T-Pain Is On A Boat: Re: [Electric Boats] Helsen 23 conversion

Monday, May 31, 2010

Re: [Electric Boats] Helsen 23 conversion

Yes Eric et al, my system is 36 volts because the large sweeper batteries (3) just fit tightly into the previous engine space just aft of the companionway. The motor, controller etc. are for 36 or 48 volts. Roughly 5 hp electric with 6" advanced dc brushed motor. System bought complete from Spincraft Electric Boats, Ottawa, Canada. I do get 4 mph at 25 amps, 5 mph at about 60 amps and top out at 6.4 to 6.7 mph at 100 amps. It could be possibly better than that as I blew my ammeter during some rewiring so it might not show increased efficiency with cogged belts. I do however have the gut feeling that an 11 x 14 prop MIGHT give me more speed, but experimenting costs about $380 Canadian for each new prop. A lot of sailboats my size, 23 feet, use a much smaller diameter prop to keep drag down. I do however have gobs of torque for manouvering.
Dave

From: Eric <ewdysar@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Mon, May 31, 2010 1:11:41 PM
Subject: [Electric Boats] Helsen 23 conversion

Hi Dave,

Your amp numbers seemed high for your size boat until I read in a previous post that you are only running 36V. Can you tell us a little more about your installation, i.e. motor, reduction ratio, batteries, etc.?

As Myles noted in another recent post, this forum seems to be one of very few places where objective data about electric conversions is available. The performance data that you provided is excellent, but doesn't have enough detail about the system to make it relevant to other potential EV converts.

Thanks,
Eric
Marina del Rey, CA

--- In electricboats@yahoogroups.com, David Brooks <avantiman@...> wrote:
>
> What you may not be aware of is that "overpropping" ie. too much diameter or too much pitch will overload the motor at almost any speed or throttle position. I observed the following with my Helsen 23 motorsailer about 3500 pounds loaded. 9 x 6 two blade got 4 mph top speed at 60 amps full throttle.
> 12 x 8 three blade got 5 mph top speed at 75 amps full throttle.
> 12 x 15 three blade got 6.4 mph top speed at 150 amps and hot, hot.
> 12 x 13 three blade got 6.4 mph top speed at 100 amps , not hot with 2 v-belts.
> Same prop with cogged belt gets 6.7 mph in calm water.
> You should always prop to motor's continuous rating, in my case 100 amps at full throttle to not overload the motor. I can run with closed engine hatch for 3-4 hours straight and easily hold my hand on the motor. Cool also means reliable. Bigger may be hydronamically more efficient, but can cause overloading and death to electronics.
> Dave Brooks
>