped accordingly.
In practice it turns out that the 20 ft integral will remain as "aircooled" only and
the 40 ft integral will be fitted with facilities for freshwatercooling.
22
-"Integrals" versus "ducted porthole boxes"
The integral system will require more fuel but it is far more flexible.
In case of the ducted system the ship will be far more expensive and dedicated to
the trade.
Application of the integral reefer system allows for a split in capital investment
between vessel and integrals.
This highly flexible system is providing the cooling of cargo during portstay and transportation over-land (for which a diesel driven generator has to be applied). The system is adopted for 100% inthe Pacific Basin (USA-Japan)
(Japan-Australia-New Zealand).
Frozen meat carried in numbers of 600 integrals per vessel is quite common. The disadvantage lies in the fact that the engineers on board are confronted with many defects of the integrals (whether leased or owned).
Therefore an absolute requirement is the pre-trip-inspection (PT!) before the container is loaded.
In case of the transportation of fruit, PT! inspection is of particular
importance. Porthole boxes
Insulated containers are connected via flexible rubber couplings to a
ship-duct-system in which cold air is circulating.
The vessel is bound to the dedicated trade.
The cooling machinery installed in the vessel is rather reliable and normally might not raise problems with regard to maintenance.
In case of the transportation at regular intervals of large quantities of fruit (South
Afrika - and South America West to Europe )
and large quantities of meat (Austr.-New Zealand-and America east to Europe), this system has its merits.
It is of primary importance, especially in the case of fruit, that a long portstay
under tropical conditions without any cooling should be avoided as cooling facilities-ashore are missing generally.
Also it is impossible to carry porthole boxes on feeder ships without cooling.
This is the main reason that the application of the porthole system is limited to the
transportation of large quantities between between the southern hemisphere with a moderate climate and the northern hemisphere with a rather cold climate, where the succeesing land transportation without any cooling is of a rather short duration.
In fact the ducted porthole system is suitable from "Port to Port".
A new development is the trend to individual cooling units on board located between the guides of the container cells.
Infection of the stack by one "rotten box" connected via the duct with the
remaining containers is not possible anymore.
Moreover a second advantage is the better adaption of cooling energy in case of a varying number of boxes in the stack.
Another drawback of the original duct system is the fact that different trades are using a different height of 20 ft porthole boxes:
- on the Austr.-New Zealand run the 8 ft box is applied since 1968. - on the Africa run the 8 ft box has been selected in 1974.
Consequently the pitch of the aircouplings in the stacks is different and it is rather
complicated to convert the pitch in case the vessel has to change her service. (The "StaI system" therefore is equipped with turning devices).
In the newbuilding department of Nediloyd it is presumed that on the long run the
integral reefer container will be adopted everywhere because of its capability to give cooling "door to door" and because of her flexibility in the chains of
Corrosion- Fouling: Smoothness
Thanks to the improvement in facilities in drydocks in comparison to 15 years ago it now has become possible to gritbiast and coat the complete underwater-part of the hull within one week.
23
-Antifoulinq:
300 micron selfpolishing copolymer to be applied in 2 or 3 coats of SPC (acrylic copolymer pigmented by organotin and copper oxide)
This coating is not a paint but a rather soft layer which gradually "dissolves' by an
abrasive action.
During portstay the poisonous action is always present and never shielded by plankton or slime.
It has been absolutely proved that the system of a few paintmanufacturers is giving excellent results over a period extending 2 years. Also in case of the next interdock period after recoating SPC.
for newbuildings there exists always the risk of bad adheasion on hardened epoxy coatings, because block coating at the yard sometimes out of control. This is the reason why Nedilody went for application of vinyltar beeing a paint which always could give proper adheasion (because it is a solvent-type).
It is also very risky to apply the final coat of SPC during drydocking preceding the trials to an undercoat of SPC which might be covered by rests of slime might contain moisture.
a+b. Therefore the safest way to obtain agood result is to gritbiast and to coat the complete underwater area in the drydock, before trials.
By following this method, there is no risk of bad adhesion, and no fouling by barnacles and algae will occur.
A constant performance of the vessel (as far as influenced by hull roughness) is
to be expected after this pretreatment.
With this paintsystem on the ship you might calculate with 12% seamargin (with a variation between 8 and 16%) upon trial trip shaft horsepower (NSMB).
You might say that the people who developed this SPC system did a great favour to worldwide shipping. Before it was quite common that after
application of so called supertropical coatings the seamargin of the vessel increased to 30% within a year. (one week portstay in the tropics was sufficient to get fouled)
During foregoing years Nediloyd has gained quite good experience with
chlorinated rubber systems. However, the fouling by algae was not prevented by
the insuluble matrix type antifouling and moreover, the quality of the
calorinated rubber was effected by restrictions due to helath requirements.
In view of the excellent practical properties of a goodt chlorinated rubber, a
SPC coating based on this binder should still be welcomed.
Anti corrosive system: Alternative for newbuildings
in view of adhesion troubles
2 x coaltar epoxy 3 x vinyl tar
1 x vinyl tar
24
-Propeller-Roughness
Removal of the calcerous film from the propeller blades at regular intervals by
divers seems to pay back.
Brushing under water is effective and we estimate that 3 to 5% reduction in fuel
consumption can be obtained.
We also have the impression that the influence of frictional area on propeller efficiency is larger than indicated by propeller diagrams of Model propellers.
A slow turning propeller having a large diameter, and relatively small bladearea is giving a rather high increase in service performance in comparison to the original one. (Also in case of highly skewed.)
Six bladed propellers showed service performance which is by far worse in comparison to 4 bladed propellers as would be expected from the propeller diamgrams (Troost series).
How is this possible? Is there a scale effect in regard to friction?
CORROSION - MAINTENANCE
Simplicity is of utmost importance.
Construction of the weather exposed surfaces - the weatherdeck in particular
should be clean and simple.
What can be omitted should be omitted!
For example: Removal of a spare anchor on a slipway, removal of steps, removal of thin protection plates. These things are corrosion caves which can hardly be
maintained.
Closed box construction for container stanchions and hatchcoaming supports are
very attractive to the owner.
Piping an cabling should run as far as possible underneath the weatherdeck or inside the deckhouse and masts.
In case a closed box construction is not applicable it is wise to make structures wide open allowing easy access for maintenance.
Shipyard draughtsmen having worked in tight co-operation with owner
-representatives during years are familiar to these maintenance requirements which sometimes might raise slightly the price of the ship.
Most shipyards, however, are not aware of these items and almost not interested how to maintain the ship in service, because for them it is important to develop constructions which are cheap in production, easy to transport and easy to erect on boa rd.
Feedback of the experience onboard towards the newbuilding yard is hardly present mainly because of the fact that there is no "auf wiedersehn". Showing photographs is the right way for understanding.
On this spot it should be mentioned, however, that there are still West European shipyards capable of building a "good Ship" for the owner. This knowledge should be kept available.
It should be emphasized to do the utmost in regard to blasting and painting during the newbuilding period in view of lacking maintenance afterwards caused by the short portstays.
Seawater- and weather exposed surfaces are of primary importance.
After finishing the welding of the complete construction, which is built up from
shopprimed steeiplates, all welds and damages are to be reblasted and primed again, because wirebrushing is a rather inadequate surface preparation.
Dust hindrance at the newbuilding yard is a severe drawback to achieve this result and on a few items a compromise has to be settled. Meanwhile the repair dock is
25
-Decisive for the lifetime of a ship is in many cases the condition of the
waterballast tanks and tanktops. Therefore, blasting of welds and damages of the
completely finished tanks should be a first requirement, which is followed by
pretouch+coattouch+coat.
A cheap system applied over "hand brushed" rusty steel is a so-called "doom to
death".
During service it is impossible to apply good protection over rust flakes.
A reduced number of crew members is justified only in case of 100% good corrosion
pro te c t i on.
Generation of electrical energy
Owners aim:
At sea in service conditions principally no dieselgenerator should be running and
electrical energy has to be raised by the main engine being a reliable source
which is turning by rather cheap oil.
With this concept, fuel costs and maintenance costs on the dieselgenerators are
saved and capital recovery time of the shaftgenerator is a few years only.
Hansen came to the following conclusion:
This recovery time will be 5 years in case the dieselgenerator is running
onMOO,
however, this recovery time will be 20 years in case the dieselgenerator
is running on HFO.Without reefers, it should be possible to cover the demand for electrical energy
by a shaftgenerator alone.
In case of the installation of bow and sternthruster it is a requirement to have
at least 2 dieselgenerators on board running during manoeuvring (with one dg
standby).
