Installing fishfinder on pontoon boat

[WHITEOSIRIS]

We just bought a 2006 Bentley Pontoon boat and a Humminbird PiranhaMAX20 fishfinder but I'm not sure what's the best way to install it.
I've heard that you're supposed to but I'd just hate having to drill holes in the new boat.
Any help or suggestions would be appreciated.
And yes, I'm sure it's obvious, this is my first boat. lol
:fish: :help:

[outfishin_]

I hooked one up on my in-laws pontoon. I didn;t want to drill any holes either....So I mounted the transducer to a piece of cedar board.Ifound a good mounting spot for it at the rear on the pontoon. then I run my cable from the transducer to the control head following the cables from the motor to the console. I was able on our boat to fit the fish finder cable through the existing factory holes already in the boat. Then I made a removable mount for the control head. I screwed the fish finder control to a board then I velcro'd it to the top of the console..... It works great.
I hope this helps....