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Jamesd View Drop Down
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Posts: 377 		Post Options Post Options   Quote Jamesd Quote  Post ReplyReply Direct Link To This Post Topic: Laser Top Mast Changes
    Posted: 28 Nov 08 at 12:33pm
i did read inthe latest laser mag, the measurer going on about recommending end for ending the top mast section. is this legal?
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Posts: 201 		Post Options Post Options   Quote Alistair426 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 12:40pm
Certainly is...lots of people do it. Doubles the life of the top-section...especially if it has already been straightened a couple of times.
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 12:42pm

It'll be interesting to see if this does reduce breakages. The mast will still bend but by rotating the mast the user can spread the bending over 360 degs...do that to aluminium and it will still break......

 

I would have thought making it out of a different material would be a better bet...same flex characteristics as ally but one that doesn't work harden.

(please consider my sig when reading this )



Edited by GK.LaserII
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alstorer View Drop Down
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Posts: 2899 		Post Options Post Options   Quote alstorer Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 12:53pm
Originally posted by Jamesd

Originally posted by dave.blakesley

ah ok... why do the breaks happen at that rivet and how are they going to
change the rivet? it must be doing something! lol

you cannot make a hole in something that is acting in tension. it creates a weakness that will fail. a bit like trying to rip something, its alot easier to rip a shirt if you make a small cut with some scissors. the rivet on a laser top mast is there to hold the plastic sleeve at the bottom (the black thing about a foot up from the bottom), that is its only purpose. If you put the top mast in with the rivet facing backwards, then most of the time the rivet is in compression which is fine, but bear away downwind in strong breeze and you can find the mast bending forwards towards the bow (this happens alot if the boat is going slowly, i.e. hitting the back of a wave) the back edge of the mast is now in tension and so is the rivet hole and thats when the problem occurs.

 

Furthermore, for a piece under tension, if the hole is filled tightly by, say, a rivet, you actually see a further decrease in strength as the deformation of the material around the hole is adversely affected (but in compression, the rivet will take some of the force).
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Jamesd View Drop Down
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Posts: 377 		Post Options Post Options   Quote Jamesd Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 1:13pm
Originally posted by GK.LaserII

I would have thought making it out of a different material would be a better bet...same flex characteristics as ally but one that doesn't work harden.

(please consider my sig when reading this )

they have been toying with composite ones for ages. Not sure if it is for all classes but was aimed at the radials and reducing the weight range for the boat. i presume by making it lighter and therefore less moment, as the bend characteristics are to remain the same as the ali, not to sure though. but the development has been postponed.

crap idea though. Imagine a carbon top mast or glass for that matter from laser. they would want £600
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Posts: 962 		Post Options Post Options   Quote Matt Jackson Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 3:20pm
Originally posted by Fraggle

Top section won't effect performance, just longevity of a mast.  I bend mine very very quickly, as do most laser sailors.  You can only straighten them so many times, not having a rivet causing a weak point should help.

Sorry I disagree, if I remember correctly the mast always goes together the same way and in time bends in effect giving some pre-bend which changes performance.

If the new system allows the mast to be put together any way then there will be less bend and less change in performance.

Therefore the change will affect the performance of the boats with the new top section.

Notice I didn't say whether performance will be increased or whether the change is a good thing or not - I just disagree the the asertion.
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Laser 173312 View Drop Down
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Posts: 416 		Post Options Post Options   Quote Laser 173312 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 3:50pm
Originally posted by GK.LaserII

It'll be interesting to see if this does reduce breakages. The mast will still bend but by rotating the mast the user can spread the bending over 360 degs...do that to aluminium and it will still break......

 

I would have thought making it out of a different material would be a better bet...same flex characteristics as ally but one that doesn't work harden.

(please consider my sig when reading this )

Gary

The idea of a carbon top mast has been 'put on hold'  the moment and whilst I take your point about the work hardening I still think the top section would last much longer without the rivet forcing you to put the 2 parts together in a specific allinement. It also means you can end for end it each time you sail and so spread the wear about.

Also thinking a little more about it, now you can use tape around the mast joint. You would be able to tape the collet to the LOWER section semi permanately and just slide which ever end of the top mast came to hand first into it.

I agree that the sail probably won't change for a few years yet, but this could be introduced relatively quickly I would hope.

Incidently what do most people do with their old tubes. Do they just throw them or can they be recycled. May be PS could give you a discount for PXing your old tube for a new one. They might not need so much raw ally if they did that and that would be good for the environment.

Sorry that's a daft idea 'PS giving a discount' I mean.

Edit

There seems to be some confusion about this. I don't think the top section is changing at all. As I read it all that will happen is the 2 collars will be taken off it and replaced by a split plastic cup that the top section will rest in.

Please correct me if this is wrong.

 



Edited by Laser 173312
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Fraggle View Drop Down
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Posts: 220 		Post Options Post Options   Quote Fraggle Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 4:05pm
Old broken top sections can relatively easily be turned into booms. 
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Posts: 0 		Post Options Post Options   Quote Guest Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 4:26pm
I thought the booms were sleeved?
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bert View Drop Down
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Posts: 584 		Post Options Post Options   Quote bert Quote  Post ReplyReply Direct Link To This Post Posted: 28 Nov 08 at 4:45pm
only where the kicker is aqttached
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