can I patch bottom of boat without gelcoat?

[TheGreatOne]

Hi everyone, I would just like to ask if it's possible to patch the bottom of my boat without using gelcoat. and just doing a straight fiberglass patch, I'm not concerned about it looking crazy nice since it will be at the very bottom of the vessel. Or is gelcoat really a must?

Also, what is the best method of fixing a crack on the bottom of the baot? Can I do it from the outside of the boat? or do I have to do it from the inside?

I do have pictures but everytime I try inserting a link to the google site they are hosted on.. my posts don't show up.

Thank you.

 

[DanB]

I would just like to ask if it's possible to patch the bottom of my boat without using gelcoat.

Sure, gelcoat is just pigmented fiberglass resin. All you’ll miss is a top coat protecting the reinforcement fibers and you can put on an extra layer of regular resin maybe mixed with one of the fillers to substitute for that.


Also, what is the best method of fixing a crack on the bottom of the boat? Can I do it from the outside of the boat? or do I have to do it from the inside?

Sorta depends on the crack. A crack in the gelcoat can be V’d out and filled with polyester resin like the top coat mentioned in the first reply. Broken fiberglass fabric should be reinforced to obtain a sound repair. In a non-critical area you can sand back the broken spot, feather back the edges so your patch has more area to grab hold of than a edge to edge butt joint, pull up a piece of backing against the inside, but from the outside, and finish by building back the hull thickness in layers of matt and cloth, again topped by a filler mix. For a critical load bearing spot it’s best to build up a wider thicker backing before filling out the hull thickness. You can do this working entirely from the outside. These are standard patching techniques detailed in all the boat repair how to manuals.


I do have pictures but everytime I try inserting a link to the google site they are hosted on.. my posts don't show up.

Are your google pictures posted inside somewhere you have to log in? Can anyone just go to your google pictures and view them without signing up?

Instead of linking you can upload into your post -
Make sure you [go advanced]
Look down below the posting window for a button that’s marked – [Manage Attachments]
You can probably figure it out from there.

 

[ylojelo]

What about UV, would the epoxy with fillers be enough?

 

[minifish]

Hi everyone, I would just like to ask if it's possible to patch the bottom of my boat without using gelcoat. and just doing a straight fiberglass patch, I'm not concerned about it looking crazy nice since it will be at the very bottom of the vessel. Or is gelcoat really a must?

Also, what is the best method of fixing a crack on the bottom of the baot? Can I do it from the outside of the boat? or do I have to do it from the inside?

I do have pictures but everytime I try inserting a link to the google site they are hosted on.. my posts don't show up.

Thank you.

You should throw some paint over it to protect the resin from any UV exposure it might get. Later, when you feel up to making it look pretty, you can sand the paint off and put gelcoat on it if you so desire. Or just leave it painted. If it's flush, you won't see it unless there's a color mismatch.
As far as fixing something from the inside or outside, it depends. Is the crack all the way through? Will you be removing damaged fiberglass creating a hole? Also, where is it located?
If it's a crack without surrounding damage that needs to be removed, you may be able to just fill it to bring things back to surface level. Usually, a crack in fiberglass has a little surrounding damage that needs to be removed. Depending on the amount that needs to be removed, you may or may not have to mess with supporting the patch as it cures. If that's the case, if you can get to it from a port, repair it from the inside (make sure gravity is helping you hold the patch against the bonding surface). If not, repair from the outside but taper the hole so it creates a V for more surface area to bond to and/or so the patch is a little lower than everything surrounding it so that, in an effort to make things smooth, you don't sand off the area it's using to bond.

For larger holes that need support as it cures, if I was able to get to any of my holes using an inspection port, I would have repaired them from the inside using this method. You can get a larger surface area for the patch to bond to without all the added work of cleaning it up afterwards:

[ame="http://www.youtube.com/watch?v=6N7YMr6E564&feature=related"]YouTube - West System Fiberglass Repair Howto Part I[/ame]
Just make sure you are able to get out any air bubbles trapped between the layers of matt.

If you can't get to it (as was in my case), you can repair it from the outside. Here's what I did-
I used cardboard to support the patch as it cured. I threaded some wire through it and the matt and constructed a wooden bridge which held the cardboard up against the hole. After it cured, I clipped the wire and used a dremel to grind it down.
On my blog I spoke of old guitar string. When that ran out, I went to walmart and got some wire from the craft section. It was made of copper and actually easier to work with.

Here's one of the patches as it was curing with the bridge I was talking about.