I'd like to properly tension the jumpers on my 1971 CAL-21 BEFORE I step up the mast. A sailor with a great deal of experience advised me to put the mast (sail track facing the ground) on 2 saw horses and tighten the jumpers till the sag comes out and the mast is straight. I've backed out the threaded rod 1 in. on each side of the triangular "gull catcher", but have not been able to completely get the sag out of the mast. I am fearful about continuing. The jumper struts are continuous, however the 4 ft. jumper struts above the "gull catcher " get much more taunt than the 8 ft. jumper struts below the "gull catcher" when turning out the threaded rod on each end of the "gull catcher".
I have backed out the threaded strut 1 in. of each side of the "gull catcher" and still have some sag in my mast, even though the upper section of the jumper strut is getting tight. The 4 foot jumper strut above the "gull catcher" now produces a low note when it is plucked. (Lower than the lowest note on the piano.) The lower section of the jumper strut is firm, but does not produce a note when plucked. (I don't a have a Loos gauge.) I'm concerned that if I continue to back out the threaded rod, the uppers may get too tight and damage the mast. I am beginning to think that it may not be possible to get the sag out of the mast unless I back out another inch of the the threaded rod. And then what? I know that when the backstay gets tight it will put a load on the jumpers and tighten the jumpers, which will transfer load to the forestay. Should i tighten the upper section of the jumper only till the wire is firm and just let the tension on the lower section just be whatever it is and just forget about the sag in the mast. ? What is a good procedure for tuning jumpers? How much should I tighten the jumper's upper section? The jumper's lower section?
The CAL-21 owners manual says "before stepping up the mast you should tighten the jumpers till the mast begins to bow slightly forward at the jumper's junction". I don't know if it is possible to get the upper section of the jumpers (above the gull catcher) to actually bow. I think before it bows slightly forward, I must let out enough threaded rod on the gull catcher to take the bow out of the mast. Should the upper section of the jumpers be tight and the lower section of the jumpers be snug? Should I ignore the advice of professional sailor with a great deal of experience and make sure the mast is STRAIGHT on the saw horses first, then tension the jumper struts so the upper section is tight and the lower section is snug?
I have backed out the threaded strut 1 in. of each side of the "gull catcher" and still have some sag in my mast, even though the upper section of the jumper strut is getting tight. The 4 foot jumper strut above the "gull catcher" now produces a low note when it is plucked. (Lower than the lowest note on the piano.) The lower section of the jumper strut is firm, but does not produce a note when plucked. (I don't a have a Loos gauge.) I'm concerned that if I continue to back out the threaded rod, the uppers may get too tight and damage the mast. I am beginning to think that it may not be possible to get the sag out of the mast unless I back out another inch of the the threaded rod. And then what? I know that when the backstay gets tight it will put a load on the jumpers and tighten the jumpers, which will transfer load to the forestay. Should i tighten the upper section of the jumper only till the wire is firm and just let the tension on the lower section just be whatever it is and just forget about the sag in the mast. ? What is a good procedure for tuning jumpers? How much should I tighten the jumper's upper section? The jumper's lower section?
The CAL-21 owners manual says "before stepping up the mast you should tighten the jumpers till the mast begins to bow slightly forward at the jumper's junction". I don't know if it is possible to get the upper section of the jumpers (above the gull catcher) to actually bow. I think before it bows slightly forward, I must let out enough threaded rod on the gull catcher to take the bow out of the mast. Should the upper section of the jumpers be tight and the lower section of the jumpers be snug? Should I ignore the advice of professional sailor with a great deal of experience and make sure the mast is STRAIGHT on the saw horses first, then tension the jumper struts so the upper section is tight and the lower section is snug?
