Ultra efficient boats

[cRiPpLe_rOoStEr]

I guess it's worth to take a closer look at a Spanish llaüt.

[Piotrsko]

I am not thinking a 'foil is winter transport friendly

[67-ls1]

It would help to have more details. How far is the commute? How quickly do you want to cover this distance? For how many people? What are the waters like, ie, current, waves, wind, etc?
Is electric an option, ie, do you have a place to charge at one end of your commute?
I’ve seen some small wave piercing type cats with small cabins that could work in fairly protected waters and make pretty good speed with relatively low power.
But a boat will never be as efficient as a car. Factor in the fun factor and the lack of traffic and I’d pony up a little extra to make it happen if it were an option for me.

[cRiPpLe_rOoStEr]

Originally Posted by 67-ls1

I’ve seen some small wave piercing type cats with small cabins that could work in fairly protected waters and make pretty good speed with relatively low power.

[67-ls1]

Like this…

[cRiPpLe_rOoStEr]

Now that looks quite like a downsized equivalent to the catamaran which is used for the passenger service between Porto Alegre and Guaíba, on the other side of the Guaíba river...

[freebeard]

It appears to be a SWATH[ull].

[cRiPpLe_rOoStEr]

You mean the catamaran which goes between Porto Alegre and Guaíba? I didn't even know SWATH ever existed, yet the catamaran looks like it...
https://www.catsul.com.br/

[freebeard]

This one? Catamaran, not SWATH. Think of two submarines with the conning towers connected by a platform.


https://www.catsul.com.br/

[ttrainxl]

I’ve had several displacement hull sailboats, some with Diesel engines. I had a Columbia 29 that weighed 8500 pounds and drew four feet with a full keel. It had a Volvo penta 2002, which is an 18hp two cylinder diesel. I went 7 nautical miles on just the fuel in the filler neck, which was only about 18” long and about 1 1/2” hose.

A similar two cylinder 18-22 hp diesel (especially with a 4:1 transmission, rather than 3:1), would propel a 13-15 foot planing hull weighing 400-500 pounds super easily. Use trim tabs to get up (though you likely wouldn’t need it, it saves fuel by using less throttle). You’d plane and probably be able to cruise at 1500-2000 rpm and make maybe 15 knots or better.

I’d imagine this would be a super economical commuter, and you could put a dodger on it with sitting headroom to stay out of the rain and sun. A Carolina skiff would be a good platform, but they slap terribly in a chop. Use a shallow to moderate V hull and you’ll still be able to cross shoals of depths 2-3 feet, or a deep V if shallow water isn’t an issue. A deep V will cut through the chop easier, but it takes more power and fuel to get on a plane.

Commuter boats in New England and the Pacific Northwest are certainly a thing, but are typically not planing hulls. I’d look for a shallow V hull fishing boat weighing 500 or so pounds and brush up on your fiberglassing skills. Decent engine beds, a skeg for the prop shaft to come through (helps the vessel track better also), and a rudder (you could use a dinghy sailer’s transom hung rudder potentially, but would be less efficient) and you’d have a nice little commuter. Look for a boat that has built in storage so your groceries stay dry. This boat would probably only burn 1/8 gallon an hour or less. My 29 ft 8500 pound Columbia only burned a 1/4 gallon an hour and half the boat was below the waterline.