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Rigid Vang Angle to Boom


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Hey crew, 

Planning to order a rigid Vang for my Tayana 37. I seem to be bumping into conflicting information on what the ideal angle is for the vang to be relative to the boom. 
 

My boat was set up by the previous owner with a boom tang and a swivel at the base of the mast but they never purchased the Vang itself. When I run a line between the boom tang and the swivel I measure an angle of appx 28-30 degrees. I’m guessing the riggers that built the rig were shooting for 30 degrees. 
 

I had a reputable rigging company come out the other day and they recommended 35-45 degrees. I called Garhauer and they said shoot for as close to 37.5 degrees as possible, but you’re fine on either side of that. The first thing that comes up on google is instructions from US Spars and they say 30 degrees. 
 

Since I already have a swivel and a tang and I’m close to 30 degrees I’m leaning toward just measuring for that... but I also would like to get it optimal as possible. If I measure at 37.5 degrees, the overall length is considerably shorter and I would have to move my boom tang and out 6 new holes in the boom. 
 

Would love any input here on whether I should leave as is and make my measurements or if I should relocate the tang for optimal angle other than 30 degrees. 
 

Thanks,

Phil

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Longer is better but you run out of space, dont have to get too anal about it. The key is to have the appropriate tangs attached to your boom and mast. Its job is just to hold the boom up when there is no topper and support the weight of crew leaning on it. Unsure? go and measure a few boats on the marina.

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There are two opposing effects. One is that the farther you get from the gooseneck, the more leverage the vang has to act against the weight of the boom. The other is that the vertical component of the vang's force diminishes as the angle relative to the mast increases due to moving the upper mount down the boom. I put together a spreadsheet to calculate this a while back and Caecilian is generally correct that all else being equal, the farther towards the end of the boom you can mount the vang the better.

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Unclear why they would think 37.5 would be optimal. Perhaps for the running rigging. Use what you have on the boom at 30. As low on the mast as  possible. 

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Thanks everyone... sound I should stick with my current set up and size the boom to that, which I will do. 
 

cheers,

 

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One other point to keep in mind on this job is the stroke and force that the solid vang can handle.  Usually the off the shelf vangs have about 6-8 inches of throw depending on the size.  You should look into the open and closed length as a major factor to the location on the boom

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On 6/28/2021 at 1:06 PM, Borracho said:

Unclear why they would think 37.5 would be optimal. Perhaps for the running rigging. Use what you have on the boom at 30. As low on the mast as  possible. 

everyone knows 42 is the answer

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On 6/27/2021 at 11:00 PM, panema said:

Hey crew, 

Planning to order a rigid Vang for my Tayana 37. I seem to be bumping into conflicting information on what the ideal angle is for the vang to be relative to the boom. 
 

My boat was set up by the previous owner with a boom tang and a swivel at the base of the mast but they never purchased the Vang itself. When I run a line between the boom tang and the swivel I measure an angle of appx 28-30 degrees. I’m guessing the riggers that built the rig were shooting for 30 degrees. 
 

I had a reputable rigging company come out the other day and they recommended 35-45 degrees. I called Garhauer and they said shoot for as close to 37.5 degrees as possible, but you’re fine on either side of that. The first thing that comes up on google is instructions from US Spars and they say 30 degrees. 
 

Since I already have a swivel and a tang and I’m close to 30 degrees I’m leaning toward just measuring for that... but I also would like to get it optimal as possible. If I measure at 37.5 degrees, the overall length is considerably shorter and I would have to move my boom tang and out 6 new holes in the boom. 
 

Would love any input here on whether I should leave as is and make my measurements or if I should relocate the tang for optimal angle other than 30 degrees. 
 

Thanks,

Phil

The distance ... gooseneck to vang is critical , 

short distance , overloaded vang 

 

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On 6/27/2021 at 7:59 PM, IStream said:

. I put together a spreadsheet to calculate this a while back and Caecilian is generally correct that all else being equal, the farther towards the end of the boom you can mount the vang the better.

You are talking about the end of the boom that's away from the mast, right?   So, the farther from the mast you can attach the vang, the better?  Just checking.

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1 hour ago, SVArcturus said:

You are talking about the end of the boom that's away from the mast, right?   So, the farther from the mast you can attach the vang, the better?  Just checking.

That's correct. You want the mast mounting point as low as possible and the boom mounting point as far aft as possible, while still allowing enough vang spring compression to hold the weight of the boom plus dropped sail horizontally or at whatever angle you need. 

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On my moody 376.  Aft side of mast to vang connection on boom is 58”

centerline of gooseneck to vang attachment on mast is 40”

My p is 41.3  e 14.1  main sqft is 292    Which won’t mean much since you oit weight me and have more sail Area and linger boom and taller mast   

 

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4 hours ago, IStream said:

That's correct. You want the mast mounting point as low as possible and the boom mounting point as far aft as possible, while still allowing enough vang spring compression to hold the weight of the boom plus dropped sail horizontally or at whatever angle you need. 

At some point, does the increased load on the gooseneck (for the same amount of down force on the boom) become a concern?

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2 hours ago, SVArcturus said:

At some point, does the increased load on the gooseneck (for the same amount of down force on the boom) become a concern?

Well the vang's force component upwards partially offsets the downward force on the gooseneck due to gravity, so it makes things easier on the gooseneck. However, the horizontal component of the vang's force towards the aft end of the boom does increase that aspect of gooseneck load. 

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I've heard that the horizontal forces from the rigid vangs increase wear on the gooseneck... I think I'm beginning to see that on my boat with rigid vang, soft alu gooseneck and a stainless pin. 

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