Making a lobster boat ride faster.

Albert Jr.: The advices of many of the posters here are that a few things determine the overall speed for any given boat. These are length, beam and draft, the displacement of the boat, the shape of the bottom of the hull, and the installed horsepower. The typcial lobster boat hull was developed as an "easy going" comfortable hull for lobstering, and then people starting putting more and more power into them to go faster. There is a limit to how fast they can go reliably and efficiently.

For a given set of lines, to go faster, you have to change any of these basic parameters:

1. Make the hull longer.
2. Make the hull narrower.
3. Make the hull less deep.
4. Make the boat lighter.
5. Install more horsepower.
6. Changing 2. and 3. together will change the hull bottom shape.
7. Change the bottom shape to a more "deadrise" speedboat form, with chines instead of rounded bilges.
8. Do any combination of the above.

I had a client with a similar problem some years ago. His Wilbur 34 was overly heavy because he kept building stuff onto it. It kept getting slower and more uncomfortable to ride because of the increasing spray. So he hired me to design full-length lifting strakes to be built onto the boat and then hired a local builder to make the changes under my direction. Essentially, we followed option 7. above--we changed the bottom shape. This modification made the boat ride higher and drier, and it was a touch faster to boot. You can read about this project, Blue Bill, on my website: http://www.sponbergyachtdesign.com/Bluebill.htm.

I hope that gives you some insight.

Eric

 

Plywood doesn't sound attractive but that doesn't mean that you can't make it attractive.
I was thinking about using cedar rather than plywood but I'll still plank them normally instead of strip planking.

You've both mentioned some brands, thankyou for that and I appreciate the picture but where can I find the plans (drawing, patterns) to build these boats ?

 

Good question.

I dont know. Google ....Smith Island Boats. Draketail boats, Oyster boats, Core sounds boats

they have been building these boats since the invention of the engine .

Modern designs are beamy and high powered...the old timers are narrow and powered by 6 cylinder engines.

ask on Boatdesign net guys like PAR...they might have a design or know of designs.

Parker Marine designs on the East Coast fishboat style.

http://www.parker-marine.com/com32page.html

http://coresound.com/exhibits/

Doug Hylan might have something for inboard power ...he draws an outboard powered 18 footer

http://www.dhylanboats.com/plans/pointcomfort18_study_plans.pdf

 

Alright, thanls alot.

 

As for going faster than 18 kts. I doubt it.

18kts is very fast for a seaworthy workboat.

Id say keep you speed requirements down and choose the most elegant boat that you can afford to build.

 

Thanks Eric, it does give me a lot more insight.
Thanks again everyone, now I know more about what to do.

 

Plywood can look good and be very strong. Just need to use lots of epoxy and glass sheeting to keep water out also care about putting proper sealant and epoxy when screws pierce wood.

 

Albert Jn,

Len Randell is the designer, contact him direct.

Len Randell
4A Blackwall Reach Parade
BICTON WA 6157

also see here:
http://www.google.com.au/#output=se...514,d.aGc&fp=2f4e0cd6eacb517&biw=1403&bih=693

 

Eyschulman nice looking vessel, looks line a Sam Devlin Design. Speaking of which, Albert Junior I have his book which will give you lots of good info on tape and seam construction as well as scarfing your ply sheets, PM me with your land address and I will throw it in the mail to you. ---Geo.

 

Alright, thanks man.

Really :O
Wow thanks man, I'll send you my address asap.

 

A correct size (ie: big enough) prop and better skeg/keel design will help the engine do it's job.

 

Nail-bitah at the Portland Lobster Boat Races

Published on Aug 20, 2013

www.nationalfisherman.com — Travis Otis of the First Team out of Searsport, Maine, keeps his cool in a close encounter with the 1,000-hp 4 Girls of Harpswell, skippered by Tom Clemons. The race winner was Whistlin' Dixie, which makes an appearance at the end of the video.

http://www.youtube.com/watch?v=aT87AClJI9Y

 

Just my thoughts after reading your query.

1, Looks (style) is important to you
2, Speed is important to you
3, large deck area important to you

My suggestions are , go for a run in an 18 or 22 knot lobsterboat in a bit of a swell and see if it is what you want. You'll know in under a mile in bad conditions just how you want the boat to handle. The boat will nearly always handle more than the driver or passenger can.
You mention "in a year or so" about the build, spend a bit of that time looking at boats and talking to owners and drivers of the boats you like at the marinas. I did quite a few trips (working for free as a deckie) to get ideas about working boat layout and features.
Talk to a few naval architects, (boat designers) about some of your requirements. Many of them will modify stock plans (within reason and with guidelines) to achieve what you want. Dont be afraid to ask these people about changes, but be aware , you wont always get the answer you want.
Look what others who do the same type of fishing as you intend are using. There's a reason their boats have evolved to where they are.

But my best advise is "Get a solid idea in your head and follow it through to the end. Dont change things midway through. "

 

The lobster race boats are built to go quick in mostly flat inshore water where they race.

If you actually plan on harvesting bugs the traditional rounded bottom would be best.

If as I think you are planning a recreational lobster boat, my choice would be an old sport fish deep V hull, chop off the deck house, and install a lobster like deck house.

Far superior ride at speed in outside snotty conditions , and huge engines would already be installed.

Copy the lobster boat practice of an engine hatch with a matching overhead hatch for over night engine changes.

 

Thanks for the advice.
I've been doing some research and looking at some engines.

I've talked with Tad about the 32 ft Lobster boat and I think it might be the one.
I've allready started saving for the plans but still have a long way to go.

There are only 2 lobster boats similar to what I'm interested in but only bigger. (46 feet)
I'll take your advice and I'll start talking with them about the boats and I'll ask
and see if I can go on a charter trip which I'll pay for ofcourse or I'll work as a free deckhand

As for the engine, I'm starting to like the idea of a 450hp Cummins 6cta.

Almost forgot.
I've been thinking what material to use and I'm really liking the idea of using cedar for the hull and divinycell foam for the cabin.