Boom Vang sizing

[Keith]

Gentleman,

I'd like to install a vang on my CP19 but am not sure what size components to use.  What kind of loads are we talking?  Would Ronston series 40 blocks be suitable?

Thanks ahead,

Keith

[wes]

Keith - after considerable research I bought the Ronstan pre-made vang model RK10-430 for my 19. It's 4:1, 5/16" line, with Ronstan series 45 blocks. At about $250 from Defender (their part # 602530) it's not cheap, but if you build your own with snap shackles on both ends you will likely spend that much anyway. Plus it comes with a beautiful splice, and splicing is not one of my skills. I've been sailing with it for almost a year with great success. On a downwind run I will pop the snap shackle off the mast, snap it onto a lifeline stanchion, and presto chango I have a preventer rigged in a jiffy. Snap shackles are my new favorite thing.

Wes

[brackish]

All the Blocks on my 23 including the main sheet set are Ronstan Series 40 from the factory, so I would assume they would work for your 19.  I built my Vang from Lewmar 50 Syncro Blocks because they were priced right at the time.  Used 1/4" double braid added snap shackles because I though I would be taking the vang off regularly, but I never do.  I did my own eyesplice because I wanted to learn how. You might look at the Garhaurer Marine made up Vangs, some 4:1 with 5/16" line and 1000 lbs working load about a hundred bucks and I think they are having a July sale.  No snap shackles on them, But I bet they could add them for not all that much. 

The Vang doesn't see the loads the sheet block set does, just there to hold the boom down so the sail shape is correct.  Mine pictured below, Think I've got about $115 in it including the two bails and the roller shackle

[Salty19]

Parts I used on this post..works fine.

http://cpyoa.geekworkshosting.com/forum/index.php?topic=3737.0

[Keith]

Thanks for the info guys.  I'm hoping to scrape together most of the hardware (blocks especially) from the used parts market.

One other question.  I see some rig their vang with the cam cleat and control line at the boom and some at the base of the mast.  Any thoughts on why?  Is there a right or wrong or is it just personal preference?

Cheers,

Keith

[Shawn]

Keith,

In my case I did it on the boom as cleating it is easier. I have a solar panel on my hatch which would have interfered with the cleating at the mast. If the cleating is on the boom in a way that you can pull the line down toward the bottom of the mast you gain additional mechanical advantage too.

Shawn

[wes]

I put the cleat end on the bottom, because I find it's easier to unsnap, pull out some additional line, and clip to a stanchion base when I want to use it as a preventer. I do that a lot, because it eliminates worrying about an accidental jibe. It's totally a matter of personal preference though?

Wes

[MacGyver]

Guys, wonderful stuff here....... I have actually been told by several to do this on our 19, and was wondering, what is the gains to having one? and what the heck is a preventer Wes? after hooking on a stancion post?

Mac

[Shawn]

Mac,

In stronger winds the vang lets you pull down on the boom to help flatten the sail to depower it. This gives more control in stronger wind conditions. Trying to do the same thing with the main sheet results in pulling in the sail instead of just pulling down the boom.

When running with the wind you can get in situations where the boat will start rocking side to side. When this occurs the boom tends to move up/down with the motion and helps to continue it as well as constantly changing the sail shape which slows you down. The vang will prevent this motion on the boom which makes the sail more efficient and helps to avoid some of the rocking of the boat itself. A vang isn't essential but it is a nice sail trim tool.

A preventer is to prevent an accidental gybe. Literally you are holding the boom over to one side to prevent a gybe. Downside is the boom is locked over to one side and if you get a big wind shift you have little control over the mainsail until the preventer is released or something breaks. Likewise if you have to make an emergency course change the preventer restricts your ability until it is released.

Shawn

[wes]

Mac - in general I agree with Shawn, but would add a couple of comments.

In my experience, the boom on a 19 has a tendency to lift on most points of sail other than close-hauled (it can't lift when close-hauled because the main sheet pulls it down). When it lifts, it is difficult to get good sail shape, which you can confirm by watching your tell-tales; you'll probably see that you can't get the top, center and bottom ones to flutter equally. The vang gives you the tool to control boom lift and achieve best sail shape regardless of wind strength. The effect is most noticeable with stronger winds though.

On a downwind run when your sails are acting pretty much as big barn doors rather than as airfoils, you want to get that boom as far out as possible, without letting the sail press against the shrouds or spreaders. When you are in that condition, the main sheet is run way out and has almost no downward pull, so the vang is especially helpful in keeping the sail flat. But now you are exposed to the risk of an accidental jibe. If the wind shifts (or you don't pay attention at the tiller), the boom can come flying around to the other side and cause damage to you or the boat. So shifting the vang attachment point from the bottom of the mast to a stanchion base allows the vang to work both as a vang and as a preventer, "preventing" the boom from swinging back around. Essentially the boom is held in the desired position by the offsetting forces of the main sheet pulling aft and the vang/preventer pulling forward. You wouldn't bother with this for a brief spell of downwind sailing but for a long run it's invaluable.

Wes

[Salty19]

Well said gentlemen.

I setup the vang with the cleat at the top (on the boom end). Seems easier to me to haul it down and release. Compared to the pic brackish posted, it's angled about 45 degrees further aft.  But others find the cleat works best at the mast base, so try it both ways to see what you like best.   
Only things I would suggest to definitely use is the swiveling mast base hardware and a good splice. Keeps the shape consistent across the arc of the boom. I thank Brackish for pointing this out to me before investing in hardware.

[wes]

Absolutely agree with that. The Boomkicker R064-095 rolling bail kit ($26 from Defender, their part #614696) was a perfect fit for my 19 mast. Pretty sure this idea came from Brackish or Salty, both of whom have been the source of many great ideas that I have shamelessly stolen.

Wes

[Keith]

Thanks guys, just acquired a used vang with Ronstan 40s off that online auction site.  Will order balance of parts and install soon.

Cheers

[MacGyver]

Thanks everyone for answering my questions as well, It makes more sense now, and will certainly be a project for the future when money is a little better.
We went sailing today, and both my wife and I almost instantly said at the same time, "We need a boom vang" as I pulled on the boom downward to see what the effect was as we sailed in probably the strongest winds / gusts we have ventured out in.

Although my test wasnt very accurate, and shortly after a few more gust I called it quits ( I am still working on my fears....) we went back in talking about the boom vang uses.     And the whole preventer idea was also prevalent as we had a fast gybe right over our heads as my wife at the helm decided to turn while I wasnt paying attention............ That may have also helped to cause me to call it quits for the day... LOL

What is this auction site? I am looking for sites to buy from for parts as it seems my discount at marina has proved to be beaten by defender on numerous occasions.......

Mac

[skip1930]

I purchased one at the All Sail Boat Show in Navy Pier, Chicago years ago.

Cost $70 or $90 [can't read the hand writting from the Garhauer invoice] I think the number reads [1] H25Vang S8S1Vb.
Anyway, the smallest boom bail I could purchase was too long I cut off the two ends as I steel riveted the bail to the boom and tapped it to hug the shape of the boom in the bench vise. The tack for the vang is simply a cleat designed to fit into the sail slot of the mast at the deck level.

I did make a error and should have moved the boom bail a little more aft on the boom, say just about equal to the aft end of the closed sliding companionway hatch.

skip.