Sure regen works! But what you offered as an example (towed gens) is not technically regen---we use "regen" to refer to using an electric drive motor as generator when the medium (in this case, water) can back drive the motor. The towed generators are not used to drive the boat but instead solely used to generate electricity---hence "regen" doesn't really apply.
On performance: If you read the last paragraph of the weblink you provided, "Final Note: On our last overnight run…we were seeing a steady 10-12 amps going into the house bank with the tow generator and mast-head mounted wind generator whirling away…Not bad for 15-18 kts of wind and 6 knots of boat speed."
Translation: a total of 250watts delivered from BOTH an Ampair wind generator AND an Aquair water-powered tow-generator. He mentioned the Aquair delivers 2amps for each knot above 4kts. So at 6kts, that's either 4 or 6amps (depending on how you read their statement). Assuming it's 6amps, that's about 70watts from the Aquair (at 6kts) and about 180watts from the Ampair (at 15-kts of wind).
How significant or valuable is 70watts of generated power at 6knots? Depends. For an electric, strictly power boat not expecting to anchor in 6kts of current, it's meaningless. For an electric sailboat that could easily be driven 6knots or greater from wind, the value of capturing water power to generate electricity depends. That 70watts will likely be delivered at about 60% efficiency. This means that about 110watts of water power was used to deliver that 70watts. That slows the boat down a little. Not much, but say your boat can hit 6knots with 1500watts---that 110watts of power loss could be noticeable. And even with 10hrs cruising at 6kts with the wind, this would be but 700wh of power delivered to the batteries. If the wind stopped, that 700wh generated would only allow ½ hr of electric cruising----it's less energy than a single charged T-105 battery carries. Not trivial, but the numbers are important. Bottom line is that each sailboat owner needs to go thru the scenarios to see if it makes sense for them. Price point ends up being key. With an electric sailboat, paying a little extra for regen in a controller is probably justified for many. For others, it's not.
-Myles Twete, electric bargeboat "The Reach Of Tide" www.evalbum.com/492
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Larry Doyle
Sent: Sunday, November 28, 2010 8:20 PM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] Re: Converting an Albin 27
Here's to those NaySayers that say regen doesn't work. Here's some boats that are doing it using towed gens as well as the free wheeling the prop/dc motor in regen mode.
From: Dave Kellogg
Sent: Sunday, November 28, 2010 8:01 PM
Subject: Re: [Electric Boats] Re: Converting an Albin 27
Mark,
I hope I can get those good numbers in tests to come, have done pretty close with my ChrisCraft Capri 30. My drive prop is a 14X12 three blade that I've ducted with a Rice speed nozzle modified. Thrust is great and the preliminary numbers are close to yours. For a 12000 boat that isn't as slippery as yours its pretty good, but I'm still working on the system. My boat needed a total rebuild inside and out so it wasn't just a put the electrics in place. I've build a 5 blade 11 pitch prop from composite, I am not as concerned about push as I am about developing the best prop for regen while sailing.... a topic that everyone says isn't worth the effort, I disagree and will continue the project until I have things in working condition... as Winston Churchill once said, "don't ever, ever, give up".... chuckle.... I won't...
Dave K
From: acsarfkram <acsarfkram@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sun, November 28, 2010 1:03:15 PM
Subject: [Electric Boats] Re: Converting an Albin 27
Hi Dave,
My boat is actually a Bruce King designed 1976 Ericson 27. And my current motoring numbers are better now that I have a larger (12x10) three blade prop; 4 knots at 20 amps.
Mark
Santa Cruz
No comments:
Post a Comment