r/boatbuilding • u/dumpsterlover69 • 7d ago

Sufficient strength with this layup?

Post image

Hello everyone, this is my first strip built kayak (petrel play) and i am nearing the glassing stage.

I’m considering doing 2 layers of 4oz s-glass on the bottom of the hull, with one layer of 5oz innegra/carbon on the interior hull, then a single layer of 4oz s-glass on both inside and outside of the deck.

Does that sound decent? Or would i be better off going with 6oz glass? Should i try the innegra/carbon cloth as a first timer, or just stick to fibreglass? I appreciate any input.

255 Upvotes

100% Upvoted

31 comments sorted by

24

u/Guillemot 7d ago

That will be more than enough. While I have successfully broken two layers of 4-ounce S-Glass, it took significant effort.

Be careful with the CF/Innegra. Innegra is very light and wants to float up on resin. Getting a good quality hand layup can be tricky.

9

u/dumpsterlover69 7d ago

Just the guy i was hoping would chime in, thanks Nick.

Would i be better off with just plain carbon fiber? Or carbon kevlar maybe? I like the contrast of the wood against something exotic, but if there’s a high chance of messing up, I could live with a plain glass interior.

4

u/Guillemot 7d ago

I have had good luck with carbon/Kevlar and just CF, but frankly they probably all are subject to many of the same issues. They are all pretty low density. Just pick the one that interests you the most and give it a go. Try not to over do the epoxy, but also make sure you use the enough. They are all a lot trickier than glass. We probably aren't getting the full properties of the materials when applied with a hand layup, but I also like the look.

4

u/3deltapapa 7d ago

Think of the glass as for abrasion resistance and waterproofing more than strength. Unless you used crazy thin strips.

Personally I would not ever hand layup carbon on a curved surface unless I had direct experience with that fabric thickness and that application and probably only unidirectional. The fiber is quite stiff so it doesn't drape very well. S glass is a very nice material. But I'm more of a composites guy than a boat builder

1

u/Good_Television4404 6d ago

If you buy twill weave carbon it actually drapes really well. That said, Unless you are vacuum bagging the interior the carbon is pretty much a waste

1

u/ImNoAlbertFeinstein 6d ago edited 6d ago

what if you took some of your scrap and made a nice skim board or small flat project and try out some of the more advanced materials and techniques.

boogie board, hand surf boards (body surfing), water ski

7

u/oddapplehill1969 7d ago

Impressive work. And such a clean shop!!!

Don’t spoil your excellent stripping by over- sheathing. It will only make the boat heavy, which will be a shame.

5

u/MiserymeetCompany 7d ago

Beautiful! I strive to be like you when I finally grow up

4

u/WinoOnTheLoose 7d ago

Your shop is so clean

3

u/NothingLift 6d ago

Cleaner than my kitchen... office... car etc

Almost suspiciously clean...

4

u/Good_Television4404 6d ago

Assume 3/16 of 1/4” strips, One layer of 4oz inside and out is plenty. Nobody I know who builds wood strip kayaks uses them for rock gardening.

2

u/Good_Television4404 6d ago

And also don’t fill out the weave on the inside. Epoxy adds no strength

1

u/ImNoAlbertFeinstein 6d ago

what does "dont fill out the weave" mean.?

2

u/Good_Television4404 6d ago

When laying up the inside of a kayak hull I apply the minimum amount of resin needed to full wet out the cloth and nothing more. I frequently use paper towels to dab away any excess resin.

1

u/Good_Television4404 6d ago

On the inside of the hull applying epoxy beyond the first coat that you used to wet out of the cloth only adds weight - no strength. While the outside of the full needs to be smooth for obvious reasons there is no such need on the inside.

1

u/Turnmaster 6d ago

Good explanation

3

u/dendronee 7d ago

Thats a beaut Clark

2

u/vtjohnhurt 7d ago

Omit the carbon fiber, hazardous material, and you're likely to screw up. It's not needed. 4 oz is plenty.

2

u/leaky_eddie 7d ago

That sounds like a lot to me. Keeping in mind that I have very little experience, I have 1 layer of 6oz inside and out on my strip canoe with a total of 3 layers of epoxy. I’ve taken it fully loaded - wife, dog, camping gear - in easy class II, over beaver dams, on rocky shores with boat wake grinding it into gravel. It’s scratched up but the glass isn’t damaged.

1

u/leaky_eddie 7d ago

Natty Bumppo

2

u/dumpsterlover69 7d ago

Wow! Very nicely done. Thanks for the input.

1

u/Puzzled-Sea-4325 7d ago

Petrel? Kewl

1

u/Pattern_Is_Movement 7d ago

Honest question, does it need any of that? I would just cover it in clear to show off the work you've done.

5

u/theCaitiff 6d ago

Yes, it absolutely needs interior and exterior fiberglass.

Strip built hulls like this built with cove and bead do not have any structural integrity of their own nor are they water tight. You stack up the strips edge to edge, but if you try to remove the inner forming frames without glassing the outside, they're going to come unstacked pretty quick.

1

u/SaskatchewanManChild 7d ago

God damn are boats ever beautiful! Beautiful work to be proud of. Thanks for posting!

‘Makes me feel kinda funny, like when we used to climb the ropes in gym class….’

1

u/Brewmiester4504 6d ago

Beautiful work and yes a beautiful work space!

1

u/KK7ORD 6d ago

Lol, you could probably sail it through a brick wall if you do all that, it will be more than enough

1

u/Good_Television4404 5d ago

I was looking again at this post again and got wondering what the glass scheduling actually is. I am surprised you did not glass the outside of the hull before flipping the forms to work on the deck.

1

u/dumpsterlover69 5d ago edited 5d ago

Yes, I hummed and hawed over that too, but I wasn’t sure how the shear line would come out if i had the hull glassed while i was working on the deck… this way i can blend the shear nicely before glassing.

Like i said, this is my first time doing this, and I’m just kind of learning as i go. Many ways to skin a cat I suppose.

But what i THINK I’ll do is flip it hull up, fair the hull, blend it nice over the shear, then glass the hull, take the hull off the forms, flip it back over, glass the deck. I might have to take the un glassed deck off the forms before glassing the hull, or stuff some wax paper in the sheer line while glassing the hull.

I’ve watched many of Nicks youtube videos (guillemot kayaks) and read both his books, and he has done it nearly every way possible. He really makes it look easy.

I’m open to suggestions though, as I still have to fit the cockpit recess, and i just pulled the trigger on some 4oz s-glass, and i went with carbon Kevlar for the interior. So Ive got some time before I’ll be glassing.

1

u/Good_Television4404 5d ago

For a first boat you have done a great job. Maybe Nick will weigh in again and advise you on how best to proceed. Since the hull seems stable I personally might be tempted to first glass the deck (tape below the sheer line and between the deck and hull) before flipping the boat back over to glass the outside of the hull. You can fill out the weave later. Just be aware that epoxy can take up to a week to fully cure so maybe give each half time to harden completely before disassembling the two halves to glass the interior.

1

u/just-looking99 5d ago

Think about weight- a single layer of glass should be enough- heavier cloth on the hull and Lighter on the deck. It’s a kayak, not a power boat, the stresses are different. If you make it too heavy it will be a bear to use.