Regenerative Propulsion Help

In this situation, technically it does make sense.
And economically? The question is - how much a Watt produced in this way costs, and how does it compares to a Watt produced by other means?
I don't know the cost of the regenerative system, so I personally cannot answer. Hopefully someone else will share the numbers here.

 

A completely different situation Mark. That doesn't slow your boat down.
All you need is a multi-V pulley on the prop shaft, an alternator and (for a sailing boat only) an electric clutch from an A/C compressor.
With the clutch disengaged, the alternator poses no drag for the sailing boat while under sail.

 

But don't discourage the research! I spend some hours every day anchored in one to three knot current. If it were simple and not too much money, I'd love to generate a little power at these times (to run the Espar, computers, radars, top off the batteries, and such).


Simply get 100+ ft of old fire hose. Place wood flaps sewn as hinges every 6-9 inches, and sew the hose to a cont loop.

Use a car wheel and bearing to mount the wheel (no tire) horizontal at the stern.

Place the hose over the wheel and trail it astern.

Done right the little wood flaps will catch the current stream , and fold flat on the return to the boat.

Great power , cheap, for 4 + hours a day of high current time .

Never figured how to keep other boats from chewing it up tho!

FF

 

The lower end (prop) of a "Walker log" combined with one of those low rev. wind gen. units would probably do the trick.

Regards
Richard

edit:
ah no, it does not! I have forgotten that the log is designed for low drag. But it could do with enlarged blades.

 

Vinosail, I think the problem is your use of the concept "regenerative". Regenerative systems work in land vehicles because they often have to slow down. In doing so, brakes turn kenetic energy in to waste heat. In a regenerative electric automotive system, this wasted kenetic energy is re-captured. On a marine vessel however, there is hardly ever a need to "brake". The viscosity of the fluid is always fighting you and is constantly disapating any energy input by the propulsion system (also true for land vehicles but most land vehicles are not large enough for this to be a significant effect). So a sailing to propel the vessel and trailing a screw to generate power is not "re-generating"...it is robbing propulsion to generate power.

That said, there are plenty of "re-generative" systems on marine vessels. Economizers, inlet air heaters, waste heat boilers are all examples of regenerative systems.

 

This was one of the regenerative systems I found, could you please explain the problem associated with Beneteau?

As for "regenerative" propulsion, one possibility I looked into was installing a wind turbine on top of the mast, or a micro water turbine of some sort.

 

No, I don´t want to explain other builders failures.

The wind gen high up in the mast is a rather bad idea, don´t you think? Imagine the power generation and the drag are related.

 

Vino-Richard can't say,so I will.

They had problems and were much heavier-bad on a sailing cat,so were slower and had more maintenance.
Last I heard, it was taken out of all except 2 or 3..one of them a full time liveaboard ( so it never moved) and Lagoon offered a program to do so for minimal cost.

But I'm not 100% sure so why don't you sign up and ask on their owners' group????

Once again-solar panels and a $2k 5hp diesel DC genset-we crossed the Pacific and stopped at almost every island,on $60 worth of diesel.

Or go spend $$$$$ on a complicated system and you'll never pay it off.

 

Thanks for the suggestions. So far from what I calculated for a small sailboat, the efficiency of the propeller functioning as a turbine appears to be extremely poor.
My university doesn't have the equipment to test any propellers, so does anyone know what power output seems reasonable.

I've just been basing all my calculations on a 5 knot boat with a 15" prop.

Does anyone have anything to comment on the water turbines? From what I gather, they basically are podded propellers that function like a wind turbine underwater.

 

This one:
http://www.ampair.com/ampair/waterpower.asp
manual and data here:
http://www.boost-energy.com/UserFiles/Downloads/UW_100_manual_rev_Feb_2007.pdf

though designed specifically for that task, has only 3.8% generator efficiency, giving 100 W in a 8 kts (4.1 m/s) current, at 1500 RPM (prop disc diameter = 0.312 m):
It will give around 70 W in a 5 kts (2.6 m/s) current, at about 800 RPM. so the generator efficiency goes to 10%.
You can confront your results with these numbers.

P.S.
I've corrected the term "Betz efficiency" to "generator efficiency", since Betz efficiency is referred to the turbine aerodynamic efficiency, while the above electrical output data include the conversion losses too.

 

No, that's not true. The prop will do very well, even better than when used to propel the boat because there will be much less slip due to the lighter load.
But to generate a significant amount of electricity, you need much more rpm than is available at the prop shaft, so the alternator must be geared at least 5:1. And you loose some power in the stern tube seal and the gearbox, but there is nothing you can do about that.

I watched the props on my boat rotating when anchored and the wind shifts, pushing the boat to the other side of the anchor. It has oil filled stern tubes with Simmer rings: you can turn the props with your little finger.

 

Your first request was Regenerative Power generation.

Your last request was pure battery recharging, while the boat is traveling fast enough to use wind power in the sails.
Somehow you need to eliminate the battery recharging from your paper.

Regenerative power should only be available or used when the boat needs to slow down. Very rare condition in a cruising boat.

You may want to discuss this with the professor. He should allow a different topic. Or he may say. Well done. Just write up all the negative findings of Regenerative Power in sail boats while cruising in no traffic or long hilly conditions.

Good luck
Rich