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Im looking for some awnsers with my fractional rig..
Any serious advise will be appreciated.
1st...... My furler seems to have some sag in it which I'm failing to remove. I have tightened the halyard and have pulled as much backstay on as I'm humanly able which has helped slightly.
Im thinking to perhaps tighten the forestay but I worry that I will put the rig out from the original setup.
2nd...... I have noticed the tappered section of the mast bending back every time I'm falling off a wave I think, Is this normal?
Do I need more back stay? I would suspect this is putting some huge tensions on the mast section.
3rd........ If I leave the back stay tensioned overnight does this fatigue the mast?
Hi Southace.
I think you should be looking at the cap shrouds and not the back stay to affect forestay tension
Does this rig have running backstays? Running backstays will straighten the forestay. Back stay will be just flattening the mainsail. Leaving pressure on the backstay should not be a problem, you need enough so the rig is not fatigued while sitting about on a mooring.
Leaving the backstay tensioned as far as humanly possible will not fatigue your mast but it may cause a permanent deformation in your hull if left permanently at max pressure.
Had this same problem - called a rigger and he called me a sissy and told me to pull on the back stay harder !!!
I was worried, as I had heard you could not crank on a fractional as hard as my previous masthead rig -
because the backstay tension was applied above the forestay insertion on the mast.
Now as it turns out I have a 9/10 fractional which the rigger advised me should be treated just like a Masthead.
(caveat - my mast section is rectangular and does not bend (between forestay and backstay inserts) when force applied.
Where does you forestay insert relative to the top of the mast ?
What type of section are we talking about ?
Boat type ?
The load applied to the backstay will transfer to the forestay assuming the mast does not bend between the forestay insertion(front of the mast)
and top of the mast where the backstay inserts. If it does bend excessively - you need running backstays.
If it doesn't - crack the backstay on harder.
Best not to exceed 20% of breaking strain of the backstay wire - basic rig tuning gauges will tell you this.
You'd like to assume that whoever installed the mast would have put running backstay's on the mast if it was required to gain stiff forestay tension in a blow.
Yes hulls do flex - It took many enquiries to shipwrights to explain the cracks I was finding front and back of the keel join.
I'm told it is a common problem with us round the can sailors who are constantly cranking on our backstays to get an extra 1 degree of pointing.
I have since found many and old racer with cracks between the hull and the keel at the join front 1 foot and back 1 foot.
More of a problem with the long keels of the older boats than the newer designs.
Yes it can indicate a loose keel but it can also be that the keel bolts aren't far enough forward to stop the separation of the keel from the hull when full
backstay applied.
Permanent deformation in the hull ? - Wouldnt have thought so - but I'm not a shipwright so will abstain.
I'd strap a gopro to the mast to video the movement you describe to confirm what its doing - then show it to a rigger.
Better still post it here for us to see !
Ok update I just took some pics of the rig I believe it might be 7/8th but I could be wrong. Also I can see some slots just above the forestay they seem to angle towards the stern. I did find some braided spectra lines in the lasarete locker but I assumed they where some spinker sheets but I didn't look close and threw them back in the locker.
So it seems the rig should have runners!
Before you fit them, consider that if the diagonals on swept back spreaders are relatively loose it
allows the mast to bend excessively (like a archery bow) and as such your backstay tension will be
transferred to mast bend instead of forestay tension.
By tightening the D1 and D2 you will achieve a straighter mast.
Assuming you don't change the forestay length then when you crank on the
backstay instead of bending the mast you load up the forestay.
Looks from the pictures like you have 2 D1's - one running forward and one running back.
It would only be the ones running back you'd adjust.
You may still need runners but they are a pain so would explore other options first.
You pictures look to me like you might have some spare mast bend that you could remove and see what that does to
the forestay tension.
I thought the idea of having swept back spreaders on fractional rigs was to alleviate the need for running back stays. Tension on the forestay could then be applied by adjusting the upper and lower shrouds. Adjustment of the backstay (while still assisting with partial tension to the forestay and keeping the mast where it suppose to be) was used for main sail shape.
If you do start tweaking the upper and lower shrouds (standing rigging), maybe run a string line up the mast to enable you to keep and eye on what each adjustment (tweak) is doing to the shape of the mast. It helps if there is no wind on the day you try this. And maybe log each adjustment so you can return to square one if needed.
My thoughts 
Could be wrong again 
Yes crank up your shrouds first, its going to take several goes to get it right, but once you have the mast should be a good shape, have a good pre bend with no wobbles from side to side and with the required rake for your boat. I have very tight outers, tight inners and 60cm rake.
Your forestay should be quite tight (you'll be surprised how much it sags when sailing) then you can tighten with the backstay. I use a coarse and a fine adjuster for the backstay.
Thanks for all the replys and yes I agree the rig may need a tweak after finding a rigging book onboard tonight.
It does state swept back fractional rigs are the hardest to get tuned.
I did notice on the leeward side of a tack the inners and outers where both loose .
Regards southace
Southace,
Setting up this type of rig has a lot of variables to consider eg cruising or racing, type of sails, wind conditions you intend to sail in (in race boats we adjust the rig tensions to suit the conditions). A couple of things to remember is the fore stay is there to set the mast rake, not to tighten the rig. The verticals and diagonals will give the rig tension and fore stay tension. The back stay on your boat will not make a lot of difference to your fore stay tension. The back stay is used to induce mast bend which will in flatten the main And depower the main as wind increases. Don't even consider runners on your boat with that rig and those sails, not even race boats use them with that rig. Rig tension makes a big difference if you are racing, but if you are only cruising you will hardly notice any difference. On race boats we back the rig tension off for deliveries . The very first thing you need to do when setting up the rig is to make sure that the rig is vertical from side to side and the rake is set to suit the boat on the fore stay.As for rig tension I would suggest an ideal tension would be when sailing to windward in 18 knots of true wind, the leeward verticals should be just firm (not flopping round). Looking at your sails you may have trouble sailing to windward with a full rig in 18 knots, so you may have to do it in less wind. it might sound easy, but it's not. I pay a rigger (S K Rigging in Brisbane) to check and re tension my rig every 12 months.
Ok thanks for that jode5 , now I will seek a yacht rigger in S.A . It's a cruising hull with a reasonably slick stick, Main concern is the forestay sag, mast flexing when dropping down waves , and reefing without runners. Not looking at going faster!
She is pointing at 30 degrees on both tacks Even with the sag in the foil.
