[Public-list] weight distribution and electric power

[Roger L Kingsland]

Wow, my head is spinning (more than usual).  With all this technical stuff, 
I am just happy to know we will soon have an electric powered A30.  Old 
meets new (well, new to us) and we get to measure the results.  Thanks Dan. 
I am so jazzed, I feel like finally learning how to recharge my cell phone.

Have a great weekend everyone.  I'm off to row on the river.


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: "isobar" <isobar at bcpl.net>
To: "Alberg 30 Public List -- open to all" <public-list at alberg30.org>; "dan 
walker" <dsailormon at yahoo.com>
Sent: Friday, September 29, 2006 3:57 PM
Subject: Re: [Public-list] weight distribution and electric power


> >===== Original Message From dan walker <dsailormon at yahoo.com> =====
>>  i was told i can motor 25 to 50 mile before empty. supposedly th batts 
>> will
> recharge as i sail. the system has "smart" chargers that i am to plug in 
> while
> at the dock. i wont know until next springs sea trials how well any of 
> this
> works. the owner of the company is an electrical engineer and a horrible
> salesman. that helped a lot in my decision to give the asmo a try. will 
> report
> in---good or bad when i REALLY know the answers from experience
>
> =====
>
> Dan. Maybe the owner is vague not because he's a bad salesman, but because
> he's a good one.
>
> 25 to 50 miles isn't clear unless you know the boat speed. Remember that
> pre-nuclear submarines could travel  for over a day at 2 knots on battery, 
> but
> only about half an hour at 18 knots. Your range is strictly governed by 
> motor
> current draw at various loads,  and your  engineer/salesman should be able 
> to
> give you a graph of that.
>
> Take some back of the envelope calculations: How much energy does it take 
> to
> push an Alberg thru the water at 5 knots? Guess 8 HP minimum - think of a 
> 9.9
> HP outboard bolted to the transom. - someplace in that ballpark. That's 6
> kilowatts or 6000 watts. With a 48 volt system (same energy as for a 12 V
> system), that's a 125 amp current draw.
>
> If your regenerative braking prop gives back 1 amp @ 48 Volts while 
> dragging
> thru the water at an average 4 knot sailing speed (Generous estimate), 
> then
> the 125/1 ratio means you'd have to sail for 125 hours to recharge 1 hour 
> of
> motoring.
>
> If you have a 25 mile range at 5 knots under power, that's 25 miles/ 5 mph 
> = 5
> hours X  125 amps = 625 amp-hours worth of battery capacity you'd need on 
> the
> boat. How much does that weigh? I don't know about the capacity of 48V
> batteries, but that's the equivalent of  over 25 Deep-discharge 12V 
> batteries.
>
> All the above is guesswork, and I could very well be wrong, but you might 
> ask
> the questions.
>
> Bob Kirk
> Isobar #181
>
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
> _______________________________________________
> Public-list mailing list
> Public-list at alberg30.org
> http://alberg30.org/mailman/listinfo/public-list
>
>
> 



 1159561760.0