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Laying up of kevlar rub strips?

Submitted by SleeperNZ - Thu, 7/12/12 » 11:39 PM

I'm interested in doing kevlar rub strips for my SW17 and have picked up some kevlar in tape form. However I understand kevlar is hard to work with because it tends to 'float' on top of epoxy, is easy to oversaturate and cannot be sanded. After a search of the forums I see a few others have used kevlar rubstrips but they don't really go into detail on their methods. My current plan is to mask the hull, then pre-wet the kevlar with 50% epoxy by weight between 2 sheets of plastic using a squeegee to distribute the epoxy, then remove the top sheet of plastic and apply the kevlar directly to the hull. After curing any raised edges would be faired in with microballoons. But before I pull the trigger I'd be interested in details of the approaches of CLC builders as well. Cheers

6 replies:

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RE: Laying up of kevlar rub strips?

» Submitted by Celeste - Fri, 7/13/12 » 7:32 AM

I will preface my answer by saying I have never used Kevlar on a boat, just race car body panels and mostly bagged.

Everything you say about armid is correct (except the sanding part, it can be wet sanded, but that is a SLOW process) However, with careful thought it is not hard to deal with. Your process sounds good, you just have to be careful working that dry without bagging that you get the air out of the joint, as capilary action will hold the epoxy in the fibers without enough extra for gravity to pull it down into the joint. If you question your technique, you might try it with a few inches of tape on thin wood, once the epoxy sets, sand the wood away so you can see it you got the air out of the joint.

RE: Laying up of kevlar rub strips?

» Submitted by dehager - Fri, 7/13/12 » 9:09 AM

sleeperNZ,

I use Dynel fabric which does not cut very well. Mask off the area, apply the cloth and be carefull not over saturate with epoxy. Trim the cloth with a sharp blade when the epoxy has cured but is still flexible. Mask and repeat if you are adding additional layers. Just remember to use a fresh, sharp razor blade!!!

http://dehager.smugmug.com/Boats/CLC-Mill-Creek-165/6686487_bgnGZ2

RE: Laying up of kevlar rub strips?

» Submitted by SleeperNZ - Fri, 7/13/12 » 9:57 PM

Celeste, thanks for the thoughts, I will have a go with this method on the edge of some scrap ply. I do actually have access to vac bagging gear through my uncle but since this is a relatively small job I thought I'd try and avoid it if possible.

Dehager, thanks for the info and photos, very neat work! I'll certainly use that method when I do the deed. Thanks again guys.

RE: Laying up of kevlar rub strips?

» Submitted by Hickory - Fri, 7/13/12 » 10:03 PM

I looked through your photo blog Dehager. Wow- outstanding workmanship. Thanks for sharing.

Hickory

RE: Laying up of kevlar rub strips?

» Submitted by Meyer, Robert - Sat, 7/14/12 » 8:09 AM

Dehager

You certainly do beautiful work. If my craft looked as good as yours I would want to keep it parked in the living room also.

RE: Laying up of kevlar rub strips?

» Submitted by nemochad - Sat, 7/14/12 » 10:06 PM

You can't sand Kevlar- you'll end up making a furry tennis ball. First trim the edge off the tape so there is no raised edge, wet it out with a squeegie/ plastic spreader on a table, transfer to the boat, and then add a slightly larger layer of wet out light glass cloth over it, then cover with peel ply (nylon sport fabric from the fabric shop works), then squeegee over the peel ply. Remove peel ply when cured, and now you have a guide layer to prevent you from sanding into the Kevlar as you fair.