Doug King replied:
No. Kevlar bonds just fine to existing hulls. I know of several boats
that have had this done. It would be better to apply it to the inside
of the the hull, where impacts put the laminate in tension, rather
than the outside (compression) face. However this is not always
practical, and it certainly helps the impact resistance of
"conventional fiberglass" to have a layer of Kevlar cloth on the
outside. A big problem to beware of is that Kevlar can't be faired...
sanding into the cloth leaves frizzies that will NOT lay down no
matter how much resin or paint you try to cover it with. So any
attempt to armor an older hull should have a thin layer of matt or
finishing cloth sandwiched over the Kevlar.

It would also be a very good idea to add positive flotation.

Fresh Breezes- Doug King

I hear ya on the flotation!

The reason I asked is that I read an article somewhere way back on some
boatbuilding site that kevlar wouldn't bond adequately to old poly
resin. I'm curious though, why would it be better for the kevlar to be
on the inside? Wouldn't that make it less effective in a collision due
to the layer being in tension so it wants to seperate? I would have
thought that being on the outside would be better to provide a barrier
to the forced entry. Could you explain further? Thanks

Red