Welcome to the board Chaozu.

I installed an Eagle FishMark 320 on my kickboat and have been very happy with it. The only thing I will do differently next time is get a color graph. The links below are to forum topics regarding the project and pics in the rigging gallery.

Phase 1 post
http://www.calfishing.com/dc/dcboard.php?az=show_mesg&forum=6&topic_id=35744&mesg_id=35744&listing_type=search

Phase 2 post
http://www.calfishing.com/dc/dcboard.php?az=show_mesg&forum=6&topic_id=35755&mesg_id=35755&listing_type=search

Pics
http://www.bass-n-tubes.com/gallery/FishMark320_Proj

I use a 12V sealed lead acid battery for power, like this one.
http://www.batteryspec.com/cgi-bin/cart.cgi?action=link&product=202&sub2=2020267
A 7.5 amp hour rated battery will run a fish finder for a weekend usually without any problem before it needs a charge and only weighs you down by about 6 lbs.

Take a look at the rigging gallery for more ideas on outfitting your pontoon.
http://www.bass-n-tubes.com/gallery/rigging

Also if you type "fish finder" in the search function you will find many more forum posts on the same subject.

Hope this helps!

MT