I have the same finder and i used
http://m.westmarine.com/webapp/wcs/s...FQ1yQgod6j4AZw
http://www.kayakfishingsupplies.com/...olutionsMobile
You have to make a 1" hole for the cap. The big blue connector goes through fine. It's not waterproof but add some silicon and you can fix that.