Wooden Boat - Rotten Beam fix

[HMSOptimus]

What about a proper survey by a recognized wooden boat surveyor,you can direct his looking to structure etc

I am trying to find one, currently the boat is in Scotland and I live hours away from it. The idea is to get the boat surveyed once I have done all the work so then I am not paying twice for a survey as it will become very costly for another inspection

 

[Keith 66]

Thank you for sharing your knowledge and advice. When you mention replacing the frame or floor (not beam), do you mean the frame beam to be replaced? I will carry some tests out next week. - Thank you

Yes Its a frame or floor, not a beam, Beams are the transverse members that support the deck. You may find the degradation extends into the planking & or fore & aft stringers.
Pouring epoxy into rotten soft wood is maybe acceptable in a museum status vessel that will never go afloat again but in a high load place like a Pbracket support it wont work.
Eoxy poured into mush makes a rock hard lump next to a soft weak bit & it will fail there. Replacement is the only way that will work.

 

[Wansworth]

There are solid wooden parts called logs for instance where the shaft exits the hull.

I am trying to find one, currently the boat is in Scotland and I live hours away from it. The idea is to get the boat surveyed once I have done all the work so then I am not paying twice for a survey as it will become very costly for another inspection

yes u fortunately wooden boats are costly but it would be a shame to repair partof it and discover additional work,sometimes it just has to be done……bodging with epoxy not a good idea …take a leaf out of the tallyho rebuild

 

[HMSOptimus]

There are solid wooden parts called logs for instance where the shaft exits the hull.

yes u fortunately wooden boats are costly but it would be a shame to repair partof it and discover additional work,sometimes it just has to be done……bodging with epoxy not a good idea …take a leaf out of the tallyho rebuild

Tallho was a hell of a rebuild!!!
I don't plan on bodging it, one of the reasons why I am here, is to get some good advice and share knowledge to get the best way to move forward. Before bringing her back from Scotland to the UK I need to get her ship shape for the sea and canal so no room for bodging or cutting corners

I have new wood ready to go in when I have cut away the old parts, then using epoxy to give bind the scarf ends together before bolting and securing it fully. Anything soft and affected will be replaced. She will make a beautiful boat once restored. I have another old WW2 wooden pilot boat, so I know how much of a headache a wooden boat can give, but they have character and the joy restoring them is a pleasure.

 

[HMSOptimus]

Yes Its a frame or floor, not a beam, Beams are the transverse members that support the deck. You may find the degradation extends into the planking & or fore & aft stringers.
Pouring epoxy into rotten soft wood is maybe acceptable in a museum status vessel that will never go afloat again but in a high load place like a Pbracket support it wont work.
Eoxy poured into mush makes a rock hard lump next to a soft weak bit & it will fail there. Replacement is the only way that will work.

So far from my poking around, testing and scraping, the worst of it is about half way through, and the bottom half is solid, but I need to take out the bolts and check underneath before confirming this, This will be a job for when I am there next week. I am going to cut back about 300mm either side to give a good fixing into solid wood away from any soft timber and affected areas.

 

[Poignard]

The danger with this sort of job is of the perfect becoming the enemy of the good.

As far as I can see from your photos, complete removal and renewal of the damaged component will necessitate stripping out much of the cockpit, and probably a lot more.

Is that really justified, just to achieve a strong and lasting repair? A repair that will be out of sight.

If it were my boat I would cut out all the rotten timber, glue in a well-fitting piece of similar timber (a "dutchman") using epoxy as the adhesive, and finally reinforce that repair with doubling pieces as shown in the WEST manual I linked to above.

I would have no qualms about going to sea in a boat repaired in that way.

 

[ducked]

The danger with this sort of job is of the perfect becoming the enemy of the good.

As far as I can see from your photos, complete removal and renewal of the damaged component will necessitate stripping out much of the cockpit, and probably a lot more.

Check

 

[ducked]

Is that really justified, just to achieve a strong and lasting repair? A repair that will be out of sight.

Er...uncheck. In sight or out shouldnt make any difference. I t does, but it shouldnt

 

[Poignard]

Er...uncheck. In sight or out shouldnt make any difference. I t does, but it shouldnt

Please don't misunderstand me.

I am not saying that inferior work is acceptable because it is out of sight.

What I am saying is that, being out if sight, perfectly valid structural repairs may be acceptable that would otherwise be unacceptable on grounds of appearance

Check??

 

[ducked]

If it were my boat I would cut out all the rotten timber, glue in a well-fitting piece of similar timber (a "dutchman") using epoxy as the adhesive, and finally reinforce that repair with doubling pieces as shown in the WEST manual I linked to above.

I would have no qualms about going to sea in a boat repaired in that way.

Check. Counsels of Perfection are OK if that's what floats yur boat, but what matters is whats most likely to float the OP's boat.

 

[ducked]

Please don't misunderstand me.

I am not saying that inferior work is acceptable because it is out of sight.

What I am saying is that, being out if sight, perfectly valid structural repairs may be acceptable that would otherwise be unacceptable on grounds of appearance

Check??

Sure, I suppose what I'm saying is that perfectly valid structural repairs should always be acceptable irrespective of appearance.

Hmm...perhaps that not very realistic in a yacht context.

Maybe I'll test it with some cable-clamped standing rigging for my refit.

 

[ducked]

That is as fine a case of Electrolytic rot as i have ever seen & i have seen many. Other wise known as Delignification. Its caused by the parts being bonded together by wires on the inside & lack or failure of anodes. As the electrical current flows through the damp timber there is a build up of sodium ions around the coper fastenings, Its literally Sodium hydroxide (caustic soda) build up in the timber & if you do a litmus test this will prove it.
Forget using epoxy or a wood hardener it isnt going to work. You need to remove the P brackets & bolts them replace that frame or floor (not beam) completely.

The bit I've bolded above seems confusing, or perhaps confused.

Isn't it the operation of cathodic protection that creates the alkaline conditions next to the "protected" metal which causes alkaline hydrolysis of adjacent timber structure?

If so then failure or abscence of the anodes would be expected to reduce the problem, not cause it.

IF a litmus test shows alkaline conditions in the affected area (high pH, blue ) my immediate action would be disconnect any wires, remove fastenings, dig out any softened timber and flush with vinegar. (I have in the past used an enema syringe for all sorts of car jobs especially brake flushing and I expect it would be pretty good for this too.) Then I'd think about how best to effect a structual repair and how to modify or more likely eliminate the cathodic protection that necessitated it

Edit: Having looked at your photos, I suppose the white powdery stuff visible in the leftward transverse frame could be NaOH +/or salt, or fungal spores, I dont have the experience to tell from a photo, but I;d think alkali is at least a possibility.

The corroded backing plate looks like steel, pehaps galvanised once upon a time. I suppose if your P=bracket is bronze, ideally the backing plate should be too, but a replacement stainless or galvanised plate should be OK with stainless fastenings and determined (splendid?) isolation. Beefing up the backing plate could also contribute to the longitudinal strength of your timber repair.

 

[Tranona]

The bit I've bolded above seems confusing, or perhaps confused.

Isn't it the operation of cathodic protection that creates the alkaline conditions next to the "protected" metal which causes alkaline hydrolysis of adjacent timber structure?

If so then failure or abscence of the anodes would be expected to reduce the problem, not cause it.

IF a litmus test shows alkaline conditions in the affected area (high pH, blue ) my immediate action would be disconnect any wires, remove fastenings, dig out any softened timber and flush with vinegar. (I have in the past used an enema syringe for all sorts of car jobs especially brake flushing and I expect it would be pretty good for this too.) Then I'd think about how best to effect a structual repair and how to modify or more likely eliminate the cathodic protection that necessitated it

Edit: Having looked at your photos, I suppose the white powdery stuff visible in the leftward transverse frame could be NaOH +/or salt, or fungal spores, I dont have the experience to tell from a photo, but I;d think alkali is at least a possibility.

The corroded backing plate looks like steel, pehaps galvanised once upon a time. I suppose if your P=bracket is bronze, ideally the backing plate should be too, but a replacement stainless or galvanised plate should be OK with stainless fastenings and determined (splendid?) isolation. Beefing up the backing plate could also contribute to the longitudinal strength of your timber repair.

Suggest you read this which explains what is going on here drive.google.com/drive/folders/1lF_IkFo5cETWJcqpZQbqc0mpDveM-WVS Look down for the file "electrolytic damage on timber vessels".

The point is that the anode is unnecessary as it is not protecting anything but by creating a circuit it reacts with the damp wood. as suggested the repair is to remove all that wiring and the plate, neutralise the alkali deposits after removing any rotten wood then hopefully a graving piece will restore the strength to floor. Unlikely that the bolts or P brackets are damaged as they are both bronze according to the OP.

 

[ducked]

Suggest you read this which explains what is going on here drive.google.com/drive/folders/1lF_IkFo5cETWJcqpZQbqc0mpDveM-WVS Look down for the file "electrolytic damage on timber vessels".

The point is that the anode is unnecessary as it is not protecting anything but by creating a circuit it reacts with the damp wood. as suggested the repair is to remove all that wiring and the plate, neutralise the alkali deposits after removing any rotten wood then hopefully a graving piece will restore the strength to floor. Unlikely that the bolts or P brackets are damaged as they are both bronze according to the OP.

I'm not getting where this differs from what I said, apart from essentially ignoring my question about the bolded text, which, as I said, doesnt seem, to me, to make sense relative to what we are both saying..

(Oh and the detail of the bolts being bronze, which I missed, or I probably wouldn't have mentioned stainless replacements. Probably shouldn't have mentioned them anyway since bronze replacements, if available, would probably be better)

 

[johnlilley]

Hi There.. various opinions on this aren't there.... I can only give you my advice which may conflict with others here but anodes on a timber boat that are wired to stern gear or seacocks or rudder tubes will definitely cause major problems in some cases leading to repairs to centreline construction that are beyond the value of the boat. The damage will always occur primarily on the inside of the vessel at the point where the protected metallic item is in contact with the timber surrounding it, literally destroying the timber. As it progresses the external timber also becomes affected. The visual clue initially is the paintwork (antifoul) becoming detached and exposing the timber for no obvious reason. Internally the build up of white crud around both the anode fastenings and the wired item and again, loss of paint. The timber will have structurally deteriorated and softened.

Limited affects of this damage can be neutralised by soaking the area in vinegar, the area will fizz until the alkali has been neutralised. Then wash with fresh water. Remove the anode and wiring if the anode is planted on the timber hull and do not refit. Remove all wiring that connects metallic parts together.

Your "beam" is a structural floor and unfortunately it appears to be quite seriously affected by this action. It also may have affected the planking but this would have to be checked.. If I am honest, the long term structural repair will be to completely replace this floor member. Possibly not as difficult as it might appear once you have access. Remove the anode and make any repairs to where the anode is fitted .

Possibly get a local surveyor (experienced with timber) to confirm, but do be choosy on your surveyor as many who are not experienced in timber will suggest to put the anode back. This will cause the same damage all over again.

 

[aqua_sax]

I had a related problem on my copper fastened Stella. After much discussion and even taking advice from MG Duff of all people, I fitted a small (~4" diameter) hull anode bonded to the stern gear. On launching a year or so later after winter ashore, she had a significant leak near the anode. I had her lifted out again and on examination I found significant nail sickness (the name I have always associated with this type of damage) around the copper fastenings in the vicinity of the anode. The anode and the copper boat nails become localised galvanic cells, with the nails as the cathodes, and the alkali produced at the cathodes (nails), then destroys the surrounding timber, which ends up like soggy cotton wool or cardboard with no strength at all. The nails however - and this may be of some comfort to the OP in relation to the P bracket and its bolts - were in perfect condition. The anode had protected them, but at terrible cost to the surrounding wood. A classic case of unintended consequences. I repaired the damaged area by scarfing in new timber and refastening.

The moral of this tale is never fit an anode to a wooden boat unless you are 100% certain it is essential. Better to replace a prop from time to time than have your boat sink on her mooring...