Mast positioning

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trebor
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Mast positioning

Post by trebor » Tue Apr 04, 2017 6:01 pm

What is the mathematical formula for deciding a mast's position ?
I am looking at converting an Express dinghy into a single hander, Una-Bermudan, so mast will need moving forward ?
Robert
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JimC
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Re: Mast positioning

Post by JimC » Tue Apr 04, 2017 9:18 pm

Its not nearly as critical as people seem to think. Most dinghies are sharing the side load between both foils, so moving the rig around changes the balance. So any crude method is probably good enough. Making a drawing of the sails, calculating the geometric centre of both, and then moving the mast enough so the centre stays in the same place is plenty good enough.

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trebor
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Re: Mast positioning

Post by trebor » Tue Apr 04, 2017 9:27 pm

I had thought about using Laser setup, plenty of abandoned rigs.
Planned on using wooden foredeck to drop mast through and manufacture a base for it that sits on top of spinnaker chute.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

Rupert
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Re: Mast positioning

Post by Rupert » Wed Apr 05, 2017 8:41 am

Mast pressures allowing (more than you'd think) it could work, but why not just sail a Laser? The Express was never the best design out there, and I can't imagine bunging the worst bit of a Laser (which has an amazing hull design) on it will improve it.

Now, putting an old bigger rig on it and throwing a trapeze on it, you'd have something slightly different!
Rupert

Alan P.
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Re: Mast positioning

Post by Alan P. » Wed Apr 05, 2017 5:18 pm

A Contender rig then Rupert?. Could not agree more about the Laser rig. Ghastly!. The pressures on the bottom mast bearing on an unstayed set up can be quite something.
OK 1211 Peter Crew wood 1968
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trebor
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Re: Mast positioning

Post by trebor » Wed Apr 05, 2017 6:33 pm

we have a few rigs to choose from, theirs a decent Cherub set up from the one I have been trying to get rid of before someone takes matches to it, must be at least 20 abandoned rigs.
Robert
Minisprint 4230
Tinker Traveller 160
Mirror 61147 Anastasia
http://www.aquabatdinghy.co.uk

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