Minor fiberglass/epoxy repair -- from below :: Catamaran Sailboats at TheBeachcats.com

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Minor fiberglass/epoxy repair -- from below

martin_langhoff

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Registered: Oct 26, 2016

Last visit: Feb 14, 2025

Posts: 235
Posted: May 23, 2017 - 07:49 PM

I need to make a minor fiberglass+epoxy repair on the bottom of one of the hulls of my cat (using the West Systems kit). Being shorthanded, and practical (erm, lazy!)... any tips for working from below?

The repair is very small - about size of a quarter coin.

My current plan is to...

- make sure I don't get the epoxy on me
- glad wrap to smooth the surface

hints and ideas welcome
fxloop

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Registered: Jul 20, 2011

Last visit: Apr 07, 2019

Posts: 323
Posted: May 23, 2017 - 07:52 PM

http://www.essentialhardware.com/oatey-31270-multi-purpose-epoxy-putty-210943.html?utm_campaign=google&utm_source=google&utm_medium=cpc&gclid=COTi7JaNh9QCFQyNaQodJ7sDaQ

easy :)

--
Tim Grover
1996 Hobie Miracle 20
Two Hobie 14's
1983 G-Cat Restored
Memphis TN / North Mississippi
--
christopher_g_lewis

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Posts: 17
Posted: May 23, 2017 - 09:36 PM

Don't use Glad wrap - it will dissolve. Heavy duty aluminum foil with some auto wax on it.

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Chris Lewis
Wilmette, IL
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Dogboy

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Registered: Mar 19, 2004

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Posts: 965
Posted: May 23, 2017 - 10:43 PM

If your repair involves adding fiberglass cloth, I would recommend wetting out the glass on a piece of wood or cardboard first so you're not trying to work resin into the glass upside down. Also paint a thin coat of resin on the hull before putting the glass on. Then place the glass onto the hull and the stickieness of the resin will hold it in place. That way all you're really doing once the glass is on the hull is smoothing it out and pulling out the excess resin.

Definitely wear eye protection when working upside down and possibly even a hat and face shield. You really don't want epoxy dripping on your head.

sm
bacho

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Registered: Jun 17, 2011

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Posted: May 24, 2017 - 12:07 AM

christopher_g_lewisDon't use Glad wrap - it will dissolve. Heavy duty aluminum foil with some auto wax on it.

Maybe with resin it will, I have used it plenty of times with epoxy.

Get your cloth wet out properly with out any extra resin if you can help it. Try to keep it off anything your not repairing, a good wax will help protect the area your not repairing from drops sticking.

--
Greenville SC

Offering sails and other go fast parts for A-class catamarans
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tominpa

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Registered: Jul 29, 2015

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Posts: 601
Posted: May 24, 2017 - 12:15 AM

Your project does not seem complicated. Once you complete a fiberglass/epoxy repair, you still need to smooth and fair the surface. You will need additional epoxy and microfiber to do it with marine stuff. The microfiber is great stuff, but you didn't say what your finishing plans (if any) are.

--
Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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MN3

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Registered: Jun 20, 2006

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Posts: 7090
Posted: May 24, 2017 - 10:06 AM

Quote Try to keep it off anything your not repairing, a good wax will help protect the area your not repairing from drops sticking.

In case this isn't totally clear: you can use a auto polish/wax on areas near the repair that you don't want epoxy on. If it drops on a waxed area - after it dries it will "slide" off with a fingernail or razor very easily - otherwise ... it will be a bear to get off.

as per the saran wrap - I use wax paper with fantastic results
Let your west system (or any brand) start to kick off - depending on temp and humidity (and assuming your epoxy/catalyst are the correct ratios) there is a 15-30 min window or so where your epoxy is getting firm but still in a play-doh state. at this time i use wax paper and my hand and shmeeer and flatten the epoxy out (that is on the boat, under the waxpaper). when done properly... the end result is a patch that needs VERY LITTLE sanding/fairing. this technique works on hulls, boards, etc.

My one other tip is: when adding glass... use multiple layers. cut the largest one to overlap your repair, then cut multiple other strips that are smaller and smaller (3 or 4). You should "DRY FIT" the largest strip, making sure it covers everywhere it needs to ... then go back in your shop and cuts out several more... smaller and smaller each time. When ready to epoxy: wet out the area on the boat then wet out the biggest strip, apply - then wet out the next strip and apply ... so on and so on. after the last one is on .. i put the wax paper on and go have a rum drink (only 1) and 15 or 20 min later i go back outside and test the firmness of the epoxy (by playing with the stir stick and pot - no need to mess up my glass work)

I also suggest you purchase west marine mixing pots (plastic cups) and west marine stir sticks. both are cheap and the stir sticks are great for mixing and getting into the corners of the pot. these are completely re-usable too: after the epoxy cures... it peels right out of the pot - i actually enjoy this - kinda like popping plastic wrapping bubbles
Dogboy

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Posted: May 24, 2017 - 11:34 AM

The down side to waxing the "non-repair" areas is that there is a pretty substantial risk of contaminating the area that you DO want to repair with wax. If you get wax on your repair, the epoxy is going to have a poor bond. Best to keep waxes and other contaminants away from the repair as much as possible.

If you're fixing a large area or need to work quickly, then you can use masking tape and newspaper to protect exposed areas from drips. Otherwise, just wipe up any drips using a paper towel soaked with acetone while the epoxy is still wet. It will come right up. If you take your time with the repair, there really shouldn't be that many drips anyway.

sm
gahamby

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Posted: May 24, 2017 - 04:16 PM

Quotethen you can use masking tape and newspaper to protect exposed areas from drips. Otherwise, just wipe

I'm gonna have to go ahead and disagree with you on that newspaper call. Resin will soak right through newsprint and stick right to the hull. The ink will run also. Don't ask how I know please.
I suggest, at minimum, brown craft paper. Proper masking paper from the auto body paint store, even better.
If you're outside, don't leave the masking tape on very long. If it gets wet and then gets exposed to sunlight it will stick like hell.

--
'82 Super Cat 15
Hull #315
Virginia
Previously owned: '70 H14, '79 H16, '68 Sailmaster 26, '85 H14T
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MN3

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Posted: May 24, 2017 - 04:46 PM

QuoteThe down side to waxing the "non-repair" areas is that there is a pretty substantial risk of contaminating the area that you DO want to repair with wax. If you get wax on your repair, the epoxy is going to have a poor bond. Best to keep waxes and other contaminants away from the repair as much as possible.

I agree 100%
What i do is tape off around the repair / several inches of tape/ craft paper - and then wax outside of the tape area
probably not a huge deal when working on the bottom from below but working on top or side of the cat - i always seem to accidentally "fling" or drip some epoxy somewhere i didn't plan
MN3

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Posted: May 24, 2017 - 04:48 PM

This is a great tutorial on glass work and how to pre for it (don't worry about the carbon fiber stuff if it doesn't apply to your cat)
par t 1 https://www.youtube.com/watch?v=9TyWSnAvI9A
part 2 https://www.youtube.com/watch?v=_7h58sONCek
part 3 https://www.youtube.com/watch?v=wr4aHY1L0M0
Dogboy

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Posted: May 24, 2017 - 09:49 PM

gahamby
I'm gonna have to go ahead and disagree with you on that newspaper call. Resin will soak right through newsprint and stick right to the hull.

You may be right on that. If you spilled your entire cup of resin, I'm sure news paper would not prevent it from soaking through and contacting the hull. However I've used news paper plenty of times just to prevent small drips and splatters and it has worked fine. Again, if you're taking your time and using care when working with the resin, you really shouldn't be making much if a mess to begin with.

sm