Hole... basic question

[HannahJ]

Hi,

Crazy (Spencer 7, wood) has a hole in her hull, near the keel band about 2 feet in front of the mast. I have two options for mending her - mill out a step on both the hull and the patch, or stick a bit to the inside and then the patch straight onto that. The former is a lot more work but nicer, the latter faster and I want to get her on the water! The hole is about 4" by 3".

It's not a bit you stand on and I don't think it would come under any stress/rig tension - advice for which is better?

Thanks

[Neil C.]

Hi Hannah,

It's great to hear that you are keeping another classic Cherub in action.

This sounds like a fairly simple fix. However, that area of the hull floor is subjected to a lot of pounding from wave action so it does need to be reasonably strong.

I would suggest, dig out the wood round the hole (I presume the hole is due to rotten plywood rather than a traumatic puncture) until you get to dry, good quality wood all round. The hole can often end up quite a bit bigger than you started, but you need to get back to solid wood. Then, cut out round the hole to make it square or rectangular. Measure the dimensions of the hole, then cut out a new piece of plywood (probably 4mm thickness) about 2-3cm bigger than the hole. This will be the internal patch. Then cut another piece a few mm bigger than the size of the hole - external patch flush with hull.

Mix up some epoxy resin. Use the resin to paint both sides, and particularly the edges, of both new patches and the rim of the hole. Add a bit of filler powder (microballoons or whatever) to the remaining resin and apply it to the outside 2-3cm of the internal patch. Push the internal patch through the hole and position it in place inside the hull. It's best to apply a bit of pressure to help it set securely. You can do this by temporarily screwing through the hull into the edge of the patch, or alternatively have a bit of string through a small hole in the middle of the patch and use this to pull the patch onto the inside of the hull.

Once this has set (next day), take a bit of sandpaper and gently chamfer the edges of the hole out, and the inside of the external patch edges to match. It only takes a few minutes to get them to line up. It doesn't have to be perfect, as the resin mixture you use to glue it in place will fill any voids or irregularities. Smear a good lot of epoxy resin / filler onto the internal patch and round the edges, and push the external patch into place. Again this can be screwed into the internal patch, or just weighed down until it sets. A bit of sanding when it has all cured and a lick of paint and it's all done! About an hour's work on two evenings should do it.

Happy sailing!

P.S. attached photos of my 2631 rebuild a few years ago may or may not be helpful.

[Neil C.]

Before:

[Neil C.]

Holes squared out:

[Neil C.]

After:

[HannahJ]

Hi Neil,

Thanks very much, very helpful! She probably won't encounter many waves from a gravel pit in Cambridgeshire although after last weekend I'm not so sure... So doing it the step way wouldn't be strong enough? We used that method when putting a different-sized bailer in my Mirror but that wasn't the bow.

The hole is apparently from a stone hitting it on the motorway and the wood is sound, so I'll just need to cut a neater hole. I was surprised that a stone would cause that much damage so it may originally have been just a smash/puncture.

Hannah

Edit: this is the hole, attached, so quite far forward.

[Neil C.]

... So doing it the step way wouldn't be strong enough?

You might get away with it, but the problem is that Cherub hull skins are usually quite thin, so there isn't much material to bond to. If you do the the technique of chiselling out one layer of ply around the hole the remaining layers will probably only be about 2-3mm thick. I would suggest a backing patch as well would be more robust.

[JimC]

I would do both, backing piece and steps: it was a notorious failure area on wood boats. If you can get hold of some veneer then multiple steps would be good, especially with the grain at different angles. I suppose in theory for a piece that small you could manufacture some veneer from ply with a belt sander, but I'm not sure I could do that and get it flat enough.

[HannahJ]

Thanks both, very helpful!

[HannahJ]

Got most of the work done today - hole enlarged to remove damaged (splintered) wood, inner patch cut out with slot for clamps, outer patch cut out and filed to shape, inner patch glued and clamped. Outer patch will go in tomorrow! Thanks all for the advice - we didn't make a step in the end as it's thin plywood but the patch is a very tight fit.

- edit: won't let me upload a photo, even a small one, oh well