When Genghis is launched each year I set the mast up to what feels about right and this occasionally gets adjusted if I feel that the rig is a bit slack in a blow.

I was just wondering if anyone has some figures that they use for setting up a fractional rig using one of the tension meters that are available.

I would also be interested to know how much mast-rake/bend owners induce and how much affect it really makes. My mast has a bit of bend in it but nothing like as much as I have seen on Gulf Kilo, with Scallywag and Snoopy being somwhere between the two.

Any thoughts would be most interesting?

George

Hi George
Sounded a bit like my own situation finding myself adjusting the rigging quite often during the season using trial and error but last year i found results
at the foot there are about 4 or 5 holes where the bottom of the mast can be bolted through i found a huge improvement in the performance after I set the foot of the mast reasonably aft (bolted through the second last hole aft) this throws the bottom part of the mast above the deck forward which forms the start of the curve and tensioning the lower shrouds pulls the center to lower part forward, and the top aft giving a beautiful constand curve from the deck up
when i plumbed the main halyard to the boom i think there was about 3-4 inches from that point into the mast , well it seems to work for me anyway
Paul Ryan

Mast bend depends entirely on how your sailmaker has cut your mainsail. I think there is a tendency to cut sails flatter in the last few years but sailmakers in Scotland will vary this depending on the use being made of the sail and local condions. You would only want to induce more bend to de-power the sail in a blow and on the GK you can do this quickly by applying back stay tension,
Rake on the mast will improve speed upwind but can your crew and crew weight handle the extra heel, weather helm and keep the boat flat.
My boat has the mast stepped in the 2nd back hole but I have not tried it anywhere else.
Alex.

I originally had Forethoughts rig setup very slack as that was what the previous owners had . Probably the boat had bent. I can remember hearing the spreaders slap around in a F4 beat. Ugh.

I then bought a rig tension gauge and then increased the tension. It relaxed again as the chain plates lifted, and the hull dimpled.
I could just about get a tension of 6-7 on my gauge corresponding to 10% tension on uppers and 1 on the lowers (by choice, I want to allow bend with backstay).

I have now fitted strops using old rigging wire and turnbuckles inside the hull from the plates where the under-deck struts are attached running to the bulkhead. On these I wind on the tension and it is scarily tight - I cant measure it as there is not enough wire to get the gauge onto . But above deck I have won back a more stable rigging tension of one more unit on the gauge. The deck has dropped about 4 mm and the dimple in the hull is visibly less noticeable. The bulkhead does not seem to have bent.

This is under test but so far on the two outings so far this January, there has not been enough wind to really heel the boat. Partly down to the fact that even here in the Solent, a F4 with 2 degrees C is still as unpleasant as up North, so we dont go out in a breeze in winter if we can avoid it.

I may have to increase the reinforcing of the bulkhead.

Just re-rigged and fitted new mast to "smuggler" and decided to have a "play" with the rigging to see what suited best.
(Alex may pipe in here and point out it cant have worked that well as he "cuffed" me in the winter series, but heres the notional findings so far.)

Slackened off uppers, and hoisted a tape measure on the main halyard and measured to chain plates to ensure mast was actually upright "side to side"by adjusting lower stays.Tensioned upper stays until a 3" pre bend was noted (again using main halyard to mast) and then tensioned lowers until mast was straight.This certainly improved things as originally boat pointed higher on a port tack than on a starboard but sail was very full and excessive weather helm was apparent.
Tightened uppers further whan boat was to windward and introduced 4" pre-bend into mast, as measured from main halyard to rear of mast and boatwas transformed. It still had weather helm, but not excessive but also found that forestay sag had been markedly reduced and thus Genoa was less "full".
I eventually raked the mast from between upright to 8" in 2" increments ( measured using weight hung from main halyard to coach roof) and found weather helm and pointing ability increased but managed to offset weather helm this by shifting the mast fowards on the step on the keel two holes from rear place. Settled on a 6"(ish) rake and seems to be ok with my sail.
Since I had no tension gauge available I can only describe uppers and lowers as "bowstrings" but could still do with more tension on forestay to reduce sag when in a blow and close hauled.
Great book available which led me by the hand called "Tuning yachts and small Keelboats, by Lawrie Smith; Fernhurst Books; cant really argue with his pedigree as his results seem to speak for themselves!! Best tenner I ever invested but not as sexy as a set of laminates!!

yes, we checked rig tension every time before casting off.. next gizmo was going to be rig tension sensors linked into the B&G Hydra for tack to tack consistency with runners .. instead of just my muscle power; never got that far.

If I remember any figures I'll post them.

Anthony