Plank fastenings?

Porthandbuoy

Porthandbuoy

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What's the strongest plank to frame fastening?
Screws, nails riveted over roves, or clenched nails?

Reason I ask is I will be doing some frame repairs this winter and, while screws I can deal with single handed, I'll need a mate holding the dolly while I'm peening over the nails. I included clenched nails out of curiosity.
 
not exactly sure what you mean by clenched nails, 'cos I've heard plenty of people refer to copper nails peened over a rove as "clenched".

Personally, I've yet to find a copper nail that has degraded, damaged the timber around it by any chemical action, or pulled through a rib, due to the surface area of the rove.

Screws on the other hand are another story!

More work in the roving, and you need to make sure they pull up tight, but I'd say they are the better way to go for strength and longevity. Of course, personal opinion though.
 
By "clenching" I mean the nail is not clipped short and riveted over a rove, it is doubled back on itself and driven back into the timber. This still requires a mate on the outside holding a dolly to stop the nail being pushed back through the timber. I believe it's more common Stateside.

As for screws; I would have though the area of the threaded helix would exceed that of a copper washer.
In CB230, August '07, there is an article on the Pilot Cutter Eleanor Mary which states "The Category Zero rating and the need to build the boat to the newly-introduce Recreational Craft Directive standard means different sets of build criteria. These modifications include the screw fastenings from plank to frame."
 
I aways understood nails/roves to be the strongest. Mostly on the basis of the surface area of the head and rove spreading the pull-out force over the largest area of wood. While it is true that the surface area of the thread helix may be greater, the stress/damage done to the wood beween the threads significantly weakens it locally.

I guess you can test this fairly easily with a bit of scrap wood and a crow-bar. Run in a screw and I think you will be able to pull it out, but a properly peened rove will not pull off!
 
I would be very hesitant to take any structural detail from the RCD where wooden boats are concerned. Half of the ones sailing today would not meet RCD specs. They obviously are not fit for purpose and should have sunk years ago!
 
I understand what you mean with the screw helix having a large area. But surely that timber is all weakened by having a hole drilled within a millimetre of it, nd also subject to possible ingress of water and softening. It's more the volume of timber that has to be weak for a rove to pull through is far greater than the volume for a screw.

that's my explanation anyway, notparticularly clear, but it's based on what I've found. As for clenched nails, I guess it's a slightly quicker method than using roves, but again the trick must be to get them to pull tight. The roving action puts tension into the nail, I don't know whether clenching would do the same. I've only really seen it in area where there was no space to rove properly.

I guess someone else here will have far more experience on the subject.

I'd go with mikef2's suggestion and conduct some tests with a few bits of offcut. Let us know what you find.
 
There's a good thread here in the wooden boat forum. I think the deciding factor for me is the plank thickness. At 5/8" (less 56 years worth of sanding and abrasion) I just don't have a reasonable thickness for counterboring and plugging screws.
Rivets and roves it is.

PS. I was on a 1940's motor launch a couple of weeks ago that had clenched screws holding the planks to the frames! Best of both worlds?
 
I assume you've got the tools for setting/peening roves?

A friend who's (among other things) a jobbing metalworker made me up various bits of steel with holes in the end, etc. On the other hand, I know of people who get by with a club hammer for a dolly and use old tubular ring spanners to set the roves. You can do a fair bit of the work single handed - drive the nails then later get mate/crew/son, etc. to push with the dolly/hammer while you crawl inside and do the difficult bit.

Good luck!
 
Remember to get someone inexperienced to hold the dolly! Anyone who has done it before will demand far too high a payment in beer/future obligations etc.

I'm still avoiding it after two of us did approximately 1500 roves over 3 days. Not something I'm keen to repeat! /forums/images/graemlins/smile.gif
 
There is an old saying;
Nail when you can, screw if you must, bolt when you have to.

It's easy to make the tool for clenching - it's just an old bolt with a hole drilled in the end. It's for driving the rove down the shank of the nail. Then snip off so that the amount protruding equals the diameter of the nail.
I have just used a heavy hammer as dolly on the outside. If planking a boat with its deck open you can sometimes manage singlehanded by holding the big hammer between your knees. The trick of listening for the change of note really works.

Bending over a longer nail and doubling it back is always said to be less satisfactory because it introduces a new forced hole on the inside that can start a weakness. The point should be driven in on a parallel section of grain, not in line.
It can be done singlehanded if the pilot hole is the right size - ie tight. Drive in from the outside, and then hammer over as far as possible, but just allowing space to bend the point over with pliars. Then drive the bent over end into the wood. This has the effect of tightening the nail in the final bending at the point where it emerges.
 
Thanks everyone.

I'll be using a turnbuckle body to set the roves, a sizeable lump of steel turned down to the nail head diameter as a dolly, a pair of end cutters to cut the nail, a ball-pein hammer to rivet the end of the nail, and my wife or daughter or son as dolly holding mate (they don't know it yet!).
 
I was told by a wooden boat person that there is no harm in using silicon bronze screws in place of copper nails but the tip of the screw MUST protrude well through the job where it can then be cut off. This ensures that the largest part of the screw is holding everything - as opposed to the tip which is very narrow.

However I still used copper nails and roves when I re-did my fastening - I didn't do 1500 though - cor bleyemey.

If you use nails make sure you do not crush the roves - they are like little hats and their shape should be maintained if possible. If you are making up a driver make sure that the hole in the middle of the tip is wide enough to just rest on the outer edge of the rove and deep enought for the nail shaft of course. Good luck.
 
I was told by a wooden boat person that there is no harm in using silicon bronze screws in place of copper nails but the tip of the screw MUST protrude well through the job where it can then be cut off.

So the screws need to be longer than the plank+rib then?
 
Make sure that the nail is a drive fit in the hole, as when you rivet the nail end over the rove it should pull the nail head up tight and if the nail hole is too large the head will very easily get pulled through the timber! Not too tight however, as then you may well bend the nail as you drive it in! A little trial and error should get the right result which is not too time consuming and very satisfying! I used to use a warrington hammer (the one with a chisel like head to one side) to work the nail end out over the rove and then round it off with the other side of the hammer head (or a pein hammer if I could be bothered)
Are you steaming in new ribs?
 
Yes, exactly so. It should protrude by a healthy amount - not just a mm or two. The excess is then clipped off flush with the frame. The point being that the strongest part of the screw is the working part throughout the plank and frame.
 
Regarding "clenching" with the nail bent over and driven in flush, this was quite common on the south coast, i have a Rye beach boat, her planking is roved up with the ribs and grown floors clenched. I read somewhere that the reason clenching was used on beach boats was that in the event of a heavy landing the nail would straighten out and pull before frames or ribs got broken or nails pulled through the planking.
My boat "Billows" was built in 1938 and her planking and floors are 99 % original as are her fastenings, she was built well by Harry Phillips of Rye and is still tight today proof that clenched nails can be just as good as any other method.
 
Yes, exactly so. It should protrude by a healthy amount - not just a mm or two. The excess is then clipped off flush with the frame. The point being that the strongest part of the screw is the working part throughout the plank and frame.


Yea makes sense Ok Thanks.
 
[ QUOTE ]
Are you steaming in new ribs?

[/ QUOTE ]

A few of the more convoluted ones aft will be replaced by laminating in complete new ribs. Further forrard I intend to repair a few cracked frames, again by laminating in replacement sections.

There's been lots of good feedback here, for which I thank everyone, but I will definitely be using nails and roves.

I'm still curious to know why the RCD directive resulted in Eleanor Mary having screwed planks/frames. Could it be to allow removal for inspection, or have they deemed them "time limited" so they have to be replaced every so many years?
 
[ QUOTE ]
There is an old saying;
Nail when you can, screw if you must, bolt when you have to.

It was explained to me that the shape of the rove was such that if fastened properly ie the nail peened over the rove with out distorting the shape of the rove , not flattening it, it would allow for minimal movement of the timber without stretching the copper nail like a mini shock absorber
A proper Rove Punch should be shaped to accept the dome of the rove not just a bolt with a hole drilled in it in it!! and you should use a "polisher" to perfect the "mushroom" shape of the nail over the rove
In our yard clenched nails were frowned upon and only used for domestic jobs and never used on hardwood hulls
 
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