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Old 20-08-2013, 19:26   #1
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Are Camberspars too weak?

I have just destroyed my second Camberspar tube and am wondering if these tubes might be a bit weak for their intended purpose. They seem to be made out of standard 6061 2.25"OD 1/8" wall aluminum tubing with a powder coated finish. I broke the first one because I got caught in a microburst and released the sheets to prevent a capsize (note that I have a cat and they don't simply lay over on their sides). When the center passed over and the wind reversed direction the jib went around the front of the forestay instead of the back and when the stop knot on the end of the sheet hit the stop The thing simply folded. That was a bit understandable as the winds were at least 50 knots and the thing was obviously never designed for he load that was put on it from the odd angle of pull of the sheet and the immense force of the microburst. This latest episode however was in wind only 15 gusting 20. I was wing on wing with a 2-4 foot sea coming off my starboard quarter when a larger wave, probably in the 6-8 foot range lifted the stern and turned the boat to starboard. The top of the jib backwinded while the bottom continued to drive and the spar folded. The the guys who made the sail, and who also are the riggers for Endeavourcat and who used to do Mantas when they were in production, says that this is a fairly common occurance. He also it is fairly common for racers to fold whisker poles this way. Never having been a racer I have no experience in this area. I was wondering if other Camberspar sailors(Manta, Freedom, and Endeavourcat sailors) have had similar failures and would like to hear about them. Also from you racers, is this really a common way to bend a whisker pole?

I'm also wondering if it might be better to replace the tube with a heavier one, perhaps with 1/4 in walled tubing. Unlike with a manhandled whisker pole the extra weight would not seem to be a major issue with a Camberspar.

Note: I would have used the registered trademark symbol after the term Camberspar if I could have figured out how to insert one in this editor, as there does not appear to be a symbols font option
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Old 20-08-2013, 20:35   #2
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Re: Are Camberspars too weak?

We have a whisker pole from Forespar, in alu and Cf , but this guys made whisker poles in CF , way stronger than thin alu sections, worth to take a look maybe..
Forespar
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Old 28-04-2014, 08:43   #3
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Re: Are Camberspars too weak?

Just had a near duplicate experience to Capt. Bill's second camberspar failure. This past Saturday Storyteller (Manta 42 Mk IV) was running dead downwind in the Chesapeake, with breeze 18 gusting 25 true, main out to starboard with boom preventer, jib winged out to port. There was a sudden wind shift maybe 30 deg to port and gusts (not above 30 I think) and I feared the jib would jibe, Instead the camber spar began putting tremendous sideways pressure on the head stay, and in less time than it took to say "oh ****", turn downwind (because heading up would have caused the jib/camber spar to slam jibe) and reach for the jib sheet, the camber spar folded in half, the whole cluster went around the forward end of the head stay, the boat flew up into the wind and everything after that was simple.

This was on a sunny spring afternoon in the Chesapeake.

My only concern about a stronger camberspar is whether the limited strength of the spar is a fail safe feature. Right before mine failed, it was putting tremendous sideways pressure on the headstay. Might we have lost the rig if the spar had not folded up?
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Old 28-04-2014, 10:20   #4
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Re: Are Camberspars too weak?

I doubt you'll find many Freedom owners that have broken their camber spars because the jib is self tending -- it can't be powered up or backwinded unless someone tries to pole it out. I have long jib sheets so that the jib can go past 90 degrees on the headstay and this allows me to fly wing on wing pretty well. When it jibes over I know I'm getting close to sailing by the lee.

I also looked on the FreedomYachts.org forum and didn't see any posts about breaking camber spars.
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Old 28-04-2014, 11:24   #5
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Re: Are Camberspars too weak?

Quote:
Originally Posted by peircej View Post
Just had a near duplicate experience to Capt. Bill's second camberspar failure. This past Saturday Storyteller (Manta 42 Mk IV) was running dead downwind in the Chesapeake, with breeze 18 gusting 25 true, main out to starboard with boom preventer, jib winged out to port. There was a sudden wind shift maybe 30 deg to port and gusts (not above 30 I think) and I feared the jib would jibe, Instead the camber spar began putting tremendous sideways pressure on the head stay, and in less time than it took to say "oh ****", turn downwind (because heading up would have caused the jib/camber spar to slam jibe) and reach for the jib sheet, the camber spar folded in half, the whole cluster went around the forward end of the head stay, the boat flew up into the wind and everything after that was simple.

This was on a sunny spring afternoon in the Chesapeake.

My only concern about a stronger camberspar is whether the limited strength of the spar is a fail safe feature. Right before mine failed, it was putting tremendous sideways pressure on the headstay. Might we have lost the rig if the spar had not folded up?
You have a good point about folding the camberspar instead of loosing the rig. I talked to Dave Beirig (the camberspar inventor) about why my jib was flying differently at the top of the sail. When the bottom of my sail is in trim, the top is backwinded and when the top is in trim the telltails
at the bottom are doing all kinds of weird things, but definitely not streaming. He said that I didn't have enough headstay tension. He said putting in more head stay tension forces the camberspar aft and puts more tension on the leech above the camberspar. He said this should solve the problem. I'm pretty sure that with the spar out about 90 degrees for wing-on-wing, that when the top backwinds and bottom is driving, this just end loads the camberspar and as you described puts a big bend in the forestay. If the spar gets out past 90 it really trys tp go round the front of the forestay which the sheet prevents. This end loads the camberspar as well. If it is less than 90 then the sail simply switches sides and does not end load the camberspar (assuming the top and bottom of the jib are driving in the same direction). It's a bit exciting when it does that but it doesn't seem to break anything. The jib is pretty small compared to the main so the rig can handle the loads of gybing the jib a lot better than gybing the main. I've had hard gybes on the jib many times and not had any issues. Since they are self tending they pretty much have to be able to handle those loads.
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