I have an observation to relate about bronze screws in oak versus PT pine

I reframed a lot of this 37 egg 25 years ago using PT wood framing ribs, cut to the same dimension as the OEM oak ribs.
All the PT pine wood is perfect, when I removed some screws in various areas, the wood is not degraded, and the bronze screws are in very good condition. The screws still holding tight and strong in the holes.

Not so for the original oak framing where I did not replace some of it.

Like in the bow, I am removing all the plugs and testing the screws. while most bronze screws are still ok, perhaps 25% of the holes are loose and full of pulverized wood dust.

As in remove screw, whack plank with hammer and a lot of dry dusty wood falls from hole.
Why is that? Screws just spin in loose holes.

25 years ago, those same holes held these screws, but 25 years later screws are loose and do not hold.
What I am doing is gluing in Chinese chopstick pieces into the holes, then the bronze screws hold in the holes.
I do not plan on checking all the holes.

Something different about oak versus pine. I was thinking maybe the oak is getting abraded by the screws as in forces on planks pull on screws and screws chew up the oak wood.
The oak framing is original to the boat from 197o.

Not all holes are affected, 75% of the holes hold the bronze screws tightly.

Maybe PINE being softer yields to the forces on a large bronze screw #12, so the screw edges don't eat into the wood like a saw? I am telling you there is a significant difference here.

I am also impressed how most 316 SS deck screws I used 25 years ago are in excellent shape, while some new bronze screws I put in 25 years ago were completely wasted.

 

I also can see why boats made like this egg harbor as of an inferior construction design and are for most people not worth the cost of repair as too much is dependent on skinny pieces of bent oak framing. I used to think cracked ribs are the main problem, but it also the choice of bent oak for frames that doomed so many of these boats.

Another problem of oak for frames, is oak splits easily, so I noticed when replacing oak frames lots of splitting ribs, screws are like wedges in hard oak wood, and oak naturally wants to split. The pine does not split as easily as oak, the wood is softer, and yields more to the screw. ALL the PT pine I used in the boat 25 years ago is still in great shape. Yes pine can split, but oak splits easier. And small frames of oak split easier than a large piece of oak. Like all the floors in the boat are thick 2" width and very tall and not really any splitting.

Egg frames are 2" wide and 1.125" height profile. That is a small frame.
Large more robust sawn frames joined together are much better construction.

 

Well, predrilling for pine and oak would generally be different. I’d want to drill the oak at just above the minor or at it and the pine can be drilled smaller. Not saying it is right or wrong, but that it could be.

So, let’s say the oak was actually a hair overdrilled this means the major dimension goes in and cuts the oak and fills the overdrilled section of the minor with sawdust. When you look in the hole; you’d see a flat and a cut versus a point and a cut.

Why? Well, as you’ve done plenty of screw work; it all was probably done by hand and so overdrilling made the screw work in oak easier. Possible they used air tools, though.

Just my theory.

It could also be the case that when they ran the screws; they were damaging the minor; cracking the inside portion of threads.

Also possible they didn’t use a tapered bit to predrill. This would mean part of the hole is okay and part is bad; but I would think you’d see this on close inspection.

 

So 25 years ago, did you reuse the same holes in the oak frames, or did you drill new holes? Also, if you did reuse the same screw holes, what did you use to re-install the screws?

 

Any idea what species of oak?For the purposes of this thread we have to accept that all oak is quite acidic and it may be that this aspect relates to the chemical reaction that seems to have occurred.Further to this there is good evidence that red oak doesn't last as well as white oak.In much the same vein,a metallurgist could say quite a bit about the various types of bronze in existence and it may be that those screws you used 25 years ago aren't from the same family as the sound originals.

 

I reused the same holes and went up 1 size in screw width to #12 from #10.
Screw length is 1 5/8 inch.
The #14 I used are Mcfeeley's and are square drive.

See back then, half of the original screws were wasted and also the screw holes were loose and worn. They looked like rough nails with a trace of screw thread remaining

I installed them using my power drill. Same as today. I don't drive any screws by hand.

 

The originals were everdure bronze from 1970. However many were wasted away.
I know the keel and floors are white oak, but the frames might be either red or white oak.

 

The dry dust in the holes is pulverized wood dust from what I can tell, it is not coarse dust, it is very fine nature, and surrounds the screw, and there is a lot of dust. It is like the entire threaded area of the wood turns into powder. The frame wood past the hole is still sound wood.
Gluing in chopstick sections holds the screws ok. I clear the hole, clean it up and simply glue in a 1 inch length.

I unscrew the bronze screw, some threads are very clean, some dirty, very few screws are spinners to make hard to remove. I take a hammer and whack the plank and a lot of fine powdery dust falls out of the screw hole.

Which is why I am thinking forces bearing on the screw are tearing the wood hole on the inside. I am presently working on the bow area where this happens, not on the flat sections back aft. It is also random, not all screw holes have this issue even on the same plank frame.

Like when a boat is pounding through water, does that try to flex bow planks outward and inward like a bellows? In my mind, it would be like tying a heavy cable to the screw and then swinging a heavy weight back and forth, making the screw wiggle in the hole. I might be wrong about what happens.

 

Here are removed #12 McFeeley screws I put in 25 years ago. Most threads are clean. Most are all greenish colored

Whether they came out of oak or PT pine, they all look the same



Lined up, one screw shows the dried wood dust on the threads. Sometimes the wood dust packs the threads solid. But the screw if you take a steel brush cleans up fine and looks good.

 

Any screw in oak can create this dust.
Here are some worse examples of this dust clinging to the screws.
I test the screws before full removal, I unscrew and then rescrew and if they cant hold, I pull them out to repair holes

 

Not all screws with dust in the holes look like that, most look like the ones on the box, decent.

Here is one real close, you can see the wood has turned to dust and coats the screw

 

Same screw as above after aggressive cleaning using a steak knife.
I agree some of this on this one is corrosion

 

Hi sdowney717, 25 years ago did you use any preparations before screwing in, or did you screw into dry, bare timber holes, and rely on top coatings to keep the screws dry. I say this because when doing a final screw in, I usually dip the threads in varnish, or drip varnish down the screw holes, then do up tight. It lubricates the screw, and seals the sides of the screw holes, and acts like a mild locking compound. The screws come out in reusable condition usually, and the holes are also good to reuse as is, or I go up one size screw if the head is burying into the countersink too far. For screws I'm never going to move ever again, I do the same thing with epoxy resin, quickly.

 

Just screwed in the screws. No dipping in anything

Everything I am screwing into is overhead.

Problem is only in oak, not pressure treated pine.

 

I completely dismantled an oak on oak boat that was built in 1947. I have a large bucket full of copper roves, nails and bronze screws that still look good enough to use. Everything hot dipped iron though was completely wasted. There was virtually nothing holding the iron keel on except a thin layer of tar.