Need help building a headlamp that's as bright as a spotlight for shrimping

Hello, I am new to the site and after searching for a little while I have still not found any answers to what I am looking to do...I'd like to build a headlamp for shrimping that needs to function like a super bright spotlight so it can penetrate deep into the water column and look far out ahead of the boat. I lost my friend's light when it slid off the back of the boat as we throttled from one spot to the next, and it looked a lot like this one:

http://www.huntinglight.com/catalog/...watt-p-28.html

I am convinced after visiting this site that I can design a bette, brighter, lower profile light, hopefully for less.

I need to be able to hook it up to a 12volt battery, and it should at least be water resistant. Can anybody help with suggestions? Thank you in advance!!