Page 10: of Maritime Reporter Magazine (June 1980)

Design And Construction Of Modern

Roll-On/Roll-Off And Container Carriers

Doros A. Argyriadis, Goran Nilsson and Harry Petsis*

A New Concept In Marine Transport Is Seeded Only

In Times Of Economic Upheaval And Bears Fruit Only

If It Is Adaptable To Economics Of A Changing Pattern

The most challenging and unique problem the naval archi- tect faces when developing the design of a new vessel is that of combining the best technical know-how with the best economic analyses, then adding a bit of magic forecasting and talent.

From the technical know-how of the past dozen years or so, many specialized vessels have evolved. If one includes in a com- parison the tankers and bulkers and their many combinations, but excludes such unique vessels as passenger and cruise ships, one *Mr. Argyriadis, president, Dormanda

International Corporation, New York,

N.Y.; Mr. Nilsson, president, Market- ing-Navire Cargo Gear International,

A.B., Goteborg, Sweden, and Mr.

Petsis, chief marine superintendent,

Hellenic Lines Ltd., New York, N.Y., presented the paper abstracted here before the recent Annual Meeting of

The Society of Naval Architects and

Marine Engineers. A copy of the pa- per may be obtained from the Soci- ety, One World Trade Center, Suite 1369, New York, N.Y. 10048. can perhaps distinguish the fol- lowing basic types of cargo ships: 1. LASH, SEABEE or barge vessels of different types. 2. Container and pallet ships which move cargo to and from the ship "over the rail." 3. Ferries, train carriers, auto carriers and roll-on roll-offs which transport or allow movable and wheeled vehicles to carry cargo to and from them. 4. Breakbulk cargo carriers which may carry any cargo, in- cluding containers and wheeled ve- hicles, by utilizing self-contained suitable lifting equipment and moving all cargo over the rail. 5. Bulkers, tankers, etc. de- signed to carry uniform or nearly uniform goods in quantities and in bulk.

The first three types fall into the category of what the authors would call specialized types of ships. Historically, the oldest type of these specialized carriers must be the ro ro vessel.

The container vessel, on the other hand, was slowly emerging in the maritime arena in the 1950s.

The 1960s saw its emergence in the more competitive internation- al trades.

Somewhat later, but in an al- most parallel development, LASH- type vessels were developed for special routes, carrying non-self- propelled barges.

Meanwhile, the ro/ro vessel was slowly emerging. Ferries in some parts of the world began carry- ing more than passenger vehicles and started looking at heavier cargo and trucking as a paying proposition. Figure 1 shows an artist's impression of a modern deepsea ro ro, clearly indicating cargo access and transfer equip- ment onboard.

A ro ro vessel is not the answer to all problems and in many cases the adaptability of the ro ro to a specific area or service may not be clear-cut and may be weighed one way or another by many pa- rameters and special situations.

Design Parameters

It may be worthwhile to con- sider some design philosophies and parameters in the selection of a ro ro and container carrier.

Basically, "a horizontally wide open" vessel is desired. No trans- versal obstructions in the form of bulkheads can really be toler- ated in the main cargo spaces, and pillars or other deck supports must be kept to a minimum. In this respect, it becomes obvious that, below the freeboard deck, a double-skin construction must be utilized for strength as well as for damaged stability reasons.

A stern ramp is a necessity. It must suit the requirements of the trade as much as possible, without limiting the utilization of the ramp or vessel too much. In larger ships, a ramp that can be oper- ated in at least two directions is the minimum acceptable. A slew- ing ramp, which allows operation in three directions is the most de- sirable but may be prohibitive in cost, Figure 2.

Containers must be carried in all decks. The standard unit, known as the TEU (20-foot equiv- (continued on page 14)

BY SHORE CRA.JE

UPPER & MN DK

FlvD CARGO ELEVATOR

MN TO 2nd DK TO TANK TOP

TO ISC & 2™ CAR DK

WEATUERTIGirr

STERN DOOR

SLEWING STERN RAHP-

HOISIABLE ist CAR DK 3a: TIRLCTER

HINGED INTERNAL RAIIP

D 2nd DK c lsT G CAR DK _ HOIST ABLE

CARGO ELEVATOR 2nd CAR DK 2nd DK TO TANK TOP f, TO 2nd CAR DK

HEAVY LIFT CARGO ELEVATOR

WITH APPROACH FLAPS

MN TO UPPER DECK

FOR VESSEL PARTICULARS

SH APPENDIX

Figure 1 — Artist's conception of a ro/ro and container vessel. 12 Maritime Reporter/Engineering News