Gene Cosloy wrote:
I need to fix some velcro to my cockpit seat so I can keep a skwoosh
pad from slipping around. I notice that some manufacturers that make
accessories for kayaks include adhesive backed velcro for this purpose.
Any off the shelf product I've tried very soon becomes loosened and
unattached by sea water.

That's pretty much par for the course with self-adhesive Velcro, even
their "Industrial Strength" product. However, if the Velcro is going to
be under pressure, rather than tension, it should hold OK. Just don't
expect to be able to remove and install the pad frequently. If you need
to do that, your best bet would be to lash/strap it in place, You may
need to install some grommets or attach some small Fastex buckles. You
can install grommets in the original holes or glue webbing tabs with
small Fastex buckles over them.

If you want to try the Velcro route. Use small piece at the edges. Clean
the seat and the bottom of the pad with alcohol and attach the hook side
of the Velcro to the bottom of the pad. Install the loop side on the
hook, then press the pad into place on the seat. Should the loop pieces
come off the seat, reinstall them using solvent-based contact cement
(not water based).