Re: [electricboats] Advice for electric conversion

I replaced a diesel/v-drive  in a similar sized boat (33', 12,500 lbs).  I used a 12kW motor and built a 280AH 48V LiFePo4 battery.  Lots of details here:
http://dan.pfeiffer.net/10m/electric_drive.htm

The 12kW motor replaces a 23hp diesel.  I did not re-use the v-drive, I made my own reduction drive with a 3:1 belt drive.  It fits well in the space that the v-drive occupied. 

The performance of the 12kW motor is at least as good as the diesel (which was a very good match to the boat) and is significantly better at slow speeds.  The only deficit the electric system has compared the diesel is range.  I have 25 to 30 miles range at 5.5 knots Vs 110 miles with the diesel.  For my daysailing use this is not a problem.   A 5kW genset would be able to power the boat t 6 knots continuously. 

Dan Pfeiffer

On 2023-09-24 9:32 pm, Alex from Frolic wrote:

Hello everyone, 

Alex from SV Frolic here, with some technical questions as I’m trying to build a system. My boat is a 1973 Columbia 30 (not the sport sailer with an open transom, but rather the raised deck one). I’m wanting to do a 48v battery system totaling around 400Ah, and convert to electric. Herein lies the issue:
my boat was originally sold with a gas motor, a Palmer P-60, mated to a v-drive transmission. 

I haven’t found much information as to the conversion process to electric for v-drives. And I’ve heard many people say they are touchy, sensitive transmissions as well. I’ve seen plenty of reduction gear setups for direct drives, even electric outboard builds, but nothing for a v-drive. 

That’s issue number one. 

Furthermore, I’m not sure what size motor to go for as I’m replacing a 4.0L 60hp inline 4 gas motor with plenty of torque (well, probably back when it ran). 

the displacement of my boat is factory 6 tons but in practicality I’m finding it’s more like 7 tons, or about 14k lbs. 

I’m new to EV’s and mechanically handy, but I’m fed up of this rusty old gas guzzling hunk of junk that always needs SOMETHING else. I’m dying to get out of the marina and shipyard routine. I miss my sea time. Thanks for your help.