Suction cup transducer?

I have Humminbird 535 portable fishfinder and am having a difficult time getting the suction cup transom mount to stay on the bottom of the kayak.  Any suggestions on some possible solutions? 

I don't know that it has ever been successfully accomplished.  That is why so many have gone the thru-hull route.

I'm using the portable too, & my solution is to re-stick the transducer every once in a while . 
One thing that really helps is to get the transducer mount adjusted for the spot on your kayak hull where you will put it. Then really push it on good & it should stay for a while.

I used a suction cup transducer for years on a variety of yaks with little problems.  Occasionally I would have to re-attach, esp if I was in the kelp.

On our Mexico trip this Spring I could not get it to stick on the rental P13.  We thought it may have been due to the scratches and rough surface of that rental yak.

didn't really need a FF anyway, since we had the local skipper Raoul who always put us on the spot.

In retrospect, Polepole mentioned that using vaseline for an extra good seal might work.  Sounds good, why not give it a try?

Or, sand the spot you are using real well, down to #200 maybe, see if that helps.

Allen

Guys -

Thank you for the inputs.  I will give it a try and let you know what works best....