I understand that Kevlar hulls are lighter and stronger than fiberglass hulls. So why don't the boat builders use it on new boats? Is there any disadvantages to Kevlar?

I've heard that some of the older Kevlar hulls are becoming more brittle with age and breaking up. Anybody have evidence to verify or negate this claim?

i've done some minor composite owrk with kevlar and it is a ***** to work with. You sort of have to hack at it with scissors. Mind you the same scissors, cutting wheel and razor will slice right through carbon fiber and makes clean cuts.

also kevlar is expensive. I believe there is the only manufacturer (dupont i think) becasue they own the patent.

I was reading a fiberglassing book awhile back. They mentioned although kevlar is much stronger, the resin did not adhere to it as well. Because of that you had to work much harder at the wet-out which means time and money. They also mentioned that a poor wet-out would result in what RedDog describes.

I have a Magnum that I am rebuilding and the hull is a 68 model Kevlar version and is in excellent shape. I have not seen any week spots in it at all. The deck I have had to replace with a new one from the factory because the core was rotten, but the hull was in almost perfect shape, once I sanded all of the layers of paint off of it.

Is carbon graphite another name for Kevlar

Turbo, No Carbon Fiber, is just that, Carbon. Kevlar is a proprietary, resilient material. Two different animals.

To answer the above, Kevlar will not get brittle. Some older resins will, though.

Kevlar is expensive and difficult to work with. It is however more flexible, more reactivly durable and stronger than glass.

Carbon Fiber is stronger yet and has a very high strength to weight ratio. It is however very expensive and corrosive.

I have a boat that I have been told is actually carbon graphite cloth with no wood coring except stringers of which there are 5 in the hull and 4 in the deck with full bulkheads except possibly under the cockpit. I have looked up some of the physical properties on it and looks to be realy strong. Please explain corrosive properties. Also woundering is this a good lay up material? Am I piloting a vurtual tank? I realize anything is breakable ... just have to give it to my son.

I was also told this boat weighed 1/3 less than a standard layup but the boat ended the same weight with the extra structural members and thickened layup

Thanks in advance

Carbon Fiber is really an incredible material. It closely resembles diamond, in a fiberous form. It is strong, and stiff, but can be quite brittle. Carbon is volitile on the galvanic chart and direct contact with aluminum and most steels should be avoided. It is advisable not to fasten through carbon without some kind of inert barrier layer.

Nick

What prompted this question is I'm looking at a 1990 Cigarette with a Kevlar hull. Do you know if that year falls into the older resin category?

Roger