[Public-list] weight distribution and electric power

Thu Sep 28 12:30:13 PDT 2006

first, i hate typing so my e mails are usually short.
   i already bit the bullet on the electric.
   i considered just getting the grey back to snuff, but do not want any gas on board. thought long and hard about a beta and a yanmar, but with my projected useage of rascal for the next five years the electric seemed the best(no, i can still convert back to a diesel if i want/need to) 
  the basic cost of the system was about 1200 less than the beta(basic beta without any additional cost of fuel tank,exhaust/water muffler and all that) and the diesel would have required all that. i know since when i went to remove the exhaust if fell apart in my hand---and i was worried it would be a chore to get the rusted components apart. don't know if any of it could have been used anyway, but it was not going to last much longer.

  the system is  48volts. needs four batteries. the motor, controller, and three batteries are going in the space where the grey sat with one battery going where the old gas fuel tank was. each batt weighs 70 pounds, and the motor about 30.

  so the fuel tank/batt exchange is about a push. the motor batts is about 240 versus rogers quote of 300 to 320 for the grey. a gain plus the loss of the muffler and exhaust pipe---another 20 or 30?  my query about the distribution was i sit and look at the space aft of the motor where the batteries would fit. less convenient, unless i put in one of those bomar hatches.  but i am tired of all this so no hatch, batteries where the grey and the fuel tank was and with luck and both weddings paid for i can go sailing in may!

dan 
  rascal 145
  Dan,

Electric sounds way cool; quiet, no smell. Are you planning on an internal 
motor or an outboard? Please document the project and report on the 
results.

Relative to weight, doesn't the Atomic 4 weigh about 320 pounds, plus 
another 70 or so for fuel and 50 for existing batteries? That leaves 170 
pounds net for the electric motor and all that crazy electronic circuitry. 
Might be about a wash weight-wise.

Relative to weight distribution, aren't the gas/diesel motors mounted pretty 
high (bottom above the cabin sole) while internal electric motors are pretty 
much in line with the prop shaft. I think more useable space for batteries 
can be had under the cabin sole by making larger hatch openings and 
modifying the "bulkheads" separating the compartments (seem to recall 
someone on the page mentioning he had done that and had photos). Don't know 
if there would be enough space there for all the batteries but, even if a 
few have to go under the main cabin bunks or galley base, net weight 
distribution would probably be lower and further forward than the original 
A4 solution. Some on The Page have opined that A30s tend to "squat," so 
weight a little further forward might be desirable. If you use an outboard, 
net fore/aft weight distribution might be a wash if the batteries go forward 
of the cockpit.

I did some preliminary investigation multiple moons ago and seem to recall 
that a burst of power can be had at the expense of substantial battery drain 
but sustained cursing speed is lower unless many batteries or a substantial 
generator are part of the package. What are the specifics of your proposed 
system?

Roger Kingsland
Managing Partner
KSBA Architects
3441 Butler Street
Pittsburgh, PA 15201
N40°- 27.83' W79°- 57.99'

(412) 252-1500 x101 office
(412) 779-5101 cell
(412) 252-1510 fax
www.ksba.com
----- Original Message ----- 
From: "Gordon Laco" 
To: "dk.campbell at sympatico.ca, Alberg 30 Public List -- open to all" 

Sent: Thursday, September 28, 2006 9:13 AM
Subject: Re: [Public-list] weight distribution and electric power

> Dan,
>
> Don brings up valid points - a reasonably powerful engine to motor out of
> trouble with is a valuable card to play when the chips are down. The
> electric motor is an interesting way to go but should only be looked on as 
> a
> fair weather aux for use getting on and off your dock in calm weather.
>
> Cheers - Gord #426
>
>
>
>
>
>
>> Dan,
>> My thoughts are that you will have increased wetted surface so slower,
>> centre of resistance moved aft, so increased helm, and no power for 
>> getting
>> through waves. Don't do anything you can't change back if the motor is 
>> too
>> dangerous, because of a lack of power, to use the boat safely. Having 
>> run
>> both LP gas and electric fork lifts, there is no question of which is 
>> more
>> powerful, and that was with 1400 lbs of battery.
>> Don #528
>>
>> dan walker wrote:
>>
>>> for many different reasons , i decided to install an electric motor. now 
>>> i
>>> need to install the batteries. i remember gordon did some scientific 
>>> weight
>>> distribution observations, so here is the question. how would the 280 
>>> pounds
>>> moved aft affect the sailing characteristics of rascal. any thoughts?
>>> dan
>>> rascal 145
>>>
>>>
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