Making a lobster boat ride faster.

Well I've talked with my cousin and it looks like in between 1 and 2 years, we'll be building a single engined 33 ft lobster boat called potluck.

I've looked at a few inboard diesels (found a nice volvo 225 hp on ebay $3000,-)
but my problem is that I feel that no matter what hp we put in, it'll keep going at around 18 KTS.

I see on youtube that people actually race lobster boats so my question is...

What can I do to make my lobster boat ride faster ?

btw How much will the estimated cost be when using the cold mold method and using cedar wood and divinycell (the foam is for the cabin)

 

More HP

 

That was my first thought but than I remembered while taking courses that the teacher said;
Displacement hulls only reach the hull speed.
No matter what hp, you'll still reach only the hull speed.

 

Oh I think you'll get lots a feedback on this one not to mention any names but there is a forum member who dabbles in this sport. Lobsta Boat Racing, hull and engines, You might want to contact PAR.

 

Your teacher is hopelessly wrong. The notion of "hull speed" is pretty useless
and it's only touted by amateurs without any knowledge of hydrodynamics.

Destroyers can exceed "hull speed" because they have large power plants.
Rowing shells and racing kayaks also operate well beyond hull speed.

 

Oh ok thanks.
But how can I get the boat to go over its wave or how can I get it to plane.

 

You can make it a little more slender and add hp, as suggested before.
Getting it to plane might be more difficult.

 

Here's some drawings from Glen-l. I cant see the boat going much faster than they say

without a bunch more hp with a much higher fuel cost. The bottom is too rounded to do anything efficiently except displace water, it will not plane or even semi plane.

How much more speed are you looking for and how much extra operating costs is it worth?

 

We like it because of the space in the back.
I wanted to have atleast 20 KTS to get move faster from fishing spot to fishing spot when the lines aren't in the water.

We won't use it for lobster fishing but more for pelagic big game fishing
(tuna, dolphin, wahoo)

 

A vee bottom may be a better choice for the intended use. Real Lobster fishing boats are round bottomed because that's what the fishermen want, traps catch on the chine.....but you are sport fishing and want speed....at a S/L over 3.5 the vee will be better.

Julie Ann is a 40' traditional plank-on-frame round bottom Lobster yacht that does 22 knots with a single 400HP Cummins.

 

On occasion boat designers know what they are talking about...
Seems to me you need to find a design intended for your target speeds.

 

Seems to me you're right but where can I find a lobster style boat that'll fit my needs ?

 

Ok ok, do you have any other designs that are a bit smaller ?

 

Yes......

http://www.tadroberts.ca/services/new-design/power/johnsbayboat32


http://www.tadroberts.ca/services/small-boats/planing/berrypoint26

 

Don't bother to reinvent the wheel.

If you want a really fast lobster boat subscribe to National Fisherman , about $12.00 a year.

They frequently cover lobster boat races , so what you want probably already has been done.

The fellow that said MORE HP is right , some of the faster boats run 700+ hp.

AS you will perhaps at best get 20 hp from a gallon of diesel, even a tiny 400hp diesel will eat 20GPH which at $4.00 a gal that's $80 an hour to make waves.

"I've looked at a few inboard diesels (found a nice volvo 225 hp on ebay $3000,-) "

These are car engine ratings , good for perhaps 15 min every few hours.

Go to a marine engine site , even Volvo (the worlds most expen$ive choice) and find a set of power ratings from M-1 to M-4 .

IF there are no duty ratings for the engine its recreational, short lived high hp only.

Choose what you need in terms of power output..

Enjoy!