GP14 Sailing › Forums › Forum › Removing rot from my transom.
- This topic has 5 replies, 2 voices, and was last updated 4 months, 2 weeks ago by Oliver Shaw.
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23/05/2024 at 10:53 am #27097EightMegsParticipant
I’ve got some dry rot around my bottom rudder pintle and I’m wondering if I could put in a graving piece with the transom in situ or if I’m better off removing it from the boat and repairing it on the bench.
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23/05/2024 at 11:24 am #27098Oliver ShawModerator
Removing the transom and then reinstalling after repair is fairly major surgery, but removal and replacement with new wood has very occasionally been done. I would expect that removal with the intention of re-using the same transom after repair would be an even bigger task. It is one thing to take out the old one without damage to the frame on which it sits or to the plywood, provided the old transom can be sacrificed; with care you can cut away the transom (whether using router or saw or chisel, etc) without touching either the frame or the plywood, but that will inevitably cut into at least the periphery of the transom, so it will end up smaller than it needs to be. One can then replace the entire transom with new wood; but I am not clear about how one could get the original one out undamaged, so that the same transom could be refitted.
Just possibly a very fine oscillating saw used all round the edge, and then used again inside the boat to separate the transom from the frame on which it sits, and accept that when it is refitted there would be the width of the saw-cut all round the edge which would need to be filled with (preferably) a thin strip of wood. Or alternatively with epoxy??? But that is no more than a best guess as to an approach, and I am not wholly convinced that it would work. And at the end of the day there is still that gap, at least the width of the saw-cut, all round the edge, which at the very least would be a problem.
Around sixty years ago I replaced the transom on a Firefly, and I know of a couple of people who have done that or very similar jobs on the transoms of GP14s in more recent years. But certainly when I did the job the old transom was being scrapped and a brand new one fitted. Don’t underestimate how big a job it is.
Whether an in situ repair is viable depends on your assessment of the damage, but in most cases I would expect it to be the easier option. And, depending on the severity and extent of the dry rot, a possible alternative to a graving piece just might be treatment with a deeply penetrating epoxy product such as Smith’s CPES, a wood-based penetrating epoxy which was originally designed for that very purpose.
Can you post some photos, please?
Oliver
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24/05/2024 at 9:54 am #27108Oliver ShawModerator
We seem to have a technical malfunction. I have just now received an email from the Forum saying “This area is the most concerning because it seems to go behind the rudder pintle, but there are a few small areas of rot around the edges”, which suggests that there is an accompanying photo; but no photo has come through, and not even the text part of the message is currently showing on the Forum.
Can you please check later in the day whether anything has appeared by then, and if necessary try again.
Please be aware that the maximum file size allowed is 512 KB, so if your photo is bigger than that it will need resizing.
Oliver
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24/05/2024 at 10:23 am #27109EightMegsParticipant
There are a few spongy areas along the edge of the transom as well. I haven’t gone picking at it yet so I’m not certain how deep it goes.
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24/05/2024 at 10:24 am #27110Oliver ShawModerator
Ah! Found your post, and photos; for some obscure reason it was a hidden reply. It appeared when I clicked on the “+1 hidden” link at the head of the page.
I suggest that the first step is to investigate further, by removing the paint. Once that is done you can asses how extensive is the problem.
I note first that the transom is painted rather than varnished, and second that you are considering just putting a fibreglass patch on it. Fibreglass applied over rotten wood is very unlikely to be satisfactory unless either the rot is treated or the wood replaced first. However when you can see the extent and severity of the rot you can assess whether it is worth trying treating it with Smith’s CPES, followed by a fibreglass patch (using a marine epoxy resin, not an automotive polyester one; the headline name is WEST System, but there are others also).
If when you have the wood exposed you decide that it is too far gone for that approach you could then replace the rotten wood with a graving piece. Since the transom is painted, the appearance under the paint is relatively unimportant, so it won’t matter if the graving piece is a slightly slack fit and you use the epoxy as a gap filler. That will make the job a little easier. You might or might not then decide to sheathe the repair with fibreglass; that decision will depend in part on your assessment of the job when the wood is exposed.
Do remember that the area around the pintle is structural, and may on occasion take significant loads. Inside the transom you may need to reinforce the bond to the hog; and it is possible that the timber there may also have deteriorated.
Oliver
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