I have recently purchased a 1988 H23, and would like to know how much bend I should have in mast. Mast is a ZSpar, with taper above forestay attachment. Mast seems to be very difficult to get very straight, seems to hav a lot of bend from middle up.
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Similar Bow here
Our 27 is normally bowed that way. Its a Z-spar thing. Ther're actually high performance masts, and you would be more likely to increase the bow to flatten the main than to decrease it. You won't see that much bend often, so it will seem very unusual. The only boat close to us that has one is a 12m class demon with a minus PHRF. So its a little strange that some of the small to mid size hunters had it, but it seems to have preceded the B&R rig.
Our 27 is normally bowed that way. Its a Z-spar thing. Ther're actually high performance masts, and you would be more likely to increase the bow to flatten the main than to decrease it. You won't see that much bend often, so it will seem very unusual. The only boat close to us that has one is a 12m class demon with a minus PHRF. So its a little strange that some of the small to mid size hunters had it, but it seems to have preceded the B&R rig.
Approx. 1"
Your mast should be plumb athwartships and have approximately one inch of "prebend" fore and aft.
Your mast should be plumb athwartships and have approximately one inch of "prebend" fore and aft.
Z-Spar mast bend
About an inch is a good place to start, with the backstay slack. The H23 rig doesn't need the backstay for support. It has a more useful function, especially with the Z-Spar mast (more on this later). Prebend (or pre-bow, because the mast is being bent in the middle like a bow) is set with the upper shrouds. As you tighten them, the mast bows forward in the middle near the spreaders. When you have the amount of pre-bend you want, tighten the lowers to prevent further bending, then tighten the uppers some more to keep the leeward shroud from going slack when sailing close hauled. As you noted, the Z-Spar mast is very flexible or "bendy". If you look at it closely you'll see that the only thing going to the masthead is the backstay. Increasing backstay tension pulls the masthead back and adds even more bend (bow) to the middle of the mast. The point where the forestay attaches to the mast barely moves, Additional mast bend flattens the middle of the mainsail and opens the leech, which are very effective in depowering the mainsail when sailing upwind in heavy air and the H23 does have a powerful main. If you're interested, there are several pictures of simple backstay adjusters in the Archives and Photo Forum that will allow you to tighten the backstay under way. There are also several articles about H23 mast tuning and sail trim in the Archives. Welcome aboard. Peter H23 "Raven"
About an inch is a good place to start, with the backstay slack. The H23 rig doesn't need the backstay for support. It has a more useful function, especially with the Z-Spar mast (more on this later). Prebend (or pre-bow, because the mast is being bent in the middle like a bow) is set with the upper shrouds. As you tighten them, the mast bows forward in the middle near the spreaders. When you have the amount of pre-bend you want, tighten the lowers to prevent further bending, then tighten the uppers some more to keep the leeward shroud from going slack when sailing close hauled. As you noted, the Z-Spar mast is very flexible or "bendy". If you look at it closely you'll see that the only thing going to the masthead is the backstay. Increasing backstay tension pulls the masthead back and adds even more bend (bow) to the middle of the mast. The point where the forestay attaches to the mast barely moves, Additional mast bend flattens the middle of the mainsail and opens the leech, which are very effective in depowering the mainsail when sailing upwind in heavy air and the H23 does have a powerful main. If you're interested, there are several pictures of simple backstay adjusters in the Archives and Photo Forum that will allow you to tighten the backstay under way. There are also several articles about H23 mast tuning and sail trim in the Archives. Welcome aboard. Peter H23 "Raven"
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