Repairing splits in mahogany coachroof sides

[Poignard]

On my boat the windows consist of perspex panels let into rebated openings in the mahogany coachroof sides, the perspex panels are kept in place with a stainless steel 'frame' which also hides the joint between the window and the coachroof sides. Each frame is secured to the wood with about a dozen woodscrews.

Several splits have appeared in the mahogany coachroof sides. These begin at the woodscrews securing the window frames. The timber shrinks across its width but the fastening doesn't and forces the grain apart, causing a split. (It's like splitting logs by driving in a wedge).

I intend to repair by sawing along the line of the grain so as to open up the crack to a uniform width, then glueing in a spline of matching timber.

What glue would people who have done similar repairs recommend?

What can I do to stop it happening again?

 

[Tranona]

Epoxy - and you can't easily stop further splits, although boring all the screw holes out and plugging them with bungs may help limit the splits. In fact if the splits are small you may find the plugs and filling the rest of the crack with epoxy may do the job. Splining as you suggest is a tricky job to get right. An alternative is to do away with woodscrews and use bolts in oversize holes, but you may find it difficult to hide the nuts inside.

 

[JumbleDuck]

An alternative is to do away with woodscrews and use bolts in oversize holes, but you may find it difficult to hide the nuts inside.

Westerly-style interscrews are quite a neat solution, though I tend to go down the "if you've got it, flaunt it" path with stainless dome nuts.

 

[guernseyman]

I wish you luck with the epoxy and splines, which may work if the coach roof sides have stabilised. Otherwise you need some more positive mechanical stabilising with wood or St St battens adding strength.

 

[john_morris_uk]

I had the same problem with my mahogany coachroof sides on our SCOD. I routed out grooves along the line of the split/shake and glued in strips of mahogany with epoxy very successfully. I used a small route bit and clamped a straight edge as a fence to run the router down if that makes sense...

 

[Gordonmc]

I had the same with my previous boat, a Hillyard 8-tonner.
As john_morris_uk describes, I cut a groove along the line of the split but I used a rotozip, something like a fine router.
The splines were epoxied.
One added feature - at the end of the split I drilled a hole the same diameter as the rotozip bit and rounded the end of the spline to stop the split progressing.
Getting scrap mahogany for the splines to match was a problem.

 

[andygc]

Seems to me that the router and graving pieces is the best way to go (not splines which are full thickness). Also, why have the fiddle and mess of mixing small quantities of epoxy when there are adhesives like Balcotan and Titebond III which will be perfectly good in this application - and much easier to handle, especially if you are working out of doors in the winter.

 

[PhillM]

Getting scrap mahogany for the splines to match was a problem.

I got a number of planks that had been reclaimed from old snooker tables circa 1960 vintage, from a reclamation yard near Liverpool. BDA Marine have some in stock, I think. If you get stuck, I am sure that they could sort you out with some, for a reasonable price.

 

[Poignard]

Thanks for the helpful advice/opinions. Much appreciated.