First Fiberglass Repair - SailNet Community
LinkBack Thread Tools
post #1 of 1 Old 09-01-2001 Thread Starter
Contributing Authors
Join Date: Jan 2000
Posts: 325
Thanks: 0
Thanked 3 Times in 3 Posts
Rep Power: 21
First Fiberglass Repair

I currently own a 1968 Johnson X boat that my Dad bought new when he was 18 years old. It looks great and sails great, but the bow section is begining to deteriorate. It is a fiberglass and foam sandwich and the foam is breaking down due to old age causing the hull and deck to flex an insane amount in certain areas. One of these days the fiberglass is going to flex too far and crack. It's not worth spending the money to fix since it would be cheaper to buy a new boat.
Is there anything I can do myself to try and save her? I have never worked with fiberglass before, but I am willing to give it a try. She means too much to me to junk her but I don't want to pay someone to rebuild her for me.

SailNet responds:
Thanks for the question. Repeat after me: There is nothing I can’t repair with fiberglass. The fact that this boat has given you and your family pleasant memories through the years is a reason it's worth hanging onto. No brand new roto-molded sailing dinghy is going to bring with it the memories this thing has. With that in mind here are a couple of fiberglass repair strategies to consider.
The scenario isn’t one that’s easy to see from this vantagepoint, so I might have glossed over some particulars, but here goes: The first thing to do is identify the areas that need repairing. If you’re talking about repairing isolated areas of delimination, first try sounding the boat with a small ballpeen hammer. You’re listening here for a dull, hollow sound that indicates where water may have made its way into the sandwich construction. Mark these areas—you’ll have to open them up with a grinder or an orbital sander. Chances are the fiberglass is pretty thin and will easily give way easily. Where you can, inspect the foam—if it’s wet mush, it's shot and you’ll have to replace it. Allow the areas to dry, and wipe them out with denatured alcohol. Then buy some two-part foam, mix it and inject it in there. Two-part foam expands like crazy—just a little bit will do you. Shape the foam along the contours of the boat. You’ll want to bevel the area around the repair out a long ways. SailNet's maintenance guru Don Casey recommend a 10:1 ratio based on the maximum depth of the repair—out at an angle that will give the new fiberglass cloth you’ll be repairing the section with a large area to bond.
Cut several pieces of fiberglass cloth larger than the area you’re repairing. Set this on the area you’re fixing. Wet it out thoroughly with fiberglass resin—I’d recommend West System Epoxy. Depending on how significant the damaged area is, you may want to lay several layers of glass over each other. Try not to get any air bubbles in the cloth—this weakens the repair, and if the glass goes off with air bubble in it, these will have to be cut out and another layer will have to go over it. Use a putty knife or a small squeegee to smooth the resin into the glass. You don’t have to wait for the first layer to dry—a stronger bond is made when the layers of fiberglass cure together. When the fiberglass is dry, take a utility knife, and cut away the excess. Clean up any runaway resin drips before they dry with denatured alcohol.
Now you’re ready for filling and fairing part of the program. Anytime you’re sanding fiberglass, make sure you’re wearing a quality respirator—and not one of those dust masks you wear while cutting the lawn. Now is as good as time as any to point out that collodial silica has many of the same ingredients used by gardeners to keep slugs away. The silica is sprinkled around the garden, the slugs crawl over it, get cut and die. The same thing happens in your lungs if you inhale the fine airborne powder that working with fiberglass can produce. Gloves are also a must and I’m partial to wearing earplugs as well while operating sanders.
Mix up some more resin, adding a fairing compound to it—try West System 410. Mix it to the consistency of peanut butter and apply the fill to your repaired areas in the aim of covering them up. Sand and fill as needed, you may need to do more than one pass. When you’re happy with the repair, you can then start worrying about matching the gelcoat—or painting the boat altogether.
If the repairs you’ll be doing are large in scope, keep in mind that anything that will help you keep the shape of the boat intact is a good idea. If you think you’ll have to cut the bow of the boat off and put a new one on, I won’t go into the scope of that kind of repair here (one strategy would be to use the old bow as a mold, fill it with foam for the shape, apply a mold-release agent to the mold, and lay glass over this. Then bevel both sides so that they mate, and attach with layers of overlapping mat and roving) know only that it’s possible.
The hull can be stiffened likewise, should you think it flex too much. Take a garden hose and cut it in half, long-ways, the length of the inside of the hull. Glassing these in running fore and aft, say spaced apart every six or eight inches, will do much to strengthen the boat and keep it from. If you need inspiration, keep in mind the America’s Cup boat, Young America who broke into two pieces and which was eventually repaired. If you plan on tinkering around boats I’d recommend you check out Don Casey’s Sailboat Hull and Deck Repair If nothing else the boat in question presents a great learning opportunity, and if your first foray into fiberglass repairs ends up looking a bit Frankenstein, it’s probably strong enough and will lay the ground work for future fiberglass adventures.
I hope this helps.
PS. We also have a Fiberglass Repair e-mail discussion list...although I'm not sure how much traffic that has on it. You can check it out at, just click on "F" for fiberglass.                                                          -MM
SailNet is offline  
Closed Thread

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Forum Replies Last Post
My First Fiberglass Repair meridiansahoy Gear & Maintenance 9 09-25-2012 11:07 PM
First Fiberglass repair i_amcdn Gear & Maintenance 32 08-01-2012 11:28 AM
First fiberglass repair: fun and easy substantial improvement... jameswilson29 Gear & Maintenance 8 01-02-2012 11:38 AM
Fiberglass Repair in the Chesapeake park128 Gear & Maintenance 1 11-07-2002 02:58 PM
Fiberglass (delamination??) repair Badfish Gear & Maintenance 4 03-09-2001 11:38 AM

Posting Rules  
You may not post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is Off
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome