T-Pain Is On A Boat: Re: [Electric Boats] Electric planing dinghy

Thursday, May 5, 2011

Re: [Electric Boats] Electric planing dinghy

Thanks Dennis, I was afraid of that (only half RPM). I wander if sufficient pitch is available.
We haven't however made the choice of which outboard to convert yet.
We'll try the 5Hp and learn.
And then there is this http://www.electricmotorsport.com/store/ems_ev_parts_motors_agni_b95r.php at 6000 rpm but a little pricy.
Btw he prefers the brushed Mars because of the possibility to bypass a toasted controller, but little difference that makes for rpm.
The whole project is cutting edge, so all choices prop/motor/batt/etc are critical.
Rob on Linda

--- On Thu, 5/5/11, Dennis Wolfe <dwolfe@dropsheet.com> wrote:

From: Dennis Wolfe <dwolfe@dropsheet.com>
Subject: Re: [Electric Boats] Electric planing dinghy
To: electricboats@yahoogroups.com
Date: Thursday, May 5, 2011, 7:01 PM

A MARS brushless motor will turn about 2300 rpm at 48 volts when loaded to draw about 80 or 90 amps. This is a little less than half the RPMs of an outboard at WOT. You will want to get the highest pitch prop the outboard leg can fit.

Borrow somebodies 5 hp outboard and try it out on the planing hull. That at WOT will approximate the performance of your ETEC conversion.

On 5/5/2011 9:40 AM, rob_linda_2000 wrote:

Since liveaboards and cruisers anchored here in the lagoon have gotten used to seeing me move around in all weather in my solar powered sailing dinghy "Big Oil", without ever having to buy gas, I do a lot of explaining (preaching),answering questions etc.
So I got an invitation to assist in the design and electrifying of a planing dinghy. Since I was impressed with the performance/weight of said dinghy, I accepted the invitation and would like ideas/comments/etc from this group.
Dinghy:
16 Feet, made from some high tech foam, so light, that the guy has to BALLAST it. Presently it has a 15 HP in the back and if you open the throttle halfway, it jumps straight on the plane and remains planing throttled back to about half that.
Range:
It will only serves as ship to shore tender, 2 15min trips and back at most per day (between charges), so design is for 1 hour usage at minimum planing speed
Motor;
DIY outboard conversion using 48V ETEK or simular
Batteries:
Lithium 130Ah (for now)
Charging from solar panels/generator on mother ship
Question:
We're trying to establish lowest RPM for planing with the 15HP and needed RPM for planing threshold, but still looking for right handheld tachometer.Any ideas out there, how RPM's of typical 2cyl outboard compares to ETEK/MARS at 48V
Other question:
We will be looking for 48V solar controller for lithium. Any suggestions?
Any feedback is welcome
Thank you

Rob on Linda