I did yet more research. The Hummingbird uses at 200khz signal and the Lowrance 192Khz. The lower the frequency the more penetrating power (old engineering days)

I was hoping someone designed a transducer that worked well in this situation.

I though some of the newer boats would have found a solution, Maybe not?

Has anyone had any luck with the Gaffrig depth gages and hull transducer?

alternative transducer mounting method
 

I am about to mount the transducer in the bilge of my boat and was instructed by Faria to use the following method (when using a thru-hull style transducer)-

Trim off the excess plastic from the body of the transducer (mine is cylindrical with a tapered flange of plastic around the head of it).

select a piece of PVC pipe that is as close to the diameter of the transducer as possible (mine is about 2") and cut the pipe to 4-6" length.

Trim one end of the small piece of pipe at an angle similar to your hull so the pipe will stand up vertically when you epoxy or resin it to the inside of your hull.

Epoxy it down, but only apply the epoxy to the pvc, don't let it spread over the center of the area your mounting to. Obviously you want the transducer to have a direct connection to the fiberglass.

Add a small amount of oil to the pipe and drop the transducer in. You have a completely fluid connection to the hull!

This was recommended by Faria, and I guess it sounds like a pretty good method. I'll know soon enough. What's everyone think?

I've got a Gaffrig "shoot thru hull" in my Checkmate which is balsa core and it works fine.When I get up to about 50+ it will start to give some funny reads. Otherwise seems to be pretty accurate.
I'll post a pic later.

Re: alternative transducer mounting method
 

This sounds like how my last Fountain was done. The boat was a nonstepped hull, with the transducer set in a 3" dia x 2" tall pvc tube filled with epoxy. I couldn't tell if the pvc tube was set into the hull bottom or just glassed to the bottom. Either way, it worked every time, all the time, at any and all speeds!

Now my new boat with a single step, it is absolutley worthless POS! Takes up dash space as far as I'm conscerned. Damn thing does not work at any speed faster than floating with the current. This I don't understand, cause even at idle speeds when the hull is still 100% wet w/o air bubbles, the depth thing stops working!