Mounting jib sheet T-track

[Dale Genther]

I'm starting to think about mounting the old 1 inch bronze T-track back onto the toe rails of our S&S sloop Radiance. They were previously mounted to the toerail. When I got the boat they had been removed and the old screw holes had been bunged over so I have no idea what the length of the screws were that fastened them on. The toerail is screwed on with #16 bronze screws about 5-6 inchs long, on 9 inch centers that go thru the toerail into the shear plank

Details: Boat is 36 ft. LOA, displacement 15,000 lbs.,The mahogany toerail is approx 3 to 3 1/2 inches high, two inches wide, the jib is about 360 sq. ft., the t-track has holes countersunk for #14 screws on 4 inch centers, the tracks are about 9 ft. long.

I have a bunch of #14 bronze screws 2 inchs long. The t-track is about 3/8 in. thick, so 2 inch screws would give me about 1 3/4 in. into the wood of the toerail. Will these be long enough to hold the track in place with the stress placed on it by the jib sheet? If I have to go longer I'll have to buy them, and everybody is aware of the price of bronze fasteners nowadays.

[rbgarr]

Are you sure they weren't bolted on?

[Hwyl]

I thought the same as Dave, and at least all the way through the toe rail.

Do you move the block around much (different jibs, roller furling) you only need the long screws/bolts in the area of block.

[Dale Genther]

I'm certain they were not bolted on as there is no way to get bolts thru the toerail as you would hit the shear plank.

[John B]

Thats very similar to what I've been running and I've never had a problem. I've shifted them a couple of times over the years.
Of course, its nice to have the fairlead positioned away from the track ends , perhaps you could beef the screws for there if it was a concern.

[Dale Genther]

The jib sheet cars should not be near the ends of the track. In any case I have about a dozen 3 inch #14 bronze screws that I was going to put at the ends of the track, just in case.

[John B]

Thats what I'd do.;)

[John Boone]

Evening Dale,

I just pulled and rebedded my 1 1/4 tracks on the toerails on Whampoa. They were installed with 2 1/2" #14 at the ends and center with 2" #14s in all other positions. No problems apparent .

Regards, John

[JimConlin]

Wood screws are much stronger in shear than in tension. I'd through-bolt them if I could with 1/4" flathead machine screws. If through-bolting is not practical, I'd use epoxy-potted machine screws. (See the Gougeon book)

[Dale Genther]

Jim Conlin - I've been thinking about your solution. It has been a while since I read the Gougeon book, but if I remember right it the process is: you drill a cylindrical hole and fill it with epoxy, then screw the screw into the epoxy. If this is correct I don't see how this is any stronger that a wood screw that has been screwed into a properly sized pilot hole. In one case you are counting on the screw thread to wood joint to create the strength, in the other case you are relying on the epoxy to wood bond to create the strength. I can't see how the West System approach is any stronger than the traditional approach.

I could very well be wrong in my thinking, but it just doesn't make sense to me how the West appoach would help with the tension strength problem.

[JimConlin]

Here's my barnyard engineer's description of the rationale for potted fastenings-
When a fastening, such as a screw, is in a piece of wood and a load is placed on the fastening, the load is transferred to the wood via the interface between the screw and the wood. The interface has an area, roughly (embedded length) * (screw diameter) * pi, and the strength of the load-passing interface is proportional to the area.
The weak link is the strength of the wood (in shear or compression, depending on the direction of the load). So, to make the interface stronger, you need to increase its area. This is what the Gougeon fastener potting method does. It interposes between the fastener and the wood a mass of filled epoxy which has a larger diameter and therefore a larger area.

A couple of bits and then I'll refer you the Good Book for the rest.
As they have greater area, machine screws are preferred to wood screws, and the diameter of the plug should be about twice the diameter of the machine screw. The fact that such a fastener-wood connection doesn't offer an entry point for water is a big plus.

I hope this helps.