I believe that my 1995 Hunter 35.5 fractional rig is tuned within tolerances, with a profurl furler, but I have noticed lately that the headstay appears not to have enough tension when the genoa is furled. If I tension the backstay more, there is an excessive bend(rake) in the top of the mast. I have trensioned the shrouds at the dock and in 10+ kts of wind under sail. I can't seem to get the right amount of tension everywhere that does not produce an excessive rake. Any help appreciated.
Fractional Rig Headstay tension
- Thread starter james2034
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Using the backstay adjuster on a fractional rig can actually DECREASE your forestay tension by allowing the middle of the mast to bend FORWARD. Not sure about the rest of your rig, but aft lower shrouds can limit the forward bend. Adjustment really needs to be made to forestay length, itself. I'm not familiar enough with your boat/rig to address the entire issue.
What do you mean by excessive rake??? If you have a properly halyard tensioned mainsail, only slight so-called weather helm, etc. then your amount of rake is 'perfect'.
If your forestay tension, which COMBINES with the stiffness of the mast even when bowed is at approx 12-15% tension, then you 'should' have sufficient forestay tension to prevent the jib from 'sagging off' to leeward when beating, the aft swept side stays combine and 'take over' the function of a backstay.
Rig tension is not to gain some esoteric design parameters; rather, its a method that establishes sail SHAPE and appropriate helm pressure when sailing. Here's the way to set up a B&R: http://www.riggingandsails.com/pdf/selden-tuning.pdf .... also includes how to do WITHOUT a tension gage in a separate section of this 'guide'. DONT GUESS when it comes to rig tension as your sailmaker depends on certain expected wire tensions when designing your sails.
James, the document recommended by Rich is an excellent source for our rig adjustment and tuning, page 44 and 45 cover our type of set-up: Fractional, multi-spreader rig, swept spreaders, deck-stepped mast. You will notice that the first phrase in the guide for our set up is " Very demanding on the sailor, since it is complex to tune and to handle". The mast on a 35.5 legend is not a B&R rig as we have a Backstay and no reverse diagonals.
My boat was set up following these guides lines and Mega Dream handle very well. We reef early, 18 knots of app wind, take second reef at 22/23 knots off app wind and leave the new laminated head sail (135%) full size until 27/28 knots app. The 35.5 is fast and very rewarding when tune properly. In general backstay and forestay length will induce rake (a straight mast perpendicular to the water surface has no rake, a straight mast pointing 3 to 5 deg aft has rake) , during installation under the crane. The mast ont the 35.5 has rake. The rest of the time the backstay will induce mast bend. Mast bend can be either induced on a straight mast or a mast with rake. In normal sailing conditions, the mast has bend as well as rake. Mast bend will move the forestay attachment point slightly forward on a fractional rig but cap shroud tension and mainsail adjustment will help create forestay tension. In general the tension in this type of rig is high and there should be no slack in the leeward cap shroud while heeling at 20 deg.
Read the guide, take your time and try many adjustments in small increments.
Good luck
My boat was set up following these guides lines and Mega Dream handle very well. We reef early, 18 knots of app wind, take second reef at 22/23 knots off app wind and leave the new laminated head sail (135%) full size until 27/28 knots app. The 35.5 is fast and very rewarding when tune properly. In general backstay and forestay length will induce rake (a straight mast perpendicular to the water surface has no rake, a straight mast pointing 3 to 5 deg aft has rake) , during installation under the crane. The mast ont the 35.5 has rake. The rest of the time the backstay will induce mast bend. Mast bend can be either induced on a straight mast or a mast with rake. In normal sailing conditions, the mast has bend as well as rake. Mast bend will move the forestay attachment point slightly forward on a fractional rig but cap shroud tension and mainsail adjustment will help create forestay tension. In general the tension in this type of rig is high and there should be no slack in the leeward cap shroud while heeling at 20 deg.
Read the guide, take your time and try many adjustments in small increments.
Good luck
Mast tuning on a 35.5
James,
I knew I had another guide for mast tuning...
Last time my mast was taken down for taking my boat from Lake Champlain NY to New York city, I measured the complete mast to have the information if needed.
On a legend 35.5 the mast is 596 inches long 49.66 feet. The forestay attachment point is at 498 inches. Our mast is neither a 3/4 or a 7/8 fractional rig, in fact it is a 5/6 fractional rig! The forestay attachment point is 8.4 feet below the mast head. I am attaching this other mast tuning guide from Kemp Sails specifically for fractional rigs.
Have a good day!
James,
I knew I had another guide for mast tuning...
Last time my mast was taken down for taking my boat from Lake Champlain NY to New York city, I measured the complete mast to have the information if needed.
On a legend 35.5 the mast is 596 inches long 49.66 feet. The forestay attachment point is at 498 inches. Our mast is neither a 3/4 or a 7/8 fractional rig, in fact it is a 5/6 fractional rig! The forestay attachment point is 8.4 feet below the mast head. I am attaching this other mast tuning guide from Kemp Sails specifically for fractional rigs.
Have a good day!
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