Mast Pre-Bend

[Tony]

I'm looking for guidance on proper tension settings for the shrouds. I've found that following the NorthSails guide (28 on uppers and 24 on lowers using a Loos model A guage) I get no pre-bend. The guide further advises to increase tension in the forward lowers to induce pre-bend. I tried this without much success. I was able to get 1/2" of pre-bend with the following settings - uppers 30, forward lowers 30, aft lowers 22. Since all tuning guides I have found recommend higher tension in the upper shrouds than the lower shrouds, how do I get pre-bend without the forward lower tension exceeding the upper shroud tension, and is this a good idea? I do have a split backstay adjuster. Am I supposed to measure pre-bend with the backstay adjuster fully tensioned?

 

[Bayard Gross]

I think you shoud do this

I have a backstay adjuster on my C-22 as well.To set up the stay and shroud tension, I first start with the forestay. The forestay turbuckle is closed the whole way down. This is fine as the adjuster takes care of its tension.Then I tighten up the backstay adjuster checking the forstay tension until I measure at roughly whatever point the Loos tension guage says it should be.From here I set up the uppers, followed by the lowers which I intially set more or less the same.When you are all said and done there should be some mast bend. If there is not, then it is possible if the the shrouds and stays were ever replaced they are not the original length.The Catalina 22 National Sailing Association has a good description for setting up shroud and stay tension.

 

[Joe]

Tony, have you tried blocking or wedging

... the mast step? A small block under the tabernacle base, canting the mast forward will help bend the mast, yet keep the shrouds at recommended tension. An alternative technique is to shave the base of the mast at an angle to achieve the same effect. Either method will allow you to set mast bend using the forestay and backstay. Using the shrouds to bend the mast is called the compression method, and the amount of bend is contingent on the swept-back angle of the spreaders. I am not a Cat 22 sailor, I only offer this method as a possibility to consider..By the way, I have no idea what Bayard Gross is talking about.

 

[David]

Rig Tuning

Try the attached link from North Sails. This is how I tuned my boat, and she performs very well.David