T-Pain Is On A Boat: Re: [Electric Boats] electric drive for a pram tender

Saturday, September 5, 2009

Re: [Electric Boats] electric drive for a pram tender

Yes , I really appreciated Eric's post too.
I'm dealing with what could be a life and death issue , so I'm taking great care to make sure i get this right.
Its pretty scary when you don't have the ability to counter the wind , and you can see yourself being blown out to sea , or maybe on to the rocks of the breakwater.
So , if I have engine power , it too will have to be able to do the job.
Yes , I would love to go electric , but first priority is to find and use whatever is the safest , in my circumstance.
Regards Rob J.
--- On Sun, 6/9/09, Arby bernt <arbybernt@yahoo.com> wrote:

From: Arby bernt <arbybernt@yahoo.com>
Subject: Re: [Electric Boats] electric drive for a pram tender
To: electricboats@yahoogroups.com
Received: Sunday, 6 September, 2009, 12:26 PM

Good advice, Eric.
In addressing the concerns of potential customers for electric conversions, the first question is usually "How many miles will is go on a charge?". A better question would be "How many years can I get service-free operation?", or "How much battery will be required for harbor maneuvering?". Range on pure electric propulsion is not the feature best promoted. My current test boat, an Ericson 27, has a range of five to 15 miles on the 200Ah 24v string. If the wind dies off while we're far out to sea, I wouldn't consider the electric drive for a long motor back to shore. I know there isn't enough energy to do the job without a deep discharge. There's a long shaft 15hp outboard in a dry-sac and five gallons of stabilized gas under a hatch. I don't know what the battery equivalency would be, but I'm certain that it would be ridiculously large. In electric vehicle conversions, the rule of thumb was 800lbs of lead equals one gallon of gas with old school wet
cells, but even 50% improvement with AGM's would still be very heavy.
Electric conversions need to promote the advantages of a clean environment, silent harbor maneuvering, and years of dependable, service free operation.. Keeping a outboard and fuel stowed for long passages is belt-and-suspenders (as my John Deere QC mentor would say). The well equipped boat should always have redundant systems.

Be Well,
Arby

Advanced Marine electric Propulsion

________________________________
From: ewdysar <ewdysar@yahoo.com>
To: electricboats@yahoogroups.com
Sent: Sunday, September 6, 2009 8:04:28 AM
Subject: Re: [Electric Boats] electric drive for a pram tender

Rob,

I have a Torqeedo 801 and it is almost as powerful driving my dinghy at full throttle as my 2hp 2-stroke outboard. Unfortunately, full throttle will drain the battery completely in about 20 minutes. To get 1 hour or operation, the motor needs to be run at half throttle or less. This equates to about 3kts in an inflatable, in still water, no headwind.

I use this motor on my inflatable with my F-27 trimaran at the isthmus at Catalina Island and I try to anchor as close to the dock as possible. At a couple of hundred yards, I can get 4-5 round trips in a protected anchorage over the course of a weekend, though I run slow whenever possible. I also carry the small wall charger that comes with the motor and plug in any where I can while I'm ashore.

Realistically, a 2hp ICE outboard will cost less than 1/2 the price of a Torqeedo, and run over 3 hours at full throttle on 1 gallon of gas. With a gas engine, you won't have to worry about range or power.

I bought the Torqeedo to be able to carry the motor folded in one of my float compartments. Now that I own it, I have accepted the considerable limitations of the system and have adjusted my usage to match the motor. It is the most efficient answer available today in electric motors considering total operating size and weight, but the cost is prohibitive. Normal trolling motors with just one L/A battery are cheaper, but will weigh 3-4 times the Torqeedo or an ICE equivalent.

Given your description of your situation, I would probably choose the Yamaha. I'm a big fan of electric, but trying to use electric under difficult conditions will be an expensive experiment that could end up very dissatisfying.

Good luck,
Eric
Marina del Rey, CA

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