photo essay, fixing gel coat cracks - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 03-22-2009
Senior Member
 
Join Date: Jul 2008
Location: chesapeake bay
Posts: 1,942
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 7
scottyt is on a distinguished road
photo essay, fixing gel coat cracks

no photos tonight but i will update the thread

my boat is an 83 hunter, and with its age it needs some paint. but before i paint i will be fixing all my gel coat cracks. the procedure i am using is to open the cracks up using my dremel, then filling them with filler.

first step is to get a decent cutter for the dremel, make sure to get a carbide one, as high speed steel ones wont last long on fiber glass. if you just have a few you can just scrape them with a screw driver, but the dremel is much faster. remember be careful with water and electric. then just follow the crack with the dremel on about medium speed, just like you where drawing on them with a pencil. this should open them nicely for filling and relieve the stress in the gelcoat. after the dremeling i wipe the crack with alcohol to remove any wax. i like the dremel because if there is any separation of the gelcoat from the glass underneath you can hear it.

filling:
okay i dont like using any thickener in gel coat because i believe the thickener can allow water into the glass under the gel coat. so the first coat i do is straight non sag gel coat from west marine, it is a finishing one so it will cure on its own. i just mix some up and spread it with a spreader, it is thin, and will run contrary to what the name of it says. all we need here is basicly a sealing coat, and to start the filling steps. once the first coat is cured, wipe it down with more alky, then lightly sand any surface build up off. the next coat i do it the same gel coat with some fairing thickener in it, the west system stuff is brown so it stands out some. when applying it i also just use a spreader but i gently spread it, so it lays over the surface and fills the ground out area. once it cures i go back and sand it with 150 grit paper, using blocks, fingers what every is needed to smooth it out. the thickener will make it easy to sand.

some will say to use epoxy for this and you can, but i like the gel coat because will cure faster and you can do several steps quickly. if you plan it right you can dremel out one area, fill it, then dremel another while the gel coat cures. then fill the second and while it cures sand the first.

final step before painting for me is to get a sponge roller and roll on a thin sealing coat of straight gel coat. after the sealing coat cures give it a light sanding after the alky wipe with 220 to feather the edges and smooth it out. if you are not painting give it a few more coats of gel coat working each out over a slightly larger area, one inch larger each coat is good, sanding each lightly after an alky wipe. when its nicely coated give it a sanding and polish to your hearts content

i will post some pics in a few days
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 03-22-2009
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,539
Thanks: 13
Thanked 149 Times in 115 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Good write up..

Quote:
Originally Posted by scottyt View Post
no photos tonight but i will update the thread

my boat is an 83 hunter, and with its age it needs some paint. but before i paint i will be fixing all my gel coat cracks. the procedure i am using is to open the cracks up using my dremel, then filling them with filler.

first step is to get a decent cutter for the dremel, make sure to get a carbide one, as high speed steel ones wont last long on fiber glass. if you just have a few you can just scrape them with a screw driver, but the dremel is much faster. remember be careful with water and electric. then just follow the crack with the dremel on about medium speed, just like you where drawing on them with a pencil. this should open them nicely for filling and relieve the stress in the gelcoat. after the dremeling i wipe the crack with alcohol to remove any wax. i like the dremel because if there is any separation of the gelcoat from the glass underneath you can hear it.

filling:
okay i dont like using any thickener in gel coat because i believe the thickener can allow water into the glass under the gel coat. so the first coat i do is straight non sag gel coat from west marine, it is a finishing one so it will cure on its own. i just mix some up and spread it with a spreader, it is thin, and will run contrary to what the name of it says. all we need here is basicly a sealing coat, and to start the filling steps. once the first coat is cured, wipe it down with more alky, then lightly sand any surface build up off. the next coat i do it the same gel coat with some fairing thickener in it, the west system stuff is brown so it stands out some. when applying it i also just use a spreader but i gently spread it, so it lays over the surface and fills the ground out area. once it cures i go back and sand it with 150 grit paper, using blocks, fingers what every is needed to smooth it out. the thickener will make it easy to sand.

some will say to use epoxy for this and you can, but i like the gel coat because will cure faster and you can do several steps quickly. if you plan it right you can dremel out one area, fill it, then dremel another while the gel coat cures. then fill the second and while it cures sand the first.

final step before painting for me is to get a sponge roller and roll on a thin sealing coat of straight gel coat. after the sealing coat cures give it a light sanding after the alky wipe with 220 to feather the edges and smooth it out. if you are not painting give it a few more coats of gel coat working each out over a slightly larger area, one inch larger each coat is good, sanding each lightly after an alky wipe. when its nicely coated give it a sanding and polish to your hearts content

i will post some pics in a few days
Two things that may help.

1) Contrary to popular belief alcohol or denatured alcohol are not good dewaxers. Finishing gelcoat is loaded with liquid paraffin. Use a good solvent designed for dewaxing like Interlux 202 or Pettit 95 and multiple rags. The solvents remelt the paraffin and the rag carries it away. You can easily redeposit the paraffin by not turning the rag or not using new ones often enough.

2) The secret to thickening gelcoat is Cabosil or coloidal silica. It is white, will not bleed through and works wonderfully for this task. I would avoid microbaloons for this..

3) New gelcoat will cure harder than the old is. It is not a good ide to try and sand the new flush with the old. A better method is to take it down with razor blades, jewlers files or sharp chisels until just about as flush as you can get it. At this point you can wet sand. Sanding the entire surface flush can result in thin spots in the old gelcoat.
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.


Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Bottom paint over Gel Coat without Barrier Coat? WagTheDog Gear & Maintenance 17 07-15-2012 08:33 AM
What is the best way to repair cracks in the gel coat saurav16 Gear & Maintenance 29 10-17-2007 10:03 AM
Hairline Cracks on deck in Gel Coat Windermere Gear & Maintenance 8 07-11-2007 12:03 AM
Gel coat cracks seac Gear & Maintenance 3 12-13-2002 06:46 PM
Fixing Chips and Cracks Sue & Larry Her Sailnet Articles 0 07-08-2001 09:00 PM


All times are GMT -4. The time now is 11:49 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.