frame screw holes damage?

[sdowney717]

I was wondering considering the planking moves around on a carvel boat, do the screws pulling and pushing on the frames tend to rip the fibers in the frames weakening the screw hole? It seems the frames on my boat are really pretty good but many holes just wont hold the screws. I was wondering if 35 yrs of use would do this to the frames. I am having to plug a lot of holes.

[Bayboat]

If you want to use the same holes for refastening planks to frames, and the replacement screws won't hold, you have two options: 1)use larger screws (not recommended) or 2) replace the old screws with copper rivets (recommended). The rivets will be tighter and won't work nearly as much as the screws. It would be good to plug the holes before drilling for the rivets. You can countersink the heads just like you do with screws. You will have roves showing on the inside, but that's not a bad thing.

[bottompaint]

It probably has more to do with the degradation of the wood surrounding the screw while the screw corrodes. Sounds like you are making good progress. smile.gif

[Bruce Hooke]

Originally posted by Bayboat:
If you want to use the same holes for refastening planks to frames, and the replacement screws won't hold, you have two options: 1)use larger screws (not recommended) or 2) replace the old screws with copper rivets (recommended). The rivets will be tighter and won't work nearly as much as the screws. It would be good to plug the holes before drilling for the rivets. You can countersink the heads just like you do with screws. You will have roves showing on the inside, but that's not a bad thing.While switching to rivets can be a very good route to go if it is possible (it does require complete access to the insides of all the frames), I would disagree with the implication that plugging the existing holes and then redrilling for screws is not a viable option. From what I've seen around here this is the most common solution to this problem and by all reports it seems to work just fine.

I do agree with bottompaint's analysis of the cause of the problem...

[Bayboat]

I agree with Bruce that plugging the holes and re-drilling for screws is a viable option IF you can't get at the inside to put roves on the rivets.
Sdowney717 suggests that his frames don't hold screws well. Or is that only after 35 years of working? Anyhow, riveting is the best solution if it is feasible; otherwise, plugging and new screws will probably last a long time, assuming that the frames are in pretty good shape.

[carioca1232001]

As for the need of plugging holes left over in the frames when old screws were taken out, especially when drilling new holes with replacement planks in place for installation......

Has the HOLDING POWER of:

PLUGS made from END-GRAIN driven in with GLUE

VERSUS

PLUGS made from ACROSS THE GRAIN (do not know the technical term for this)also driven in with GLUE

BEEN TESTED ?

[bottompaint]

The plugs should be of the same species as the frames and when glued in and trimed flush, present the grain in the same manner as the frame. HOWEVER.....the oldtimers I knew said that GLUED plugs of hard wood should be put in with the grain 90 degrees to the existing frame, because hardwoods do not absorb as much glue into thier grains. This maybe splitting hairs...BUT in unseen frames where grain orientation is not cosmetic.....it might make sense. This advise was given concerning glues and was pre-epoxy. The adhesion of epoxy, perhaps, makes this a mute point.

[carioca1232001]

bottompaint wrote:

HOWEVER.....the oldtimers I knew said that GLUED plugs of hard wood should be put in with the grain 90 degrees to the existing frame, because hardwoods do not absorb as much glue into thier grains. This maybe splitting hairs...BUT in unseen frames where grain orientation is not cosmetic.....it might make sense. Am half-way through a major undersides refurbishment, part refastening, part replanking.

Frames are of a medium-hard Brazilian species called "Peroba do Campo", unavailable today.

During replanking, I plugged the "empty nests" left over from the old # 8 screws in the frames, with END-GRAIN plugs (dowels) made of Brazilian Ipê (a very hard wood which is virtually immune to rot). Knocked them in gently with epoxy glue, after reaming the hole with a 5mm dia. drill.

NO PERCEPTIBLE PROBLEM WHATSOEVER with the holding power of the new # 10, as the new planks are seen being firmly drawn onto the frames.

Has any forumite done some serious testing on the subject of plugs during replanking jobs ? Do recall reviewing tests done on joints and glues of diverse types.

Woodworker-supply stores cater for END GRAIN plugs (basically dowels)of various sizes and wood species.

But the woodworker is left to his own devices for the "preferred plugs" (STRAIGHT GRAIN ?)using a plug-cutter and wooden board , as only a limited selection (size) of plugs of this type are ofered in the market.

May END GRAIN hardwood plugs (dowels) safely substitute STRAIGHT GRAIN plugs ("preferred plugs") in frames ?

[bottompaint]

I make all of my own plugs and would never use "end grain" dowels. Use the same species for plugs as the wood you are plugging.

[carioca1232001]

bottompaint wrote:

I make all of my own plugs and would never use "end grain" dowels. Use the same species for plugs as the wood you are plugging. You are obviously following the "conventional wisdom" route.

Can you tell me of a practical way to make 1000 or so plugs, of the preferred type (not dowels), of 5mm dia and of two lengths, namely 25mm and 70 mm ?

[Bruce Hooke]

Originally posted by carioca1232001:
As for the need of plugging holes left over in the frames when old screws were taken out, especially when drilling new holes with replacement planks in place for installation......

Has the HOLDING POWER of:

PLUGS made from END-GRAIN driven in with GLUE

VERSUS

PLUGS made from ACROSS THE GRAIN (do not know the technical term for this)also driven in with GLUE

BEEN TESTED ?There is a LOT of engineering data out there to demonstrate that screws driven into end grain have a MUCH lower holding power than screws driven into side grain. I see no reason why the fact that the end grain is in the form of a dowel driven & glued into a hole would have any impact on this because the failure mode is basically the wood shearing along the grain along the outside of the screw, which does not depend on the dowel expanding at all. HOWEVER, it is certainly true that if the dowel were made of an especially hard wood this would increase it's holding power. Whether it would increase it to the level of a side grain plug is harder to say because it would depend on the various strength figures for the woods in question -- both the dowel wood and the original wood that the frames are made of, which is what you are trying to match in terms of strength.

I'm afraid I do not know of a way to make "proper" plugs in the length you need...

[carioca1232001]

Bruce Hooke wrote:

There is a LOT of engineering data out there to demonstrate that screws driven into end grain have a MUCH lower holding power than screws driven into side grain. I see no reason why the fact that the end grain is in the form of a dowel driven & glued into a hole would have any impact on this because the failure mode is basically the wood shearing along the grain along the outside of the screw, which does not depend on the dowel expanding at all . HOWEVER, it is certainly true that if the dowel were made of an especially hard wood this would increase it's holding power . Whether it would increase it to the level of a side grain plug is harder to say because it would depend on the various strength figures for the woods in question -- both the dowel wood and the original wood that the frames are made of, which is what you are trying to match in terms of strength.

I'm afraid I do not know of a way to make "proper" plugs in the length you need.Your response has given me food for thought over the conventional wisdom approach !

No doubt, the new planks are being drawn solidly onto the frames.

No urge to be different, but the motivation was there to find a practical alternative to making "proper" plugs. Hope this solution at least outlives me !

Many thanks

[sdowney717]

I tested end grain beech hard wood dowels, they may appear to hold but if you torque em down they strip. If you run the screw in and out a couple of times they strip.
I tested a 'brazillian hardwood' dowel from Home Depot. They held on the first try, run in a couple of times they failed. I tested white oak 'face grain' plugs. They always held the screw. Problem is IMO, working forces on the planks may eventually pull the fibers in end grain plugs.
It is an onerous job cutting thousands of plugs. What you need is a good plug cutter that can cut 1 inch deep plugs. Check out this link for an awesome plug cutter.

http://woodworker.com/sitenews/selfeject.html
Anyone else using these?

[carioca1232001]

sdowney wrote:

............It is an onerous job cutting thousands of plugs. What you need is a good plug cutter that can cut 1 inch deep plugs. Check out this link for an awesome plug cutter.

Only had I known earlier...... would have purchased half-a-dozen for good measure !

However, 3/8" dia. plugs would be max. allowable dia. on 1" thick frames like mine and 1/4" dia. more appropriate.

Can you supply some more data on the tests that were run ?

1. Screw size (#?) and plug/dowel dia.(mm /" ?)

2. Were screws dead-centre on the plugs/dowels or were some 50/50 ?

3. Did it make any difference lining up (or not) the grain in the plug and board ?

Thanks

[sdowney717]

screw size was #14 1.5 inch silicon bronze boat building screws square drive from Mcfeeley.
They were driven in with a 3/8 chuck Dewalt power drill.
all my trial plugs were 1/2 inch wide and 1 inch long.
they were all dead center.
Did not make any difference lining up the grain.
They were glued in with epoxy.
When a screw like a #14 goes into a good hard wood such as white oak, it should stall the drill.
I suppose if you are hand driving screws you might not notice that the screws wont hold in the wood.
I tell you some of the old #12 slot drive screws that I am replacing in those rotten frames felt like they would tighten down, but if you kept trying to twist they would eventually just spin. A screw hole can let some water fresh water in and rot just the area around the screw. I did end up having to replace 13 frames from the stern forward. My boat has heavy large floors so I simply cut the frames back about 3 feet and screwed the cut ends of the frames into the floors. I will then use PT wood to replace the rest of the frames and also screw these into the floors. No way am I prepared to replace the entire frame from keel to toe rail. I am also going to replace one rotted floor in the lazarette. The hatch dripped on this for 30 years.
Also this 1970 Egg Harbor has no broken frames. There are cresent shaped gussets? on every frame at the turn of the bilge. I was always wondering about people complaining about broken frames, perhaps Egg harbor yachts in the last year of the wooden boats made this improvement.
I had some worm damage in the stem and had to tighten up the stem bolts. Took one out and it was perfect. I also removed the shaft log. What a heavy piece, all the bronze bolts were perfect. I need to replace the strut log. This one supports the strut and rudder.
They used a lead tube to join and seal the shaft plank to the shaft log. The lead was completely eaten away. I can see where this was a strong boat when new. But I would never have built it like they did. One example is using socketed frames into the keelson. This simply creates pockets where rot can eat the lower ends of the frames or keel. I also catches a lot of dirt.

[carioca1232001]

sdowney717 wrote:

screw size was #14 1.5 inch silicon bronze boat building screws square drive from Mcfeeley.
They were driven in with a 3/8 chuck Dewalt power drill.
all my trial plugs were 1/2 inch wide and 1 inch long.
they were all dead center.
Did not make any difference lining up the grain.
They were glued in with epoxy.
When a screw like a #14 goes into a good hard wood such as white oak, it should stall the drill.
I suppose if you are hand driving screws you might not notice that the screws wont hold in the wood. Am using a BOSCH rechargeable-battery-powered professional (industrial) screw driver.
Could not imagine myself doing it unassisted. This tool´s tightening torque is way above my manual capability.

A screw hole can let some water fresh water in and rot just the area around the screw. I did end up having to replace 13 frames from the stern forward. Noted that about 5 % of my new #10 screws end up spinning when I tighten them.
It could be that these screws are 50/50 on a 5mm dowel.
Or they could be dead-on the 5mm dowel, and are efectively biting into rotting wood (frame).
In such cases, the screw is removed, and the screw hole is drilled deeper (say 2 ") and a longer dowel with glue is tapped in, so as to adhere to good wood up into the frame.
Once dry, I drill again and the screw holds as new ! Believe it or not !
I am considering SISTERING every alternate frame, from the transom forward to the bulhead that separates the stern part from the main cabin.



My boat has heavy large floors so I simply cut the frames back about 3 feet and screwed the cut ends of the frames into the floors. I will then use PT wood to replace the rest of the frames and also screw these into the floors. No way am I prepared to replace the entire frame from keel to toe rail. I am also going to replace one rotted floor in the lazarette. The hatch dripped on this for 30 years.
Also this 1970 Egg Harbor has no broken frames. There are cresent shaped gussets? on every frame at the turn of the bilge. I was always wondering about people complaining about broken frames, perhaps Egg harbor yachts in the last year of the wooden boats made this improvement.Sometime next week will post some photos of how my frames and ribs are set up in the bilge area. I don´t think I have FLOORS in mine ! Yes, there are gussets on every frame at the turn of the bilge, on mine as well.


I had some worm damage in the stem and had to tighten up the stem bolts. Took one out and it was perfect. I also removed the shaft log. What a heavy piece, all the bronze bolts were perfect. I need to replace the strut log. This one supports the strut and rudder.
They used a lead tube to join and seal the shaft plank to the shaft log. The lead was completely eaten away. I can see where this was a strong boat when new. But I would never have built it like they did. One example is using socketed frames into the keelson. This simply creates pockets where rot can eat the lower ends of the frames or keel. I also catches a lot of dirt.I don´t believe there is much rot worth worrying about in mine. It was always used in salt water. You seem to know a substantial deal about boatbuilding/restoration. I am very much a novice in comparison..