Screwing things to timber spars

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I'm well aware of the protocol for fixing things to a cored deck, having repaired part of mine since the previous owner wasn't so careful (and then re-made the holes properly). What I want to know is whether there's an analogous procedure to protect the inside of wooden spars. I need to add an extra cleat to my mizzen, and it seems to me that drilling screw holes will pierce the protective layer of varnish and potentially allow water deep into the wood to rot it.

Is there some special technique to be followed, or can one just rely on the wood being a tight fit round the screw and the outer layers sufficiently impregnated with varnish to resist water?

Cheers,

Pete
 
Bedding compound, white lead paste and putty, or the proper stuff, dolphinite.
Must be many non setting bedding compounds from builders merchants, for wooden window frames etc.
 
Hi Pete,

Not much different to the way you treat a cored deck really.

Drill oversized and over depth hole and wet out with epoxy thinned with up to 30% Methylated Spirits so it soaks into the timber, then add some micro fibres (not Balloons) to a batch of epoxy resin and fill the hole. Make sure no air is trapped by poking the resin home with a toothpick or match stick and apply tape if horizontal to stop runs.

After curing, drill the hole the size required for the screw and be confident it will last many years.

PS. If any part of the epoxy is exposed to UV light, make sure you cover it with a dob of paint or a very high rated UV blocking varnish.

Good luck.
 
oldsaltoz said:
Hi Pete,

Not much different to the way you treat a cored deck really.

Drill oversized and over depth hole and wet out with epoxy thinned with up to 30% Methylated Spirits so it soaks into the timber, then add some micro fibres (not Balloons) to a batch of epoxy resin and fill the hole. Make sure no air is trapped by poking the resin home with a toothpick or match stick and apply tape if horizontal to stop runs.

After curing, drill the hole the size required for the screw and be confident it will last many years.

PS. If any part of the epoxy is exposed to UV light, make sure you cover it with a dob of paint or a very high rated UV blocking varnish.

Good luck.
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Sorry, but when you screw wooden fittings to wood, do you do this on everything? I certainly dont and have never heard of this before. I have fitted many cleats to wooden booms and masts, but I'm willing to learn.
 
ccscott49 said:
Sorry, but when you screw wooden fittings to wood, do you do this on everything? I certainly dont and have never heard of this before. I have fitted many cleats to wooden booms and masts, but I'm willing to learn.
Click to expand...

The above will give you protection against moisture getting into the timber and greatly improve the strength of the joint.

Some use Araldite or other fast setting compounds, but the timber must be protected.

I have been using the above for over 30 years and never had a problem.

Hope this helps.
 
oldsaltoz said:
The above will give you protection against moisture getting into the timber and greatly improve the strength of the joint.

Some use Araldite or other fast setting compounds, but the timber must be protected.

I have been using the above for over 30 years and never had a problem.

Hope this helps.
Click to expand...

I have used epoxy, when driving big machine screws into tapped holes in hardwood, for big fittings, works well, but never used your system for other things, normally use dolphinite, which seals the wood and screw and cleat joint. But for critical things, can see the benefits.
 
I have used this method and it works very well. Some fairleads I fitted in 1997, and which have had some very heavy loads on them [:o], have never budged. I also saw the strength of this technique demonstrated on a test rig at Wessex Resins Ltd; the wood to which the fastener was attached gave way first.

Obviously you would only go to the expense and trouble of using this method when the application justified it. If the cleat was for a sail halyard I would use it, if it's for a signal halyard I would just wet out the holes with epoxy resin.
 
If strength is the issue then choice of fastener is paramount.
Silica bronze screws (or bolts if you are really worried) on a bronze fitting would be the answer.
White lead putty seems to have worked fine for more than 100 years
on the classic boats. If it works don't fix it.
Awful shame that Dolphinite is so hard to find this side of the pond.
Several times in the last 20 years I did some varnish work on Ticonderoga and all the screws were bedded with Dolphinite.
There wasn't one that stuck or had any damage to the slot and they had been in place for decades. Seems it was good enough for the Trans-Pacific record :)
Cheers,
Chris
 
Over Size Epoxy Plugs May Be Overkill For Your Requirements

There is a Poor Boy version of the oldsaltoz method. I first came across it in the Gougeon Brothers Book On Wooden Boat Building . It may be more suited to what you want.

After drilling your pilot hole, or screwing in the wood screw, remove it and squirt some neat epoxy into the hole with a syringe. Re screw the wood screw and work it in and out a few times. Leave the Epoxy to thicken slightly and then back out the wood screw before it sets. This will leave a clean, impregnated hole, with the wood grain sealed.

Let the Epoxy fully cure and and attach your item in the normal manner. It is suitable for fittings where the strength of the wood screw in the wood only is good enough.

Tests documented in the book demonstrated that this method increased the fastening strength by a significant margin compared to wood only.
 
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One thing not so far mentioned is that you should use proper wood screws,
many folk use self taps, but they can allow moisture to penetrate along the thread.

Wood screws are designed with a tapered smooth section under the head which effectively seals off the holes as the screw is tightened down.
 
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Magic of bees

I always kept a lump of beeswax on board. Any time a screw wqas to go it I wrapped a "thread" of wax on the screw thread & a slightly thicker thread of beeswax around the top of the screw. The beeswax lubricates the thread, protects the wood & the bit around the top of the screw squeezes out to form a watertight seal. Rub the excess over the screw head to fill in the slot to protect the screw head too.

20 years it seems to do OK. I never had a screw come loose in that time.

It worked for me is all I can say, and it's quick. The 'poxy method sounds good but also sounds a lot of effort.

Cheers
 
Cheers for the pointers. This is for the topping lifts on a small gaff sail (mizzen on a 24-foot boat, so about the size of a large bathtowel :-) ). The load is not high.

Unfortunately I don't have any epoxy handy, nor exotic things named after dolphins. To be honest I'm tempted to just use a smear of sikaflex - this seems to have been used for various other fittings.

Pete
 
Goodness me - the amazing lengths that people go to when putting screws into varnished wood.

1. The trick with epoxy resin and working the screw in and out is a good one - no need to do anything too fancy - just a drop of epoxy on the screw before you put it in.

2. The old boat builders method was simply to dip the screw in varnish before finally driving it home.

I have used the latter technique and it works a treat every time. If you don't do it, you'll get a spreading patch of lifting varnish round the fitting eventually as the moisture gets in through the screw hole and under the fitting.
 
Leighb said:
One thing not so far mentioned is that you should use proper wood screws,
many folk use self taps, but they can allow moisture to penetrate along the thread.

Wood screws are designed with a tapered smooth section under the head which effectively seals off the holes as the screw is tightened down.
Click to expand...

Proper silicon/phosphour bronze screws are not tapered, they are made from parrallel blanks, they look tapered, because the inside of the "thread" is tapered. Have a good look at/measure one and you will see. Unless you are talking about the coutersink, but thats only on countersunk screws.
 
If the job's worth doing ....

Of course you could always make a proper job of it and have a varnished pin-rail surrounding the mast. Supported on cast bronze dolphins and with highly polished belaying pins and a bell.

Where's my coat? :D
 
ccscott49 said:
Proper silicon/phosphour bronze screws are not tapered, they are made from parrallel blanks, they look tapered, because the inside of the "thread" is tapered. Have a good look at/measure one and you will see. Unless you are talking about the coutersink, but thats only on countersunk screws.
Click to expand...

I stand corrected :o. However the smooth unthreaded section below the head of a woodscrew does make it more watertight than a self tapper.
 
Leighb said:
I stand corrected :o. However the smooth unthreaded section below the head of a woodscrew does make it more watertight than a self tapper.
Click to expand...

I agree with you, self tappers are absolute s...t and should never be used for wood, use proper screws!
 
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