Hybrid sailing trimaran with electric outboard and regenerative capability

Well the question always was
"is the losses from all the compromises in said developmental syste
Worth it based on the free electricity generated"

I don't know the answer. I wonder what the actual percentage of loss would be based on one 90 degree turn...

 

That would depend on the efficiency of the method used to make the turn. Outboard motors make one 90 degree turn, Outdrives make two. Both use planetary gears.

I have heard numbers from 5% to 10% loss from a 90 degree shaft turn for these systems. There are hard numbers for these losses as thousands of industries have been using these methods since the first waterwheel was used to grind grain.

You may have additional losses for what you want to do because you have to make the unit robust enough for thrust which will be major overkill for regenerating which will increase losses because you now have to turn much bigger stuff than you have to to generate.

All the energy you use to actually turn shafts and gears is lost. And as masalai said the shape and style of the propeller between what is efficient for propulsion and what is efficient for generation is quite different. Any compromise with the propeller will contribute to further losses in both propulsion or generation.

The combined total of all these losses against the small amounts of energy you may generate only when sailing fast enough to generate anything substantial will make the system too inefficient to be viable.

I think

Again, thats why electric drives are almost always direct shaft drive.

Steve

 

So what if we changed out the prop when we wanted to regenerate, or what about some sort of variable pitch prop?

By the way this boat's average cruise speed is much faster than most monohulls. Over the last 120 miles sailed we averaged 7 knots.

 

Planetary gears are not used for turns. Perhaps you mean bevel or hypoid gears.

Auto industry experience is turning power 90 deg with bevel gears results in a loss of 1-2%, hypoid gear losses are slightly higher.

The largest source of "losses" in generating power from a propeller or similar device while undeway is the propeller efficiency itself. Marine propeller efficiency is typically 50% to 60%.

 

Thanks for the correction DCockey.

My last sailboat was a Mac Gregor 36 and I have raced on F27's so I am aware of the speeds. Avg 7 knots is fast, but only by sailboat standards.

"So what if we changed out the prop when we wanted to regenerate?"

That would eliminate some of the loss, but only a part. You would still have the losses from turning gears and shafts larger than you need and losses from shaft turns plus several other small losses like voltage drop and corrosion resistance. Balanced against your average speed and how long you sailed I personally don't see anything effective let alone cost effective.


or what about some sort of variable pitch prop?

It's not just the pitch, it probably includes diameter and blade area too as far as what is optimum between thrust prop and generation prop. Remember, even a hi thrust prop is designed to turn much faster than a prop that generates power at 7 knots.

Take a duo gen unit which seems to be an efficient unit. The manufacturer says it makes 11 amps at 7 knots which is about as good as any manufacturer's claim but lets go with that for now. At 10 amps it will take you 9 hours to fully charge a medium sized deep cycly battery. The duo gen is a direct drive mission specific carefully engineered unit. http://www.duogen.co.uk/ I doubt you can cobble together something with gears and / or belts that can even approach that kind of efficiency, especially when you will also ask it to provide propulsion.

What would be more effective is seperate thrust and charging units.

Steve

 

I like the duo gen concept, I just don't like the price

So if you wanted to build just a system to generate electricity what would you suggest?

Obviously a system built off of a car alternator would be easy to assemble from off the shelf parts.

 

"Obviously a system built off of a car alternator would be easy to assemble from off the shelf parts."


Not really , car alts have to spin at a high speed to produce rated output.

In the past folks have re wound car alts to put out something at very low RPM.

I have seen them , but have no idea how it was done.

FF

 

The people I have working with me on this project seem to think that a pulley system to spin the alternator at an appropriate speed would be effective.

 

Have you seen this?

If you follow the Ikanos link, and then the 'marine' section, you'll find what sounds like a fascinating system for regenerating power under sail.

I like what you're trying to do - it really should be possible to have a fully functioning sailboat without a diseasal onboard.



Note: Brand new member, first post, big fan of Farrier trimarans.

 

I have been looking at http://www.re-e-power.com/ coupled with a Honda 3000 and 1000watts of solar power for a folding proa design I am working on.

 

StanLee keep up the good work (ie. thinking and attitude, as well as choice of boat). The drag from an outboard is not that significant, my little Farr 6000 can drag the outboard along without a huge penalty and the prop has not been optimised for being dragged. My thought is that the the use of electric propulsion makes great sense, if you need an IC engine generator the weight is better low down and nearer the middle rather than hanging off the end. Using the electric motor to generate makes sense, why carry a separate tow generator when one device with all the right wiring and connections is already present. As well, tow generators tend to loose their empellers as sharks find them enticing.

 

I like your idea BUT!
You are asking one machine to do two different incompatible functions as practically EVERYBODY above pointed out.
Here is an option that WORKS.
http://cruisingresources.com/Water_Power

With a tri, you could tow 3. One from each stern!
and they stow securely and compactly.

i'm planning on getting a couple for my mono hull!

 

I would have thought that the losses are greater then 1 % when you look at the lower numbers when outboards went from crankshaft to propshaft rated.
I'd say 5% to 10%
Most gear sets are spiral bevel cut, race only stuff is straight cut

 

Do you do that propeller locked or free wheeling?

 

Suggest a chat with the owner of current sunshine...the trimaran...you will get the real story from the horses mouth...so to speak.
Mick