Kevlar hull

[r.mike]

Hi,

I am looking for info on repairing a kevlar hull. The boat hit a rock and the hull has an area that is pushed in (4'x2') and a hole the size of a tennis ball.

Is it going to be "like new" in terms of safety if a good yard will fix it?

The other question I have is about the pros (or cons) of a kevlar hull.

Thanks,

[astevo]

kevlar is great, right up untill you have to do something with it. horrible stuff to repair or work with.
you say a 4*3' area is pushed in? need to determine full extent of any delamination/core failure

the finished product is going to be at least one laminate above the original as you have to cover the edges of the kevlar, and can not afford to sand down to it even a little, elseit goes all furry.
you can definately repair to full strength, just be prepared to pay for it.

[r.mike]

Thanks for the reply.

Why is kevlar hull better than regular fiberglass? I can understand carbon since it is really stiff.

Would anyone know of a good yard in Fort lauderdale?

[Chris Ostlind]

Originally Posted by r.mike

Why is kevlar hull better than regular fiberglass? I can understand carbon since it is really stiff.

The answer is in the characteristics of the various fiber types.

Fiberglass has good all around properties and is affordable, easy to work with and comes in lots of woven flavors and absorbs a fair degree of physical abuse. You can easily do hand layups with glass

Carbon is amazingly strong in both compression and tension. It's stupendously light in a strength for strength comparison and is something like 7 times more expensive than glass. It can also be fairly brittle and does not like to be subjected to impact. Works best when laid-up with vacuum bags, or infused, to keep the resin content as low as possible

Kevlar can handle impact with aplomb. It is really strong in tension and incredibly less so in compression. It costs about 5 times what glass will cost you. It attracts water (hydrophilic) AND... as was said so cleanly above, it is one bad mutha when it comes time to repair it.

Each fiber has its strengths and weaknesses and the use of these fibers depends on what is designed and how it will be built. For an everyday boat that does not need to be world record light in weight, or will not see regular or extreme abuse during use, there are hardly any real reasons to build in Kevlar.

Save your money, your repair bill hassles and get on with it using fiberglass. If your boat is going to be subjected to some measure of hard lick abuse, add more glass to that area and get back on the water.

Sorry, I forgot to address the original question.

This repair is going to make you crazy. To really do a great job on a Kevlar hull you need special shears/blades, an understanding of the fabric and its madness and a bit of masochism to boot. I've fixed about half a dozen drift boats for fishermen after they have thrown-on a layer, or two, of Kevlar because one of their buddies said it would be bulletproof for running rocky rivers. I ended-up heating the epoxy soaked Kevlar with an industrial heat gun until it got soft and then peeling it all off the hull so I could make a solid, clean surfaced repair.

Good luck.