The mast on my elderly wooden Fireball has always troubled me with a bend to port when set up symmetrically with rig tension applied.  I have up to now fudged the issue by placing the starboard speed pin several holes lower than the port one, but have recently spent some time trying to diagnose and fix the issue.  I'm unsure of the mast make and model as it has no marks, but may be Superspars.
 
I have checked the following, making adjustments where necessary:
 
1.  Mast.  Is straight when not under tension.  I re-sited the heel plug as it appeared to be slightly twisted, and is now true and aligned with the track.  Sighting across the stern, everything appears to be central, as far as I can tell.
 
2.  Shrouds.  I checked their lengths by removing them from the spreader ends and drawing them tight to the track at the lower end.  They are the same length.  The shrouds are attached at the upper end by passing inside the mast and onto a bar. 
 
3.  Shroud levers.  These are old RWO type with seven holes for speed pins.  They appear to be of identical length.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4.  Spreaders.  I have adjusted these to be as symmetrical as possible, and checked they are the same length and raked at identical angles. 
 
Despite all this faffing around, I still need to place the starboard speed pin three holes lower than the port one in order to completely straighten the mast when under rig tension. 
 
Questions 
 
1.  Is this particularly strange?  I have heard it said that a truly symmetrical hull is rare, and this one has, of course, had a few decades to morph into something else.
 
2.  Can anyone suggest the best approach to resolving this?  Shortening one shroud by three holes' length is one obvious solution, but quite tricky to achieve I should think.  Given the way the shrouds are integrated into the mast, it isn't even as easy as shelling out for a completely new bit of wire, as I imagine the internal bar to which the wire is attached at its upper end has to be drilled out to fit the new one. 
 
3.  If no-one has a better solution than what in effect amounts to making the starboard shroud shorter, I am tempted to go for a completely different arrangement for adjusting rake, as I've seen an interesting one consisting of an 8:1 cascade with knots denoting the different positions - this is of course infinitely adjustable, depending on where one places the knots.  
 
 All thoughts (other than "Would you like to buy my foam sandwich boat in full race trim?") will be gratefully received!

Hi Iain,
 
I presume this is FB95 you are referring to? 
 
My only suggestion is to see if the mast gate is correctly centred although I note you have already sighted from the transom and everything appears balanced. 
 
Of course, FB95 was never built to take modern day tensions - even shroud levers weren't around in 1962 -  so the hull will flex under load.  
 
The multi-purchase shroud adjusters you refer to work very well.  A lot of the Hayling boats use them if you want to pop along to take photos, measurements etc.
 
Chris  

Chris,
 
Many thanks for your comments, and apologies for not having checked back in a couple of days - somehow I thought the forum would email me when a reply was posted.  
 
My thoughts have indeed been returning to examining the gate, as this is probably the bit that I was least confident of when checking.  I think I'll look for an opportunity to redo that part and see what I find.
 
After that, an eyeball check on boats with the string-type adjusters may well be in order - although my rapid estimate of the cost of the parts is quite chastening!
 
Kind regards,
Iain. 
 

Hi,
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Regards

After much examination of everything I could think of, I finally figured that it was indeed the mast gate that was out of true with the rest of the boat.  Installing a couple of differently-sized blocks to either side of the mast has miraculously straightened it!