Monday, April 24, 2017

Re: [Electric Boats] Re: My Electric Boat Conversions

 

I am going to target boat conversions but very exclusive club.  1000HP+ drag boats. Someone who wants to spend a lot of money to go very short distances like to the marina bar and grill and back. But wants to get there at 100MPH and still hear his radio. 




On Apr 24, 2017, at 5:42 AM, Hannu Venermo gcode.fi@gmail.com [electricboats] <electricboats@yahoogroups.com> wrote:

 

I meant to illustrate the need for lots of power in planing powerboats..
and why they are the worst target for EV conversions.

The power of the motor, and the power of the batteries, have nearly nothing to do with the consumption of that power, in a good modern efficient electric motor.
Ie the eFusion example, say "55Hp" outboard...
The eFusion example You linked to was set up on a tiny, light, small, very easily planing boatd of perhaps 3-5-8x less needed power, vs that of the 11 m SeRay that the OP referred to.

So THAT BOAT might use 5-8 kW to stay on plane, and thus be about 3-5x more long-range than the SeaRay.
Its a small rib, vs a much larger heavier powerboat.
The OPs BOAT is what needs the power, and using an eFusion kit, Thunderstruck kit, or DIY has nothing as such really to do with the basic power needs of the boat itself.

A sailboat of the same length, 11 m == 37 ft, will slip through the water quite well at 4 knots, 4-5, using minimal power, circa 3-4 kW.
As hundrends of examples here and elsewhere attest.

The SeaRay will need 3-5 more power for the same speed, 4-5 knots, perhaps 12-20 kW.

The basic issue is that the SeRay and other similar go-fast planing power boats have a round, heavy, volumnious underwater body, resembling a mango.
This gives them lots of wetted surface,
lots of water to move,
and a geometrically increasing need for power beyond about 2 knots.
They also have a lot of interior volume, since they are so bulbous, relatively speaking.

In comparison, a sailboat is more like a peapod.
Long, slim, gradual taper.

So the searay might use 15 kW for 5 knots, while wallowing, and 15 kW, for 15 knots, while planing.
Range = 30 miles. Planing. 1 hour to get there.
Range = 30 miles. Displacament. 3 hours to get there.

But the same-length sailboat would use 3.5 kW.
Range = 128 miles.
3 hours to get there.


On 23/04/2017 00:19, 'Dan Hennis' dhennis@centurytel.net [electricboats] wrote:
Hey Hannu, you might want to look at the eFusion 550.  https://www.youtube.com/watch?v=ocBjwDom0rA
 
I think they boast 55 H.P.  And they have something like and hour of runtime on a set of batteries, at full throttle.  This is one of several that have successfully built a higher power unit for the consumer.  I personally researched several for my 18'-6" ASD e-Tug.  I settled on twin 25 Kw units, opting for the most I could afford and the best suited at the time.  I have seen several one-offs that seem to be using the 20, 30, 40 KW brushless and "cosmic" batteries (LiOn, LiFePo, etc).  I think it is possible, just not cheap.  A lot of due diligence, and D.I.Y. are involved, and possibly some Devine providence. <mime-attachment.png>

--   -hanermo (cnc designs)

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