Tuning the woodentop Firefly mast?

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ACB
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Tuning the woodentop Firefly mast?

Post by ACB » Tue Oct 28, 2008 11:32 am

Have Firefly with original Reynolds (plate actually reads "Fairey Marine"!) mast, with intact spruce upper section. Lower section has been repaired, with a new length sleeved in at some time and pop rivetted with rusty pop rivets.

The diamond shrouds are what I would once have called piano wire, but which surely must be stainless, with eyes made with ferrules over the wire. One popped out of its ferrule but quick thinking saved the mast. I bent it back and its OK in light airs but of course I cannot get any real tension on the diamonds now. What to do?

F 3163 "Aquarius",
IC K229 nameless for the time being
I14 K377 "Mercury" - long term rebuild project

Garry R

Re: Tuning the woodentop Firefly mast?

Post by Garry R » Tue Oct 28, 2008 12:12 pm

Why no tension? If you put a small stainless bottle screw on one end of each of the "piano wire" diamonds you will be able to tension them up OK. I did this on Secret Water as the old bottle screws were steel (originally galvanised) and looked as if the screw portion could pull out at any moment. I got them through one of the sites on ebay and they were pretty cheap for the small ones. Certainly more cost effective than a broken mast. I also had a piano wire break (fortunately no wooden mast damage) and replaced it courtesy of Chris who had a little spare. I would be inclined to replace the wire all over just in case. The copper ferrules are easily available. He could advise as to the wire supplier but think that Ormston wire is a possibility but may stand corrected. Hope this helps.

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Ancient Geek
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Re: Tuning the woodentop Firefly mast?

Post by Ancient Geek » Tue Oct 28, 2008 2:08 pm

The Fireflys I recall from -oh so long ago- at Schooland University did have tensioning on the diamonds butit was a slotted machine screw with a nut the nut stopped it going into the actual spreader and the slot took the 16g piano wire tighten upthe nut and push the head out and you tensioned the wire, neat, inexpensive Robert was your fathers/mothers brother!
Simples.

ACB
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Re: Tuning the woodentop Firefly mast?

Post by ACB » Tue Oct 28, 2008 6:20 pm

She does have little bottlescrews on them, and I recall that they should be tensioned to about an "A" according to the original Firefly handbook (tuning with the aid of a tuning fork!) but without a secure ferrule I fear they will not stand it.

Conversely, I fancy the lowers should be on the slack side, no?

F 3163 "Aquarius",
IC K229 nameless for the time being
I14 K377 "Mercury" - long term rebuild project

Garry R

Re: Tuning the woodentop Firefly mast?

Post by Garry R » Wed Oct 29, 2008 10:21 am

The ferrule on Secret Water (and Iska as shown) is a copper tube. The wire goes inside it, through the end of the bottle screw in a U turn, back through the ferrule which is then flattened - doesnt need to be too tight then folded back on itself. It is the bending that keeps the wire in place. Hope the attachment works and that this helps.
Attachments
chris ferrule.jpg
This was a photo sent to me a long time ago by Chris Barlow showing what I have tried to describe.
(23.11 KiB) Downloaded 252 times

Garry R

Re: Tuning the woodentop Firefly mast?

Post by Garry R » Wed Oct 29, 2008 10:28 am

Should get an appropriate ferrule here - although these are talurit fittings for what you need I reckon they will squeeze up in a vice OK - as I said it is not the grip which keeps it in place but the bend back.

http://www.tecni-cable.co.uk/Stainless- ... -Wire-Rope

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Ancient Geek
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Re: Tuning the woodentop Firefly mast?

Post by Ancient Geek » Wed Oct 29, 2008 12:19 pm

Or a bit of brass or copper tube from a model shop squeezed oval in a vice or hit carefully with a hammer! From memory warming -not heating red hot- makes the piano wire rather more melleable.
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chris
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Re: Tuning the woodentop Firefly mast?

Post by chris » Wed Oct 29, 2008 1:50 pm

I am about to order some stainless 'piano wire' and the minimum is a kilo if I remeber so will have plenty over. Someone else has asked for some too so if you need some let me know. 16 gauge is 1.6mm and 1/16" diameter but note that music wire gauges are different and Music gauge 26 is 1.6mm.

To calculate the tension from a known length, pitch diameter and density of wire use
Tension=frequency squared x length squared x diameter squared x 3.1416x density of wire

Frequency of A (which A though?) 27.5, lowest note of piano, but keep doubling it for each octave. Density of steel wire 7.85grs/cmcubed. (Stainless is slightly different but I don't have the details for this particular stainles).

Now get calculating!

Garry R

Re: Tuning the woodentop Firefly mast?

Post by Garry R » Wed Oct 29, 2008 3:13 pm

I really should replace all of mine as it is the old stuff she came with and there are no prizes for the mast breaking because of a snapped diamond. I'll get the length I need and mail you.
Doh - a deer, ray, me, soh - a needle pulling thread which reminds me I should get the cotton sails repaired!!

chris
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Re: Tuning the woodentop Firefly mast?

Post by chris » Wed Oct 29, 2008 5:53 pm

I can suplpy a set of tuning forks too!

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Ancient Geek
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Re: Tuning the woodentop Firefly mast?

Post by Ancient Geek » Wed Oct 29, 2008 11:19 pm

Joking aside, one of the dinghy size tension meters would do the job very well you might even persuade a few fellow sailors to share one! They change the rigging process beyond recognition.
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Rupert
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Re: Tuning the woodentop Firefly mast?

Post by Rupert » Sat Nov 01, 2008 10:17 pm

I think you may be getting a little ambitious on your tuning of a 50+ year old mast. I would suggest that getting the wires to an even tension would be about the best you can do - if you take into account the amount of corrosion in the mast, there is no way that a tuning guide from the 50's is going to be any more accurate than guess work.
Rupert

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