Improved hull design

[gudi]

Hi Boating experts, am quite new to boat building design. Somehow it took my interest seeing an Indian boat construction yard making 32 feet long wooden boats, 10 ft. beam that appeared to me to use very antiquated methods of hull construction or may be even design on which it is based. These displacement fishing boats are powered by 400 HP automobile engines, rated 2500 rpm, speed 7 knots approx. for about 12 tons fish catch per trip consuming 8 litres of diesel oil per hour.The users seem disappointed about fuel cost.

Construction is old practice. Lofting curves drawn on plywood boards. Logs are cut into straight wooden frames and four timber reapers joined (one above bilge and one below and to keel at center). Inverted gable frames of mid line progressively narrowing at bow and reversed curving towards transom. Two feet wide wooden planks 1.5 inches thick and the carpenters nail the boards to frames after shaping frame edges by experience so that there is minimum gap between them which are filled by caulking with cotton and resin. At the rudder block and stem the strakes are forcibly twisted by C clamps nearer keel and nailed in locking in permanent stresses in the timber.There is a polyester glass cover for hull outer finish layer in sea water contact.

Only aspects of 3D hull shapes and possibility of using thinner laminated marine plywood instead of thick planks was my starting interest based on earlier composites experience. But before that, can someone guide with suggestions incorporating alternate design contours qualitatively using catamaran, planing (or hydrofoils? -- surprising that human powered water skipping scooters exist.) for better fuel efficiency? I shall post further details or pics of the same. Questions welcome. Thanks in advance.

Narasimham

[Gilbert]

I don't understand why these boats should have a 400 horsepower engine.
With that amount of power installed they should make 7 knots at almost an idling speed if they had a properly sized propellor.

[Fanie]

Narasimham, if you're not going to haul fish for which you need the flotation, then you may be interested in a catamaran instead... ?

[terhohalme]

Few pictures, please.

[ancient kayaker]

Thee may be an error in those figures, that fuel consumption is much too low for a 400 HP motor. Do you have a sketch or picture? Alternatively if you know the name of this type of boat we can google that, as there are lots of boat pictures on the Net from India.

Yes Paddler, these figures are wrong, and there is no car diesel on the market at 400hp. But 40hp cont. output would roughly fit the consumption, and the speed figures too. 165 g hp/hr = 6600gram = 7,9 ltr.
Regards
Richard

[McFarlane]

I would say a truck is classed as an automobile and trucks have engines powered well over 400HP apex.

[Landlubber]

Obviously if the engine really is rated at 400hp, then it is not developing full hp, it is running at about 60 to 80.

Originally Posted by McFarlane

I would say a truck is classed as an automobile and trucks have engines powered well over 400HP apex.

Thanks Macka I did not know that. Your statements are always a joy to read!
And a 400hp truck Diesel is consuming roughly 8ltr / hr yah?

Lubs: 40hp not 60 -80 see the calc.s above (and that sounds consistent at a 32´by 10´ boat running at 7kn)

[CDK]

Originally Posted by McFarlane

I would say a truck is classed as an automobile and trucks have engines powered well over 400HP apex.

Consumption and horse-power figures are that far apart, I think "gudi" does not have his facts straight.
Yes, a truck could be called an automobile if you are not familiar with the word truck. A 400 hp truck engine is an enormous block of cast iron, far too heavy for a 32 ft. wooden boat. Like Apex1 pointed out, there must be a decimal error in the original post.

[gudi]

Thanks folks for your responses, the figure given to me could be wrong , Shall check it out.