Forgive my total ignorance, but that's why I'm here.  I'm doing a lot of research on sonar, as I just bought a kayak.  I'm pretty pumped for the ice to go away so I can get out there.  My question is this:  I'm reading about "Through-Hull" stuff.  Does that mean that you do not attach the transducer to the bottom of the boat?  Do you put it in the cockpit with you?  That does'nt seem to make sense, unless the sonar waves go through the boat. 

It also seems that I should be spending around 150-200?  Does that sound reasonable?  My wife will go nuts if it get's much further north of that.

Any info would be amazing.  Thanks guys!

Here's a shoot through installation on a Tarpon 140.

http://www.kayakbassfishing.com/kbfBB3/viewtopic.php?f=124&t=3569

Nice!!!  Thanks so much.  I did'nt know you could just mount it on the floor of the boat.  Thanks again.

That's the easiest way.  I use one of these through a scupper hole on my Prowler Big Game, though there is a recess in the hull designed to accept the transducer.

You can see the install here:

I bought the lowrance x50 with the kayak install kit from the Hobie catalog. I had to pick it up from a local Hobie dealer. It has everything you need, including a double A battery pack in a dry bag for a power source. It was around 200 bucks. If you get some rechargeable batteries it is a pretty convenient system. You can check it out online in their catalog.

Before you drill holes you might want to find some people with your exact model kayak in kayak forums who can tell you where they put their display, and where they had to drill holes.

The local forum that I learned everything from is norcalanglers.com, but there are lots.

  The through hull transducers are mounted inside the hull, on a flat part of the hull away from anything that would cause turbulence right under the transducer.

I've got a Predetor K111...I will do that.  Thanks for the advice/info guys.