Bottom keel repair plan - please critique

[jimTheSailorMan]

I have some damage on the side of the keel of my pocket cruiser. I was at a very shallow launch and was slightly offset of the trailer and dragged the bottom of the boat on the sand/rocks at the launch. Since that time every time I pull out the boat from the water, I see a stream of water and gravel parts from the bottom cavity.

Here is a picture looking at the rear while the boat is on the trailer. The damage is on the port side and has now exposed an open cavity. Here is a picture of the boat.

My plan is to lift the boat off the trailer and do the following:
1. Remove any loose materials in the cavity - may have to water blast it with the garden hose.

2. Fill the cavity with a low slump concrete with very small aggreate. This should replace the old gravel and have some weight.

3. Grind the edges of the damage back until I get to clean - no cracks fiberglass.

4. Add 3 layers of fiberglass tape and resin. Not sure what to use - was look at this type.

This is an old boat that I paid $500 for so just want to seal up this problem and not have to deal with again. Not too concerned about final appearance as long as it's structurally sound.

My main questions is what / how to fill the open cavity in the keel and what is the best weight fiberglass to use on this type of repair. Can post better pictures when I get it up off the trailer next week.

[dcstrng]

Is the gravel you see some sort of ballast, or is it debris that gets picked up? Not sure I totally understand the picture, but it looks like damage I had on a B24 some years back. It is very hard to force concrete uphill (or at least I don’t know how to do it competently) and get it to stay solidly in place without creating a cavity above it, and/or allowing it to stay loose.

I think if it were me I’d clean the heck out of the current cavity where the damage is, let it dry thoroughly, bore some sort of an access hole above (side of keel), build some time of a sacrificial form and glass the bottom as you proposed – layers of the the 6oz cloth is fine, but I’d probably use 10oz since I have some… once that is set, fill the cavity with a ballast and water-impervious epoxy (GFlex or whatever) and glass from the top (let gravity work for you), and then glass the temporary access hole closed… Just an idea…

[psk125]

An open cavity in the hull full of gravel ballast does not sound right. Metal punchings would be much denser, but anything is possible with a $500 boat. Filling the space with concrete sounds like a mistake. Moisture that gets in there (it's a boat - moisture WILL get in, and the concrete will act like a huge sponge to soak it up) will freeze in the winter and blow the keel apart. Loose gravel might have enough spaces to keep that from happening, but even so is not very good ballast - it isn't as dense as other materials would be. Otherwise, your & DC's fiberglass fix ideas sound OK.

[jimTheSailorMan]

Originally Posted by dcstrng

Is the gravel you see some sort of ballast,

I believe its some type of ballast since it's always been consistent. Like your idea about a sacrificial form.

Good ideas - thanks.

[jimTheSailorMan]

Was thinking about using

something like this mortar gun

to force the concrete/mortar into the holes you suggest. Was going to use a high entrainment cement to avoid freeze cracking.

[jimTheSailorMan]

Originally Posted by psk125

Metal punchings would be much denser,

Wondering, where can you get metal punchings?

[guyrj33]

consider bi-axial tape, it's stronger.
https://www.westmarine.com/buy/west-...02?recordNum=2

A thick pour of epoxy releases a lot of heat, fillers mixed in with the epoxy will absorb some of that heat.
You could use lead shot pellets mixed with epoxy to re-ballast your boat.
Lead being much denser than gravel, don't over do it if you choose to use lead shot.

[psk125]

I looked up metal punchings Chicago and found this:
Ferrous Metal Recycling in Chicago, Non-Ferrous Metal Recycling in Chicago, E-Waste Recycling in Chicago - C&R Scrap Iron and Metal LLC

[jimTheSailorMan]

I was able to lift the boat off the trailer for some photos and to estimate the material I would need. More damage than I expected. I think an 8" fiberglass would work on either side. Wondering if it's better to do one piece than fix each side of the damage (i.e lay pieces that span from the rudder envelope side to the port side. I also found that the filler material, definitely not a ballast was the consistency of lightweight plaster.

Was thinking of laying in a 1x2 treated lumber on the bottom inside the cavity to use to wrap the fiberglass from side to side. Since the the filler material is definitely not a ballast, was thinking that maybe non-expanding GREAT STUFF may be good enough to fill the cavity after the repair.

Image 1 https://imgur.com/a/uauHIWq

Image 2 https://imgur.com/a/LQsmjZG

[guyrj33]

I think you could carve a piece of blue foam to fill that space and to provide a form to layup your glass.
I think i'd grid out everything I could reach, apply one piece of glass on the inside followed by the insertion of the foam. Then finish the layup on the outside with another two layers of glass.
I suggest you use biaxial which will give you strength and a relatively quick build up.