What size rigging wire is required to support the mast of a '28' adequately? I know Andiamo was originally fitted with 5mm wire and a babystay. I have heard that in her younger cruiser racing days, she suffered a dismasting. She was then fitted with 6mm wires and the babystay was replaced with port and starboard forward lower shrouds. This, of course, required a new pair of chainplates to be fitted. At some time, the backstay was also replaced with 7mm wire which looked more appropriate to a 40 footer!

The 7mm backstay was very heavy, and considering the original (maybe a bit marginal?) spec of 5mm, well over strength. I have replaced it with 6mm wire.

The problem is that, although I have all these fine strong 6mm wires, they all terminate onto mast tangs and clevis pins sized for 5mm wire. And indeed - the swaged ends of the lower shrouds interfere with each other in the mast tang. It was necessary to grind away part of the swaged eyes to get them to fit.

I would like to keep the masthead rigging at 6mm, since the forestay must be that size for the Rotostay and it seems 'unbalanced' to have the other wires a different size. There is also a good argument for having the backstay slightly over-spec. I would like to replace the lower shrouds with 5mm, though, so that they will fit the mast tangs properly.

I'd be interested to know if the rigging other Seal 28's has evolved over the years in the same way that mine has!

Neil



Neil Sinclair
Seal 28/27
'Andiamo of Exe'

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Hello Neil
I replaced the 5mm rigging on Aztec with 6mm for the 4 upper shrouds and stays and replaced the 3 lower ones with 5mm. I did have a dismasting following this, but this was caused by excess compression stress (not by the failure of any rigging or fitting) because I had recently tightened all the rigging to keep it stiffer for racing. Also the mast had a slight twist in it which could not be removed.
I had only adjusted all the stays to 10% of their breaking strength.
I would be wary of an old original proctor mast as there can be hidden corrosion and fatigue on the inside of the mast.
In my mast it started to fail around the rivet holes fixing the chafe plates for the internal halyards.
In my view you need to restrict the deflection (curvature) of the mast. On Aztec this was alarming whilst sailing on a close reach in a force 5. It is believed it was this deflection and the added compression which caused the original failure.
I replaced the original Proctor mast with a new heavier duty Sail Spar one, about 5mm bigger all round and thicker wall. I am happy and confident in my rig now. Expensive though.
I have spent so much money on Aztec now that when I look at the prices of other 28's for sale it makes me think that Aztec is the equivalent to gold plated.


Mike Edwards
Seal 28 "Aztec"

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Many thanks for your reply, Mike. I do have an old Proctor mast, but I'm going to try and make sure it stays up - I can't afford a new one! It doesn't seem to be distorted. I haven't noticed the mast bending very much, even in winds of F6 - perhaps the 4 lowers I now have help to support it, in which case, maybe I'd be better off sticking to the 6mm wires which would stretch less than the 5mm. I use roller reefing, so I generally set the mast up with only a small (about 2-3 inches) of pre-bend so that it doesn't flatten the mainsail too much. I do try to set the bottle screws reasonably tight - although I don't have a guauge. I just go sailing and if the leeward rigging goes slack, I take some more turns on the bottlescrews until it stays taught all round.

Soon be Spring, again! Neil


Neil Sinclair
Seal 28/27
'Andiamo of Exe'

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