Hull rot

[Travis Grauel]

Just got a hand built boat from my grandfather and come to find out it needs much mite repair then I intended. I work construction and consider by self very handy but boat repair is pretty new to me! The hull has some rot and transom needs replacing...my main question is how should I go about fixing a rot hole and 4 by 4 inches in the hull? It seems there is about 12 by 12 inches of rot total around it? I need details! Pictures included. Thanks

 

[bajansailor]

I think it is a done deal that you should replace the transom, especially if you want to attach an outboard motor on to it.
And replace those aft deck panels as well if they are required - what useful purpose do they serve?

Re the holes in the hull - for small holes you could glue on a plywood 'patch' on the inside and then fill the hole from the outside with epoxy filler.
Maybe even use a small layer of cloth with epoxy over the filled hole.
Or extend this a bit further, sand the hull exterior right back, and sheath the whole hull with glass cloth and epoxy, and seal all the interior with epoxy...... but then you effectively have a new boat with old wood.
It all depends on how far you want to go.
Probably best to just adopt a 'cheap and cheerful' approach, replace the transom, fill the holes, paint the boat and splash her.
And she (along with your family) will love you even more if you can incorporate some positive buoyancy to give everybody a bit of extra reassurance.

 

[Travis Grauel]

thanks a ton! My plan was to glass the whole hull so do you think a good idea would be to rip out all rotten hull? Even if a portion is about 2 feet by 2 feet? Reinforce the inside with new wood replace outside hull with new wood? And then use epoxy filler , glass and it should be good to go? So to wrap it up the big holes would have 2 pieces of 3/4 laminated together one inside one outside the. Filled and glassed? Thanks! All the information is very much appreciated

 

[gonzo]

If you are fiberglassing the boat, you will have to completely seal it inside and out. A patch on plywood is relatively easy. Cut the plywood back to where it is good and bevel the edges. Make a patch the size of the hole with beveled edges. I you are fiberglassing, you can temporarily screw a piece of plywood larger than the hole to the inside. Put plastic between the backing piece and the bottom. Install the patch in the hole and hold it with a few drywall screws. Fiberglass the beveled edges.

 

[Travis Grauel]

If you are fiberglassing the boat, you will have to completely seal it inside and out. A patch on plywood is relatively easy. Cut the plywood back to where it is good and bevel the edges. Make a patch the size of the hole with beveled edges. I you are fiberglassing, you can temporarily screw a piece of plywood larger than the hole to the inside. Put plastic between the backing piece and the bottom. Install the patch in the hole and hold it with a few drywall screws. Fiberglass the beveled edges.

Thanks! So only patch the whole with one piece of plywood and seal it? Don’t leave the peice on the inside? Take it off after outside is patched filled and glassed?

 

[bajansailor]

Travis, re your post #3, be careful - if you go down this route you could very quickly find that you are replacing so much, it would be easier in the long run to simply build a new boat from scratch.

 

[Mr Efficiency]

Actual holes you can put your hand through, whoa, that does not augur well. If you are intent on giving this thing every chance, because of its sentimental value, I would suggest you sand the paint off it all, to start with, to expose the bare wood to the cruel light of day. You may have heard how paint can hide a "multitude of sins". You will be better able to assess matters, sans the paint. A steady hand and not too aggressive a sander, tearing into the surface. Some people, most people even, I would not let loose on a disc sander.

 

[gonzo]

The piece of plywood on the inside is just to hold the patch piece aligned.

 

[fallguy]

Do not attempt to modify that to a fiberglass boat, that is a fool's game. You will do it wrong and the boat will rot out completely within 3-5 years.

The first thing you need to do is some simple integrity testing. Oftentimes, old hulls like that simply have loosened up point a past of safe operation. My advice is to put all your weight on each side and see if you feel the hull twist or give. It really should not do so. If it does a lot; it is probably past a point of safe use even repaired or it will require extensive repairs. If it does a little and you are able to pinpoint a cause, then some simple frame repairs are probably also in order and far more important than the planking. It is also important to either keep the boat on a dock and wet when repaired, and to keep the hull interior dry now. When boats like these go through wet and dry cycles; it can be disastrous if they are not painted (when dry). And they will rot quickly.

Keep asking questions. Wood boats can be nice, done right, but that boat is as much a gift as a job. I also recommend you post on woodenboat.com forum for some good advice from wood boat users.

 

[fallguy]

Once you do some integrity testing, you'll need to remove all the really bad panels, like the aft deck tops and the rotten stuff on the hull bottom? I think it looks like major rot in the bottom toward the back.

A mistake people make with wood boat repair is tearing the boat apart without placeholding it. The boat will misshapen and you can never get it back right, so take a lot of measurements and write them down and use some good quality lumber that won't twist and bend to keep it in place. I really like the stability of walnut, for example and I would put a piece across the gunwhales forward of the aft decks. You will be screwing it in place well enough that it cannot move or shift, so something like a 1x6 with multiple screws, etc.

 

[sdowney717]

pound on it with a hammer and check the plywood is still ok, and if not, it it is dull sounding and rotted, replace all that wood. I always use PT wood. In my local area, there is a store that sells really nice looking treated to a higher standard plywood, guaranteed ground contact treated wood. It is called treated lumber outlet. The treated plywood I have seen at Lowes or Homedepot is really awful in comparison and it will rot. There are differing standards for wood treatments, one is so bad it is not meant to touch the ground or even get wet, makes it about worthless, it rots when used in a deck in about 5 years, that is the kind H Depot and Lowes sells a lot of. If you want cheap easy sealing of seams, use the Loctite Black PL roof and flashing polyurethane, it is like 3m 5200 only a lot less pricey. IT is a strong adhesive, caulk, and waterproof sealer all in one. I use it above and below the waterline with never a failure. This is particularly good for gluing PT wood products, which many other glues eventually let go of.
Loctite PL S30 10 fl. oz. Black Polyurethane Roof and Flashing Sealant-1675273 - The Home Depot https://www.homedepot.com/p/Loctite-PL-S30-10-fl-oz-Black-Polyurethane-Roof-and-Flashing-Sealant-1675273/203163733

You can smear it on the entire hull bottom and make the boat waterproof.