Engine placement at bow

[Wckoek]

Probably a compromise for the massive fuel capacity, but bearing in mind that they operate in the offshore pacific for month(s), so the design/configuration doesn't render them less seaworthy.

[TrentePieds]

In the 70's, before the stocks were drastically reduced through overfishing by precisely these sorts of ships, there was trend here in Vancouver towards the same sort of configuration of ships for the salmon fisheries.

As I understood it at the time, cargo carrying capacity was the end all and be all since the catching, then, was no trick at all. The fish lined up to ask permission to come aboard. Therefore the midships spaces were reserved for the "bins" in which the iced fish was kept while in transit to the canneries. The mechanicals and accommodation spaces of these ships were pushed to the ends in order to reserve the midships spaces for cargo.

Think of the weight distribution. The midships spaces were to all intents and purposes filled with water. The "bins" extended from side to side and through the entire depth of hold. Adjust for the lesser SG of fish as compared to solid water and the weight of the cargo might be estimated at, say, 45lbs/CuFt. That is far more than the weight per cubic foot of machinery and accommodation spaces, which might average 10lbs./CuFt. so the principle of "keeping the ends light" was observed AS APPROPRIATE for the ships' particular trade. Note also that fully laden these ships were kept afloat by the empty, i.e. light, endspaces while the centre portion of the ships would have sunk like a stone but for being attached to the end spaces.

Mechanically there is obviously no problem in accommodating the long shaft.

TP

[Wckoek]

Alaskan combination seiner/trawler up to 100 feet.
At this size, it is for fish hold capacity.
How about living space for yachts?

[Wckoek]

90 footer.

[Wckoek]

Even twin engined 100 footer.

[Wckoek]

I think if the designer knows what he is doing, and the boat is properly balanced, it would still be a valid solution in some cases.

[Terra Nova]

Unsubscribed.

[TrentePieds]

I can assure you that the designers of these ships DID know what they were doing. The design criteria for these ships were really quite peculiar. They were money making machines, and they are not IMO suitable ships from which to seek inspiration for yachts, the operational requirements of which are entirely different.

You CAN place the engine in the bows of a yacht if you like, but why would you? In yachts up to say 50-ish feet, you cannot get standing headroom under the wheelhouse, its "air draft" being constrained for a number of reasons, nor under the cockpit. So when you have 3 or 4 feet twixt keelson and underside of wheelhouse or cockpit sole, why not use that space for the engine leaving other spaces unencumbered by the least attractive - if necessary - component of the yacht? Remember that in ship design EVERY cubic inch counts and should be exploited.

Remember that ships for particular, peculiar purposes, such as yachts have EVOLVED as they have in order to achieve a sort of maritime "Pareto Optimum". recent fishing vessels, on the other hand, have been designed to meet a PARTICULAR owner/operators particular requirements.

If you have a GOOD reason to divert from the tried and true, by all means do it. But make sure you are acting for GOOD reason, and not just on a whim.

TP

[FatBear]

Originally Posted by boatpoker

Is it a compromise ?

Of course it is. Ask a naval architect or engineer: every single aspect of a boat design is a compromise in some way.

[Pelagic]

Originally Posted by Wckoek

I think if the designer knows what he is doing, and the boat is properly balanced, it would still be a valid solution in some cases.

I agree on Fishboats where you need a large working aft deck and below deck spaces for fish holds and brine systems etc.

Putting the machinery directly under a fwd wheelhouse is a good solution for that fishboat application where they are towing nets.

But not on a yacht!

Noise is 80% structure borne so the penalty of engines, shaft and propeller cavitations in accommodation behind the drive train, is significant.

The perfect design is a 7° shaft angle power train formula for a large power yacht in a semi-aft engine room configuration, where the guest rooms are fwd of engine room (usually with a workshop store room noise buffer inbetween)

This is the most comfortable and deepest part (giving you larger fuel and water tank capacity underneath guest quarters.

No structural or airborne generated noises under the accomidations and the prop cavitations/steering gear vibration noise is released outside in an aft cockpit area.

Yachts I have done this way achieved 44dBA noise targets in marble bathrooms just fwd of engine room at 12knts (harbour conditions with aircon and one generator running.)

Impossible to achieve in a forward engine room configuration without major loss in use able space and a significant weight penalty in additional mass sound materials.

For those not familiar with dBA noise comparison.... here is a list

http://www.industrialnoisecontrol.co...e-examples.htm