Thread: Transducer mounting plate

Originally Posted by scout-j-m

I have been researching this for mounting my new Helix 5 SI transducer on my 1648 flat bottom. Going with no screws and 3M 5200 is a fine method, however, most of the advice I have read said it works best if the boat transom mounting location is coarsely sanded then wiped with acetone. It's also recommended to even "mill" (prob not the correct term) out some grooves/pockets in the cutting board for better adhesion.

I did scuff the transom and prep it with acetone but I did not put grooves or holes in the cutting board. I've been pleased and kinda surprised so far because that 3D structure scan ducer is pretty heavy. I'd guess 18 ounces or so.

I've never been a big fan of the smaller mounting plates. I prefer the bigger ones myself. Unfortunately, Cabela's stopped selling the larger ones. We actually purchase oversized cutting boards and cut them down.

I simply do not trust the adhesive.

The picture below shows the boards that we use and the size of them. If there are any rivets or anything where the board goes, we recess the board before installation. This photo shows the side image transducer on the outside. I was tired that night and placed it to the inside the next day when I found the error of my ways. All screw holes are above the water line (total of 5 stainless screws). A small amount of marine grade silicone is placed on each screw. In the event you are going over existing holes, recess the board really well, insert a screw with silicone to plug the hole, and then fill the recess with silicone before installing the board. No need to put silicone around the board.

My fish finder reads bottom at 45mph. IF adjusted correctly, you shouldn't lose bottom.

I bought a piece of PVC board from Lowes, a 3/4" x 5 1/2" by 8' long piece cost $13. I used the JB Weld Marine Epoxy with 3900psi strength rating. I read that the 3M5200 can cause oxidation on aluminum hulls. Probably take 50 years for it to rust out, but who knows, plus the JB Weld was easy to get, it was in stock at Auto Zone. Wish I would have saw this sooner, I could have cut you a piece and sent it to you OP. I have 7ft of board left and no use for it...

I thought about that snubby but that is about $40 at the local lumber yard and Lowes is 50 miles away.Thanks for the offer though.
Snake that is a great picture. Are you saying the SI transducer does not have to be below the hull if it is spaced back on a board?

Originally Posted by deltarat

Are you saying the SI transducer does not have to be below the hull if it is spaced back on a board?

The water coming out from under the hull is naturally trying to rise to get back to the surface level ...

So the xducer can be somewhat higher on the transom than attached directly to the transom with no spacer ...

How much higher would just have to be experimented with ...

Rickie

ok thanks

Search on ebay for hdpe. A lot of machine shops sell scrap pieces for cheap. I bought 3 that were 4 x 10 x 1 for $20 for all 3.

1" Black King Starboard HDPE Lot of 2 Pieces | eBay

You know I thought I had it adjusted slightly with the rear end of it up, so that it would skim the surface. The parting line on the transducer is about where the bottom of the boat is. Should be in water all the time there. I do not throw a rooster tail and on dead calm water I might be able to keep bottom but the least little chop or porpoising and it is gone and jumps to 1000 ft or something strange. I just need to fiddle with it.

I managed to get it about 6" to the right of center. I hope that works. That is the only place I could get it with only half of the transducer hanging below the bottom of the boat. I am really glad I bought the board to mount it or my boat would look like swiss cheese.