Howdy,

Hmmmm... good question.

I have not tried fitting a trans to a SOF so this is just my best-guess, but I don't think the choice of skin material will have much impact on the success. Skin (canvas or PVC) is thin compared to wood or plastic, so I think the chance of trapped voids in the thickness is almost non-existent, but I would guess that PVC would be the better of the two.

I'd be more worried about how well the trans can be attached to the skin.

In plastic sit-on-tops I favour using epoxy to glue the trans down, but the epoxy must be gently mixed to minimise the amount of air bubbles introduced, the pool of epoxy left to allow bubbles to rise to the surface before the trans is rolled into position (the rolling action pushes bubbles away) and then weighted down to prevent the trans lifting off the hull surface.

Using this method, I reckon the flexibility of the skin would cause the epoxy joint to fail prematurely.

There is another method where you take a small square of minicell foam (around 4" x 4" x 1-1/2" thick) and cut a pocket in the centre that is a bit smaller than the outer profile of your trans. Glue the minicell to the inside of the hull using a flexible adhesive like silicon, contact cement or polyurethane, put about a 1/4" thick layer of petroleum jelly ('vaseline') in the pocket then shove the trans into it. The jelly provides the sonic continuity needed for the signal & if you find air has been trapped, just pull it out & shove it in again until it works.

This system is more tolerant of the hull flexing so would work better in a SOF, but you have to monitor the jelly. On warm days it'll get hot, runny & you'll loose some, especially if you transport your kayak hull-up on your car.

Another idea would be to attach a 1/8"- 1/4" thick plate of, say, a hard plastic sheet to your frame positioned so it'll lie right up against the inside of the skin. To this plate you could attach the trans using either method above (but epoxy would probably be the best) & the water pressure would keep the skin pressed aginst the plate for sonic continuity. If you lash this arrangement to the frame near the cockpit area & find you need to remove it, just cut the lashings & take the whoe assembly out.

Like I said though.. I have not tried this so it's my best-guess.

Regards,

Phil.

: I have been planning the same in my first SOF that I am building. Any
: comments about the difference between canvas/vinyl and the wood for an
: interior mount? I'm a little concerned because once I skin the boat it
: will be hard if not impossible to get to the transducer.