Lowrance or Humminbird?? GPS/Sonar combo

[BP Swing]

sorry I forgot to mention, this is an aluminum boat

[fishfish]

Use this style stainless washer on the outside of your boat and a tapered phillips head screw with a washer and locking nut.

Use marine tex or the 3m below water line sealant gooped up between your washer and the inside nut.

[BP Swing]

Qwerty, That makes sense but will those washers and screws still allow me to use a mounting plate? (going over them)

[Chromeslayer]

another hard to pass up deal right here on a plotter..

http://www.marinedeal.com/product_p/raya65chart.htm