Repairing keel bolt holes on oak keel

[jorodrigues]

Hello,

I have a Dragon yacht under restoration and need to repair a few 20mm keel bolt holes on her oak timber keel. The keel bolt holes in question are slightly misaligned with the holes in the ballast keel and off vertical.
My initial plan was to drill an oversized hole to fit an iroko dowel and redrill the new hole through the dowel. However, I have a few reservations about this approach and would like to get the views of the forum on them:

1) I am not sure if the dowel, with the grain across its length, is the right choice. Perhaps a cross-grain cut plug would be more appropriate?
2) I am also not certain about the size of the plug. Given that the keel bolt is 20mm, which plug size should I consider? The cross-section of the keel over the ballast varies between 200 and 280mm wide and is 63mm thick.
3) I am considering an Iroko dowel/plug mostly because it is similar to oak but without the iron sickness problem. Given that the keel bolts and the ballast are iron, the iroko collar surrounding the bolts would give me some peace of mind.

Thank you!

 

[Bod]

I would try to find a Wooden Boat forum to ask this question.

Bod

 

[baldkev]

Im pretty sure i saw a boat section or boat thread at least. I know theres a few in here who have worked on boats.... but not me

 

[Inspector]

I would try to find a Wooden Boat forum to ask this question.

Bod

That is exactly the forum I would go to. That is where the expertise is for your problem.
You are being redirected...

I always thought the Dragon was a pretty boat. Post some pictures of it when you can.

Pete

 

[AJB Temple]

Get onto the Dragon association. Some dragon boat experts there. Renovation | British Dragon Association

I would not plug with Iroko. I might well look at a copper rivet, epoxied and rounded over at both ends.

 

[Wildman]

Iron should never be used in oak should use phosphor bronze keel bolts as to alignment they did fit originally what has moved and why is a question I would be asking. Fill the existing holes with molten pitch then drill and ream before putting in the bolts, not forgetting the caulking cotton unde the washers. as you drive them home coat the bolts in high temp grease so they turn in the pitch when trying to screw them in. Good luck

 

[jorodrigues]

The original plans for the Dragon Class call for iron bolts on a cast iron keel. I'd much prefer to deal with bronze bolts on a lead keel, for example, but as this is a restoration, it is really not an option. I could also consider replacing the material of the bolts, but I would have to consider galvanic corrosion as well.

The misalignment cause is easy to find: it is 100% my mistake. I messed up the alignment of the drill bit by trusting too much on a softwood jig. The whole keel is actually being fully replaced.

 

[TRITON]

That is exactly the forum I would go to. That is where the expertise is for your problem.
You are being redirected...

I always thought the Dragon was a pretty boat. Post some pictures of it when you can.

Pete

Its a lovely yacht, and so sleek.
I also like the way the cockpit sits separated from the deck. Very racing styling.
I used to race in a 10m class3 IOR, about the same size as the Dragon, but despite being fast it had the usual cruising set up(aka A water caravan ) so the whole boat was in use and not like this where you feel the boat consists of 1. The boat, and 2. The cockpit.

Post some pictures of it when you can.

I'd actually like to see a series of the job start to completion

I guess we all here like wooden boats cos they're wooden, and a large wooden yacht is so bloody lovely.

 

[Keith 66]

I was in the boat trade for 40 years, Firstly Iron bolts & fastenings were & are often used in Oak because it was cheap. You would not use bronze in Iron keels due to electrolysis problems. The problem arises today that you most likely will only be able to get mild steel for your bolts which is far more corrosion prone, If you can get it Wrought Iron is excellent but is liable to be hugely expensive, last set i had made cost as much as Silicon Bronze (for a lead keel). If you cant get wrought iron use mild steel (possibly galvanised) dipped in hot tar or If you can get white lead paste it is great stuff for slathering keelbolts.
Do not be tempted to use Stainless steel, In a wet oak keel it will likely corrode at a faster rate than mild steel & crevice corrosion is a real likelyhood. I have seen 7 of a new set of 10 316 marine grade 12mm keelbolts shear with crevice corrosion after just 5 years.
Dont get hung up over what wood to plug the hole Iroko, pitchpine it wont matter in the slightest.
But first job is check the old wooden keel is sound!