View Full Version : Nail Sickness repair options?
11-01-2001, 06:16 PM
QUESTION: Is there any fix for nail sickness other than replacing the plank? We have a 52 year old English-built trawler that has 2 1/2" Larch planks over 5"X7" sawed oak frames. She was fastened with zinc coated iron bolts and nails. Probably 40% of the fasteners are bleeding and in some areas has caused nail sickness to the planks.
11-01-2001, 08:57 PM
Originally posted by Niles:
Is there any fix for nail sickness other than replacing the plank?
PIRATE is double-planked teak over cedar on oak frames. She was fastened with galvanized cut boat nails (5 per strake per frame) way back in 1927. Needless to say, we're in the midst of a 100,000 mile rebuild on her: all new frames, new deckbeams, decks and house. We just don't talk about the surgery to the structural keel http://media5.hypernet.com/~dick/ubb/frown.gif
Anyway, there's a lot of iron-sick wood. And a lot of old nails that are never coming out. You can't get to the heads to pull them and they've mostly become One With The Wood. The only way we found to get them out was to drive them out from the inside.
The decision was made to refasten her screws, 3 per plank rather then the 5 fasteners per plank that she was built with. We're using #10 and #12 silicone bronze screws, depending on how iron-sick the wood is the fastener needs to be big enough to find healthy wood.
The other big decision that was made was to pull only the nails that will be replaced by screws. Why? Well, a number of reasons: removing the nails damages the wood for starters and we figure that electrolyis shouldn't be a problem -- we're not installing an engine (she's a raceboat) and she'll be living in fresh water. And we'll get the rest of them when we do her planking some years down the road. This trip is largely structural.
The nails that don't get removed, we are treating with some variety of phosphoric acid-based rust treatment (Ospho, etc.) after grinding down to clean metal. They presumably react with the iron to form a phosphate coating and prevent further rust. We'll see how well it works.
Note to self (after removing hundreds of old nails and seeing large quantities of iron-sice teak, cedar, douglas fir and oak): Never, ever use ferrous stuff in a boat. It is a false economy.
Anyway, our procedure for dealing with nails goes something like this:
0. Remove ALL the plugs from the outside of the hull. Yuck. Especially on PIRATE -- some previous owner, in a vain and not terribly effective attempt to stop a bunch of weepers back in the early 70's, pulled a lot of the plugs and replaced them with...
Wait a second, are you ready for this?
He took a bunch of white plastic golf tees, melted them and used the resulting hot goo as putty. Evidently, the story is still good for a laugh in the boatyards in San Diego where the job was done. The stuff does seems to stick better than 5200 though.
YUCK. Removal is slow and agonizing work. Drill bits want to slide off the stuff and into the wood. Wooden plugs *much* easier to deal with. Note to wife: shoot me if I ever come up with an idiotic idea like that.
1. Cut out every third frame. We cut through the frame every 6 inches or so (being careful of course to NOT cut into the planking.)
2. Next, Get out your grottiest chisels -- not a job for any chisel you care anything about -- and your pounder of choice. Go to town and chop out the cut-up frames. Since you've already put them in coarse dice, you're pretty much just chopping around the fasteners to release the pieces. It goes fairly fast. Except for the persickety bits.
Now that you've got the frame out, the faying surface on the inside of the hull looks like an instrument of torture, what with all the nails sticking out. Amazing how cork-screwed they all went in.
4. Take your gallant mini-grinder (we like Porter-Cable, but YMMV) and load it up with a thin cut-off blade for ferrous metals. Take of the safety guards on the blade -- useless tool until you do. Don't forget the heavy cowhide glove, the safety googles and the hearing protection. Don't forget a spray bottle full of water and a fire extinguisher either. Cut the nail ends off about 1/8 inch above the inside surface of the hull. You need a clean flat surfce to drive the nails out.
5. Now you'll need a faithful assistant. You'll also need an assortment of center punches, etc. and a hammer, along with something like a backing iron you'd use for riveting. You'll also need something like a disposable chopstick as a placeholder. I also recommend Fuller's ESB as a thirst-quencher.
So, to get the nails out you need to work as a team. One of you will be working the outside of the hull and driving the operation. The other will be inside the hull and providing motive power. Since PIRATE has two layers of offset longitudinal planking, it takes some figuring to figure out what nail to remove. Starting at the shear, the outside guy measures down to the first nail to be removed that is closest to the shear. Call this measurement out to the inside guy, who uses that measurement to find that same nail on the inside of the hull. Now that we're on the same page, we can remove the nail.
Since this is somewhat akin to setting a rivet in reverse, you need something like a backing block or iron to support things are the nail is driven out. The outside guy sets up with this. The inside guy sets up with punches and hammer and proceeds to drive the nail out.
It's a little tricker than it sounds -- you'll be amazed out the circuituitous paths the nails take on the way in. Once the nail head emerges on the outside of the hull, the outside guy can grab it and remove it with the nail pulling tool of choice (Vice-Grip makes a dandy "locking wrench" for this -- it looks something like an old-fashioned "end-nipper" style nail puller.) Careful not to damage the hull planking!
The outside guy measures down from the last nail removed, calls out the measurement. Find that nail on the inside and repeat the exercise.
Use your chopstick to mark the last nail removed -- it give both parties an origin to measure from (2-1/8 down, 3/4 over, Leroy!)
6. Once you've gotten the appropriate nails out, we change to the mini-grinder with the face-grinding wheel and carefully grind the ends of the nails that didn't get pulled flush with the inside of the hull.
7. Treat the end of the nail with rust treatment (Ospho or equivalent).
8. Steam new frames and bend in place. Fasten down. Repeat.
I told you you'd need the Fuller's ESB!
John R Smith
11-02-2001, 02:52 AM
I think we all owe you a big vote of thanks for such a detailed account of dealing with the problem. I found it very instructive, and also very daunting!
We had similar issues way back in the 1960s with a big (90 foot) Brixham trawler, but no-one bit the bullet (she's still sailing, though).
Makes me think the moral is, perhaps, never buy an iron-fastened boat! http://media5.hypernet.com/~dick/ubb/smile.gif
11-02-2001, 10:10 AM
Very impressive Nicholasc.....
11-02-2001, 01:18 PM
Lucky for you she's massively built. There may be another option you might want to try. Get some of those "screw extractors" which are essentially hollow drill bits that cut a ring around the fastening. Core out the old rusty nail and pop out the resulting plug, leaving a nice big hole maybe 1/2" or 3/4" in diameter. (A big enough diameter to get you to some pretty solid wood.) If you don't get the whole nail, it doesn't much matter, as long as you keep track of whether or not the treenail goes into the frame deeply enough. Epoxy in a tight fitting treenail. If you want to be really slick, slot wedge them at either end. If you want to wear a belt with your suspenders, add a good silicon bronze screw or three placed elsewhere on the plank/frame interface. Think "dentures" rather than "root canal."
11-02-2001, 01:42 PM
Rick Prose is using essentially this concept with Frigatebird.
11-02-2001, 04:03 PM
Thank you all for the great input - please keep it coming! I had wondered if treenails could be a possible solution - certainly would end the rust-bleeding and nail-sickness issues.
Ed, any way you can put me in contact with Rick Prose on the Frigatebird?
Everyone's input has been very comforting - especially after getting an estimate from the local shipwright who insist the only fix is a total re-planking ... for a mere $250K!
11-03-2001, 02:49 AM
Well, there is a catch... once you get iron oxide (rust) staining the wood, you will pay hell to stop the "bleeder" even if you replace the fastening. I've had some luck soaking stained wood with CPES and keeping it painted well. That lasts for a good long time, but eventually, it tries to work its way out and you paint again! It doesn't mean anything, though, as long as the fastenings are good.
11-03-2001, 08:10 AM
Really good info Nick. I'm looking at a boat w/some bleeders right now and was wondering how one tackled the issue. You did a great job of explaining. Thanks.
11-03-2001, 12:20 PM
I've seen Mike Kortchmar use a circular saw with a dado blade to make a plunge cut over bad fastener spots. This leaves a semi circular cut with sides parallel to the direction of grain and the deapest part of the cut right over the old fastening hole. He then cuts out half moon shaped pieces with the same diameter as the dado blade. These are epoxied in and faired off. You've just made a dutchman that should take care of the nail sick spot. With such heavey planking you might have to go to a larger diameter blade to keep the scarf ratio acceptable.
11-03-2001, 05:27 PM
Niles, do a search (search gizmo in upper right corner of the page) for Rick Prose. He does hang out here some, tho I think he realizes that to get anything done..., LOL. Good luck!
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