...to the cabin top is what I'm hoping to do on my old Annapolis 26, which will facilitate the addition of a bimini. I currently have the mainsheet attached at the aft end of the boom, with blocks on either side of the cockpit--no traveler. I intend to move the blocks forward to the cabin roof, and add a bail 1/2 way along the boom. Would I give up any performance by doing this? Anything else to consider? Thanks for the help!
Moving the mainsheet...
- Thread starter Mook16714
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well
First remember, a boom made for mid-boom sheeting is usually a larger section than one made for end-boom sheeting. The stress induced in the boom is much, much higher, and if you happen to get the end of the boom in the water while headed downwind, your chances of something breaking go up immensely. You also lose leverage on the sail (imagine the boom as a wrench turning a bolt at the gooseneck), so smaller lever needs more power - you'll need to add more purchase, at least 150% what you have now, and spread it out to at least 2 or 3 plases on the boom (say, if you are 4:1, go to 6:1) unless you don't mind the sheet being sifnificantly harder to trim and a lot of stress at one point in the boom. Your call, but do it right. (Note the magnitude of the maximum stress in the attached picture: it is 3x higher for the same boom and sail with mid boom vs end boom sheeting!)
First remember, a boom made for mid-boom sheeting is usually a larger section than one made for end-boom sheeting. The stress induced in the boom is much, much higher, and if you happen to get the end of the boom in the water while headed downwind, your chances of something breaking go up immensely. You also lose leverage on the sail (imagine the boom as a wrench turning a bolt at the gooseneck), so smaller lever needs more power - you'll need to add more purchase, at least 150% what you have now, and spread it out to at least 2 or 3 plases on the boom (say, if you are 4:1, go to 6:1) unless you don't mind the sheet being sifnificantly harder to trim and a lot of stress at one point in the boom. Your call, but do it right. (Note the magnitude of the maximum stress in the attached picture: it is 3x higher for the same boom and sail with mid boom vs end boom sheeting!)
At the risk of sounding like someone
who tows his 30' boat with a yugo and has no problems, I did change to a mid boom attachment point with a traveller on my V222 last year, no problems yet, If it breaks I will get a bigger one. How does adding a boomvang affect the stress on the boom? It would seem to me that you would have even more leverage. Is there a program or formula to calculate the boom section necessary for a given sail area? Any pics of boom attachment hardware with multiple points? Tim
who tows his 30' boat with a yugo and has no problems, I did change to a mid boom attachment point with a traveller on my V222 last year, no problems yet, If it breaks I will get a bigger one. How does adding a boomvang affect the stress on the boom? It would seem to me that you would have even more leverage. Is there a program or formula to calculate the boom section necessary for a given sail area? Any pics of boom attachment hardware with multiple points? Tim
Cabin Top Strength?
Brian M is right. Also make sure the coachroof is strong enough to bear the upwards loads of the traveller. I watch my traveller 'pump' on a gybe because it is only attached at each end, the centre span being over the sliding hatch garage - and my boat was designed with mid-boom sheeting. Also I once converted a racing dinghy and the flex of the boom meant I lost control of the mainsail leach. I reverted to boom end so make sure you leave both options open.
Brian M is right. Also make sure the coachroof is strong enough to bear the upwards loads of the traveller. I watch my traveller 'pump' on a gybe because it is only attached at each end, the centre span being over the sliding hatch garage - and my boat was designed with mid-boom sheeting. Also I once converted a racing dinghy and the flex of the boom meant I lost control of the mainsail leach. I reverted to boom end so make sure you leave both options open.
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