Cutter rigs forestays tension

[C08]

I have a cutter rig on an old cat, the inner stay I use a working jib and on the prodder/bowsprit end I use an oversize genoa mostly for light airs or off the wind. I can have the inner stay reasonably tight but the forestay is slack which for the style of sailing and ythe way I use the sail I do is not a problem. Is any way of getting both stays tight?

 

[fredrussell]

Do you have running backstays on the inner stay or is it a Solent rig? To my befuddled mind, if the forestay was opposed by backstay (assuming masthead rig), and the inner stay was opposed by running back stays (or is it check stays???) both should be nice and tight. I have a removable inner stay (Solent rig) and when you tighten one, the other looses some tension.

 

[[70521]]

The usual figure is 15-20% of the breaking figure.

Do you have a Loos or Spinlock Rig Tensioning kit?

I hire mine out with a £1,000 deposit and a couple of pints in the bar for payment.

 

[William_H]

The inner forestay should possibly have intermediate side stays to the top of the inner forestay which will provide some pull back. (ie chain plates aft of abeam the mast) This in lieu of running back stay less power but less trouble.
So the outer forestay should be tensioned by the back stay. The back stay may also provide some counter tension to the inner forestay depending on stiffness of the mast.
So you want tension in the forestay to avert curve in the forestay which then feeds in to excess camber in the jib. (desirable when hard on the wind)
I would not be concerned if outer forestay appears slack when inner is loaded up with sail and outer is redundant.
However when outer forestay has jib working you should look at the mast and see some bend middle forward exerted by the inner forestay. With both sails on then look for tension in both forestays.
Do you have an adjustable back stay if so then tension is added for stronger winds. If not then just tension it all up to feel right (no I don't go for 15% of breaking figure. The boat will not handle the tension) Do however observe the mast shape when under load. Adjust the inner shrouds to get more tension on inner forestay. ol'will

 

[geem]

A rigger friend of mine taught me about this problem last year. We spent about 2 hours setting up my rig before a West to East crossing of the pond.
You need to identify wich of the two forestays is the main stay for supporting the mast. This is usually the outer forestay on a masthead rig. This is the stay that you can set up with the backstay pressure to provide the correct tension. I was a little shocked at how much more load the rigger added to my backstay in order to get the forestay tight.
Once we had the forestay set up correctly using backstay pressure, the inner forestay which had been left slack, was now tensioned. We set it up with far less tension so as not to take load off the main outer forestay. We then used the dtneema running backstays to load up the inner forestay. The runners pulled the mast back at the head of the inner forestay to create adequate tension.
One other benefit of having more tension in the outer forestay was that the furling gear ran more smoothly. Any catenary in the forestay creates friction in the furling gear.
Hope this helps

 

[dunedin]

As GEEM says it is importantly to first ascertain what is the main structural forestay supporting the mast. In your case it may be the opposite to GEEM and possibly the inner one attached to the hull.
Sometimes the height of the attachment point for the side stays can give a clue.
In an “old cat” where the outer forestay is attached to a bobstay, it is quite likely there is a lot of flex in the structure - and even more in the bobstay. You would need to be very confident of the bobstay’s downward attachments to put a lot of tension in this.
Details of the boat type and pictures might help.

 

[C08]

I think my problem is that both stays are attached at the masthead, If the inner stay was lower down the mast then the outer stay the top one could be tightened by mast bend but this will not work with both attached at the top. There is also a babystay.
The bowsprit is 100mm x 75mm with an understay to withstand upward pull rather than bobstays to each hull which would foul anchor or swinging mooring lines.
Thabks for thoughts I think I just have to live with this.