Gelcoat Chips Repair :: Catamaran Sailboats at TheBeachcats.com

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Gelcoat Chips Repair

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samc99us

Rank: Mate

Registered: Apr 15, 2005

Last visit: Feb 21, 2024

Posts: 574
Posted: Apr 12, 2018 - 10:02 AM

Best is to take the boat by a professional gelcoat shop and have them mix you up a batch of color matched gelcoat.
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Apr 24, 2018 - 06:05 PM

QuoteI use credit cards for small areas and this block for larger areas:

Hey Sam, Are you saying you use a credit card as a sanding block?

If so, you just fold the sand paper around the card?

thanks
samc99us

Rank: Mate

Registered: Apr 15, 2005

Last visit: Feb 21, 2024

Posts: 574
Posted: Apr 25, 2018 - 02:39 PM

Yep, I just 3M 77 sandpaper to old credit cards or room keys, or often just fold it over and grip with my fingers.

For larger areas, this is the sanding block I use: https://www.amazon.com/gp/product/B003WUYG1E/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Apr 25, 2018 - 03:54 PM

Got it - thanks

one mo' question if you don't mind

I just purchased some PVA and am gonna try using it instead of wax
can you elaborate on why you suggest waiting 30 min to 1 hour before applying?

My guess would be to allow the gelcoat to start to kickoff and solidify so it doesn't mix/contaminate but that's just my guess.

thanks!
martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 25, 2018 - 04:03 PM

At work we wet sand defects out of freshly primered kia bodies by hand with a 3 inch diameter squishy foam palm sander that has a sponge in the center of it and is called a "nubby". We use 800 grit in the primer booth that I work in and the nubby is fairly flexible. I think it would work well for gelcoat repairs.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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samc99us

Rank: Mate

Registered: Apr 15, 2005

Last visit: Feb 21, 2024

Posts: 574
Posted: Apr 26, 2018 - 09:47 AM

marty, do you have a link to said palm sander? That does sound pretty perfect.

Yep MN3, want the gelcoat to get a bit solid but not mix with the PVA.
MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Apr 26, 2018 - 11:39 AM

QuoteYep MN3, want the gelcoat to get a bit solid but not mix with the PVA.

cool - thanks for all the advice
martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 26, 2018 - 07:26 PM

Samc99us, I cannot find anything online but when I get to work tomorrow I will find out who makes the palm sander.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 27, 2018 - 09:25 PM

Okay I found out that the palm sander is made by 3M. Being not very "tekie", I still cannot seem to post pics within the forum so I created an album in the Beachcats Technical album labeled "3M 3 inch diameter palm sander" . If anyone wants to post the pics in this thread, then by all means, feel free to do so. Sorry the pics are sideways also but I think you can see that the palm sander is a bell shape and fits your hand very well. I hold on to one of these things for 8 hours a day so i know these things well. Hope this helps somewhat but I have no idea how to order the things.

Edited by martyr on Apr 27, 2018 - 09:28 PM.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Apr 27, 2018 - 09:27 PM

Quotealbum in the Technical album labeled "Palm Sander"

https://www.thebeachcats.…c1f9224ee65bf4ba657010cc

so is the rolling pin to beat out any dents?

Edited by MN3 on Apr 27, 2018 - 09:41 PM.
MN3

Rank: Master Chief

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Posts: 7089
Posted: Apr 27, 2018 - 09:40 PM

I can't find those exact ones but here is one that is very close
https://mirka-online.com/…ipment/hand-sanding.html

they also make 5"
martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 27, 2018 - 09:40 PM

Bwahaha, that's for rolling the good stuff!!!

Edited by martyr on Apr 27, 2018 - 09:41 PM.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 27, 2018 - 09:43 PM

Yep, we use 3M and Mirka sandpaper st work.

I googled "3M hand sanding" and found the palm sander. It's called "Hookit". I added a screen shot picture to the sub album in the Beachcats Technical album.

Edited by martyr on Apr 28, 2018 - 05:01 AM.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: May 22, 2024

Posts: 7089
Posted: Apr 28, 2018 - 08:48 AM

QuoteI googled "3M hand sanding" and found the palm sander. It's called "Hookit".

https://www.3m.com/3M/en_…002385+3293083554&rt=rud

this one has a hole "Proprietary center water feed system allows water to flush sanding residue"
(I like it)

https://www.3m.com/3M/en_…002385+3293083517&rt=rud
martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 28, 2018 - 10:10 AM

Yep, that's the one. I didnt think to show the hole in the pics of the one I have, but it does have the hole in the top as well. Thanks for adding the pics MN3.

Edited by martyr on Apr 28, 2018 - 10:11 AM.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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DVL

Rank: Lubber

Registered: Mar 16, 2005

Last visit: Dec 29, 2019

Posts: 16
Posted: Apr 29, 2018 - 09:12 AM

I just went to a gel coat seminar by a large working marina (Torrensen Marina) that serves mainly sailboats. They perform all types of fiberglass work, paint and repairs on boats up to and over 70'. They have rebuilt & repaired production yachts as well as hi-tech racing boats. The service manager said that if he could get a guy that could get the gel coat color right on the first try he would hire him immediately. They do have a system that is hard to explain, but he said most mistakes are made by not cleaning and getting the immediate area clean and brought up to a nice shine but no wax. Because when you go to sand the new into the old you will get to that shine and the color match will be off.

He also said that you should mix up 3 x more than you need for the color match, (no hardener). Keep the extra in a refrigerator. One guy gets it as close as he can and then at least two others look at it from no closer than than 3' away. Natural light only, no fluorescence lighting. Adjust color until all three say its OK. If you have a quarter size ding, he tapers up to 8" and uses plenty of Duratec for thinner, never acetone. Spray & sand. His final coats are more thinner than gel coat so they can blend the gel coat in.

If you want a perfect patch you will need to spray the whole boat as there is no such thing as "perfect", only very close.
klozhald

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Registered: Apr 19, 2011

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Posted: Apr 30, 2018 - 01:54 PM

DVLI just went to a gel coat seminar by a large working marina (Torrensen Marina) that serves mainly sailboats.

Wow, you got decades worth of expertise in that seminar.
Jealous.
Where is this marina?

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Bob
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Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
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MN3

Rank: Master Chief

Registered: Jun 20, 2006

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Posts: 7089
Posted: Apr 30, 2018 - 02:35 PM

Quotehe said most mistakes are made by not cleaning and getting the immediate area clean and brought up to a nice shine but no wax. Because when you go to sand the new into the old you will get to that shine and the color match will be off.

I replaced both bow tangs last year and spent lots of time trying to get the exact amount of pigment to match my boat. working in small and numerous batches it was a giant PITA to repeat the exact amount of gel/mekp/pigment/and wax since i am in a garage, not a controlled lab/shop (and not an expert by any means)

it never really matched all that well but since it was only the top... and not "lined up" with the freeboard) it's really not noticeable unless someone with a good eye examines it. and i don't care enough to care about their opinion

i am currently doing a bottom job on my spare catamaran and have added a fair amount of non tinted gel coat

while fairing: i have sanded through a couple spots on the tape line: only to find the white gelcoat I am using is an almost exact match for my boats original gelcoat (1994 model, never re-gelcoated as far as i know)

So it ends up: all that tinting i did was color-matching to old dirty gelcoat

i gonna leave the brilliant white new gelcoat and the old dirty gel coat the way it is - and call them racing stripes
MN3

Rank: Master Chief

Registered: Jun 20, 2006

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Posts: 7089
Posted: Apr 30, 2018 - 02:36 PM

martyrYep, that's the one. I didnt think to show the hole in the pics of the one I have, but it does have the hole in the top as well. Thanks for adding the pics MN3.Edited by martyr on Apr 28, 2018 - 10:11 AM.

i think it's brilliant to be able to run water through it

do you do that on primer?
martyr

Rank: Mate

Registered: Jul 01, 2016

Last visit: Aug 30, 2023

Posts: 631
Posted: Apr 30, 2018 - 04:15 PM

We simply dip the sanding end in a water tray and the center sponge soaks up water and also holds any sanding residue. We use this sander on freshly primered bodies of multiple colors. The water trays are like small sinks mounted on the wall of the booth at each station and have two chambers, water is in one and a flat brush is in the bottom of the other for cleaning the residue from your sandpaper. The process is dip, scrub the sander across the brush, squeeze out the excess water, sand in a circular motion keeping the palm sander flat.

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Marty
1984 Hobie 16 Redline Yellow Nationals, "Yellow Fever"
Opelika, Al / Lake Martin
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