Possible boom vang attachments

[GreenLake]

Here's a detail view of the mast sleeve / mast hinge that a PO added to my boat and which I have found useful in stepping a keel stepped mast.

However, it makes attaching a boom vang perhaps not straightforward.


(click to enlarge)

As you see, there isn't a fixed bottom part to the hinge, other than the circular plate. The hinge itself is not very substantial. In conjunction with the sleeve, it merely acts as a pivot while raising the mast. (The sleeve has a wooden base and a wrap-around piece of sheet metal.) After tipping the mast up, the mast slips through sleeve and deck and is supported by the mast jack on the keelson.

The vertical alignment of sleeve and mast is not fixed, it depends on the rig tension (how high I crank the mast jack) as well as on flexing of the cuddy deck.

I guess I could drill holes through the mast and make corresponding, but elongated, slots on the sleeve, so I can put a removable pin through, to which to attach a U-shape vang support. Does anybody make hardware like that?

Unlike other mast arrangements, I couldn't leave the vang bail in place during stepping the mast.

Also, what's the minimum vertical separation for an effective vang? The whole space deck to boom seems to only be about a foot?

[Peterw11]

From what I can see, this device is designed to hold the butt end of the mast while you walk the mast up to the vertical position, and then allows the mast to slide down, through the hole in the cuddy to the step on the keel.

It appears to be constructed from a simple door hinge, a T shaped reinforcement plate, a tubular section collar which holds the mast, and a block of wood which forms the backbone of the tube and to which the hinge is attached.

Is that about it?

If that's the case, couldn't you drill a hole horizontally through the wood block just above the hinge plate, install a bail the width of the block and allow that to pivot on a pin, or screws or bolts of some kind?

When the device is in it's lowered position to allow you to insert the mast, the bail would merely fold flat to provide clearance. When the mast is raised, you could attach the vang by either tying it to the bail, or better, use a shackle or snap hook of some sort.

The vang available from D&R has a cable with ball end on the boom side, and a length of 1/4" line on the mast end. All you need is a bail to attach it to.

As an alternative, you could forget the bail and simply screw a couple of eyestraps to either side of the collar where it attached to the block, (as close to the cuddy as possible to provide the best angle) run the vang's rope through the eyestraps and just tie the ends together in front of the mast.

[K.C. Walker]

That one is kind of a head scratcher. If you like that arrangement for stepping the mast maybe you could rework it to make it a little cleaner and/or sturdier so that you could attach a vang to it.

Because I happen to know that you're trying to get more speed out of your boat you definitely do want to install a vang. You will end up using it on the windward leg for leech control and mast bend. I think many of the top racers are using powerful vangs in the neighborhood of 20:1 and this includes Phill Root, Dave Karen, and Mike Gillam.

The distance from the cabin top to the band should be 2 feet and that works pretty well.

KC

[GreenLake]

It appears to be constructed from a simple door hinge, a T shaped reinforcement plate, a tubular section collar which holds the mast, and a block of wood which forms the backbone of the tube and to which the hinge is attached.

Is that about it?

Peter, that's an accurate description.

The device looks a little odd, and if I were designing one from scratch I might make some stylistic improvements, but it works like a charm, despite the fact that the hardware seems somewhat undersized, given that you stick a 25' lever in it.

[GreenLake]

I think many of the top racers are using powerful vangs in the neighborhood of 20:1 and this includes Phill Root, Dave Karen, and Mike Gillam.

The distance from the cabin top to the band should be 2 feet and that works pretty well.

That 20:1 ratio is giving me some pause. If you assume 50lbs pull as the limit for what you can pull unassisted, then 20:1 would result in nearly 1000# of pull. Even if you assume slightly less pull and figure in the effects of friction, I think you want to make sure the working load of your vang attachments are 500#

Will a 3" door hinge hold that much?

The plate to which it is screwed is in turn screwed into the deck with plywood backing. Would the deck hold that much?

Because of the angle, it would need to hold about 350# sideways (that should be no issue) and 350# up to give a total force of 500#.

The pin in the hinge is something like 3/16" of mild steel (size is a guesstimate). One set of screws would need to hold 500# in a diagonal direction, or 100-150# each. The other set is loaded differently, but there are only 2 (hence the T reinforcement I added at one point).

Peter's idea is otherwise not a bad one in terms of leaving the attachment in place permanently.

[MrPlywood]

Check this thread: http://forum.daysailer.org/forum/viewtopic.php?t=3213

and read kleanbore's reply (the 4th post). The image he linked to is not coming up now and I can't find it on the Intensity site, but he describes how he added an eyestrap to the front of the mast (in your case it would be the sleeve), then add a loop of line which becomes the attachment point for the vang. Something similar may work for you. That would place the stress on the mast and the sleeve instead of the hinge or wood block.

The rest of the thread is about an idea that I had for using a boom bail attached to a tabernacle, a variation of your pin through the mast idea.

re: your sleeve - is there a pin at the bottom which keeps the mast from sliding down until you're ready?

[GreenLake]

I remember reading that thread, now that you remind me. That solution would provide good support for the force component that is horizontal to the deck, but the component pulling up would probably tear the sleeve apart, but only because this particular sleeve is very flimsy (like a grille it has lots of slots in it and is made from thin aluminum). A sturdier sleeve might angle back slightly under pull and transmit some of the force to the mast by friction - possibly.

To your question: I found that a pin isn't needed. Until the mast is nearly vertical, the butt end of it rests on the edge of the mast partners, so it's not going anywhere.

That is true if I manually "walk" the mast upright. I also have a tripod contraption which I use when I'm by myself and don't want to overexert myself (although the sleeve is enough to allow me to single-hand). If I use the contraption, I do need a pin, because the pull will try to slide the mast forward before it can angle enough to catch the butt end on the edge of the opening.

Lowering doesn't need a pin, if fast enough - the mast may slide a foot at the last moment before it comes to rest on the mast crutch.