Loosefoot main and vang

[dasein668]

Do the Ariel/Commanders share the same extrusion with the Tritons? I know Tim wrote that he had watched his boom bend. I just figured that the Tritons weigh more and have more sail area leading to more stress.

I don't know about that. If the boom pictured in the shot with the strop is a standard Ariel/Commander boom, then no, they aren't the same extrusion.

As far as breaking his boom... no, I don't think it would break. But it wasn't transfering the shaping force of the vang very efficiently to the sail either!

[ebb]

Sure looks like these boomend fittings are due for replacement. Who was it here that was going to look into this?

From my perspective (searching for the ultimate Ariel boom, if that IS what I'm doing) certainly the family here has opened a Pandora's Boom of problems. Real and Imaginary. I am just plain inexperienced with aluminum spars. Need this discussion to help sort it out. Our old spars seem to be beefier tho than that photo of sheet metal (a Catalina boom?) Tony's sailmaker sent him to illustrate the strop set up.

That group of (4?) outhaul and reefing sheaves on that Catalina boom looks like just the ticket to reduce gear, BUT I don't think that much could be put into the end of the A/C boom. Never say never, if something like that exists in an aluminum casting, it'ld be easy enuf to shape to fit an Ariel boom. Wouldn't it? But, of course, that fitting is all stainless.

I'm suspicious of old aluminum castings. There are plenty examples of substantial wear, pitting and crystalizing around. Maybe it is time to design, or have designed, new modern fittings. It can't be any more difficult to have aluminum castings made than bronze. Naturally, I want my new set done with Almag 5, which will never corrode. I just recall that the idea was to have new fittings machined from billets. Anybody want to bite the billet on this?


And while fantasizing here about this loosefoot boom (it isn't brunettes any

more) why not reverse the boom, putting the groove on the bottom side and

weld in a truss. The stiffner would be widest at

the vang attachment and toward the middle, graduating to zero at the

ends. The vang could attach to the new flange. Not much weight, and a

lot less bendy. Any thoughts??

[Tony G]

Now that's down right scary, Ebb. I've thought the same thing about flipping the boom (not only the flippin boom). I'm not so sure you'd have to add a truss because the bolt rope channel would add alot of resistance to the (then) upward flexion.

Yes a piece milled down from billet stock is a better choice than cast. But look at how well these 'old tech.' castings have held up so far. I'm all ears/eyes for a repacement boom end that has sheaves for the outhaul and a tang(?) for the main sheet AND slips right into our extrusion. Yah-right.

I can get access to a CNC but I don't even know how to turn it on. What we need is someone that can write the 'plans' for the piece we want in format that I can bring to my buddy. He'll know what to do with the rest. We need that and time. This guy makes the machines that build machines and he's pretty busy. Meanwhile I'll keep surfing for the slide-in upgrade that may exist somewhere on the web. Tony G

[ebb]

Interested in new generation end fittings. Repeat for emphasis.

It is still a bendy boom groove up or groove down. The only way to stiffen the boom is to add something to the girth. IE the middle. You have to make a sort of bridge girder, if you will. We have seen modern (ugly ) booms with fatter mid sections.....what helps to keep them from bending.

But, not being an engineer, why couldn't a long triangle of gusset material be added in the groove on TOP? Opposing the bending pull of the vang. And not have to redesign the end stuff an upside down boom would require! In fact THAT is the answer to the bending problem and keeping the old boom! The material would be 1/4" plate that likely would not have to go clear to the ends. Maybe like two thirds or even less of the boom length.

.........Just took a look at the boom.
How much of a gusset would it take to really stiffen the boom? It'ld be a long narrow triangle with an apex of 3" at the vang? Would that be enough?

How long would it need to be? A plate with a section like a sail slug could be slid down the groove if the front fitting was taken off. It would have to be machined very well to be able to fit snug in the groove and still move into position. A couple machine screws would hold it in place. 1/4" plate with a square or round welded on a long side and machined. If it fit well, it would keep the boom straight, and be removable. Might work! Wonder if there is some fantastic plastic material?

Might then be able to get the bottom of the sail to respond to the vang.

[Bill]

As I recall, not only did Zoltan managed to make it to Greece with his original (40 year old) boom, but the boat has been bought and sold a couple of times since still with the original spars. To me, that argues for using similar cross sections and hardware when making replacements.

Lickety Split, for example, had a replacement boom that would probably meet Ebb's requirements for stiffness. Rectangular in shape, it looked like a bridge structural member. Very, very stiff. It was originally from a 1970's high tech yacht design that has since disappeared from the sailing scene. Ask Joe Antos about it. He finally removed the boom and replaced it with something closer to original. (see member profile for address)

[Theis]

In my experience, the gooseneck gives/breaks first. This disaster involved my loose footed mainsail, the sliding tracked gooseneck with a downhaul and a preventer claw on the boom positioned perhaps five feet aft of the gooseneck. The claw I am talking about is the old yellow moveable horseshoe-like device with the two plastic pads that contact the upper side of the boom.

When we went into a flying jibe in heavy weather a couple years ago, fortunately the gooseneck gave way, not the boom.

As for the downhaul, I use a 2:1 purchase, the line being tied to the block on the cabin top, going up through a block at the bottom of the gooseneck, back through the block on the cabin top and up to a cleat on the mast.

As for the outhaul, I have a 6:1 purchase (loose footed mainsail). There is a slider in the mast track that holds the clew down to the boom. The outhaul only pulls the clew out. The line from the outhaul runs around a cheekblock on the boom, into the boom interior and continues forward to come out at the forward end of the boom where there is a cleat. (all my lines, halyards, reefing, etc. are at the mast and forward end of the boom - centrally located.)

The problem with the 6:1 is that there is not enough room between the boom end and the outhaul so that the lines and blocks rub against one another and won't release or pull readily, even when there is no wind. They bind. I am thinking of either getting a smaller line (I think now it is 1/4 inch) and/or going to a 3:1 or 4:1 outhaul so it releases easier.

I have had no trouble with or evidence of the boom bending, but I have been very cognizant of that possibility so it isn't like it would have gone unnoticed.

I would have some concern, however, about moving the main sheet connection forward from the end of the boom.

[Tony G]

Doh! There's another one of those 'inside' guys! I'm turning green with envy for that clean boom look. Maybe I'm complicating things in my mind too much. I've just gotta cut a couple of holes in the boom and call it good.

Or else...if we are indeed running with the Pearson D section spar for our boom, as alluded to in another thread here, then we have a nearly identical extrusion to the Dwyer DM-375. In which case one daring Ariel/Commander owner could try ordering, say, the DH 6100 Internal System Outhaul end piece and, maybe, the DH 3100-1 Internal System Gooseneck and use them on, whataya say, a 'stroppy' loose footed main sail. Of course the main sheet tang (is that what it's called) would probably have to be changed to a 'bail' type attachment. Being that far aft on the boom it could easily be secured through the extrusion wall, through the mounting flanges of the DH 6100 and backed with a compression tube. Just off the top of my head this is.

http://www.dwyermast.com/items.asp?c...=DM%2D375+Boom

With my hopfully sometime soon before X-mas goose neck I'd have to throw about half of the DH 3100-1 away.
I'd have to be dared.
Maybe even...double dog dared.

Just found te same thing at Rig-Rite
http://www.rigrite.com/Spars/Kenyon_...html#D-Section Internal Outhaul Assembly and Parts

[ebb]

Thanks to all for the vang input,
I'm at this moment getting the required templates together, etc. for the Garhauer order. Including a request that the control line goes to the cockpit.

My original soft vang attached to a bail on the boom about 39" out from the pin on the goosneck.

Would somebody know if this is the correct measure for a rigid vang. Same place? Correct in the sense that you haven't had any problems with it. How does one know where to put a vang in the first place? Is there a formula?


Maybe Garhauer has kept records, I'll ask, and a TUSEN TAKK for the measure!



Good name for an Ariel, eh???

[Ed Ekers]

My opinion to the location of the aft (upper) end of vang is determined by the height of the forward (lower) end. If I had to do mine over I would have raised the mast mounting one inch which would move the upper mounting aft. This would give a bit more clearances over the cabin top...ed

[ebb]

Thanks Ed,
Taking a look at Bill's installation on the thread 'Rigid Vang', looks like the flange of the vang is maybe 1 1/2" off the bottom of the mast. Seem right to you? While not clear, the parts do seem barely to clear the front of the dog house.

My guess is that the bigger the angles you can get - ie the corners of boom, vang and mast - the more efficient the vang will be. Within reason - too short on the boom would actually make it harder to haul the boom around.
Too long on the boom would pull the boom more into the gooseneck. Has to be a right place on the boom. Just wondered how that was arrived at. And who arrived at it.

Also the further out on the boom the vang is attached the more bending force would be put on the boom. So obviously there is a 'neutral' point of attachment that equally divides the pull in and down. I got here because of Triton Tim's bending boom problem that caused him to go with a stiffer one. I believe.

Thusly, who decided the soft vang bail position on 338. 39" out from the pin. Class rules & racing regs? Or is it entirely left up to the vicissitudes of the individual skipper.

Bill doesn't bend his boom and neither do you, so it has to be in exactly the right place!

[ebb]

I'm certainly aware that since I do not own a rigid vang yet that I'm out of the zone. When Bill was describing his vang install awhile ago I just accepted the laurel and hardy without question.

Why did the boom have to be raised to the prescribed 40 degrees? That broke the goosneck. I still don't know why the boom has to raise to such an extreme angle unless it has something to do with the reach of the vang. I thought it had something to do with attaching the plate to the boom.

But 40 Degrees is in the realm of efficient vang installation angles. What little I can find out from the outside here is that 45 degrees is the optimum angle. But because the boom is often designed low to a deck or coachroof that angle has to be stretched. Vangs are installed with effective angles of 30 degrees (US Sails).

Found out that rigid vangs are also rigged to curved travelors. Too confusing!