How much does in-hull mount distort sonar signal?

It would <seem> like mounting in-hull would seriously degrate/distort the sonar signal.

Has anybody tested outter/inner mounting and can expound on the differences?

Some people have recommended not goop'g transducer in-hull...but rather using a small section of 3" PVC which is then goop'd to bottom of hull, then transducer is placed inside and tube filled with water...then capped.

Would you have to use saltwater for ocean and freshwater for lakes? Or would this make a difference.

It just seems that I will get serious degradation from mounting transducer this way.

I've not tested mine both ways, but I'll say that I've never had a problem with the signal by having it gooped inside the hull.  It is pretty standard procedure as a mounting option for boats as well as kayaks.  For a good sonar signal you need a continuous path of material to transmit the sound through... this means no air. 

With my Eagle Fisheasy 240, I actually have to knock the sensitivity down to about 50% because it is usually too sensitive for the shallow (<100 ft) waters I mostly fish.   

If you read your manual, it'll probably have a little something to say about through-hull versus in the water mounting.  It'll probably say that there will be some small loss in sensitivity... however in my experience it is not appreciable in the depth of water that we fish.  If you were fishing in 300 or 500 feet of water, maybe you would begin to notice the slight drop in sensitivity. 

I think of it this way... If a sonar signal can effectively bounce through 600 feet of saltwater (1200 feet both ways), I'm sure 1/8" of plastic isn't a big deal.

Erik

before i installed my transducer i went to a dock and tested it[this was long before we had this club and all this good info]. i really had no idea whether or not it would work. i lay on the dock and allternately held the transducer in the hull [no glue] and in the water. while in the hull there was a line at the surface[on the screen] and a 5% difference in the depth. i think the through hull recorded 5% deeper water.

My finder is mounted this way and I don't see any difference between my readings and those around me. I feel my cup up before launch so the whole fresh vs salt thing is moot.

Don't be afraid to try stuff, nothing is permanent. I monted and remounted my transducer 5 or 6 times and will probably tweak it a bit more this winter.

I feel my cup

Bill...you're disgusting  Only baseball players do that......

Gotta check the jewels...