Hybrid speedboat

[Ichiro]

Just saw this article on the SF chronicle (sfgate):
Hybrid boat waves hello to S.F. Bay

Only $185,000! I wonder how many (nautical) miles to the gallon it gets.

[qbee42]

Marine serial hybrids have been in use for decades: tug boats, ice breakers, submarines, and other working ships. Use in a recreational speedboat is new. Some sailboats are starting to use electric motors for auxiliary propulsion, sometimes with an ICE, sometimes without.

Tom

[mingoglia]

I'd imagine a boat is probably similar to a plane where a hybrid system wouldn't really make much of a difference on mileage. These type of applications typically require the engine to run towards the top of it's RPM range for long periods of time. This is in contrast to the typical stop/go/sit at traffic lights way a car typically lives it's life.

I can see these in some marine applications as an electric motor (that's powered by a generator) is useful because it limits the amount of space a drivetrain would take up in a ship.... in addition an electric motor in these applications can rotate close to 360 degrees which allows better handling during slow speed operation.

[qbee42]

Exactly. The electrical system replaces all of the complexity of a transmission, and allows multiple engines to be coupled to one or more screws as needed. For low speed cruising you can use one engine. For maximum thrust you can bring more engines on line. Using an electric motor also allows nearly instantaneous shifting from forward to reverse.

The old icebreaker Mackinaw uses two 5,000 Hp electric motors for main propulsion - one for each screw.

You are also correct about the steady loads on a marine engine. There isn't a lot of stop and go. Besides, most big marine engines are diesel. Our sailboat has a 10 Hp single cylinder marine diesel that weighs almost 500 pounds. I don't think that engine would work well in a motorcycle or airplane.

Tom

[Sufferin' Prius Envy]

Oh great! Now a 'hybrid' hole in the water to dump money into.

[qbee42]

An auxiliary sailboat is kind of a hybrid hole in the water, into which we dump money. We get to spend money on the sails and the engine, although with current fuel prices sailing is getting better and better.

Tom

[hobbit]

Problem with a boat is you won't get much in the way of
regen, since water viscosity pretty much makes a boat fall
flat on its face and slow down immediately as soon as you
stop pouring on the coals. A recovery system of any sort
would be infeasibly inefficient if it could work at all.
.
_H*

[Brodie]

Interesting. So basically they use the electric motor to drive the boat at low speeds, where the big engines would be inefficient. Then rev up the big ones to go fast. It does make some sense, particularly for a boat that lives in a marina or canal and has to travel a ways at slow speed to reach open water. Planing powerboats get lousy mpgs no matter what you do, though, and the hull shapes that are efficient at speed are terribly inefficient when going slowly.

it is going to be interesting to see if there are less huge powerboats out and about this summer because of the fuel costs. I wouldn't mind a few less gigantic wakes to deal with!

[qbee42]

Originally Posted by hobbit

Problem with a boat is you won't get much in the way of
regen, since water viscosity pretty much makes a boat fall
flat on its face and slow down immediately as soon as you
stop pouring on the coals. A recovery system of any sort
would be infeasibly inefficient if it could work at all.
.
_H*

There is no need for regen, since there is no stop and go. As you point out, drag stops a boat very quickly without any need for brakes, but boats don't stop very often.

Some sailboats use a towed turbine to generate electricity. It's not that common, but is sometimes used by blue water sailors to generate enough electricity to power electronics and some lighting. Solar panels are becoming more common, as well as wind turbines.

Tom


Tom

[hampdenwireless]

Hybrid makes far more sense for sailboats. They can make power while under sail and have it for cruising in and out of port. The weight of the batteries can be put in low and not effect the boat badly.

In a hybrid sailboat you entirely replace the diesel with electric. The boat is powered by wind and electricity exclusively.