Hi Carter,
While you might not use the diesel engine much, I would not replace it with a diesel generator. That would turn your boat into a serial hybrid rather than the parallel hybrid system that you have now. See what the owners of Dragonfly (slowboatcruise.com) did for their great loop trip. Given your small motor, you won't have the power to deal with adverse conditions like heavy crosswinds or strong currents. Your current setup should be ok for most days, but I would hate to see you stuck or worse because you misjudged your power output needs.
I was going to comment earlier that your small motor seems ok as long as you've got a diesel driveline to fire up in emergencies. The whole 1kW per ton guideline is geared to provide enough power to deal with most situations (not Coast Guard rescue boat type conditions) and to keep our electric only boats safe. If you do go serial, you should upgrade your electric motor to something more appropriate.
The only real reason to run an Autoprop is for less drag while sailing. Since you can't sail, a fixed prop will be fine (notice that no power boats use autoprops or similar). You will be able to go much more aggressive in pitch and E.A.R. (expanded area ratio)with the electric motor, but you'll have to temper that with your diesel driveline capabilities. Again, if you go serial, you should be able to improve your electric efficiency by optimizing your prop.
If you get up to 5kW of solar collection, you should be able to collect more than 20kWh per day. That works out to about 8 hours at 2500W, give or take. Most of our sailboats with similar hull shapes can hit 5kts with 2500W. If you get a chance, can you perform some controlled speed trials (multiple passes over a set course in opposite directions) to figure out what your watts to knots performance number are? Without your rig, you'll have less wind resistance, but your stock driveline will suck up more power than you think. I'm really interested how your numbers will turn out.
Fair winds and smooth seas,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Carter Quillen <twowheelinguy@...> wrote:
>
> Tim,
>
> The boat came with the autoprop and unfortuneately it is about worn out so I'm not sure if I'll have it rebuilt or go back to the original 3 blade prop that came with the boat. The old owner did do some comparisons and the autoprop definitely increase the boat performance, by about 15%. I could go back to the old prop and just change the gear ratio of my sprocket to compensate. I'm thinking a couple of sprockets might be a lot cheaper than having the prop rebuilt but I'll look into it before I make a decision.
>
> Regen from the prop is not really an option because I don't have sails to drive it. I think the controller does have a regen feature but the drive train would have to be significantly modified to use it and with 5kW of solar I'm hoping I won't need it. I'm leaning toward eventually scrapping the ancient diesel and putting in a small diesel genset that puts out 48V for when the sun is not shining.
>
> My first mate is the blogger but I'll tell her about the eyefi card. I've never heard of it before.
>
> Carter
>
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