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Laser with a carbon mast??
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Grumpycat View Drop Down
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    Posted: 20 Apr 22 at 12:45pm
Originally posted by eric_c

Originally posted by Grumpycat

....
It’s only the top section and it is designed to replicate the same mast bend so the only real difference is the the fact it weighs a bit lighter ( and before a ILCA sailor comes on and says it weighs the same as the old ali section . This was confirmed to me in writing by the Australian manufacturer  Smile )

....


Does this refer tot he official ILCA composite spars, which have been around maybe 7 years?, or maybe to the unofficial ones which a certain well known spar maker was selling before that?

The weight of the ali spars can vary, 'off the shelf' ali tube is not that finely toleranced.

The official ILCA top section. The lighter weight has also been confirmed on Performance Sailcraft Australia fb page .
Personally I don’t think there is any performance advantage for the average ILCA sailor but I do know a couple of sailors that are racing against ILCA sailors using them that think there is a very small performance gain in certain conditions. Could just be in their own minds though  LOL
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seasailor View Drop Down
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Posts: 30 		Post Options Post Options   Quote seasailor Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 11:58am
I haven't read all of the chat but my understanding is that carbon lower mast is now legal on the ILCA 6, but not on the ILCA7.

I've done a fair bit of medium quality Laser/Laser Radial club racing in my time and never bent nor broken a bottom section.

My problem with the carbon bottom section is not that it may or may not be slightly lighter, bendier or whatever, it's that it costs upwards of £900 which, coupled with the cost of a carbon/composite top section, means that a Laser Radial mast costs some £1,500 quid, which is more than my boat is worth! 
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eric_c View Drop Down
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Posts: 382 		Post Options Post Options   Quote eric_c Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 11:39am
Originally posted by A2Z

But *all* the mechanical properties cannot be identical else the composite one would also deform plastically and stay bent.   I guess the only ones that need to be matched are weight, EI and outer diameter. And how the properties change with temperature in a range of -10 to +40 should be matched.


All that's needed is for the spars to make the boat go pretty much the same speed.

Same as withthe MK1/MK2 sails, they are a little different, and people may sail a little differently to get the best out of them, but on the water, they are not different enough to affect the outcomes of races significantly.

It becomes irrelevant after a coupe of seasons when all the top sailors are using the same kit. The old kit is generally then a bit tired anyway.

Likewise the GRP foils, no big performance gain relative to a properly fettled old blade, but easier to keep in good nick so everyone has the same.

People who actually sail Lasers at club level are generally not able to use the equipment as an excuse unless it's really clapped out.
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eric_c View Drop Down
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Posts: 382 		Post Options Post Options   Quote eric_c Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 11:23am
Originally posted by Grumpycat

....
It’s only the top section and it is designed to replicate the same mast bend so the only real difference is the the fact it weighs a bit lighter ( and before a ILCA sailor comes on and says it weighs the same as the old ali section . This was confirmed to me in writing by the Australian manufacturer  Smile )

....


Does this refer tot he official ILCA composite spars, which have been around maybe 7 years?, or maybe to the unofficial ones which a certain well known spar maker was selling before that?

The weight of the ali spars can vary, 'off the shelf' ali tube is not that finely toleranced.
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Oatsandbeans View Drop Down
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 11:14am
This may be more complex that just matching the quasi static mechanical properties. Polymeric materials are actually viscoelastic. Simply put they have solid properties (elastic) and liquid properties (viscous ). This means that their response is complex and not purely elastic (like a metal). Engineers don’t consider this, (because they don’t understand it and can’t model it)but we see it all the time when we look at polymers.
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 11:11am
But *all* the mechanical properties cannot be identical else the composite one would also deform plastically and stay bent.   I guess the only ones that need to be matched are weight, EI and outer diameter. And how the properties change with temperature in a range of -10 to +40 should be matched.

Edited by A2Z - 20 Apr 22 at 11:14am
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 10:09am
If *all* the mechanical properties are identical then the behaviour surely must be identical. But of course the mechanical properties are anything but identical, unless, like the Laser spar, great care is taken to make them as close as possible. And that's before you get into the possibilities inherent in varying the layup over the length of a carbon spar in a way which is impractical with extruded aluminium.

Edited by JimC - 20 Apr 22 at 10:13am
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Oatsandbeans View Drop Down
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 9:41am
Whether a composite rig has a better gust response than an Aluminium one is interesting. I talked to a composite engineer on this and he was adamant that if the stiffness and weight is matched ( would need a carbon/glass mix for that) -the gust response would be the same. I am not 100% convinced-it would be interesting to do some testing. If there’s any spar builders out there-I will do the testing if they provide the tubes (I have access to an Instron test frame )
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423zero View Drop Down
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 9:01am
Demelza, I apologise unreservedly for any distress caused, but please reread my post which you have just quoted, I can't see where it suggests that I thought you were encouraging people to cheat.     
Robert
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Grumpycat View Drop Down
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Posts: 497 		Post Options Post Options   Quote Grumpycat Quote  Post ReplyReply Direct Link To This Post Posted: 20 Apr 22 at 8:49am
Originally posted by 423zero

I think it is griff, one of his pseudonyms.

I don’t think so , it’s far too short a post for him  Wink.

Now we know who he is . It’s the angry LP ( or what ever it’s called these days ) sock puppet who’s first posts were about how to pass off none class legal boats at class events.
It all makes sense now .  LOL
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