Cracked seam repair

[paddlesores]

So...it looks like I'll finally have to learn how to work with fiberglass. My wife's Tahe Greenland has developed a crack along its seam. It starts about 12" from the rear on the left side and runs forward for about 30". The kayak has been taking on a bit of water while rolling for quite some time and it's finally decided to not let me put off fixing it any longer.
Never having worked with fiberglass before I really don't know where to start. The seam tape is only 1/2" wide and on our other kayaks it is a full inch. Should I commit to running new seam tape the entire length? I like the idea of making it better than before as I don't want this to happen again. To do this would I grind/sand the original tape flush with the fiberglass and then apply new tape and gel coat after? Would I just lay new tape over the existing?

And....while I'm at it I would like to strengthen the area of the deck directly behind the cockpit. The layup of this kayak is pretty light so I would like it to be able to take a bit more abuse without worry. Would this just be a matter of prepping the underside of the deck and laying in some cloth and epoxy?

Any advise/comments on cloth/epoxies/processes much appreciated. Thanks in advance.
Doug

 

[JohnAbercrombie]

Doug:
Can you get a good look at the crack from the inside of the hull, and/or get some pics of that area?

 

[Astoriadave]

Ideally, there is a glass/epoxy tape reinforcement on the outside of the hull/deck seam, which could be repaired by grinding down to solid glass/epoxy surfaces for hull and deck. Then renew that seam reinforcement, fill the weave with epoxy, smooth, and renew the gel coat to match the existing color.

This is not a job for someone new to using epoxy/glass and gel coat. Better to pay a reputable shop to do the job.

Further, that should not normally be a high stress area. You may have cracking other areas. If you can, inspect the inside of the hull/deck seams. Put the boat onto saw horses, upside down, don a strong head lamp, and poke your head inside the boat while sitting on a stool, as John suggests.

The manufacturer, really, should take responsibility for a failure of this type, unless the boat has been abused.

In the worst case, the manufacturer did not use glass tape on the outside, and grinding would reveal gel coat only. You might Google on "Tahe seam failure" to see if others have reported this.

 

[paddlesores]

Thanks guys,
I'll try and get some inside pics this evening after work.
Dave, this is an older kayak I bought used and wouldn't expect the manufacturer to go good for it. Knowing you've done extensive fiberglass work in the past, what is it that makes you recommend taking this to a shop for repair? I was hoping to take a shot at it myself but also don't want to get in over my head, not knowing the ins and out of the repair. Is there more to it than just grinding it down and running new seam tape? What are the possible worst case scenarios?
Doug

 

[AM]

I have a Tahe as well (different model - Wind 535). The Tahe line has some beautifully designed boats that, sadly, suffer from being underbuilt. The crack in your seam does not surprise me, as the seams are weak - mine only has tape on the inside, with a bead of gelcoat on the outside. The flex in your back deck is also not surprising.

When I first damaged my boat (cracking the coaming/deck seam while doing a cowboy scramble), I took it to a professional, who reinforced the area beautifully with carbon and epoxy. The bill was not so beautiful. After that experience, I decided that cheap, strong, and ugly repairs were the way to go, so I set about with glass tape and epoxy to bring this boat up to expedition strength, reinforcing areas in the hull, coaming, and bulkheads, and installing a glass keel strip. This in addition to replacing the cracked seat with a foam one and the cracked footpegs with a foam bulkhead pad. As I said, underbuilt.

Because I really like the design of the boat and because I intend to paddle it for another 10 years, the freakish appearance of my boat doesn't bother me. I don't intend to sell it, which is a good thing, as I would have to give it away!

If aesthetics and resale are important to you, do as Dave suggests and bring in a pro. But these boats were sold cheaply for a reason, so the other option is to embrace that low price point and live with a DIY boat. The fundamental design is solid.

Cheers,
Andrew

 

[Astoriadave]

paddlesores wrote: Knowing you've done extensive fiberglass work in the past, what is it that makes you recommend taking this to a shop for repair? I was hoping to take a shot at it myself but also don't want to get in over my head, not knowing the ins and out of the repair. Is there more to it than just grinding it down and running new seam tape? What are the possible worst case scenarios?

Andrew pretty much laid it all out. He obviously knows a lot about what you are facing. My guess is that once you start, you will likely need to rehab both seams, end to end.

I recced a pro, thinking that you wanted to restore the exterior to something like its original appearance. OTOH, if you pursue a path similar to Andrew's, are handy with tools and meticulous in use of epoxy and glass, a full seam repair should not be out of reach. Maintaining registration of the hull and deck is not difficult, and once you have practiced a bit with the resin and the glass, the actual job will be enjoyable. Esthetics and UV protection demand either Gel coat or a durable marine paint over the finished seam. System Three's two-part water reducible WR-LPU would be my choice, but a decent marine supply store should have good choices. Some paints do not cure well over epoxy, but a competent sales person can steer you to what will work.

Both WEST Systems and System Three have excellent, free support manuals to guide you over the major pitfalls, with the choice between the two likely dictated by whichever is available to you, or perhaps Andrew favors something else. Shipping from a US manufacturer may be expensive.

Couple links to get you started. Much of these manuals is applicable to any epoxy resin system. I have used System Three, exclusively, but others have had equal success with WEST or other resin lines.

https://www.systemthree.com/pages/literature

https://www.westsystem.com/instruction-2/

 

[JohnAbercrombie]

Both WEST Systems and System Three have excellent, free support manuals to guide you over the major pitfalls, with the choice between the two likely dictated by whichever is available to you, or perhaps Andrew favors something else. Shipping from a US manufacturer may be expensive.

Industrial Plastics and Paint carries both WEST and SystemThree epoxies, and they have stores in Richmond and Port Coquitlam, so shipping shouldn't be necessary.

If you decide on an extensive 'reno' job with rear deck reinforcement, consider removing the bulkhead behind the seat to give access to the aft part of the boat. Working through a hatch -even an oval one- isn't that easy; I've done it a number of times.
My guess (like Dave's) is that you will find more problems with the inside tape on the hull. This assumes that there is glass tape on the inside - the boat may have been assembled without tape on the inside (like a surfski).

It's not 'standard' to find boats with glass tape on the inside and outside of the hull, though better quality boats (e.g. Mariners!) do have both.
For example, many kayaks were (are) built with a vinyl 'H' molding joining the hull & deck with tape added only on the inside.
Some (all??) of the NDK boats have inside and outside glass tape but the outside tape is not very 'structural' as it is just tape set in a thick gelcoat layer.
Look how easily the tape is removed from both the inside and outside of a Romany in this video:

Glass tape should not 'peel' off when cut with a utility knife!
Here's an outside repair on a kayak that has a 'structural' outside tape:

It looks like there's no tape on the inside of that boat, but it's not clear.

On your Tahe, the molded 'drainage channels' on the aft deck are probably partly there to stiffen the deck - if it had been left flat it would be even more flexible than it is.

 

[Astoriadave]

John wrote:
It's not 'standard' to find boats with glass tape on the inside and outside of the hull, though better quality boats (e.g. Mariners!) do have both. For example, many kayaks were (are) built with a vinyl 'H' molding joining the hull & deck with tape added only on the inside.

John's cautions are germane. Andrew may have a good idea of what you are facing, paddlesores. What follows is not intended to intimidate you, but perhaps to illustrate how a rehab job can "expand" to a real project, simultaneously serving as a "free" lesson and test bed for learning how to work with fiberglass boats. Glass boats are repairable, with patience and rudimentary skills.

My first boat was an "older" Eddyline Wind Dancer, all-polyester/styrene resin layup, light, with FOUR-INCH wide seam tape laid on the inside of the boat end to end, "adhered" with polyester resin, likely using a vacuum bag technique to get good squeezeout across the seam tape. That worked well enough until the previous owner oil canned this eggshell boat in a six foot plunging breaker.

Eddyline fixed the deck and hull fractures, but missed the coaming-deck seam rupture, and the seam tape failure, which extended the entire length of the cockpit, from bulkhead to bulkhead (yes, they leaked). Having no money and little experience with fiberglass or polyester resins, I took on the repair.

The tape could be peeled off with a scraper! The seam tape never properly bonded with the deck and the hull because Eddyline likely used resin with wax in it, to facilitate release from the mold and the airbagging cloth/bag surface. Much grinding to reach solid, untainted material later, I laid in fresh 4 inch seam tape using wax-free resin, one side at a time, employing about 80 1-pound lead ingots to achieve squeezeout. And scraped and sanded off all the resin stalactites. A finish coat of wax-containing resin and a little finish sanding, and my 500 dollar boat was cured!

I used it for a year , sold it for 700 bucks, and bought a well-constructed, new Wind Dancer in 1992. (Eddyline had learned a few things.) That boat took me everywhere for almost 20 years.

 

[JohnAbercrombie]

The tape could be peeled off with a scraper! The seam tape never properly bonded with the deck and the hull

I 'renovated' a Northwest Kayaks boat where the inside seam tape was loose for several feet in the forward compartment. Seam tape was generally laid into the hull 'one side at a time', with the hull tilted on edge. What I think happened was that when that particular boat was built, the hull was flipped 'other edge up' before the resin had hardened. The seam tape on one side was 'drooping' over a span of 2-3 feet! I slid a putty knife under the tape and peeled off about 4 feet until I got to areas that were properly bonded. Thankfully the defect area did not reach all the way to the bow!
That particular repair was made easier because I had a good-sized hole in the deck where I was going to install a new recess for the forward hatch. Without that it would have been a long stretch (resin brush on a stick) from the cockpit to the repair area. (18.5 foot boat).

 

[paddlesores]

Thanks for all the replies. This is exactly the info I was looking for.
Dave, I'm not looking for a professional finish in the end, more along the lines of what Andrew describes. Glad to hear you say it is doable with a little patience and practice.
I had just assumed all kayaks were taped inside and out. So I sanded down a short length of the crack and like Andrew said, found it was just a thin layer of gel coat on the outside. On the plus side it is taped on the inside and I couldn't find any loose or cracked areas there.

Since the inside seam doesn't look cracked I'll wait until the weekend and put some water in the rear compartment and see if I can find where the water is coming in from.
I think I will go ahead and redo the exterior seam the whole length of the kayak. So any suggestions on the process itself would be a big help. I'm assuming it would be best to do one side at a time. Simply stated I'm thinking it is a matter of sanding off the original gel coat, prepping the surface and applying the 1" wide tape with epoxy and then gel coat over that. Sound about right? Any special glass recommendations for this? I'm hoping I can buy a roll of 1" wide tape. I'll head into Industrial Plastics this weekend and talk to them about the job.
Thanks again all. Doug

 

[nootka]

I think you'll find the skeg box is just gel-coated in place.
So don't bump it hard unless you want to fiberglass it.

I still haven't glassed mine yet - mainly because of the tight access.

 

[Astoriadave]

Doug, if you have been getting water inside the bulkheaded compartments, it is possible you have some very small holes which are not readily visible. Might be smart to give the inside and outside of the hull a scrubbing with soapy warm water, followed by a clear water rinse, to remove any grime, etc., which might make it difficult to see the leaking spots.

The inside of the boat looked pretty good to me. This looked like a straight forward job to me. I expect a renewal of the external seam tape, and new gel coat over the tape should do it. That Stealth video (last one) illustrated pretty well what a swift, skilled operator of a RO sander can achieve. And you probably noticed they did not worry about getting a super smooth surface at wet out, saving the sanding/smoothing until the two layers of seam tape were cured. And their gel coat mixture was pretty fluid, but lots thicker than water, allowing them to paint on a nice thick layer, suitable for fairing if you have some bumps, etc. You can sand, using progressively finer grits, to reach a smooth, even shiny surface.

Doing the entire seam fresh means you won't have to match the new gel coat to the old. I think your prospects are very good for a skookum outcome.

Oh, one last suggestion: no worries if they do not have 1 inch seam tape. You can carefully scissor lengths of the correct width off 6 oz glass cloth, following the weave of the cloth. Does not matter if they are less than full length. Overlaps of a couple inches or so will sand out smooth after the two layers are cured. You might lay out some seam tape on a two foot length of 2 inch lumber and practice wetting it out, and sanding it smooth, ahead of doing the seam tape on the boat.

 

[JohnAbercrombie]

Dave, I'm not looking for a professional finish in the end, more along the lines of what Andrew describes.

................. Sound about right?

If you are careful you should be able to make your re-do of the seam look 'professional'.
Watch the video from Stealth kayak for some pointers. Notice how they mask off the hull and deck to prevent scuffing it up. You can save yourself a lot of fine sanding and buffing by doing that. Also, I wouldn't count on the gelcoat being very thick, so you may not have a lot to work with before going 'through'.
About glass tape: If it were my project, I wouldn't make the seam any wider than it is already, so that might call for 0.5" tape. If you have to order some and wait a while, it may be worth it.
The Composite Store http://www.cstsales.com/glass_tape.html does mail-order (Be sure to specify USPS shipping).

You can get System Three white pigment for epoxy, which would allow you to use epoxy for the whole job. Fill the cracks with epoxy thickened with silica (AntiSag), sand smooth. Apply tape wetted out with epoxy. The edges of the tape will leave raised ridges. Sand smooth. Topcoat with thickened epoxy with white pigment. If you get the consistency right it will flow out to a presentable surface without further work. If it's lumpy, sand till smooth and apply another coat if necessary.
At each step you will need to renew the masking tape, so visit an autobody supply and buy a few rolls of good Scotch-brand masking tape.
Fix the scratched areas (from sanding) on the hull and deck by wet sanding with grits up to 800 or so, then use rubbing and polishing compound to bring up the gloss.
It will all add up to some expense to get the materials, but having the right stuff makes the job easier, especially if you haven't done this type of work before.
BE SURE TO PROTECT YOUR SKIN FROM EPOXY CONTACT. If you do get epoxy on your skin, wash with white vinegar, then soap and water, NOT SOLVENT.

 

[JohnAbercrombie]

For removing gelcoat along the seam stripe, and for opening up cracks and cleaning them out, the carbide 'corner scraper' from Lee Valley is an excellent tool. It uses square carbide tool inserts, so there's a point and a couple of 1/2" flat scraping surfaces available. And it stays sharp a very long time; then you rotate the cutter 180 °.
http://www.leevalley.com/en/wood/page.aspx?p=20095&cat=1,43456,43390

 

[paddlesores]

We have two more weeks of Friday night pool sessions coming up so I've done a temporary repair so Lila can use her kayak. I taped off either side of the gel coat and sanded off the cracked area. I then chipped out some of the old epoxy in the seam, used a Dremel to make a shallow groove, roughened up the area and then cleaned with acetone. Then I retaped the seam and just filled it with epoxy. That should keep until I get to applying new seam tape in a couple weeks. In case anyone is interested I will post pics of the progress when I get to it.

Doug

 

[JohnAbercrombie]

Doug-
That repair looks a lot more workmanlike than the factory job with the voids!
Good start!

I would be interested in seeing pictures and descriptions as you progress with the repair. Every job seems to have its own 'peculiarities'; always something for me to learn.

Did your experiments with putting water in the compartment to find leaks show that the seam (not the skeg box) is definitely the problem?

 

[paddlesores]

John,
I put off doing the water tests until tomorrow. Wanted to keep the area bone dry to be able to get this part done.
Will likely reinforce the skeg box while I'm at it. Like Nootka says, it doesn't look like much holding it in place.
Appreciate the help and pointers.
Doug

 

[Astoriadave]

Doug, I concur with John. That looks solid, the tape having overlapped clean, sound glass on each side of the void. If you had added another layer of tape and resin when the first one was still "green" (not fully cured), your two layers of tape would have been chemically bonded, sometimes termed a "monolithic" glass/resin repair.

Not a big deal, though, because roughing up the existing repair prior to adding the next layer of tape/resin will ensure a good physical bond between the layers, plenty good for what you are doing, and with monolithic fill coats and some gel coat on top, ACRES better than what was there before.

Your work shows a very high level of skill ... certainly far, far better than most resin newbies attain on a first serious repair. Hope your spouse provides some apropos rewards!

 

[JohnAbercrombie]

Doug, I concur with John. That looks solid, the tape having overlapped clean, sound glass on each side of the void. If you had added another layer of tape and resin when the first one was still "green" (not fully cured), your two layers of tape.....

Dave, I think that Doug just filled the gap with epoxy (thickened?) and will tape later. IMO that's the best strategy anyway, considering the number and extent of the voids that Doug uncovered.

Your work shows a very high level of skill ... certainly far, far better than most resin newbies attain on a first serious repair.

Agreed!
Masking tape is our friend!

 

[Astoriadave]

Ah, looking at the photos more carefully, you are correct, John. The void has been filled, but no seam tape yet. Comments about the value of a monolithic seam tape method still apply.

When possible, I piggyback the second tape layer when the underlying layer is still a bit squishy with resin, using the second layer to draw the excess out, stippling in fresh resin onto the dry areas to get full wet out. But, one layer at a time to the green stage is just as good strengthwise, and easier to control.