SD's comments are spot on. Basically, you can wire the thing properly with a 50 amp in-line fuse, or just never draw that much power with it by running something smaller or running big wires to a smaller circuit breaker.
Another consideration, and one perhaps more flexible, is what I did: I got a 700 watt "power pack" with a light and an air pump and two AC outlets that is charged while at dock and then kept in a locker.
Basically it's a 28 Ah AGM in a box. It carries enough juice to charge VHFs and to charge/run laptops for several hours without the cost or hassle of wiring, and with the convenience of portability. I've used it to run sanders and Dremels for up to an hour when I didn't feel like running 150 feet of extension cord across the yard, and it's been nice to have in the Zodiac to run truly bright spotlights to see debris in the water ahead when running at night.
Oh, yeah, and you can start your engine a couple of times with it.
Another alternative is this, of course. I tested it with a 1500 W hair dryer on "melt head" and it didn't flinch.