"Thanks for the photo. When I zoom in on the photo to look at how the transducer's mounted it gets a bit distorted. Looks like you've fitted the tansducer on the transom on a small block. Is this block glued (silicone) to the transom or screwed? Did you also run the sounder power off the jetski battery or did you fit another battery?"
image.jpg
This is is a close up of the alum block.
The block is essentially two plates of 3mm ally.
It is 'stuck on' with a piece of double sided tape either end, and adhesive sealant.
So, no holes drilled into the back of the ski, which would all have been under the waterline. The transducer screws onto the outer plate only.
The biggest hole in this installation is for the plug end of the transducer cable. It required a hole of something like 15mm. (There was no way I was going to make a hole that size at the back of the ski, below the waterline.)
I should also point out that most Sea-Doos have a thru hull transducer mount inside the ski. Mine is on the port side.
I first tried to use it, and fired thru the hull and it works just fine. So you may not need to put your tranducer out the back after all.
My only real hassle was a poor choice of a Lowrance Elite 5DSI, and it was later pointed out that it is not suitable for thru hull applications.
Further, the lowrance control buttons on that unit are on the stb side, and that is a real pain.
As my Seadoo throttle grip is on the stb side of the ski, I basically have to stop the ski to adjust the depth control or map settings.
If you reach across with your left hand, your hand is blocking the screen.....
So choose a sounder with the controls on the correct side, and a transducer that can work from inside the hull.