Repairs to transom

Hello Dan,

This is one of those grey areas where there is a difference between how it should be and what happens in the real world. The use the boats sees is a big factor. Outboards and rudders put considerable stresses into the transom assembly. Oars just tear the gunwales apart (eventually).

My boat is also 40 years old and has had glue failure and rot problems for the last 10 years (since I bought it) I accept it's an old boat and not as strong as a new one.

While you've got it apart try to assess the condition of the vertical piece inside the transom which the bottom rudder pintle screws into. This carries a lot of stress while sailing. Bolting the bottom rudder pintle on would be stronger than screwing it into the wood but for this to be effective you may need a hatch in the bouyancy tank. Check that this won't put you out of class.

My boat has a vertical plywood stiffener inside the bouyancy tank which runs accross the boat about 10 inches forward of the transom. It's about 9 inches wide and braces the deck against the bottom of the hull.

"My question is whether I will be able to seal adequately with tape only on the outside or if I need to tape inside as originally made?"

Yes probably if your careful
and lucky
and the wood you stick to is really clean and dry.

I've had plenty of seams begin to leak and have repaired them from the outside only. Two layers of glass tape on the outside is worth considering.

"Also, is it better to use polyester resin or epoxy?"

Epoxy is much better. I've had failures with it but very few. Polyester can work and often doesn't.

Epoxy is toxic and some people are allergic to it. If you get it on you're hands you can become allergic to it later in life.

Epoxy needs to be mixed properly or it won't go off. A friend of mine started building a boat using it and found the epoxy hadn't gone hard after a work session. Uncured epoxy had soaked into the ply and he had to scrap the whole hull.

The west epoxy guide http://www.westsystem.com/ss/assets/HowTo-Publications/GougeonBook%20061... tells you how to use it properly.

Cliff

Hello Dan

After just refurbing an old Mirror I would rather replace than repair the transom, as Cliff mentioned, it takes a lot of stress. and a simple repair may lead to more repairs and time not sailing. It is a quick job redoing the transom.

If I recall correctly I did in a few evening after work - 1 evening to remove all, 1 evening to prep and cut and one evening to refit, fiberglass and epoxy.

On that point, I would recommend Epoxy too and getting wider fg tape for the seam ( I used 3inch tape).

I did not have access to the inside so only taped on the outside. I epoxied the transom to all contact areas (the wooden beam that runs across the transom horizontal and the vertical one) just to add some additional stiffness and then tape the seams. Previously the beams weren't epoxied to the transome.

So far it is holding up (touch wood), but I will keep an eye on it.

Keep us updated on the repair/replacement

I had a bit of a pick at the top of my transom with a fingernail and all isn't well. In addition one of the pintle screws turned when I checked it.

I think a lot of the reasons is that the boom knocks the varnish off when it lands on the transom and condensation runs down the boat cover and the exposed wood gets wet and stays that way.

My plywood bow shapes (knees) have suffered for a similar reason and I looked at the Trident website for prices which are £27.16 for the transom and £13.58 for the bow shapes. This seems fair considering the tooling costs Trident have invested but it's a lot of money for a little bit of ply.

Virtually all dinghy kits are manufacured from Robbins Elite gaboon marine ply which costs £46.90 for 5mm or £52.20 for 6mm. I'm not sure if this includes VAT. They can also supply half and quarter sheets. Robbins charge per delivery which involves a lorry arriving at your delivery address and needs to be added. A local boatyard may be able to supply marine ply but they may not stock 5mm.

Cliff

If you can obtain marine plywood, most parts can be made at home. Puffin was stored outdoors upside down in the winters for several years and the bow "knee" bits came unlaminated (without rotting) so I simply bought some leftovers of suitable size from the local boat supplies shop (they have a box with cut-offs sitting in front of their shop) and used the old ones as templates. They have lasted for at least 18 years now (can't even remember when I replaced them). As the hull sides are stabilized by the thick mahogany transom top and the support of the rear deck keeps the bottom skeg at the right distance, it should be possible to trace a cardboard template for the suitable plywood replacement. I'm not trying to do Trident out of business, as I am thankful that they supplied my new mainsail within a very short period last year, but I've always thought that doing your own wood-butchering givs you at least a bit of the satisfaction of "building a boat" even if it involves only a fraction of the effort.
Looking forward to pictures and progress reports. If you've not got a site for posting pictures, Facebook members can join the group "People who love Mirror sailing dinghies" to post pictures.
Gernot H.