I have no plans on pushing the specs any, its the right motor for the application as far as power goes. The battery bank will be 8 cart batteries, and the controller the Sevcon.
I've certainly read the opinions about carrying what amounts to an entire spare drive train but there are limits to what a single owner can afford and what a single boat can carry. Do I carry a spare motor or a spare anchor? Enough standing rigging to replace everything or enough running rigging? Extra sails? Extra pumps? I know these aren't 'either/or' choices, but I'm not a survivalist sailor worrying about every possible problem. It all gets a little out of hand, so we have to make choices. From what I've read, no personal experience with electric propulsion, an electric set up should not require major spares (like motor or controller) in a vacation cruising context. On a 32' 1960s boat there isn't room or carrying capacity to load up on doubles of everything. I consider two full size anchors and rodes to be prudent but the third 'storm anchor' many carry isn't something I need enough to buy and store.The propeller is inside an aperture protected by a keel, in the unlikely event it is damaged I'll just have to find another way back to port.
$500 is too much money for a thirty pound spare part that will more than likely never be needed and if it is, the situation could probably be solved in some other fashion (getting a tow, sailing in, using the dinghy as a yawl boat.) I don't cut corners when its important and I don't spend more than I have or can either.
If no one has had problems with these motors failing then that's good enough for me to give it a go. If I have failures I'll switch to another motor until I find one reliable enough to fit the service. I suspect the Mars motor is going to be just fine.
David
The good news is that I haven't heard of any problems specifically related to manufacturing quality with a Mars PMAC motor. EV people have been able to burn them up by applying way too much current (> 400A), but that shouldn't be an issue on your boat. The only other problems seem to be related to people hammering on, prying into and generally physically beating up their motor. I'm not sure that a manufacturer should be trying to compensate for an owner's gross negligence.
As for reliability when cruising, since the motors cost little more than a new quality propeller (you should carry a spare), carrying a spare motor is reasonable. The best thing is the ability to replace the entire motor in about 15 minutes after a complete failure. That's faster than most cruisers could replace a cooling impeller on a diesel.
If you're balking at $500 for a spare motor, then it sounds like you might end up cutting other corners that could put you at greater risk than a failed motor.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, David Goldsmith <suntreader@...> wrote:
>
> I don't mean to keep replying to my own posts but I wanted to ad this link.
>
> These guys had the same problem I did and they fixed the motor.
>
> http://acuteaero.com/2010/06/16/breaking-and-fixing-the-mars-bldc-brushless-motor/
>
> Their concerns about the quality of the motor have me wondering if its
> really the best choice for my boat. I'm not a survivalist type but
> reliability is important, I'll be cruising rather than daysailing.
>
> David
>
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