Ideas for Improving the Top section

Discussion in 'Laser Talk' started by rippa, Nov 5, 2007.

  1. Laserite

    Laserite New Member

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    Re: Top section

    I sail on the East Coast in Australia and have been testing these masts. I tried one out one in about 25-30 knots last weekend. I could not tell an ounce of difference in performance an my results for the day pretty much backed that up. However, what was different was when I came ashore after a day of extreme vanbging my carbon top section was (of course) perferctly straight. The same could not be said of an aluminium one.

    One quick note anbout trying to make the playing field level by having all of the same equipment. I weighed four of the carbon masts - and guess what... not one was the same weight. I cnanot understand why, more fibre? More resin??? Obvioulds this would result in slightly stiffer/bendy top sections.
     
  2. Looper

    Looper New Member

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    Re: Top section

    A bayonet to clip them together might be nice.

    My top section slipped off a bit as I was threading the sleeve on and then somehow slipped back on a bit trapping a tiny bit of the sleeve which got a little tear in it which will become a big tear if my lovely bit of silver gaffer tape repair does not stay put.

    Yes my boat is a classy looking girl :)

    My old wooden grab rails now have strips of camping mat foam gaffer taped on top. It is now lovely and comfy and also looks totally shithouse :)

    Class legal? You tell me.
     
  3. paulmarshall

    paulmarshall New Member

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    Re: Top section

    I too broke the top section of my mast last weekend. Yes - it let go at the collar rivet. Some sign of corrosion and what looks like stress-hardening in the break itself.

    The jagged edges tore the luff pocket beyond repair, so ... $1600(NZ) later ... this thread is at the front of my mind.

    I have some questions for the "cf" top section advocates:

    1. how much stronger/resilient is a "cf" section than an aluminium one?
    2. how would the collar be fixed to the "cf" section?
    3. (bearing in mind the exhorbitant mark up on "class legal" sails etc) how much might a "cf" section cost?
    Staying with the aluminium status quo, it should be possible to design a socket to attach to the top of the bottom section into which the "naked" end of the top section would slide. That would remove the need for both the plug at the base of the top section and of course the collar and offending rivet.
     
  4. Chainsaw

    Chainsaw Brmmm Brmmm

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    Re: Top section

    so much more that I doubt you would ever see another broken top section. If you could get it to break, it would snap just as suddenly, but without the enjoyable pptang! sound. I look forward to seeing 12 year old 4.7 owners scrapping the end of their booms on the aft deck with the help of a 15:1 vang very soon.

    it would cost so much, that all the threads on here that rail against the price of class legal sails would be forgotten in an instant. Not only would teeth be knashed, teeth would actually crack in the knashers jaw.
     
  5. paulmarshall

    paulmarshall New Member

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    Re: Top section

    So, Chainsaw, given the "cost hurdle" what about a socket attached to the top of the bottom section idea?
     
  6. vtgent49

    vtgent49 Member

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    Re: Top section

    If the rivet in your top section is looking worn or rusted if you replace it does it extend the life of the spar?

    Yes, even better if you end for end it. The bottom section too. To be legal you have to waterproof the old rivet holes. I just use packing tape for this.

    tore the luff pocket beyond repair

    A good sailmaker can fix this so it's hardly noticable. I prefer a new luff sleeve about 2-3 feet long, not just a patch. $US 60-70 last time I did this. It's legal because it's a repair.
     
  7. John Gilmour

    John Gilmour Member

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    Re: Top section

    Just as a point of reference, the cost of a carbon fiber mast (both sections) for the Byte is $1800. Ouch!!
     
  8. 49208

    49208 Tentmaker

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    Re: Top section

    And a Finn mast is $3500 and up - not sure that or the cost of a Byte mast is relevant because:

    1. Lasers are not looking at a full carbon section, and not looking at a complete mast.
    2. The quantity that PSE would be buying from a vendor is going to result in some significant purchasing power, driving the purchase price down for PSE
    3. Like all the things Builder supplied, the price we pay is going to be set by the Builder. There have been some numbers thrown out in The Laser Sailor, IIRC price they were hoping to sell at was described as 2 or 3 times the current section. That puts it between $400-$600.
     
  9. Chainsaw

    Chainsaw Brmmm Brmmm

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    Re: Top section

    I have no idea why the original design didn't use that idea.

    In fact there are plenty of things about the laser that can make a guy wonder what Bruce Kirby was thinking about. At least it doesn't have a lanteen sail.

    Maybe Laser cemented it's OD status too soon: There should have been a 15year period of tweaking and development first.

    I was recently turning a broken top section into a boom. Those blocks really are crap. Sure they work ... but they really are crap. LOL
     
  10. Chris123

    Chris123 New Member

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    Re: Top section

    The current mast sections (and boom for that matter): Are they custom extrusions made specifically for the Laser? Instead of going further down the custom fabrication path, would it be possible to re-spec them, while preserving the desired bend characteristics, using some sort of standard aluminum tubing?

    Aluminum tubing is made in many different alloys and wall thicknesses and degrees of precision, and it's made by the mile. Using a standard size, sourcing multiple vendors, etc. ought to make it possible to get a highly consistent product for short money.

    (Maybe that's already the way it's being done; I don't know, but it seems that with a standard product spec'ed appropriately, inconsistencies in wall thickness ought to be pretty minor.
     
  11. vtgent49

    vtgent49 Member

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    Re: Top section

    The top and boom are a standard (inch) size and thickness, probably a standard alloy spec, then anodized. (think about the original design, done reportedly on a napkin on a presumably low budget). I doubt its standard in a metric based society, but I don't know. All specs have a tolerence (+ or -) in size, heat treatment, and alloy. The plastic parts have a +/- range also.

    Since the original design, I have no doubt that some engineer(s) has/have searched all over, and even lost sleep, over the tolerances and general QC issues like scratches, nicks, weight, flex etc. No doubt they also tried all of the ideas that we can think of. Lately, more and more Alum. is recycled, adding a new set of tolerances re. allowable amounts of non Alum. elements such as copper, lead, zinc, chrome, etc. The product, as delivered is great in cosmetic terms, and probably in weight/flex, etc.

    I doubt the original designers and engineers anticipated 2 blocking with a vectran traveller, radial masts, 15:1 vangs etc. etc. Could they have guessed that people would sail with 20-30 year old tops? The fact is the topmast is just barely strong enough, and can be bent back shockingly easy by supporting both ends of the full mast, and leaning on the joint. I'd guess 100 lbs would do it, but I'll measure it next time I have to do one.

    I believe the original tops had 3 rivets around the stress zone, and it definately had two rivets for many years. Now we have one rivet in the stress zone, all without a need to vote as a class, etc. Now, we just need to move that rivet down an inch or so, out of the stress zone. Again this would be a change to the builders manual, not to the class rules. This would help change breaks to bends, not solve the problem, but that's not a reason to take the smaller step than a radical change.

    Al "move the rivet" Russell :)
     
  12. Merrily

    Merrily Administrator Staff Member

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    I have changed the name of this thread to make it easier to find with the Search feature in future.
     
  13. dougreynolds10

    dougreynolds10 Member

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    what do you mean by end to end it?
     
  14. 49208

    49208 Tentmaker

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    Pretty much exactly what it implies - move the caps/collar to the other end of the top section, so you flip the top section upside down.

    It can extend the life of the top section as you are now bending/stressing (via the rivet hole) an area that was prev not subject to the same loads
     
  15. vtgent49

    vtgent49 Member

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    Yup, as 49208er says. This is especially important if you've bent and straightened the top a few times. That causes "work hardening" which stiffens and makes the stress point more brittle.

    Also, if you see a jagged edge to any of the holes, then your spar has corroded on the inside, and/or around the rivets. If so, the end-for-ended spar will be stronger, but a lot weaker than a new one. Find some broken tops at your club or wherever, and look closely at the fractured edges, and these concepts will be pretty clear.

    Really waterproofing a salt water spar when new would really be a good idea.

    Al
     
  16. Chainsaw

    Chainsaw Brmmm Brmmm

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    My new top section comes with a delightful orange sticker. It basically says the top section will break, the Laser builders are not responsible, and then goes on to offer a quack remedy.

    If a top section needs to be soft to bend without breaking, why would the builders recommend you go out and work harden the piece before cranking on the vang?

    DOH!

    LOL
     
  17. fracisco

    fracisco New Member

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    Why carbon fiber? Why not fiberglass? Worked for the skiffs for years.
     
  18. 49208

    49208 Tentmaker

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    Fracisco, Read post #9 in this thread..
     
  19. SFBayLaser

    SFBayLaser Member

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    sigh....

    In this posting (in this thread) are two photographs of an actual prototype composite spar which has, originally, been developed for the 4.7 and Radial. Its less than 5% carbon, the rest fiberglass, and it is not cutting edge technology (according to my board sailing buddies here in San Francisco - but what do they know? they are all kite sailors now...). The construction technique does produce a very uniform spar, reducing by a lot the variation between the current aluminum spar. And, not being super high tech, it is relatively cheap.

    Note that the collar is molded into the spar - no rivet and no directionality.

    Both PSE and Vanguard are now sourcing their aluminum top sections from a brand new production facility in Hungary which, we're told, has the best "processing" capabilities of any available aluminum extruder and these spars are considered to be the best possible within the current specifications of the Laser Construction Manual. They are certainly not off the shelf items... in fact I've been told that worldwide use of aluminum tubing (presumably primarily for irrigation) has dropped dramatically in favor of cheaper alternatives (e.g. pvc). But I am not an aluminum tubing expert and am only relating what I have been told (well, when I drive home from work the local farm fields do seem to use pvc irrigation piping).

    Now... sleeving the top section at the joint might help solve some of the permanent bend problems but wouldn't that result in a stiffer top section? I suppose as someone weighing in at 90kg I shouldn't complain about this idea, but I'm not sure that the bulk of the Laser Class wants to move in that direction.

    During testing of the previous round of composite spars (tubes from a different company), there was a serious look at developing a "cup" for inserting the top section into the bottom section. I believe it got to the prototype stage before being abandoned as not a viable solution. A major problem is accommodating the tolerances on the ID of the bottom and OD of the top. We already see part of this, the effect of the ID on the bottom section, that's why its hard to find a top section that fits snugly into a bottom section without liberal use of tape.

    Ok, I have the advantage of getting to hold a composite top section in my hands and even go sailing with it. What I see is the choice between something that looks like it has the ability to solve all the problems with the aluminum spars (variability, lifetime, permanent bending, etc.) versus continuing to try to band aid solutions onto something that was never intended to be used as it is today.

    I agree that adopting these composite spars for the Laser Standard is problematic in that the spar is more flexible than the aluminum uppers (and, again, at 90kg I'm not looking for something that reduces my competitiveness). In fact, feedback I have had from testers (in Radials) in semi-racing conditions is that unless the breeze is up they feel disadvantaged relative to the aluminum uppers. On the other hand, the composite spars "restore" more quickly than the aluminum... its not clear to me that what is perceived to be a disadvantage now might not go away as people adjust their sailing styles to the spar. If these spars really turn out to be vastly superior to the aluminum perhaps it is worth the trade off.

    As to price... I don't know that the builders will try to retail them for. As has been stated in this thread, Ned Jones wrote in his "Builder's Column" in The Laser Sailor that they would go for somewhere between 2.5-3 times the current uppers. The question to the Class is "what would you pay for a spar which promises not to develop permanent bends or break because of corrosion around the rivet?"
     
  20. I break things

    I break things New Member

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    I havent had time to read this whole post but i have used the radial carbon top section in Cabarete DR and i have to say it was the most amazing thing i have ever sailed with, you can feel more power in the sail because it bends higher in the mast than a standard top section yet it is perfect its balanced, lighter and much more innovative. As soon as they hit the markets im going to get one.
     

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