Hi machael,
The Fisher 37 pilothouse ketch looks like a nice boat. The displacement is what the displacement is, so it it's going to take a decent sized drive. One rule of thumb is 3hp ICE:1hp electric but with Fisher 37s with diesels that range from 75hp to 150hp, that number will probably be misleading. The manufacturer used 80hp engines for a long time and that translates to 20kW, but the installed range goes from 18.5kW to 37kW. Alternatively, we know that boats seem to operate well with 1kW/ton of displacement and that puts you right at 16kW.
With EY spec of 17kW for their 360ibl at 48V, the drive should be able to drive the boat acceptably. Your batteries could get hit with a 335A load at full throttle, but that can be handled with appropriately sized cabling, fuses and other components.
Given the size of your boat, you might consider bigger AC induction drives like the Solomon Technologies systems rather than the aircooled PMAC or BLDC motors. You could also go with a big DC motor or another type of EV motor. I don't know how efficient these EV motors are at low speeds and/or current.
But I believe that a quality electric solution will cost as much or more than a typical rebuilt diesel repower, especially in a boat your size.
Since you brought up regen, I'll say it again. I haven't seen any substantiated report of 80W @ 5kts. Push the boat up to 6kts and I would be very surprised to see 120W of regen. I've seen brief moments of 60-70W while sailing my boat at 6kts but nothing consistant. Once a boat hits a consistant 8kts+ (big boats and multihulls), then regen starts to cover more than conservative house loads. It's the data that nobody likes to hear, but if one motors at 4kts, you typically have to sail 40 times as long at 5 kts to recover all the used energy. That means 15 minutes motoring at 4kts will take 10 hours at 5 knots to recharge the traction bank, longer if you're using any of the energy for house loads. At 6kts, the time to recharge 15 minutes of 4kts motoring drops to 6.7 hours. Again, adding in any house loads extends the recharge time. But on a long passage, 100W for 24 hours does come to 2.4kWh. If you can keep your house usage to half of that, then 1.2kWh could end up back in your batteries. It will rarely be of any significant value during coastal hopping or gunkholing. I still want somebody to prove me wrong, I've been waiting for a while now....
Wind generators don't seem to deliver as much as they sound like they would. The noise, hassle, and aerodynamic drag of a wind generator while sailing has convinced a number of electric boaters to remove them after a while.
Photovoltaic panels seem the be the most predictable source of renewable energy for a boater. They're silent and work when you're at anchor. Virtually everyone who has them, likes them.
A number of people have come up with an ICE generator solution as an additional backup (including me), but in practice, most electric sailors in the group rarely have to resort to using them. They may be more of a psychological benefit to a boater. Therefore, i wouldn't commit too much time, money, and effort into an ICE generator solution, I think that minimal emergency support should suffice for this type of system (kind of like a life raft).
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, Michael Mccomb <mccomb.michael@...> wrote:
>
> i really didn't read this post until i had already offered up a bit more about the boat...
>
> going electric to become more independent... my tendency is to gunk hole and avoid civilization EXCEPT for the fact that i used to get quite nervous as my fuel depleted... it's mainly psychological but with regen i don't believe that I would worry much about it at all
>
> at the reasonable 85% hull speeds of the boat regen would be almost non-existant based on speeds stated by some but then others claim that regen would begin at 3.5-4.5 knots and that is consistently done.... realistically i could almost always rely on getting 6 knots
>
> of course voltaics could contribute significantly as well.... like the looks of the "stik"
>
> getting back into sailing after more than a decade away from any of it and 25 years since anything too serious.... boats on the hard
>
No comments:
Post a Comment