Replacing Fastenings

I have a timber carvel planked 35ft cruiser built in 1937. She has 1" oregon planks on spotted gum frames (1' x 1 3/4", and about 8" apart throughout the length of the boat). Fastenings are clenched copper nails. She takes a little water when underway and I think it will need to be re fastened at least below the waterline. I would like to do this progressively over time, commencing with the next slipping, due shortly. I intend to use silicon bronze screws. Is it necessary to remove the existing copper nails, or can I screw new fastenings in along side the existing ones. The problem I have, apart from time, is that as the boat is in running order, many of the frames are inaccessible from the inside (motor, water and fuel tanks, plus furniture are in the way) making it difficult to get at the clenched part of many of the existing nails. Any advice would be appreciated.

Peter

 

member Waikikin should be able to advise you expertly on this.

 

Most people are going to screw next to the clenched copper nail
Copper is pretty soft, you could drill a hole thru the copper and ram in a steel screw to clear the hole and make threads, then replace with a bronze screw.
1937 and salt water is a very very long time for those copper bits, may not be much left of them.

You might find your inaccessible gum frames wont hold screws.
I did read its a durable hard wood in the Eucalyptus family , so maybe much better than oak.
I reframed my 1970 wood boat that had oak frames, and had rot in the old screw holes and rotted and broken frames to deal with. I removed the mahogany planks and used PT pine cut into framing size back in 2006, held screws and still solid today, look like new. I also have large heavy strong oak floors that sit on top of most of the frames, so they also share any frame loading that exists. My frames are every 7 inches, 37 foot boat.

I also caulked with Loctite PL premium polyurethane construction adhesive mixed up to 50% with sawdust, so my hull goes in dry, no soaking, and I coated the hull with that and some other things too. In 2014, coated some areas with Loctite black PL roof and flashing polyurethane mixed with 1/32 milled glass fibers, I really like that coating.

Here are some pics showing some of what I did.
https://goo.gl/photos/Y876jwe1jceTp9Zz6

Your going to find people who say it wont work and you ruined your boat, but all their wood boats are gone while mine is dry and working great. It sure did strengthen the hull, what I did.

 

here are some earlier 2005 pics when I did a lot of reframing.
https://photos.app.goo.gl/vUW46tHaRBWDHhTd7

Just so you can see I actually did it.
Somewhere I have more pics of some inside work on the shaft log, I cant find them now.
Oh, here they are. The coating is sanitred, but I decided it was not worth the trouble compared to buying locally the Loctite products.

The black stuff is Loctite roof and flashing. The grey Sikaflex polyurethane is a flowing sealant used in concrete crack repairs, It flows in to seal out water,
https://photos.app.goo.gl/glCvzmlgBonUAxkw2

I used a piece of electrical conduit to line the log. Glued in with polyurethane adhesive glues. The shaft log wood split and I did not want to relead tube it, much better products exist today. I used my drill and a large hole cutter and managed to enlarge the hole to fit it in there. Then cut it off smoothly to hull and belt sanded it flat.

I had both shaft logs out and I replaced both strut - rudder logs. I actually wish I had been even more aggressive replacing frames that were ok at the time which have since gotten worse. But all my work is still like new. I replaced every lower frame from mid hull aft.

A future repair could be done by removing the screws and cutting out the old frame and slamming in a new one sideways, then running 3" long bronze screw up into the floors above the frames every 5th or 6th hole hole. The upper parts of the frames were fine, its just the lower parts that rotted which sat under the oak floors.

See the way my boat is now made, it is encased in a flexible rubber like skin which seals out the water and aids in holding it together. I have been in some big pounding seas and it been solid. I reconstructed it with durable products and its built much sturdier than new.

 

It's hard to tell. There are over 700 eucalyptus species, so the term "gum" is pretty vague.

If the boat is lucky, it will have used a variety of "swamp gum", which can be really durable.
Unless the boatbuilder was also the tree feller, he may not have even been sure that he was even using the same species throughout the boat, as they are often hard to tell apart after milling.

We just have to hope that they used a long-lived variety.