Mid Boom Sheeting - need help with attachment points

thats what i meant waterdog,
try to use Harkin if you can, they realy are bombproof, we went into a bad gybe when the wind backed, befiore we had the brake, and we had no preventer on, broke the strop holding the block on boom, the crash was unbelievable, but the blocks held, on out sistership, they had Lewmar, they had to replace all the cars on deck with Harkin
some nice posts here by the others
I dont want to correct posts Masa, its ok to make mistakes!! least you tried, I could see you were in a pickle

 

But I would like to learn here too? Please?

 

Take a look at my post ... I'm a retired rigger.

 

Thanks very much....

 

Well -
The tech rep from Harkin took my dimensions and got back to me with a number - 1.3 ft. No less he said.

ok...

I wrote back to ask how he arrived at that number and got no response.

I installed the rig last weekend at 18".

Had her out for a sail off the Georgia (USA) coast fully reefed in 20-25kt winds and it worked perfectly.

Time will tell... I'll post a pic when I get a chance.

 

Seems to me it depends on the role of the vang. If you're using a traveller then you probably have the vang working as a preventer rather than to apply much extra downforce to the boom. If that's the case, then you wouldn't want a mainsheet and vang all-in-one arrangement as then you'd have the vang slack when you have the mainsheet slack - the opposite of what you need. If the vang is a preventer, then the most efficient setup would be to fasten it at 45 degrees to the boom. Then fasten the mainsheet midway between the vang fastening and the end of the boom for the most even distribution. You'd only have three fastenings for the mainsheet at the boom if you were concerned about the overall strenght of the boom or the quality of the fastenings wouldn't you? Three fastenings on the boom for the mainsheet seems unnecessarily complex to me - I'd just use double blocks at the traveller and boom if it was me (actually it is me - this is what we use).

 

I love people that use vang tackles as preventers.

The very last thing you should do is to try to stop a gybe from the vang attachment point. Booms are designed for vertical loads, not horizontal loads. The vertical load at the vang attachment point is very high. Most booms will not take that load horizontally. On monos, the boom gets strapped down to the side deck, toe rail, or a stanchion base. What happens when the boat heels and the boom dips into a wave? ... the boom folds at the vang attachment point.

Proper gybe prevention starts with not sailing dead down wind. It is not comfortable or fast in most boats. If your helmsman or autopilot cannot hold a course that makes an 'accidental' gybe nearly impossible, you have too much sail up. If you insist on sailing deep angles, a gybe preventer should be rigged to the end of the boom from the bow, not to the vang point. It does not solve the boom in the water problem, but it does lower the chance of the boom getting broken if it does go into a wave. If the preventer is rigged just aft of the forestay and lead aft, it can be eased to gybe under control and then transferred to the new gybe and reset, crew has to go no father forward than the mast to make the change.

For 'accidental gybe' prone boats and drivers, a boom brake is a better choice. It allows the boom to move slowly but not slam to the new gybe. If/when the boom rolls into the water, it lets the boom swing aft without loading the boom to the failure point.

Vangs are twist control devices, they are not preventers. Gaff rigged boats use vangs to the end of the gaff to control twist. On a schooner, the foregaff vang can lead to the main mast, the maingaff vang leads to the deck at the weather corner of the boat. The foregaff vang can be self tending, the maingaff vang gets attended to when the running backstays are set up during tacks and gybes.

Sorry, but vangs being used as preventers have caused much damage to boats. If all the breaks is the boom, the boat is lucky, if the boom is strong, the other failure point is the deck attachment ... and that can be very scary.