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A Fast Offshore Cruiser - 4. Choice of hull configouration.
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4. Choice of hull configuration.

There are three configurations of hull or hulls that can be chosen from and they are monohull, catamaran and trimaran. There are others arrangements but as this is a cruiser with a small crew anything more extreme or innovative is not feasible. To select the hull configuration that best fits the design brief a logical comparison is needed.

The logical comparison is worked by completing an analysis of various aspects of a cruising vessel and comparing it with its counter parts, with the different hull arrangements, and scoring each vessel relatively and summing the scores.

The descriptions of the boats used in this comparison are.

Monohull: Fast cruising yacht, water ballast, long waterline.

Catamaran: Cruising cat with solid bridge deck and central accommodation pod, shallow draft, high freeboard.

Trimaran: Fixed floats, netting, narrow main hull.

Comparison of hull configurations.

Area

Monohull

Catamaran

Trimaran

Speed upwind

3

3

5

Speed downwind

3

4

5

Stability sailing

1

5

5

Stability total

5

1

1

Sailing comfort

3

5

4

Feeling of safety

4

2

2

Accommodation

3

5

2

Stores

4

2

2

Mooring

5

2

1

Total

31

29

27

Scores are relative to each other, 5 = best, 1 = worst.

Speed upwind:

VMG, speed

Feeling of safety:

storm conditions, breaking waves

Speed downwind:

speed

Accommodation:

space, comfort, usability

Stability sailing:

tender/stiff

Stores:

amount, distribution

Stability total:

inversion, self-righting

Mooring:

space, cost, ease of

Sailing comfort:

heeling, spray, motion

   

The table show that the logical decision making process produces a very close run contest with the monohull just coming out on top. From the table it can be concluded that the trimaran will be the fastest sailing and the most fun but living with and on it may not be as appropriate. The catamaran has slightly less sailing performance but has the best sailing comfort, thanks to its solid bridge deck giving no spray and minimal heeling Along with a vast improvement in accommodation volume due to the bridge deck the catamaran comes in ahead of the trimaran. Both of the multihull variations do fall down in terms of mooring, total stability and therefore the feeling of safety.

The monohull has the worst sailing performance, relatively, but gains greatly in terms of mooring, ability to carry stores, total stability and feeling of safety. Though a monohull may not get there as quickly but it will be much more habitable than the trimaran and will be able to carry greater amount of stores without noticeable detrimental effects on performance that would occur with the catamaran.

This logical comparison method has chosen a monohull vessel, this as well as the author’s preference of monohulls for this type of cruising yachts has confirmed the best choice to be that of a monohull.

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