Paul,
I forgot about the prop design and you are correct. The pitch is more and 3 blades is a normal design. It's not a switch, you're in neutral or in my case a slight bump on. It's more again dependent on the size of the boat as to how much drag you incur. Heck I have 2 of them down there! Anything is going to incur drag but how much depends on a number of factors. A fast, light boat is going to be much more susceptible to anything hanging down below on a fixed installation. There are several manufactures with retractable props for smaller boats out there and I would probably be looking at that for light air. But us big nasty CondoCats are not so susceptible to anything hanging down. We might loose a 1/2 knot or 1 knot but we don't care sitting in the back drinking coolaid and burning the dogs! :o)
Steve in Solomons MD
Steve,
For me at least -- and this may be because I don't fully understand the technology -- the issue is that regen isn't just a switch you flip or an option you order with the controller...it's also about selecting a prop that can regen efficiently. Such a prop will incur worse drag whether it is re-gen'ing or not, correct?
My boat has a two-blade prop which hides in the aperture when vertical (or pretends to, at least). I feel like this makes a difference when sailing, though I don't have a knotmeter so I can't back that up with data. If I keep this prop (or one similar), my understanding is that regen performance will be even worse than otherwise.
In other words, you commit to the drag when you affix the prop, and you can't take it off in light air when you can't stand the drag.
Is this understanding correct?
Paul
--- In electricboats@yahoogroups.com, Steve Dolan <sdolan@...> wrote:
>
> Eric,
> I would suggest that the regen may not be practical on a 2 or 3 hour 5 knot sail but what if you sail for a distance and use power for the stereo or a few gauges? What if the total usage of power during an overnight run equaled your regeneration rate? "Anything that is free is for me" so any power I can get is good thing. It may not be able to fully charge your batteries but it's better than nothing unless the drag exceeds the benefit. What if you're on the back of a 20 foot wave heading down and can get 6 amps (or more) all the way down and half the way up the next wave? You could run your motors at 2 knots and gain 50 miles in a 24 hour period at no cost. I didn't do the math but should be close. Anyway even a little regen is better than no regen. But then again the majority of boats here are smaller and don't travel as far. I think if I had a smaller boat and it was free or included in the package I would think of it as a plus. Now if I had a tri (I do have a MR2 spyder) for nothing but speed the weight would definitely be a consideration. I'm surprised you don't just have a couple of paddles! You could probably still get up to 5 knots :o)
>
> Steve in Solomons
>
>
> I know that my 30' ketch has only touched 6kts a couple of times in over 10 years. 5kts takes a solid breeze for my old boat. So I don't expect much from regen from my electric drive, even when headed offshore to our local islands.
>
> Alternatively, my 27' trimaran has hit 6kts boat speed in only 5kts true wind. If I converted that boat to electric, that kind of performance would no longer be possible. I'm not willing to sacrifice my good runs at 15kts+ boat speed to go electric. The 9.8hp outboard is auxilliary power that works for me.
>
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