Yes. I ran mine to the ign. It didn't work for shit, ran a 10GA primary wire from the battery, it works bitchin'. Thanks Ralph!
X2, That's why you'll normally see a relay on there, as mine did. The more crap you run through the ignition switch, the more load you put on the contacts in the switch. They're not designed for that. Hence the relays, that actually take the load the switch just trips the relay, if your dead set on everything coming on with the ignition switch. Not that complicated to wire that way, and convenient if you want to make sure when the key is off, EVERYTHING is off.
Your boats not that complicated. No bilge blowers, electric fuel pumps or stereo, yet, shouldn't be a real issue. Just do what Ralph and Skip said.
Ray