Cedar splines ‘blown.’

Alfredmylne

Alfredmylne

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My mahogany on oak hull (36ft sloop) which is now 57 years old has up until now never shown the plank joins probably because she was wintered ashore under covers most years. This year she has been afloat all winter and the low temperatures seem to have sprung the cedar strips that the original builder inserted between her planks and they have broken through the paint surface.
I think this is due to water penetrating through the deck hull joint, running down into the plank joins then expanding when it freezes.
My request is for advice on how to get the cedar strips ( I think they are called splines) back into the joins leaving a smooth surface for repainting. I did plan to gently tap them back in and carefully cover with some filler. Should glue or Epoxy be involved as well?
Anyone done this job before? Any advice gratefully received.
 
I think your supposition that there is a deck/hull joint issue is possibly/probable the cause. If caulking was 'pouting' a primary cause would be the deck/hull joint. But with spline could it also be the spline gluing failing. Back in the '60s, spines would probably have been glued with Cascamite and I believe would not last for ever. If the glue has started to fail, that could be the cause. I guess if it's a spline glue issue, it would be quite simple to remove the splines, dry and re-glue. If it's a deck/hull joint issue that needs to be sorted first - I hope not, I have had to replace the deck. But that said ignoring the cost and time, replacing the deck has extended the life of the boat significantly.

As to glue, I would tend to avoid epoxy in that application. I think epoxy is great with new fresh wood, not so good with sound old timber because it has 57 years of seawater use. I was suffering a problem with the rudder. The rudder shanks were copper riveted and over 50 years, the shanks gave a slight crack either side of the blade part of the rudder. Epoxy never got hold of the cracks and when I took the rudder apart to replace the shanks, there were two 'splines' of epoxy - nice and hard and set but not sticking to the central blade. As I was reusing the central blade I had 50 year old 'used' timber with new timber for the shanks. I opted away from using Epoxy but preferred a Polyurethane as it 'likes' a bit of moisture. Many people rave about Gorilla Glue as a polyurethane and it is very very good but is pretty aggressive with foaming. For the rudder I used Semporac which had similar properties but did not seem to be so aggressive on the foaming (it does still foam). The Polyurethane will want to push the splines out but doesn't need too long to hold it in place.

Good luck.
 
Thanks for your input tillergirl. Deck itself is in good condition but every year I have to replace the sikaflex in the hull deck joint. Despite that there always seems to be a stanchion base or some other bit of deck gear that leaks slightly but I suppose that’s Sod’s law. Will try removing one spline to dry, glue and replace and see if this works.
 
The problem with splines letting go is that they tend let go on one side only and are not easy to pull out. I had some success with working epoxy into the small gaps at the edge of the splines and tapping them home. It areas where both sides let go, you can pull the spline, make new ones and glue them in then plane off. I had no trouble using epoxy on on Oregon planks/white pine splines.
 
Several questions come to mind.
Is it happening both sides? Or just one side?
Is it happening along one plank join,several, all of them?
If it isn’t all of the joints, then is it happening high up near the deck? Or lower down near the waterline
Is it happening in one place or all along the boat?

Answers to these should help identify the cause more exactly. Addressing that before re splining would be sensible. Cedar is a good timber to use as it will compress if necessary. Harder woods make poor splines; if planks swell too much they can pull away from the frames.
 
Thanks for all your replies. Unfortunately the various solutions may now be academic as the beast from the east has batttered our harbour on the Firth of Forth for the past 48 hours so badly that the last time I was able to get near my boat I could see she was badly damaged where she has been repeatedly driven against the pontoon due to tidal surge and gale force winds. Difficult to keep fenders in position when the weathers this bad. This afternoon it was too dangerous even to venture onto the pontoon. I’m afraid resetting the splines will be quite far down the list once things calm down!
 
A resorsinol / formaldehyde glue (Cascamite or Aerolite) may be preferable to epoxy or polyeurethane.

Hopefully a closer inspection will show that recent damage isn't as bad as feared and that you will be able to concentrate again on the splines.
 
Thanks everyone. All noted.

Damage is mainly superficial but looks orrible. She’s being lifted into the boatyard for a refit in April so hopefully all will be sorted. Did have some pics but don’t seem to be able to upload from my iPad. Is it possible from iPads?
 
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