Hi Dan,
A turbine blade isn't going to work unless it is inside a turbine housing. A regen optimized prop isn't going to be that much more efficient than a propulsion optimized prop. Since the maximum regen potential of any hydro generation at speeds under 7kts (max average sailing speed for this size boat) is pretty limited, I don't believe that all of the extra complexity in building an non-standard drive system is justified by the small potential increase in regen power.
I know that some members here don't agree, but I think that going with a proven, strong, reliable drive system will create a better boat in the long run. Any regen is just a bonus. Big Multihulls with their higher speed potential make regen a different proposition. But monohulls under 40' should focus on other aspects of their boats.
A MacGregor with internal water ballast is the MacGregor 26, much smaller than Bryan was discussing. MacGregor did build a few 65' ULDBs around 1990, but they're not water ballasted. I don't know many experienced boat people that consider a MacGregor 26 to be a well found coastal boat, but they're pretty good for inshore sailing. I haven't heard of anyone that has spent any length of time as a liveaboard. They seem to be more of a day sailor/weekender type of boat.
I don't think I've ever seen a photo of a 10 ton cruising sailboat with a "dragon tail" drive, that's a pretty novel concept. However, as I said before, I don't think that it's justified.
If one is really focused on a maximized regen system, using an independent, retractable regen unit is probably the most effective way to implement that. But that has it's own cost and installation considerations. Again, I believe that the regen that people are seeing from their regular electric drive systems is pretty close to as good as you're going to get, certainly for most electric sailors here, it is good enough.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, danbollinger <no_reply@...> wrote:
>
> Hi, Bryan. It's OK to start a new thread. New topic, new thread. I think your concept is sound. Look for a MacGregor sailboat with internal water ballast. It doesn't have the weighted keel or daggerboard trunk you will have to deal with. Just replace the ballast tanks with battery bank.
>
> One of the bugaboos of regen is that the shape of a efficient propeller isn't the shape of an efficient turbine blade. If only it was easy to switch between the two. Perhaps a dragon tail shaft so you can lift it out of the water and switch blades from the transom.
>
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