Why not put it on the inside of the hull and shoot through the hull? It works really well when done right. The only problem is if your transducer also gives temperature - won't get that with an inside hull mount.
Here are some links to check out:
http://yachtvalhalla.net/articles/trans ... ducer.html
http://store.humminbird.com/download.ep ... P_6_16.pdf
http://www.tomneale.com/tips13.html
Good luck!
I have had great luck with 1000 watt shoot thru ducers.
The 600 watt shoot thru version loses temp and speed if you need that.
Shoot thru ducers require a solid laminate with no air bubbles or pockets and a perfect hull to transducer seal.
They eliminate any problems with turbulance but will still blank out if the hull has a lot of air bubbles at speed. So, placemant is again an important consideration.
Remember a transducer is basically, a speaker and microphone. The shoot thru the hull will reduce the sensitivity of the fishfinder.
It depends on what you are looking for , I guess.
