37' Power Trimaran Design: 20mpg/

rustybarge

rustybarge

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What do you think this Kurt Hughes design Trimaran?
.....and the hull form?
http://www.multihulldesigns.com/designs_stock/38tri.html

Length overall: 38'-0" (11.6 m)
Length at waterline: 37'-6" (11.5 m)
Beam: 16'-11" (5.16 m)
Draft: 1'-6" (0.46m)
Weight: 4,125 lb
Displacement: 5,278 lb (2.394 kg)

Half load, both engines at mid speed (4,000rpm).
Fuel consumption is 0.62 gph. per engine
Speed is 11 knots.
100 gallons fuel gives 887 nautical miles


Half load, one engine at low mid speed (3,000rpm).
Fuel consumption is 0.407 gph. per engine
Speed is 8 knots.
100 gallons fuel gives 1,965 nautical miles

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Surely, even on the figures supplied the fuel consumption is per engine &, therefore, the distance shown - 1965 nm - needs 200 gallons?

John G
 
seastoke said:
sounds like car manufacturers gph , not right
Click to expand...

Sounds incredible, all on 30hp......wondering what's the hitch.
The range figures mean nearly Trans-Atlantic possibility.
With detachable outboard pods it would fit in a 40' container......

Do you know anyone with a Trimaran?
 
Jegs said:
Surely, even on the figures supplied the fuel consumption is per engine &, therefore, the distance shown - 1965 nm - needs 200 gallons?

John G
Click to expand...

I think the hull is so slippery that it can cruise on one OB at 8kts......
 
15Hp will use iro 1.5gph at WOT depending on the usual factors.
About 3/4gph at 4000rpm.

The figures shown are possibly mildly optomistic, but not massively so.

However, there won't be much room onboard for serious long term living on board.
A cat with two hulls akin to the single living hull of the triamaran would be more my thing.
 
Nautibusiness said:
15Hp will use iro 1.5gph at WOT depending on the usual factors.
About 3/4gph at 4000rpm.

The figures shown are possibly mildly optomistic, but not massively so.

However, there won't be much room onboard for serious long term living on board.
A cat with two hulls akin to the single living hull of the triamaran would be more my thing.
Click to expand...

I have a small Cat, the problem is the deck is very high above the waterline with the hulls underneath, meaning the wheelhouse roof is going to be very high causing a lot of windage. the height under the connecting beams, the bridge deck clearance is dependent on how high you are willing to let the wheelhouse roof go; the better the clearance the higher the deck: the higher the deck the higher the wherlhouse roof to get standing headroom. A Cat with low tunnel clearance will slam into waves, stopping your progress dead in the water.

Cats are also super sensitive to weight because of the slim narrw hulls; a tiny increase in payload will sink the water line by a massive amount. Another hitch with Cats is the beam, how do you get a 18' wide boat onto a lowloader?

Enter the Trimaran.......

Slim monohull 8' beam with outriggers, low drag good wave piercing, no bridge deck to slam.
No rolling, a similar beam mono would fall over in a beam sea.
all the weight is low down in the hull.
No payload restriction, this design carries 100 gall fuel.
Massive range.
possibility of a small lightweight sail.
Same accomodation as a narrow boat, all seating can be parallel with the the hull. lots of people have sucessfully lived on narrow boats for years. you have to think long and narrow, instead of wide.
Outriggers will dismamtle for transport.

And the most important thing:
38' monohull about 1.5mpg at 11 kts, 38' Tri nearly 10 mpg ( uk gallons)

What are the disadvantages?
 
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It's still remains too small.

The living space is tiny compared to a mono or a cat.

I understand a lot of the benefits you suggest, but if I was to have 38' then I would want 38' of trawler style accomodation and not 38' of pokey canal living accomodation.
 
Nautibusiness said:
It's still remains too small.

The living space is tiny compared to a mono or a cat.

I understand a lot of the benefits you suggest, but if I was to have 38' then I would want 38' of trawler style accomodation and not 38' of pokey canal living accomodation.
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looking at a 38' trawler:

Engines will be under the wheelhouse floor, meaning steps down to the cabins, and if it's has a aft cabin steps down to that, as well as a companionway up to the flybridge. A trawler has 2 or 3 levels........

The Tri is all on on level because the engines are outboards..........so you can walk through the hull without having to negotiate steps when the boat is at sea, that's a big advantage.

My experience from living aboard is it's the distance you can walk inside the boat that counts, not the width of the hull.
A lot of boat 'furniture' can be built along the length of the hull, leaving a walkway down the middle.

The dinette is dead, thank God! Most modern boats have long couches arranged lengthways including the galley, leaving a long open area in the center which allows access to the cockpit without a step.
 
rustybarge said:
looking at a 38' trawler:

Engines will be under the wheelhouse floor, meaning steps down to the cabins, and if it's has a aft cabin steps down to that, as well as a companionway up to the flybridge. A trawler has 2 or 3 levels........

The Tri is all on on level because the engines are outboards..........so you can walk through the hull without having to negotiate steps when the boat is at sea, that's a big advantage.

My experience from living aboard is it's the distance you can walk inside the boat that counts, not the width of the hull.
A lot of boat 'furniture' can be built along the length of the hull, leaving a walkway down the middle.

The dinette is dead, thank God! Most modern boats have long couches arranged lengthways including the galley, leaving a long open area in the center which allows access to the cockpit without a step.
Click to expand...

Not doing it for me...
 
boguing said:
From memory, Adrian Thompson's 65ft Paragon VSV only had 200hp. Long and slim is the key.
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That's a very interesting boat. this explains is all:
The new design allows for improved performance under power thanks to the ground-breaking shape of her hull. Traditional thinkers say that hull forms should be either displacement or planing. However, a displacement boat will give range but not speed, and a planing boat will give speed but lack range. The VSV uses a combination of the two for the best of both; its long thin hull runs in displacement while it planes on the hull chines. A conventional planing boat rides the surface of the water so it bounces off the top of each wave making for a very bumpy ride, and once the swell becomes too large it has to reduce speed to the same as the displacement vessel. The VSV pierces the waves, smoothing the ride and enabling it to travel quickly - making her perfect for fast long distance exploration and adventure.
Click to expand...

View attachment 36951
 
The age of open plan living in modern apartment blocks has meant the development of long narrow living spaces. minimalism has also helped to de-clutter the living area, stretching it out with linear kitchens etc.

A typical saily boat layout works very well on a slim hull, but with the seats on one just side, with pull out table on the opposite side. this way the accommodation is laid out just like an apartment.

View attachment 36957
 
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