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Eye straps for boom attachments?


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I’m working on an internal 8:1 outhaul for a pretty small boat/boom/main (a little over 120 sq. ft.)

The boat is end boom sheeted with an 8:1 vang. The owner has a pair of forged (not stamped) eye straps for both main attachment and vang. They both have curved to match profile #10 (~1”) fender washers and nylocks on the inside of the boom everything looks well insulated. The boom hasn’t seen much use so these attachments are still untested. Boom is pretty much round in this area with an estimated 3/32 wall thickness in this area.

In the opinion of the SA engineers is this sufficient? Normally I would suggest traditional bails but I don’t want to fix what isn’t broke. 

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hard to tell just from the description, but vangs generate a lot of load so if you’re worried the easy hack is to loop a spectra strop right around the boom and the through the strap and attach the vang blocks to the strop. then your straps are just locating the strop along the boom,  taking very little of the load. the strop spreads the load over the entire boom instead of point loading at the strop fasteners. And if you feel uncomfortable building your own strops you can buy ready made ones in a variety of lengths dirt cheap at any outdoor/climbing shop.

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s-l300.jpg.236be41dc3413facfa49081d390b06d3.jpg

The keel boat I sail on has about a 100sq foot main, and the picture illustrates the  fitting used on the boom for the vang   just riveted in place.. The alternative being a loop eye for a shackled on connection.

The fleet has raced in 40+ mph of wind without problems with that fitting.....

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How many #10 fasteners? Two for each eyestrap? A #10 could shear at as low as about 250 lbs, so two is 500 breaking strength. Probably enough for a 120 sq ft sail without being overkill. 

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i use a standard bail through bolted on the boom on a 120 sqft main for my 8:1 cascade vang..  I have another bail bolted to the tabernacle and then use a climbing ring to attach the cascades to...   strong as an ox, no problems, have used it in 30+   i have my  8:1 internal cascade outhaul,  exit the boom down to another climbing ring on the same bail on the tabernacle ,  vang and outhaul both route back to the cockpit via a deck organizer..

 

553727_1500.jpg

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On 4/29/2021 at 12:13 PM, DDW said:

How many #10 fasteners? Two for each eyestrap? A #10 could shear at as low as about 250 lbs, so two is 500 breaking strength. Probably enough for a 120 sq ft sail without being overkill. 

Correct. My concern on the main sheet side is side loading the eyestrap during a hard gybe. Boom is long gone so I guess time will tell...

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