Vang questions

Moderator: GreenLake

Re: Vang questions

Postby jalmeida51 » Mon Dec 30, 2019 2:18 pm

Rob, If you don't like using the groove in the spars or if you think it might get damaged I would install a bail on the spars. Some bails are riveted and ones I prefer are through bolted. Either one will work. The bolted ones you can adjust the angle while the riveted ones are a fixed angle. I think it's ever you prefer, most small dinghy's use the fix due to the cost factor. Also bolted bails with the right diameter to fit are spars some times hard to find.

Sorry I can't answer your physics question. Didn't due well with physics in high school. John
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Re: Vang questions

Postby RobH912 » Mon Dec 30, 2019 2:56 pm

John - thanks with the thought on the through boom / mast bolted bails... having the ability to adjust the angle of the bail if I need to go that way makes a lot of sense.

It seems like the groove in the boom maybe the weak point for the vang, but didn't know. May reach out to Selden. My main sheet blocks on the boom are attached the same way.

I have ordered the Harken 29 carbo triple blocks ( p/n 347 (becket with the cam that can be switched to an up release, attached at the mast) and p/n 345 triple attached to the boom. Will also get some 1/4" sea-set line. This set up will give me 6:1 and a set of blocks & line that have a higher working load than what came with the boat. Thinking that is a good start. :)

Didn't do very well in HS physics either, but this discussion has been very informative. Really appreciate all of the posts by you and GL on this topic, spurred me on to do more research on vangs, and hope that it has become a good knowledge base asset on the this topic for the forum.

Thanks!
Rob


DS1 #2444
Cape Cod
Eastham, MA
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Re: Vang questions

Postby IslandFarmer » Mon Aug 31, 2020 12:02 pm

My DSII (1983) new to me in June 2020 has no boom-vang fittings (on either boom or mast). My brother suggested that a BV would help with strong weather helm when reaching in a stiff breeze. (He also suggested raising the CB.) I read in the PDF manual for DSIIs (excellent purchase decision) that BVs were standard on DSIIs so am wondering if I have a non-standard boom or if it just wasn't standard on mine (12250).

from the Glossary in the manual
BOOM VANG: The wire pendant attached to one of the boom vang blocks slides into a plate secured to the bottom of the boom about 3' aft of the gooseneck. The other block attaches to an eye at the base of the mast. See Fig .10 and main photo. The vangs purpose is to keep the boom steady and horizontal while sailing.


I am wondering about having fittings installed in the off-season for a boom vang.

Is this a good idea?

If so, what hardware do you recommend on the boom ... I've seen two different kinds of boom hardware -- a plate with a hole and a V-shaped strip of metal.

What about placement on the boom? About 3 feet per the above? (I've seen lots here about rigging the forward end.)

Where do I find someone to do this for me. Boat in Stonington CT; I, in Natick MA. Does D+R do this kind of work? I am only an hour from Assonet.

If I missed answers to these questions somewhere on the forum, please point me in the right direction. I was having a hard time with key word searching on this topic.
1983 DSII 12250
Stonington CT
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Re: Vang questions

Postby tomodda » Mon Aug 31, 2020 12:18 pm

Strong weather helm? Where are you (and your crew) sitting? First, most fundamental control for weather helm is balance. I'll be happy to answer your other questions when I have a bit more time, but you can search the site using google: site:forum.daysailer.org + vang. And adding a vang is a DIY project, it's quite easy.

BR,

Tom
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Re: Vang questions

Postby IslandFarmer » Mon Aug 31, 2020 12:32 pm

Tom, thanks for mention of balance. The one day when weather helm was a big problem was the day my 87 y-o mom was skippering (so she wouldn't have to move around). Strong breeze. We went out to windward on starboard tack for a several minutes and then tacked to reach back to our starting point. Unable to easily change sides she was now on the leeward side. With skipper and crew to windward, I haven't had that much of a problem but will keep the balance thing in mind and play around with the CB as well.

Will also google the forum on vang. : )
1983 DSII 12250
Stonington CT
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Re: Vang questions

Postby GreenLake » Mon Aug 31, 2020 12:35 pm

Tom is correct, adding a boom vang is a relatively simple project.

The most important thing is to not get the "stock" version of it, with it's puny 3:1 purchase. You'll want to set up something at least 12:1. Some people go as high as 20:1.

Here's my 12:1 (click to enlarge):
2663

The red line forms the 2:1 cascade and the blue line is part of the 6:1 block and tackle.

I opted for riveting a strap to the boom, but you can also use a U-bail and through-bolt that. Attaching to the mast, you can use a U-bail (mine isn't bolted through the mast, but through my mast-raising sleeve, but same difference). Alternatively you can use a strop around the mast that is held at the front by an eyestrap.

Also check out this thread: viewtopic.php?f=12&t=6343
~ green ~ lake ~ ~
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Re: Vang questions

Postby tomodda » Mon Aug 31, 2020 9:10 pm

@IslandFarmer:

Ahn, well, Rule #1 of sailing is: "Don't Argue with your Mother!" All kidding aside, glad to read that you and she shared a sailing trip, that's rare and very special. If she wants to sit on the low side, then let her, of course! And great that she's at the helm. If I may suggest for next time, make sure to counterbalance her weight (when she's on the lee side) by sitting out on the rail (far edge of the boat) on the high side (windward), maybe even leaning out a bit. If you're sailing a boat with a coaming (small wall) around the cockpit, then sit on a boat cushion on the side decks, anyway get your weight out there, keep the boat as flat as possible.

For a fuller understanding of all forces involved, read this:

viewtopic.php?f=43&t=6280

The 4th and 5th sections explain exactly what's going on with your weather helm - the center of effort (CE) from the sails is too far behind the center lateral resistance (CLR) from the hull and centerboard, making you "round up" to weather (weather helm). You do want it only a bit behind (slight weather helm is good!), but not a lot. One way of solving that is certainly to raise your centerboard, but you'd be counteracting the benefits of the CB when you most need it. Going to windward in a strong breeze, you need it all the way down to keep you from drifting to the side. A better idea would be to loose your mainsail a bit and trim (tighten) your jib, which brings your CE forward. (Note, flattening the vang with the main would also work, but is not the first, best option). Likewise shifting your weight forward will cause the CLR to go aft and the CE to go forward, counteracting lee helm... in other words, get Mom to sit as far forward as she can while steering the boat (you do have a tiller extender?) and then move yourself around to compensate for her not moving.

Now, in your specific case on the port tack - boat heeled way to far to the lee, due to Mom on the low side - you are running into another problem which is the hull's tendency to turn away from the direction it's heeled. In other words, you were making the hull sit in a way where it naturally wants to steer itself to weather, that's why you were seeing so much weather helm on the port tack only. Read here for more:

https://theewater.sailingacademy.co.za/ ... t-a-rudder

Anyway, a good 12:1 vang is a great thing to have for many reasons, and is easy to set up. But it's not your first or even 3rd line of action for countering your weather helm. That being said, the fun of sailing is exactly in learning to make you boat go in whatever conditions, including immovable Mom. Enjoy your time together - and slack off the mainsheet a bit on the port tack!

Best,

Tom
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