Mast Track

[tonyE]

Happy new year all!

Just wondered if anyone has some pearls of wisdom for re-doing the pop rivets on the mast track of needlespar masts.
The bottom 1/4 of the track has some play an I want to sort it before it becomes an issue. I had a go at a couple of rivets but
found it a bit of a nightmare – not wanting to damage the track with a rivet gun etc!

cheers

Tony

[bob193]

going back a long time but when i sailed moths had the same problem and found it easier to gently pry the track open use a standard rivet gun on it and then clse the track back up with a pair of pipe grips or mole grips, gradually and gently hope that helps

[Bill B]

Hi,

It was always a regular thing to replace rivets that came loose because of the shearing action on them as the mast bends. I had a rivet gun where I ground the “nozzle” so it would go in the track and then made up the last bit of reach by putting a small nut, or a bit of tube, on the stem of the rivet first before using the riveter. There used to be tips for rivet guns made which were a bit longer and small enough to go in the track but only mast makers would bother to buy these.

Bill

[davecooper]

@Bill B wrote:

came loose because of the shearing action on them as the mast bends

Bill, is that why tracks quite often have regular saw cuts across them? I imagined it was a (probably pointless!) effort to increase the mast bend, but it would be much better as a measure to protect the rivets by reducing the load on them.
Dave

[Bill B]

Cutting the track does reduce the shearing action a bit. The main objective was to soften the bend fore and aft. It did actually make quite a difference. In the period when Needlespars became the norm after the wood era, sailmakers were not making sails to fit masts very well (with wood rigs you bought a good sail from someone and made your mast fit it).
If you got a sail for a Needlespar, the luff curve was not alway bang on for your mast so you did a bit of fine tuning and the only option you had was cutting the track (which could be replaced). In the late 70’s and 80’s, we got used to measuring the bend and the sailmakers like Musto and then Ullman would make to a curve – in theory.
The track makes a lot of difference – John Hulmes made a wooden mast and fastened a Needlespar track on it. It was impossibly bendy f/a until he put the track on.

Bill

[davecooper]

Well, well! I was thinking that the track is so light in proportion to the mast section that it wouldn’t affect the mast bend much, but I guess the other way of looking at it is that it does extend the section fore and aft quite a bit. Thank you, Bill!
Dave

[Richard]

When I had to re-do some of the rivets in my mast a few years ago, rather than damaging the profile of the track to fit the rivet gun in, I put a bush over rivet pin to basically extend the length of end part of the rivet gun where the pin goes in. I was using a modern rivet gun and don’t have a lathe, so didn’t have the same option as Bill to machine it to a profile that fits inside the track.
Richard

[tonyE]

Thanks for the replies people,

I ll see what works best, although I’m not sure I fancy opening the track up!

Tony

[bradjohanson]

I am looking to change the mast track on my tune up boats mast.
It is a Needlespar with a damaged track.
I plan on glueing on the same plastic track the C-Tech carbon masts use.
Any one tried that? What adhesive did you use?
Thanks
Brad Johanson
US OK Dinghy Association
OKs USA-1010 and CAN-500

[Bill B]

I understand that the adhesive to use on the plastic track to put it on a CTech carbon mast is one of the Sikaflex p-u types with the appropriate prep and primer- (like a mastic out of a gun with a surface primer). The mast people should be able to advise you. This may not be so good on to Aluminium. Sikaflex do types for Aluminium but they may not suit the plastic.

I have used two part acrylic glues successfully on Aluminium but I would have to test them on the type of plastic you have. Over here, I would get hold of a rep from one of the major adhesive groups and ask them – Ciba-Geigy, Sikaflex, Permabond, Loctite. You can ususally get samples off them to try.

You may well find that the fore and aft bend curve will change if you put on a plastic track instead of the aluminium one.

Bill

[X]

Brad,
I would be very cautious about gluing a plastic track on a metal mast. The track is a very significant component of the FA bend, you will find the mast will end up significantly softer than it is with a metal track rivetted on.

Cheers
Terry

[davecooper]

Hi Brad!
I’m right with Terry on this: From what I’ve learnt on this thread so far it sounds like any aluminium mast is going to be much too bendy with a plastic track. What’s up with the current track? If it only has a short piece of damage, can you cut out the damaged bit and move the rest of the track up? Moving the throat up shouldn’t make much difference (will it, anyone?) and best of all it’ll only cost you a handful of pop rivets, instead of having to buy plastic track and a gunfull of high tech gloop to stick it on with.
Dave

[bradjohanson]

Bill,
Terry and Dave,
Thanks for your insight and concern.
The mast had multiple cuts in it every few feet to limber it up The cuts now interfer with raising and lowering the sail. This is my number three mast on a guest boat so I am not too worried about the bend.
I am just trying to get enough parts to get some more boats going.
I will do a before and after bend test and see what the deltas are.
Thanks
Brad

[davecooper]

Well, if you can’t get the sail up, you’re hardly going to ruin the mast by taking the track off !
Dave

[Greg]

Tony
A long time ago I made an alloy L shaped bit with a hole in it for the rivets as a spacer. It is L shaped so you can get it in and out of the track. It worked very well and all I did to the rivet gun was file the sides of the end down a bit so that also went into the track. it made it very easy to re-rivet the track on. The more rivets you use the stiffer the mast will be. If you need to add a few so the bits of track don’t swing around just do it as it makes it easier to hoist the sail if they are all attached properly. Use 1/8 monel rivets.
have fun and if you can’t figure it out I still have the spacer somewhere so I could send it to you.
cheers
Greg

[Author]

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