Yes, you can apply the Kelvar on outside just like fiberglass, but to take advantage of very high strength and flexibility of Kelvar its better to layup on the inside.

When your kayak hits a rock or oyster bar,  the outside of the hull causes compression ( a ding/scratch) of the hull material. And on the inside of the hull the impact will cause expansion of the material; therefore, causing a possible crack, if the material doesn't have some flex or give.  Of course, causing water to invade the hull.

You have numerous options to build a kayak that has hiigh durability and abrasion resistance on the outsdie, and high tensil strength and impact absorption on the inside of the hull.

1) A low cost way is to do an expedition type layup as outline in Nick's book "A Strip-Built Sea Kayak"  See page 110.

2) Another approach is to lay Kevlar on the inside of the hull, either entire length or only around the cockpit.  And/or apply a combination of graphite, epoxy, and slica to the bottom or the hull to reduce abrasion and improve impact resistance.  Beauty about Kelvar is that it has very high tensil strength and good impact absorption as compared to fiberglass. Carbon fiber has high tensil strength but little impact absorption.

Also, using 3 inch minicell bulkhead will have good impact absorption  around the bulkhead area.  Good luck with your build

dogger54,

Thanks for your input.  This being my first build I'm finding it difficult to decide on which option.  I'm leaning towards maybe using the kevlar/carbon just on the inside of the hull now and fiberglass on the rest.  I have Nick's book and have read it and reread it, and I'm getting psyched to start my build.  I believe its being shipped next week from CLC.

Nick maintains a very informative web site that you should check out. You might also ask him directly about using these materials.

Generally speaking, your first boat should be built exactly by the book with no modifications. Hundreds of others have built these boats before you, so the likelihood that you find a better way to do it the first time is pretty slim.

Good luck with your build - it is a very rewarding process. Use the epoxy sparingly and don't fret over being less than perfect. And if you are not having fun with it, put it aside for a day or two.

-Wes

From your initial message it reads like you be taking long multiple day trips with a lot of gear.

Please describe the waterway environment you will be paddling.  We can help further in you making a decision.

For me, my first kayak was a Guillemot L.  I did an expedition plus type lay up. I have been paddling it two years and have nunerous scratches and scraps on the bottom.  I also ran full steam into a log with no damage other than  scuff of ash outer stems.  My son was at cruise speed and ran right on a shallow oyster bar reef.  Instead getting out and backing out, he used his paddle to make a 180 turn, putting huge "U" shape scratches on the bottom, without cutting into the fiberglass.  So I feel this kayak is pretty tough, but differently no match for whitewater.

You  probably saw with Nick's video, the problem with Kelvar and carbon fiber is knowing when you have enough epoxy absorbed into the cloth.  Fiberglass clears out after a few seconds, no problem.  So you might a do very small practice patch on plywood to see how it flows.

Another point you must consider and this is from my personal experience or if you will, my mistake.  After you fiberglass/Kelvar hull's inside, you need to cut across braces at each station when you remove the hull from the forms to work on the deck.  This especially important in dealing with Kelvar/carbon fiber, which will stiffen the hull and may make it difficult putting the hull and deck together.

 If you are going into the wilderness, there is fast setting epoxy kits you can buy to make repairs.  I saw them in a local kayak shop.  It sets in about 5 minutes.. But I do not remember the name of it.

Again, let us know your paddling environment and we can help further.

I do plan on using it on multiple day trips with gear.  One trip I know i will be taking is across Missouri on the Missouri River.(MR340)  I'm hoping to have  the kayak finished early July at the latest so I have time to practice in it before the race.

I've paddled the MR340 several times and know how sometimes submerged dikes can sneak up on me in the dark when fatigue has set in and I find I'm on the wrong side of the river.  Or when pulling up to the shore there are some pretty rough rocks. The added strength I'm wanting to achieve is just an assurance the integrity of the kayak will remain strong.

How long does it generally take a first timer, moderately skilled person to build a kayak as large as the great auk double?  I realize there are many factors involved but is it reasonable to think this can be accomplished in three months in spare time off from full time work?

I do not believe you can build this kayak for the first time builder working part time, and complete within three months.  Maybe its possible for full time effort using stripping with staples.  I built several kayaks and it has taking me about 5 months for each build.  Now I didn't use staples, so I had to limit my stripping to two to four strips/day due to glue clamp time.  I usually work 1 to 2 hours in both the morning and evening, working seven days/week.(maybe I just work slow).  I know it probably took 300 to 350 hours to build a Guillemot L.

So I have a layup that may work for you, which is a modified expedition layup. Change it up as you wish.  I did an expedition lay up on my Guillemot L and I think it added about 10 pounds using 4 oz fiberglass.

1) Lay up the hull with either 4oz or 6 oz fiberglass.

2) Lay a second layer on just the bottom of hull, carrying the fiberglass to the external stems on the bottom.

3)  Put two layers on the bow and stern external stems, extending pass the end of the stems on the bottom.  You will have four layers of fiberglass located where you hull comes in contact with the shore during beaching.

4)  Lay up on the interior of the hull with Kelvar 49 cloth or a hybrid Kelvar/carbon fiber.  5.7 oz.  Nick's videos are pretty good on laying out Kelvar.  I think you can do it.  Just make sure you following Nick's recommendations on wetting out Kelvar. ( You just have acquired good skills by fiberglassing the hull)

5) Lay the deck with 4oz fiberglass.  Add a second layer on the tips of the bow and stern deck back 6 to 12 inches.

6) Add multiple layers of fiberglass around the cockpit per Nick's books, expedition lay up.

7)  Add a carbon fiber tape (3 or 4 inch wide) behind the cockpits for added deck strength. (Because you will probably sit on the back of the cockpit rim at some point in time.)

8)  Do a micro balloon end pour per again Nick's videos.

9)  Ensure you have solid hatch straps, bungee, and life lines around the kayak for safety!

Let's get building

K.Greer

Sounds like a great plan!  Thanks for all the input and advice.  Now I just have to wait for my kit.

Tim Marino

I'd be asking someone who has already used this weave on the outside of a strip boat or is used to working with Kevlar.

No problems on using it on the outside BUT, I hear that you cannot sand Kevlar.

I have never used it ,  but I've heard that it just furs up when you sand it and is a real problem.

I've seen K1 racing kayaks and paddles etc made from the Carbon - Kevlar weave and the do look great, better than straight Carbon in my opinion.

Good luck and please post pics when your finished, I'm considering building a K1 racing boat from strip and I might do the same on the outside.

Bris Paul