American Fiberglass 2+2 mini ton hull repair advice

[bamidon46]

Hi,

I posted a bit back about repair to an American Fiberglass. After sanding down the cracks in my hull I found a bunch of rocks and what appeared to be sand inside. I was baffled. After some digging around I found out that this model of boat was a fiberglass hull around a concrete pour. What was falling out of the boat was broken up concrete. Gave me a laugh as I was so damned confused. Anyway, I want to fill back in what's come out and don't have the slightest clue what to use. I thought about just grabbing an 80lb bag of quikrete, but figured it wise to ask everyone here first. Any product recommendations?

Pictures attached.

[tkeithlu]

I'm sorry that there is no one available with words of wisdom. I've thought about it, and yes, it's a very unusual way to build a boat. Ferroconcrete boats have lots of wire reinforcement to overcome the brittle properties of concrete. There is none showing in in your first photograph, so what's in there? is it actually concrete used as filler between two layers of fiberglass? Like balsa or foam board? It would be awfully brittle, as evidenced by your bucket of gravel.

The literature calls this boat robust, without mention of its unusual construction. It also suggests that it's not really blue water, because it is beamy enough not readily to right from a knock-down.

So far, I can't find or think of a reason for you not to pour Sacrete into the space.

Good luck with it.

[1affiah]

Its kinda hard to tell from your photo if the concrete has any structural purpose. If not, I would consider filling the hole with spray can foam, sanding smooth, then cover with glass cloth & epoxy.

[Nicholson58]

The concrete was ballast. I doubt that there has been enough lost to seamount to much. Many early yachts were ballasted with concrete, rocks and iron with some of them a mix. Our 1984 Camper & Nicholson 58 has 15000# lead encapsulated in the keel.

My thoughts on your repair:

The boat is small https://americansail.com/about-us/company-history, 17 feet. The stresses are small and manageable. They were entry level boats, thus the cheap filler.

Your worry first is to make sure it is dry inside especially in the north where water freezing causes damage.

You have probably not lost much but the material should be replaced structurally. You can grind a proper tapered, beveled repair for the glass.

Fill the lost material with epoxy-cabosil paste. If you can invert the hull all fill and repair will be a lot easier.

Get your fillers, glass and epoxy from US Composites. Fiberglass , Epoxy , Composites, Carbon Fiber - U.S. Composites, Inc.

Use only the 635THIN 2:1 resin. This has the best wet out and penetration I have used. It has zero blush so bonding multiple layers is not a problem with amine blush. It is also a very slow resin so you will never run out of time. Wear gloves of course but unreacted material can be scrubbed off using liquid dish soap. I never use anything else if this is available. It is also lower cost than store resins especially We$t.

USC offers a variety of affordable glass. I just bought some of the 8.25 oz twill. Very inexpensive and the stitched twill will drape easily over complex curves. Use a release film over your wet repair to help restrict the resin to the patch area and also elevate the resin to the glass surface. This reduces grinding later. Apply as many layers of carefully pre cut glass patches as you can handle. The release film will help hold stuff in place. Add painters tape or duct tape at the edges if needed. The film needs to overlap the patch by several inches.

USC sells many fillers. The cabosil is structural and dearly as hard as concrete. For your finis fairing layers you will find 3M micro balloon filler strong and flexible while also easily sanded. Allow at least four days at 70F before sanding or the paper will gum.

Check out my Nicholson58 photos for some of my projects. There is a thread, ‘this old tornado hull’ as well which is this week’s project.

Is this a sistership?

[Spot]

https://www.shortypen.com/?boat=45
Shorty's write-up indicates 300# (137kg) ballast. Same as pic from Nicholson58.

Originally Posted by 1affiah

Its kinda hard to tell from your photo if the concrete has any structural purpose. If not, I would consider filling the hole with spray can foam, sanding smooth, then cover with glass cloth & epoxy.

Is all of it loose like that? I would consider removing it for the duration of the repair and add it back in afterwards (assuming there is some sort of inspection cover in the cockpit to allow access between the cockpit and inner hull)


The idea above of providing some sort of backer before beginning the repair sounds good to me. I take it that there is no room to work from the inside so it will all happen from the outside.

[bamidon46]

From what it looks like some water got in the hull and the freeze thaw cycles of the north cracked the bottom of the keel housing and busted up the concrete closest to the bottom. As I chipped away with a screwdriver, it got much more solid pretty close to the holes.

I've already got everything pretty well sanded down and ready to epoxy the holes and patch them up. I was just concerned over a weight imbalance or possible changing of how she's meant to sail because of the loss of the 40-50lbs so thought of mudding in something of similar density then outting my patch over it.

[tkeithlu]

The original post sat there for 24 hours with no one touching it. I finally have a go, without any particular knowledge to work from, and immediately there are four more responses, with helpful and extensive details.

Where were you guys?

[Nicholson58]

If you lost 40-50 pounds then you might want to replace it.

Latex modified cement might be adequate but follow my above posts and substitute lead shot sold for reloading shot shells instead of cabosil. It is available in 50 # bags or quart size bottles. You could use discarded wheel weights from a tire shop. Don’t melt lead and breathe vapors.