Rot in transom

Summertime of wight

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Hi everyone
,bought this boat last fall,weather just getting good enough to work on outside here in BC now.
Wanted to change the name and home port and people told me in order to take the decals off I had to change the plywood out.
Ok so I got the plywood off now and noticed there is some rot on the left frame,just about a 6 inch section,luckily the mahogany planking is in good condition,no rot,also no rot on any ribs.
It looks in the pictures like there is more rot but it is just the black tar used between the joins.
My question is,should I dig out rot,fill and repair with epoxy,cut the frame on a large wedge angle and splice a new piece in or change the whole rounded piece out which involves pulling bungs and screws from planks.
I do a lot of carpentry but not quite sure how to make that round back frame,looks like it is not laminated but might be made up of more than one piece,I will know more once I clean it up if there are joins.
Any info would be much appreciated.
 

Summertime of wight

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Hi
I am currently repairing some rot on the transom of my sailboat,the plywood is off and I found a bit of Rot on the left 6 inches of the frame,not sure if I should just clean the rot out and fill,reinforce with epoxy,cut the rot section out on a wedge shaped angle and splice a new one in or replace entire round frame which would mean pulling out bungs and screws from planks.
Some pictures below
 

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Hacker

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Difficult to see the extent from your picture. If we were doing a restoration on this one thing we would not do is to cut it out and replace with epoxy. The final repair strategy depends on how much rot there is. I’d remove it all and cut back to sound wood. The choice of inserting a graving piece, splicing in a new section or something more serious should follow from that. Epoxy could be used to glue the relevant pieces in. If all the sections are dry then I’d treat with Bonda G4 before replacing the transom ply. If you have to replace the whole curved section then remaking it as a laminate would work (if you can’t get solid timber).
 

pmagowan

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Cut all rot out and see what you have left. Then modify your remaining wood to give a good surface to either splice or laminate in new wood I.e a good step or graduation that gives a good surface area for glue/epoxy. Treat wood around area with whatever locally available rot treatment. Laminating up a new transom depends on whether there is a 2d or 3D curve. If 2d then thin sheets of ply held with many clamps or a vacuum bag and epoxy glue would work. If 3D probably easier to do off boat or layer up as if planks.
 

Summertime of wight

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Thank you for the replies and information, I will clean it up and then re assess,the one thing I'm wondering is if rater than going through the work of laminating the ply,since it's 5/8 and only around an inch curve each side why I couldn't just suck a solid 5/8 piece in.It is only curved 2 way.
Thanks again
 

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You wouldn’t be able to easily shape a piece of 5/8th ply. An option would be to prepare a flat section to glue a piece of solid timber in situ and then shape once it is fixed. Obviously it would need to be wide enough to create the final curve/size.
 

Summertime of wight

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Ok now I'm becoming overwhelmed,there is rot at the end of the planks where the leak was.
I thought that by getting both a boat builder and a surveyor to look the boat over before I bought it last fall they might catch something like this.
Now
 

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DownWest

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Since you are in BC, it might be an idea to put those photos up on the Wooden Boat Forum. There is a long thread by 'Dody' on doing something similar, but much more extensive. Plus a lot of other wood 'butchers'.
DW

Very pretty boat!

Ah! Just seen your post over there....
 

Hacker

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Sorry to hear the news. You need a decent wooden boat builder to help you plan the repair. It’s likely that you will need to replace those planks to at least 3 frames but with joints that are staggered; some planks will need to be quite long. The port side and top transom timbers will need replacing I suspect. As others have said a beautiful looking boat and well worth saving.
 

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Probably with modern glues is possible to make a good solid bodge of the corner after all the rot is cut away but on the other hand a proper repair is the way to go to respect the original and for resale value.While your at it maybe another survey……..by some other wooden boat surveyor
 

pmagowan

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A properly graded splice will be just as strong as solid wood but may not behave identically I.è. It may not take a curve the same way. However wood is easily shaped so you just put in some oversized timber and then adjust to suit. Of course, you can use traditional techniques and be ‘authentic’ but if you want the boat back in the water just cut out rot to good timber and then create a good overlap (IIRC you want a 12x thickness as overlap so a 1 inch thick needs a 1 foot splice). Wood is very malleable and forgiving. Just buy a lot of clamps. You will find it very hard to curve thick ply even 2d but you can run regular grooves on the inboard side with a circular saw (evenly spaced) to ease the curve. Then you simply squidge a load of thickened epoxy in, bend it to shape, clamp well and tidy up on the inside.
 

DownWest

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On replacing the transom, if ply, I would just laminate thinner layers rather than try and curve a thick bit. Much easier and more stable. On the planking, 8:1 scarf is OK. 12:1 is more for masts and spars.
 

Summertime of wight

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Awesome and thanks,wondering though how to make an 8 inch say scarf joint in between 2 other planks on the boat,not hard to make a scarf join on the one going in.
Thanks
 

DownWest

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Awesome and thanks,wondering though how to make an 8 inch say scarf joint in between 2 other planks on the boat,not hard to make a scarf join on the one going in.
Thanks
Sharp chisel and a block plane. You could get inventive with a jig and a router with careful control (and check for fastenings).

The best help you are getting is from 'DebenRiver' A lifetimes experience in traditional boatbuilding and design., along with wood/epoxy techniques.
 

Hacker

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First of all you need to get the scarf the right way around! It should point away from the water flow. This means that replacing the aft planks will require the existing plank to be scarfed from the inside (think about the water flow, it shouldn’t flow into the joint). This means that you need to wedge the plank out in order to make the scarf and that requires you to release more fastenings. Tool wise you have choices. If the planks are thick then you could remove the bulk using a saw and finish with a block plane. If you are careful then an electric plane could be used. In an ideal world you would make the inside scarf joint hide behind a rib.
 

DownWest

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First of all you need to get the scarf the right way around! It should point away from the water flow. This means that replacing the aft planks will require the existing plank to be scarfed from the inside (think about the water flow, it shouldn’t flow into the joint). This means that you need to wedge the plank out in order to make the scarf and that requires you to release more fastenings. Tool wise you have choices. If the planks are thick then you could remove the bulk using a saw and finish with a block plane. If you are careful then an electric plane could be used. In an ideal world you would make the inside scarf joint hide behind a rib.
Given the short repair pieces and epoxy, I am not so sure it matters as to aligning the scarf away from the water flow, esp as this above the water line. Far easier to do it the other way. 95% of the time (or more.. ) the joints will be out of the water flow.
What does interest me is the close joint, no caulking fit of the planks, as having some hassle with a skandi boat recently. Older, from the 50s and kept in fresh water for the last 20 yrs. But, likely it was rain that caused the problems.
 

pmagowan

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Perfection is the enemy of action! Don’t let perfect get in the way of good. Thickened epoxy will cover a lot of sins. An electric plane will help with the scarf. You can use a jig but it will be work setting up and you can eyeball pretty good. I have seen bits repaired with no scarf, just butt joints, epoxy and a wooden block internally over the join and adjoining planks. It all seems to work but it is best to go for a decent repair even if not perfect. Once sanded down, faired and painted nobody will know and it will outlast you
 

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