Deck Delamination Repair - suggestions?

GeoffS

Member
Hi all,

I've been working on boats for some time, but I'm new to the intricacies of Laser repair. I have a '94 Laser with some deck delamination (spider cracks). I was planning to do the normal trick of drilling a bunch of holes and injecting WEST into them, but I thought it would be a good idea to tap into the collective experience of the class for any hints/tips.

My current plan is to drill a series of 1/8" holes on an approx. 1" grid through the deck and core, but stopping just at the inner skin. Then inject unfilled (neat) WEST and wait for a few minutes so that whatever absorption may occur can happen. Finally suck the excess unfilled epoxy out and fill the hole with a fairly stiff mixture of spoxy and some high-strength filler (probably WEST 404 High Density Filler).

Any hints, tips, or suggestions on better ways to approach this problem?

Cheers,

Geoff Sobering
[email protected]
 
I don't have any tried and true unconventional solutions to the DECK delamination repair problem, but I have successfully taken care of COCKPIT delamination problems.

The standard epoxy resin injection method outlined above adds much unwanted weight to the core foam if the delaminated area is significant. The method I used on my cockpit sole was able to keep my late 1980's Laser at its original 128.5 lb. hull weight (inc. standard hull fittings).

You can find the details in the drLaser website, "Maintenance & Fitness" section.

See: " Major surgery for severely damaged Laser cockpit soles".

Available to ILCA members only (except in North America, where it is available to ALL sailors.)

Cheers,

Shevy Gunter
 
Thanks for the reply. So far, I haven't be able to get to the drlaser.org articles with the asterixes... Please let me know what I need to do to access them (I'm quite interested in a number of the maintenance articles).

While I was working on my boat, I also discovered rather substantial cockpit sole delamination (I'm not sure if there was much foam core left between the glass layers!). There was also a similar problem on a large area of the rear-deck. I was also worried about adding weight, and did consider carefully cutting off the top deck skin, scraping (or vacuuming) out the remaining core, bonding new core onto the inner-skin, and finally bonding the original skin back in place. I've used this technique on other boats and it works pretty well. In this case, I decided to try an alternative technique (mostly because I didn't realize the extent of the problem when I started, and I didn't have any foam-core handy...).

To keep the mass of the epoxy injected into the "delaminated" areas as low as possible I tried to mix in as much WEST 410 Microlight (tm) filler as I could and still get the epoxy through the luer-lock tip of the syringes I was using and into the underdeck cavity. I always started by injecting a bit (ca. 5 ml) of un-filled epoxy into every hole to try and wet-out the core and skin. After a bit of experience I could estimate how thick a mixture of epoxy I would be able to inject from the resistance I felt during the first injection. For the really bad areas I usually ended up with a mixture of 1:1 (by volume) of epoxy and 404 High-Density Filler, then about 1:2 (or a bit more) of that mixture and Microlight. My guess is that I added somewhere between two and three pounds to the weight of my hull. That estimate is based on materials I consumed during the project, about 1 qt. of WEST 105/205 resin/hardener (ca. 2.5 lbs), and 1/2 container each of 404 and 410 filler (which don't have a total weight of 1/2 lb).

I'm a bit concerned about the shear-strength of the Microlight-filled epoxy (since the core is mostly in shear). If it does fail, I suspect (hope?) it will be fairly easy to scrape/sand out and replace with something better (hence my interest in other repair suggestions).

Once I have a chance to evaluate the repair a bit, I'm planning to write it up and post the procedure/techniques on the boating section of my web-site (see URL below).

Cheers,

Geoff Sobering
http://sobering.terracom.net/iceboating/index.html
DN: US 5156
Laser: 145234
 
"Cutting off the top deck skin, scraping (or vacuuming) out the remaining core, bonding new core onto the inner-skin, and finally bonding the original skin back in place" is the ideal system if you have a solid core, cut or layered in sheets to the right dimensions (e.g., end-grain balsa wood, Klegecell and Divinycell, Honeycomb, Core-Cell, etc.).

If using a non-solid foam (e.g., in cans or spray tubes) which expands upon contact with air, leaving the top deck skin on but merely drilling holes to inject or pour the foam from works better. That's the technique that I had used in the drLaser article titled "Major surgery for severely damaged Laser cockpit soles".

(The article also covers how to repair the hairline cracks that caused the cockpit sole core failure in the first place.)

When using the resin injection method, mixing in WEST 410 Microlight (tm) filler to keep the mixture light is an interesting idea, but there may be some problems with WEST 410 - which is basically a soft fairing compound: first, it is not recommended for surfaces subject to high tempretatures (keep your deck down if the sun is up, baking the deck!); and secondly, if I am not wrong, the mixture you mention probably works out to something like "catsup consistency" (rather than mayonnaise or peanut butter consistency) and should not lighten the epoxy much.

I have no sheer strength / modulus / elongation data for the resulting mixture.


As for access to the password protected drLaser articles:

I can post a detailed explanation here (in a separate thread), but all the info is already available in the drLaser FAQ.

In short:
- If you are in NA (CAN & USA), the system *should* allow you access when you click on any of the "available to ILCA members only" links.
- If outside of NA, a special password obtained from your local Laser class association is necessary.

If you are in NA and the syetem still asks for a password, there is a problem with your ISP and you can contact [email protected] to resolve the problem.

Shevy Gunter
Editor, drLaser
 
When using the resin injection method, mixing in WEST 410 Microlight (tm) filler to keep the mixture light is an interesting idea, but there may be some problems with WEST 410 - which is basically a soft fairing compound: first, it is not recommended for surfaces subject to high tempretatures (keep your deck down if the sun is up, baking the deck!);

Gougeon's usually recommend against using 410 under dark painted surfaces. My deck is white (although my deck-cover is blue!) but I store the baot in a partially shaded location, so I'm hoping things won't get warm enough to cause problems. I'm more concerned with the structural characteristics of the mix, although considering it's compeating with *foam*, I think there's a chance it will be OK. I'll report back at the end of the season.

[...]the mixture you mention probably works out to something like "catsup consistency" (rather than mayonnaise or peanut butter consistency) and should not lighten the epoxy much.

Actually, it's surprising how stiff a mixture you can force through the luer-lock fitting on a standard syringe. In the areas that had no foam I was able to inject pretty much peanut-butter consistancy epoxy/filler into the deck. Based on how many 60ml syringes of mixture I got from a single WEST "pump" of epoxy, I'm guessing that the volume of my stiffest mixture was somewhere around 3-4 times larger than the original (neat) epoxy. That would put the mixture density in the range of 0.3 to 0.4 g/ml, which is about 3-4 times the density of Airex foam-core, but still pretty light (for the volume I used).

I'm planning to make up a batch of epoxy the same way I was doing during the repair (based on perceived stiffness) and record the proportions of each component (epoxy, 404 filler, and 407 filler). Then measure the density of the cured material. Hopefully there will be a new drlaser article soon (although sailing will probably make it take a bit longer...).

Cheers,

Geoff S.
 
> Hopefully there will be a new drlaser
> article soon (although sailing will
> probably make it take a bit longer...).

We will all look forward to it, and be grateful to you for sharing it with us.

Best,

Editor, drLaser
 

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