I'm very fond of my
DeWalt DW928K-2 14.4-Volt 3/8" cordless drill. This unit has lots of torque and can go a long time
on a charge. And it comes with two batteries, so you can keep working while it
charges. It outperforms every corded drill I've owned. I bought mine after an
ordinary drill started smoking on the second hole when I was using an auger bit
through 2x10 rafters. This unit handles it with ease.
The fact that it's cordless is a real boon when I go to do work on the boat. Have you ever gotten the extension cord wrapped around you when you're stuffed into a locker trying to reach your work? That's a thing of the past. Plus you can easily work at the top of the mast or out on the mooring.
This drill has a nice balance and isn't too heavy. It can be set on the slow range with the torque clutch eased up and used as a cordless screwdriver.
I wouldn't bother with lower voltage cordless drills, though the 12 volt one is probably OK. Of course the DeWalt DW929K-2 18-Volt 3/8" cordless drill should be fine. I think the 14.4 volt and 18 volt are the tools of choice among building contractors.
Of course, drilling stainless steel and fiberglass is very hard on the drill bits. A basic high-speed steel bit won't last very long. You're much better off with a set of titanium-coated bits or at least a set of cobalt bits so they'll hold up a little while. (Note: I see they have a larger set of titanium-coated bits, but they don't say what sizes and the case is steel and likely to rust on the boat. Still, at this price, it looks like a deal to me.)
For drilling through small pieces of wood, almost any drill bit will do. For heavier drilling, I like auger bits. This set includes sizes 1/4", 3/8", 1/2", 5/8", 3/4", and 1" bits. You'll need a hefty drill, like the DeWalts mentioned above, to keep from stalling when these bits dig in, but you'll drill holes much faster and easier.