The fuses are there to protect the wiring, not the attached electrical devices. So if you have the usual 16 gauge wires running from the fuse block, 10 amp fuses will be fine.
I know this post is 10 years old, but grateful to find it! Even a Clymer manual did not tell me! Even better, my brother used this 1987 Sea Ray Seville on Senaca Lake in NY before he passed to me when he died! Thanks!