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Dog Bones - Are they class legal

Andy B

Member
Since the introduction of the MK6 Radial I had been sailing with a 6:1 Cunningham but with the MK2 Standard I found I needed an 8:1. After trying several combinations I opted for a two block system as shown on South East Sailboats. I found the best blocks were the Allen because the sheaves are wider and the ropes do not rub on the cheeks so easily. The last issue was a quick way of securing the primary and secondary lines to the mast below the kicker tang. The constraints are that any fitting on the primary must pass through the small cringle on the MK2 Standard sail, not slip under load and be easy to undo after sailing with cold hands. I tried a few different methods with balls, knots, shackles, spliced loops etc but they were all a bit fiddly and then I found Soak Dog-bones in my local chandlery. With a spliced loop in the end of the line and a clove hitch to secure them to the line they tick all the boxes and are working well.

But are they class legal?

IMG0070A.jpgIMG0071A.jpg
 

LaLi

Well-Known Member
No, they're not, and neither are balls or shackles in that position, attached to the stationary end of a control line. Whether they're allowed with blocks or elastic lines is not explicitly stated, but I'd count them as a "clip, ball or hook" in this context. If so, it would be legal to use one at the other end to attach the line to a block.

The rule in question isn't totally logical, and is probably broken pretty often.

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Andy B

Member
Thank you.

I will have to keep this for club sailing and go back to the same arrangement using a figure of eight knot and a cow hitch for class competitions.
But that always ends up so tight at the end of the day.
 

LaLi

Well-Known Member
Legal matters aside, why do you want to tie either of the lines below the vang tang?

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I do that to take the stress of the cunningham control lines off of the vang tang. The fitting was designed in the '70s and already has enough strain on it from the upgraded vang arrangement.
 

LaLi

Well-Known Member
The "upgraded" vang doesn't fundamentally strain anything any more than a "non-upgraded" one, and even if it did, the cunningham doesn't add much more to it.

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Rob B

Well-Known Member
Legal matters aside, why do you want to tie either of the lines below the vang tang?

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I tie mine down there too. I've seen some stretched sails bottom out the Cunningham a little early when the line is tied around the gooseneck. It's like some leverage is lost as the 180 degree turn on the line looses angle as the cunning grommet gets closer to the tie down point.
 
The "upgraded" vang doesn't fundamentally strain anything any more than a "non-upgraded" one, and even if it did, the cunningham doesn't add much more to it.

In theory, you're right, however, with the increase in purchase, it is easier to put more strain on the vang tang without much effort. It probably doesn't matter in the short term, but it doesn't hurt your spars' longevity to spread the load by not tying your cunningham to the top of the vang assembly as the stock kits do. I've seen a few people break masts at this point, and doing this gives me a bit more peace of mind to crank down on the vang when I need to.
 
In theory, you're right, however, with the increase in purchase, it is easier to put more strain on the vang tang without much effort. It probably doesn't matter in the short term, but it doesn't hurt your spars' longevity to spread the load by not tying your cunningham to the top of the vang assembly as the stock kits do. I've seen a few people break masts at this point, and doing this gives me a bit more peace of mind to crank down on the vang when I need to.
 

LaLi

Well-Known Member
it doesn't hurt your spars' longevity to spread the load by not tying your cunningham to the top of the vang assembly as the stock kits do. I've seen a few people break masts at this point
Those two (cunningham rigging and mast breakage) have nothing to do with one another.

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Those two (cunningham rigging and mast breakage) have nothing to do with one another.

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I agree, I go through radial lower sections like there is no tomorrow. I have my vang and cunnigham rigged the coventional way. 4 lower section broken in the last year and only one went at the vang tang. All the other went at the deck.
 
Those two (cunningham rigging and mast breakage) have nothing to do with one another.

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I primarily am concerned with taking it easy on the rivets of the vang tang. I like to do it this way and will continue to do it this way. Regardless of the reasoning, this gives me peace of mind when racing.
 

LaLi

Well-Known Member
bclark, David isn't really talking about the same thing - he does tie his primary line directly to the tang, so he's not worrying about the rivets but the pin. The additional load on the tang isn't huge, and it's next to nothing when he ties that line (illegally) around the boom as well.

If you get to the Olympics you're a very good sailor. It doesn't mean you're good at mechanics, or even the class rules.

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He is talking about the same thing in that it is important to reduce stress on the vang tang. By tying his lower cunningham turning block around the base of the mast, and dead-ending the other end to the base of the tang, he is getting the additional force of the cunningham as close to the base of the vang tang as possible.

When you attach the c'ham to the pin on the top of the vang assembly, it can act as a lever on the tang's rivets (and the pin in question.) Thereby increasing the force to those fasteners, as well as the pin. He discusses this in the comments of that video.

I rig my boat in accordance with class rules, and with the overall goal of reducing any loads put on the boat and its fittings for increased reliability on the water. I do not emulate David's rigging here exactly but I found this video informative in that he points out some (legal) approaches to rigging your boat in the most robust and reliable manner possible.

I wanted to share these insights on this post to help those rigging cunningham arrangements, and I found these points to be useful IMHO. I will probably never make it to the Olympics, nor am I trying; I just enjoy seeing innovative approaches from people like David who spend way more time sailing Lasers than I, and most everyone else, are able to.
 

Andy B

Member
Like the comment in the linked video I found some blocks did not sit well against the mast when mounted on a strop and the ropes sometimes pulled at odd angles. If you happened to have a very slack a cunningham because you have just thrown it out of the cleat at the windward mark either the block would fall away or the strop slipped unless it was taped and it all made rigging a faff. The arrangement which works best for me is to keep the 16mm Air Block on the kicker attachment. This means some of the moving lines and blocks are now near the mast. I found if I dead ended the primary and secondary lines on the kicker or the tang as you pulled the cunningham on there were points where blocks and ropes rubbed together creating friction. Dead ending on the mast itself keeps the lines free of all the moving parts and with the dogbones, or similar, it is quick and simple to rig and unrig so more time on the water.
 

LaLi

Well-Known Member
I don't think one can rig the cunningham in a way that would actually break anything (besides the head strap) even if you wanted to. I'd actually like to see someone do some real load testing so that we'd have some solid data instead of what might be called "folk physics".

But to come back to the original topic, I think that dogbones, just like other smart and cheap little attachment devices, should be legal everywhere on a Laser. The current partial limitations are illogical and impractical.

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Wavedancer

Upside down?
Staff member
I agree, I go through radial lower sections like there is no tomorrow. I have my vang and cunnigham rigged the coventional way. 4 lower section broken in the last year and only one went at the vang tang. All the other went at the deck.
So many breakages!

In some ten years of 'club-level' Laser sailing with an occasional regatta thrown in, I have seen one upper and one boom break (not mine, fortunately). All were sailing 'full rigs'. Is the Radial lower more prone to breakage?

 

LaLi

Well-Known Member
Is the Radial lower more prone to breakage?

It is, as well as to permanent bending. The wall is quite thin, and although it's a double tube most of the way, it's still vulnerable. There should be a solution coming soon (hopefully) in the form of a carbon replacement, which was already talked about a year or so ago.

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Andy B

Member
We are going off thread but the problem with the carbon spars is the price. Nearly four times the price for a carbon top section; so you are paying carbon prices for aluminium performance. My experience using the modern rigs on the Laser's competitors is they are much more flexible across a wider range of wind strengths so I can sail a 7 in another class when I would need a Radial in a Laser. Increasing the price point with no performance gain loses one of the Lasers advantages. Advantages it still has are it's robust construction, long life, low hull cost, excellent hiking position and always people to sail with.
 

Horizon

Active Member
It is, as well as to permanent bending. The wall is quite thin, and although it's a double tube most of the way, it's still vulnerable. There should be a solution coming soon (hopefully) in the form of a carbon replacement, which was already talked about a year or so ago.

According to the comment at the bottom of the 2020 Winter Laser Sailor on page 13 in the article about PSA produced ILCA dinghies, carbon bottom sections for the radial have been approved.

 
So many breakages!

In some ten years of 'club-level' Laser sailing with an occasional regatta thrown in, I have seen one upper and one boom break (not mine, fortunately). All were sailing 'full rigs'. Is the Radial lower more prone to breakage?
With the new "carbon" top sections, which are much stiffer, the radial lowers just seem to go. I also sail 3, days a week all winter and more during the summer.
 
It is, as well as to permanent bending. The wall is quite thin, and although it's a double tube most of the way, it's still vulnerable. There should be a solution coming soon (hopefully) in the form of a carbon replacement, which was already talked about a year or so ago.

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According to some buddies at PSA, the carbon lower should get the states by late March.
 

LaLi

Well-Known Member
According to the comment at the bottom of the 2020 Winter Laser Sailor on page 13 in the article about PSA produced ILCA dinghies, carbon bottom sections for the radial have been approved.
According to some buddies at PSA, the carbon lower should get the states by late March
Ok, points to "grassroots" legalization on 1 March or 1 April, and full legalization on the day after Tokyo 2020. Would be similar to what was done with the MkII Standard sail four years ago.

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Andy B

Member
Right: so the carbon section might be stiffer than the aluminium Radial section but not as stiff as a Standard bottom section. Again IF this were true the aluminium section would become obsolete overnight for serious racers.

It will be interesting when we have a few more reports of the carbon lower in use.
 
Right: so the carbon section might be stiffer than the aluminium Radial section but not as stiff as a Standard bottom section. Again IF this were true the aluminium section would become obsolete overnight for serious racers.

It will be interesting when we have a few more reports of the carbon lower in use.
Pretty much, I have my name on the first carbon lower sent into the states. So I’ll get back to you once we get a little testing.
 

DJ1

New Member
For whatever it's worth, there were a few of the composite radial lowers in the US last summer and we gave it a try in reasonably windy (20+) conditions. There was no noticeable difference except that it was still straight at the end of the summer. And it's quite a bit lighter.
 
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