installing sound system

Hi all, was wondering if anyone has any advise. I have a '91 ski nautique, I am looking at putting a sound system in it. I am going to run an amp, sub, head unit and then the speakers in the boat. my question is, since my boat has never had a radio in it do I run the power from one of the accessory switches or do I run straight from the battery?

Thanks

I agree with Quinner above. Also in addition to wiring the amp/s directly to the battery, a stiffening capacitor (TM) can improve the quality of your installation if you are going high power. If you are going 500 watts or above (RMS) I'd definitely use one. If you google car stereo installation, you will get lots of good tips.

thanks guys, went with a marine boss head unit an speakers, mounted it in a watertight casing that I glassed into the glove box. used a sony Xplode sub with a MTX amp that I had lying around the house, mounted the amp on the sub box so I can remove the whole system when not in use ( I live in South Africa and they like removing sound systems at night). built the box for the sub out of plywood that I then drenched in resin, so hopefully that will last, would have liked to use marine ply but couldn't justify the price of a whole sheet! Anyway, sounds great so am very happy! thanks for the help!