Downwind sailing with a solent stay isnt going to be a problem; however, without other radical changes the boat will now, when going upwind, point like a PIG.
Adding a 'solent stay' will adversely affect the upwind performance of any boat. There are significant structural issues also ... with respect to the BACKSTAY system. Add a solent stay and the boat will 'point' like a pig, will begin to aggressively heel over when attempting to point, and you can also develop more 'skid to leeward' when pointing. Pointing ability is affected by how close the headstay or forestay or solent stay is operating to the boats centerline.
Most sails are target designed to be flown in 15kts of windstrength with the stay that they are applied operating at 15-20% static (dockside) tension in the wire. This 15% static tension will, when the sail is fully windloaded to max. (15kts / beating), cause a very predictable sag in the wire. To compensate for this predictable sag the sailmaker
will slash away a portion of the luff to *compensate* for the expected sag of the wire - this is called 'luff hollow'.
The problem with solent stays on sloops or 'forestays' on cutter
rigs is that two 'forward' stays are reacting with only ONE backstay. If the backstay is operating at 15% then each (unloaded) forward stay will 'divide' the force and each will be operating at ~7.5% in total reaction (7.5 + 7.5% = 15% to react with the backstay.
Not a problem you say, just apply double the tension (30%) to the backstay. If you said that, go to back of the class as you are 'crossing' some very important structural/metalurgical properties of 300 series stainless - the most common materials used in rigging
: fatigue endurance limit of the material. The commonly accepted *fatigue endurance limit* of 3000 series stainless is 30,000 psi. Loads, especiallly 'cyclical' loads, over 30,000 psi cause the material to rapidly fatigue/fail. The 'rule of thumb' is 1 million load cycles above 30,000 psi will cause the material to catastrophically fail by embrittlement or fatigue failure. Keep those loads UNDER 30,000 psi and the fatigue will be minimal and you can get the number of applied loads approaching 'infinity'. So loading up the backstay tension to solve the 'unloading' of EACH forward stay to configure/adjust the correct windloaded SAG in the wire is going to cause the rig to have premature FAILURE. The problem with flying a headsail on a wire that is tensioned LESS than 15% is that the (elastic) wire will now be operating at midpoint of span .. *WELL* off to leeward ...about 18'' off of center on the typical 65ft. mast
hgt. instead of the normal approx. 7-8'' 'off-center'. This leeward and rearward SAG of the head/forestay when 'pointing' will cause the boat to aggressively heel over, the position of max. draft
in the sail will move radically 'aft', the leech section will be 'hooked up' to weather
, the amount of draft
will increase ..... the result: a boat that become increasingly tender
, heels over aggressively, cant point worth a damn, skids off to leeward, and is SLOW.
Add a 'heavier' backstay? ... still a problem as youve now added axial compression
to the mast which influences the possibility of 'buckling failure', etc.
Recut the luff hollow section of the luff, recutting so that the new luff shape matches the wire at 7.5% tension? Will work for upwind sailing; but now when going 'downwind' the headsails sail(s) will be 'draft forward', flatter, and the leeches will be 'more open' - the exact opposite of what you want in a downwind sail shape configuration.
So if you want to add a 'solent stay' (or add a forestay to the existing headstay of a cutter rigged boat) you really should have at least one of the forward stays so arranged that you can 'adjust' the amount of tension it receives ... and then go forward and 'readjust' every time you NEED to go onto a beat !!!!!!!
The reason that cutters are such poor performers when beating is this 'interplay' of variable sail loading causing 'variable' headstay/forestay tensions !!!!!!! A tight forestay (the stay just in front of the mast) will cause the headstay to unload which causes the headsail to operate waaaaaay off to leeward, etc. when beating. If you want a cutter to perform well when beating ---- you HAVE to manually unload the forestay so that 'most' of the tension 'transfers' to the headstay !!!!!!!! ... same thing with a solent stay arrangement. For a solent stay rig, to make it 'Point' you must be able to 'unload' the 'unused' stay. You can do this by terminating the 'tack' portion of the wire to ultra high tech line (dyneema) running to a reinforced deck
mounted block then back to a 'winch' or 'magic block', etc. so that you can 'vary' the loading to affect the 'proper' sag in the wire (but that loading shouldnt go much 'above' causing any the rig wire to go 'over' that 30,000 psi fatigue endurance limit ... or you risk premature rig failure.
With 2 forward stays when you add winch pressure to the sail loaded stay, the tension will 'equilibrate' to the other stay that isnt 'windloaded' .... and excessive winch pressure on the 'jib sheet' becomes an *additional* problem on the now 'loosened' windloaded stay ... causing even more draft aft, increased draft and leech hooked to weather shape.
(FWIW - all my jibs and headsails have 'luff stripes' applied so that I can 'eyeball' the amount of SAG in the luff shape that is occurring and so that I can make the proper rig tension adjustements ... so that I can make my cutter point. This is just a straight as an arrow 'run' of stitching that is applied to the sail... aboout 12'' back from the luff and runs from near the tack all the way to the head
. When I NEED to 'point', I just walk forward, eyeball to see if the 'luff stripe' is straight when viewed at 90° from the centerline and then make any adjustment (but not going above 30% rig tension) to get that 'luff shape' correct. I can outpoint most cruising type 'sloops' with a crab-crushing 'cutter'. Adding 2 forward stays adds a great amount of (unneeded????) 'complexity' and structural requirement considerations. A sloop
is a uniquely simple rig ... and all the 'wire tensions' are easy to ascertain especially to affect GOOD sail SHAPE; a solent rig (or a 'cutter rig') becomes a VERY VERY complex situation especially when there are TWO headsails flying and the windloading and Sail Areas are different and you WANT to preserve that necessary (already designed-in) luff (hollow) shape.
Ignoring the above discussion If I were to add a solent stay to a sloop I'd add the solent in front of the existing forestay, make it tension adjustable so I can control the LUFF shape and position, and thats where Id load the 'light weight' lighther wind jib
. This would allow one to keep 'normal' jib free for tacking 'through' the foretriangle .... the 'light sail' would have to be tacked through 270° in 'light winds' ... and besides in 'light wind sailing' rig tension isnt as important as when at 15kts and above. With a solent stay rig, you will also need to add running backstays
... to secondarily 'help' with tensioning the 'forestays'.
Thats my story and Im sticking to it: Solent rigs and Cutter rigs are a ROYAL PITA to sail .... if you want to 'point'. Hope this helps. :-)
So, if you want to make the boat point like a PIG, add a 'solent stay' and provide NO means to (constantly and independently) adjust at least one of those forward stays. FWIW ... if you want your rig to last, dont exceed 30% backstay tension for long periods of sailing time.
Sorry for all the run-on sentences but Im using Firefox and when uploading to this particular website all the paragraph marks are always 'erased' - sorry.