If you find you have too much power, just buy a watermaker, that'll fix that problem pretty quickly.
Yes, I already have a watermaker that I'll be installing with the panels. That's specifically why I also purchased the panels. These panels in direct sun put out 4.2 amps each. The 90 psi pump for the watermaker requires 4.5 amps...the good news is I've installed 4, series 31 glass-mat 1100 amp batteries. Adding the wind generator should put me on easy street, unless of course, it breaks, but I'm only looking for 5 gallons per day, and the boat came with a 50 gallon water tank. If I've calculated reasonably well, the panels alone will fill the bill on sunny days, by themselves.
Keep in mind that armorphous panels require about 50% more surface area to do the same job a monocrystalline or polycrystalline panel will do in terms of output. Also mounting on either side of the spar is a location that will suffer from some pretty extreme shading and panel performance, even with armorphous panels, drops off rapidly with any sort of shading.
A bimini frame can be a much better location that suffers from considerably less shading and an array 1/3 the size can often out perform a significantly larger array when the location chosen is chosen to minimize the potential for shading.
I will let others chime in on safety....
Safety is my biggest apprehension, but these particular panels are tough as nails and will last. I did measure the loss from shading, it's fairly dramatic, thus the wind generator added next. Really, if you don't have wind for the wind generator, you might as well drop your sails and rely on the panels.
My old Irwin has a very long boom. It reaches only one foot or so shy of the end of the cockpit, so the panels would need to be over the transom.
I really intend on being able to set out in the middle of nowhere and enjoy the ocean, and not have to go anywhere. Fish, write, compose music.....what ever I feel like doing.