Boat Idea for Inboard Detroil Diesel 3-71 100 HP

Looking for ideas for s simple open deck boat that would work with a 100 hp 1500# inboard detroit diesel and plane 25-30 MPH? Open to aluminum or wood / fiberglass construction. Any ideas? Basically trying to figure what might work to acomplish that with this engine.

 

Welcome to the Forum Manuel.
Are you looking to buy a suitable second hand boat that would be a good match for your engine, or are you planning on building a boat from a set of plans?

If a second hand boat, would a vessel like a Shamrock appeal?
1995 Shamrock 220 Stalker Center Console for sale - YachtWorld https://www.yachtworld.com/boats/1995/shamrock-220-stalker-3817956/

I think that she would be hard pressed though to achieve 25 - 30 mph with a 100 hp diesel.

If you are looking to build a boat, would something like a dory be suitable?
There are a variety of them shown here -
Spira Boats - Wood Boat Plans, Wooden Boat Plans https://spirainternational.com/hp_wood_boats.html

 

Want to build, already had a 26 open shamrock that I put a 370 cummins in it. Was not a success, although I love the shamrocks and the keel, the prop is too small which I belive hurts them in efficiency.

The dory's look nice and simple, but that flat bottom may be a little rough, although efficient for acheiving my desired speed with a heavy 100hp diesel.

Thanks

 

Have a 23-3 formula in the back yard also that needs to be redone, but dont think 100 hp will move it with its aggressive deep vee

 

Why not blow out the Shamrocks prop tunnel to fit a bigger prop?
A Cummins 370 with about an 19” prop should be real nice in there.
I did just that a few years back, it worked really well.
I’ll provide details, if you’re interested?

 

100 hp would not drive a 3000 lb boat to a 25-30mph cruise speed, which is realistically about the minimum weight you could hope for, starting with 1500 lbs of engine, using the best lightweight construction methods. low 20's mph might be possible with careful hull selection, the fact you want a stripped-out open boat gives you some hope.

 

371..... maybe a giant muffler that looks like a boat.

371 was a decent but noisy gen engine but that's a heavy 100hp engine. Good at converting diesel to noise.

Maybe a ply skiff with a decent beam would plane to 25 and help spread the weight?

 

Yes, the noise factor is an obstacle

 

One of our local fishermen runs a 371, and has acquired the nickname “Machine Gun Kelly”!

 

My dad had a 1978 Baja, 22' , built by Gary Detling in San Diego with a naturally aspirated 3-53 Jimmy good for something like 80 horsepower in it, dry stack exhaust. It was a screaming Mimi, especially in the tower with the exhaust right behind your head. The boat/engine/transmission/fuel (80 gallons)/equipment was around 8,000 pounds, fiberglass/foam/fiberglass, center console with a small v-berth. Set up for commercial sword fishing, 12 foot plank off the bow and a 10 foot high tower. It cruised at 22 knots unloaded, with a half a ton of ice in the fish hold and up to 1,500 pounds of broad-bill carcass it would squat and load up on pull approximately 16-18 knots depending on how much fish was onboard. So 25 mph is definitely possible in the proper hull. A wet exhaust and well insulated engine box will drop the noise considerably and make for a more pleasant experience. But you can't beat an old Jimmy for fuel economy and time between overhaul, they are a beast of burden in my experience.