Rational for a Hybrid?

[Wayfarer1008]

Reading all these comments its obvious some one is trying to sell hybrid systems that unless you are running a commercial craft have no purpose in a boat. Diesel Electric systems have been around a long time there is nothing new about it. Diesel locomotives, large heavy equipment and ever large harbor tugs all run on diesel electric systems. The advantage is it allowed the diesel to work in its most efficient power range while allowing the electrical motor to work over a range of power needs as required. It also allows the actual motor to be located anywhere without the cumbersome mechanical attachments of a standard motor setup. The new pod style drive systems are a prime example of this and are found on most modern tugs. In a power cruiser and or a sailboat retrofitting to a diesel electric is really stupid in in that the power needs, weight distribution and needs as a main power and or axillary are completely different and are inherent to the design of the boat. One of my favorite mistakes I see out here is people converting race sailboats to electrical power aux. in the weight is a real issue and sticking a bunch of batteries in it make it sail like crap. With power boats the hull design and cruising speed is well established allowing the motors to work within their most efficient range mechanically with no need for an electrical system so what's the point.

[billknny]

Originally Posted by Corvidae

A hybrid diesel only runs at the most efficient speed for the engine, regardless of what speed the throttle is set at.

The most efficient speed to run a Diesel engine IS cruising speed...

Originally Posted by Corvidae

...they can be charged with solar and never run the diesel...

We are not going there... any simple analysis will show that solar can't make a boat go.

Originally Posted by Corvidae

However if you regularly run your sailboat at full motor speed for long stretches, maybe a sailboat isn't the best boat for you?

Most full time cruising sailboats (the ones who actually go somewhere) put about 10% to 15% of their miles on under power. That’s the real world of pragmatic sailors, as opposed to purists. Sometimes you just need to haul butt away from bad weather.

[CarlF]

The "generator running at it's efficient speed" argument doesn't apply to boats as the diesel engine is running at it's most efficient speed (25%-80% RPM) most of the time. As mentioned, cars, trucks and train engines are an entirely different thing.

And solar panels can't generate enough power for motive power - except maybe to get in and out of slip. Few sailboats can find unshaded space for more than 1000 watts of solar panels - which create about 700 watts going into the battery and about 600 watts coming back out.

By comparison, a 45hp Yanmar running at 2000 rpm to drive a 45ft boat at 6 knots is generating about 25,000 watts. While this is a very rough estimate - a full 8 hour day of solar from 1000 watts of panels would drive the boat at the same speed as the Yanmar for about 12 minutes.

[Wayfarer1008]

In Hybrid form the only boat I can think out there that was designed from the ground up that was not a commercial vessel is the Duffy 30. Duffy build electrical harbor cruisers that the wealthy wine and cheese crowd on the west cost love to death. Several years ago they came up with a Duffy 30 based of the Hershoff motor launch that was really trick but at a price tag of $100K + did not have a lot of buyers waiting in line. The power plant was a hybrid system based off the VW diesel Hybrid sold in Europe put into a boat. The diesel would only kick in when the batteries ran low or the boat was pushed beyond its hull speed which was around 6 knots. From a practical standpoint it was an electrical boat with a backup diesel motor to get you home and not a cruiser by any shape way or form.

[David M]

For something floats or flies, it is about energy density related to weight and energy density related to space taken. The more potential energy that can be stored per amount of weight, the better. The same goes for space taken

When you think about it this is why we do not have large passenger aircraft that are battery powered. The stored energy to weight ratio is not favorable. Nor is the amount of energy that can be stored by the amount of space that batteries take.

Battery technology is not there yet and may never be.

[SDChristian]

I'm surprised there aren't a ton of of all electric boats being sold now. If you consider that probably over 90% of sailboats in marinas only get used in the local bay, an all electric charged off shore power makes so much sense.

[john61ct]

Getting ready for transitioning to a big flat slow sailboat plus mostly solar / wind / hydro, genset for when needed only.

[Wayfarer1008]

There are electric outboards that would work fine in a sailboat but the expense trumps their use every time. With inboards the shear weight of the setup is a real issue.

[SDChristian]

Originally Posted by Wayfarer1008

There are electric outboards that would work fine in a sailboat but the expense trumps their use every time. With inboards the shear weight of the setup is a real issue.

Not sure if it was in re to my post, but I was referencing electric inboards. So simple, maintenance free, and adequate for day sailors.

[Perna]

Originally Posted by hamburking

Another advantage is that you don't need to start the engine for those many many times you only need it for a few minutes...like arriving at or leaving a dock or anchorage. For many small boats, that the ONLY time the engine is run, so a hybrid makes a ton of sense.

Also, it separates the engine from the boat. The engine can be placed anywhere convenient. You can still maneuver around a marina with no engine (run on batteries), and you can even remove the engine entirely for service (or replacement) much more easily than if its connected to a shaft. Imagine for instance, a small boat that uses a little portable honda generator. Wow, so easy to maintain (take it home for maintenance) or replace. And so much cheaper too than say, trying to rebuild an atomic 4.

And finally, the hope is that one day we will have another, better power source than batteries. Maybe hydrogen fuel cell, new battery technology, or cold fusion...who knows. By separating the power generation from the propulsion, the boat is ready for whatever may be just around the corner.

I agree with you on all these points. A hybrid for a sail boat is not about fuel consumption but about practicality of design.

Cold fusion might make me nervous though

[barnakiel]

I can see a major advantage of having unlimited electric power onboard.

Another advantage could be being able to motor from the batteries only (short periods).

b.

[Scott Berg]

Nigel Calder, working on an EU grant, actually built a test boat and researched this a few years ago. Read the series in ProBoat for a full analysis
We actually have hard data on the very subject...

[billknny]

Originally Posted by Wayfarer1008

Reading all these comments its obvious some one is trying to sell hybrid systems that unless you are running a commercial craft have no purpose in a boat.

That was exactly what I thought when I started this thread, but hybrid systems get so much attention I thought I might be missing some benefit that was subtle.

Now I know, I was NOT missing something. The posts that say "No" to hybrids are logical and discuss with point with data and calculations. Those that try to argue for hybrids, either are pie-in-the-sky, OR they change the subject from a long range cruising boat to a day sailor--which was not the question.

The moment I see someone arguing for a solar powered drive train on a boat, I know they do not understand the power needs or sources available on a boat--even within several orders of magnitude!--so every other argument they make is discounted as equally uninformed.

[mitiempo]

Originally Posted by Scott Berg

Nigel Calder, working on an EU grant, actually built a test boat and researched this a few years ago. Read the series in ProBoat for a full analysis
We actually have hard data on the very subject...

And Nigel's conclusion was that it is not practical for smaller boats. He suggested it would be practical on a superyacht using electric power in harbors and diesel at sea.

[billknny]

Originally Posted by Scott Berg

Nigel Calder, working on an EU grant, actually built a test boat and researched this a few years ago. Read the series in ProBoat for a full analysis
We actually have hard data on the very subject...

What a waste of grant money. Just to prove what any decent engineer could have told you up front.