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SkiprJohn · 08-06-2006, 18:18

Aloha all,

I'm building a new boom and have a tang fitting to attach to the underside of it for a vang. How far from the mast should this tang be? Boom is 18' total from mast and from the base of the mast to the bottom of the gooseneck is about 3.5 feet.

Any thoughts?

Regards, --John--

delmarrey · 08-06-2006, 20:23

30 degrees is the recommended angle. And the lower vang attachment on the mast should be around 80 mm from the deck.

............................................_/)

08-06-2006, 20:26

When I purchased my vang from Garhauer they recommended 45%.

SkiprJohn · 08-06-2006, 20:38

Aloha Delmarry,
Thanks for your input. Was that 30 degrees angle on the boom to mast base or 30 degrees from mast base to boom?
Regards, --John--

delmarrey · 08-06-2006, 22:15

30 degrees from the boom. Go here, it'll give you a lot more info

http://usspars.com/productmainfiles/vanginstall.pdf

SkiprJohn · 09-06-2006, 10:46

Kai Nui and Delmarrey,
Thanks for the information. Is the Garhauer one of those hard vangs?
Regards, --JohnL--

09-06-2006, 17:11

I believe Garhauer makes a rigid vang too, but the one I have is just line. I prefer the simplicity.

SkiprJohn · 10-06-2006, 10:55

Aloha Kai,
That's what I'm going for. The simpler the better. I also like the idea of a spring loaded starter which you mentioned in another post. I can't find one for my engine otherwise I'd have one.
Regards, --JohnL--

**Alan Wheeler** · 10-06-2006, 14:44

I made my own Rigid vang. Dead simple and cheap to do. But then, rigid vangs are not easy nto get here in NZ. At the time I made mine, only two years ago, no one stocked them at all and they were really expensive. I have since see a few around some suppliers, but they are still very expensive.
For me, the big reason of the rigid vang was getting rid of the topping lift.

**Jeff H** · 10-06-2006, 14:48

30/60 degrees is way too flat an angle and will put the gooseneck in tremendous compression, which unless the boat was designed for it, can also dimple the mast. A flatter angle was used on some older style race boats where the booms were pretty close to the deck, but the spars and hardware were designed for the loads involved.

45 degrees is a more normal angle for a vang.

Jeff

delmarrey · 10-06-2006, 20:37

I guess you would either have a real short boom with a short vang or a lot of space between the boom and cabin sole.

The other objective it at 30º the lines would have to strech more to get the same lift as at a 45º. So, you surely would have to have a stronger line and I think that would put just as much stress on the neck attachment and maybe even more shock.

Mine is at 26º and I don't see any stress on the neck attachment.

The advantage of rigid/hydraulic vangs is one doesn't get that back-lash effect while rolling over a wave before the wind (mainsail puffing).

But every boat is different, just like people! What works for one may not work for another. One reason the marine supply co's do so well, if they're organized..........................._/)

**Jeff H** · 10-06-2006, 21:23

When you talk about the compression loads on the gooseneck and mast generated by the vang, it is a simple trig. problem that comes from the geometry of the vang. If the vang is at 30 degrees between the vang and the boom, the compression towards the mast would be roughly 173% times the vertical load. Where as at 45 degrees the compression towards the mast would be essentially equal to the vertical load.

Boats like Trix were designed with comparatively flat vang angles and their masts were reiniforced for these high loads when power reaching but were at risk when running where could easily bring down their rigs if they dipped thier booms during a broach.

Jeff

SkiprJohn · 11-06-2006, 13:45

Hey Guys!!
If I do 45 degrees my vang tang will only be about 3.5 feet back from the gooseneck. Dang!
Anyway thanks for all the information.
Regards, --John--