How many layers of fiberglass to repair wing tubes?

I have to repair all 4 wing tubes on my Hobie 17. One was completely broken (suspect wing not fully inserted and the light weight tube snapped during a sail by previous owner).
I have cut out for ports as suggested by others and have sanded the tubes to get better adhesion. I plan to insert a 1 1/4" PVC pipe into the tube to "line-up"the broken parts, also drilled a hole in the top of the pipe so I can insert a rod and rotate the PVC to assure no sticking while the fiberglass cures.

Big questions - 1). How many layers of fiberglass cloth should I use?
(resin-cloth-resin-cloth-etc.)
2). Should I use a combination of fiberglass cloth and fiberglass mat?
3). How can I get a longer "life" before the fiberglass sets up?
(instructions I have found are vague and only say slightly less catalyst)

Any insight would be appreciated

Most cracking is caused by freezing ice inside the tubes.

The cracks are typically to the middle of the tubes, so only water barriers and not structural. The structure is at the top and at the base inside the hull.

Woven glass of a lighter weight and maybe two layers with plenty of resin or a putty mix on the surface after the glass to seal.

Practice with the resin / mix cooler temps and less catalyst for slower cure time.

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Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

I have repaired all four my my 21SE some time ago...and I got better at each time.

Don't use Kitty Hair Fiberglass as the finish is too sharp! This I found out the hard way....

Practice and do a Dry run first. Working with one hand through a small hole is difficult with at best, so mix up small batches and take your time. Several layers worked best for me. Be sure you use a length of fiberglass cloth long enough to wrap completely around the sleeve, clothes pins helped a lot to..by pulling these strips tight without removing them....

Call me and I will help all I can PM sent

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Bill 404 21SE

Fiberglass mat will give you faster buildup but probably pretty difficult to work with in this application because it tends to want to all fall apart. If you use it, I would say lay down a layer of cloth on either side of it. Your best bet is probably to use 2 to 3 inch wide tape and wrap it in a spiral around the existing tube. I find it is generally easier to wet out the glass first and then put it in place. The other option is to paint a coating of resin on the existing tube, then wrap the glass, work the resin into the glass, then paint on another layer of resin, repeat. The difficult part will be working in areas where it's hard to reach/see. This is why wetting out the glass first can be better. Its a good idea to have a mirror and a shop lamp handy. It may also be easier if you take the boat apart.

As for thickness, if you're repairing a fully broken tube, you will at least need to match the existing tube thickness with your repair. 8 oz fiberglass tape is about 0.010" thick. So if the wall thickness of the tube is 1/16" (.0625") then you would be looking at about 6 layers.

For the resin, polyester resin can be a little tricky to dial in. Different manufacturers have different cure rates and the temperature and amount of hardener you use have a big impact. You will need to experiment if you are new to using resin. You may also want to consider using epoxy for this repair. Epoxy is stronger, has better adhesion, and generally has longer and more consistent cure times than polyester.

sm

Definitely use a fiberglass or carbon tape. If the damage is just a small crack I would wrap it twice, this wound make roughly 4 layers. Make sure to use 5" ports and do the repair before and install the port afterwards. Otherwise there is very little space to work.

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H17

Thanks for the comments and insight.
I'll try to post pics of the repairs with comments to build on what folks sent me.