Ideas for Improving the Top section

rippa

Member
Recently there a more and more reports of broken top sections of the Laser mast and many anticipate a move towards a carbon fibre top section. It would seem that we have not explored all options regarding the aluminium part. Discussion: increase the lenght of top section that slides into the bottom section and/or put a sleeve, similar to that in the boom, into the lower 50cm of the top section. We will see dramatically fewer broken top sections plus a more organic curve of the whole mast under load. Old top sections could be upgraded with a sleeve and would not become obsolete.
 
Re: Top section

I think the idea of a sleeve has a lot of merit. The other idea that should also be considered (and has also been mentioned in the past) is the idea of a rivet less collar. This rivet less collar would essentially be a 305mm deep cup that would insert in the bottom section and accept either end of the top section which would be sealed at both ends with the current top plug. This would overcome the stress concentration and corrosion problems associated with the current rivet collar part.
 
Re: Top section

I don't see how lengthening the upper section would help. If the fit is tight, like it should be, adding more length in the mast won't take load off of the point right where the lower mast ends, it would only make the whole joint stiffer (but still just as likely to break). You could make the uppers out of thicker aluminum, but then they wouldn't depower as much. Carbon lasts longer anyway- I think it is the way to go.
 
Re: Top section

Mountain Bikers have gone through the discussion "carbon against aluminium" for some time and lately there are some amazing examples of very light and stiff alu bikes on the market-at half the price of a carbon product.
Consider that:
a) the Laser Class has adopted change in the past only in mini steps (e.g. sails) it is unlikely that I as a Grand Master sailor will ever enjoy sailing a Laser with a carbon mast.
b) Aluminium is a common element on this earth although it gobbles up a large amount of energy in the production process.
c)Carbon fibre composite requires oil based materials which will be in short supply for some time to come.

I will fit out one of my permanently bent top sections with a sleeve this summer and will let you know what happened during training.
 
Re: Top section

As far as I know, the furthest you would need to insert the top section into the bottom section from a strutural point of view is 6-8 times the diameter of the tube. I think it's about that now.

Mixing carbon and alloys is not a good idea from a corrosion point of view. You'd need to make sure that the collar was made of a completely neutral material and free from any salt residue.

It may be time to go the whole hog into a carbon fibre mast. All these half pie additions to the laser, attempting to modernise without modernising, are ridiculous. Just do it properly.
 
Re: Top section

Just to push the discussion along a bit... here are a couple of pics of the composite section being considered for the Radial right now. These aren't very good photos, I must admit, but hopefully you can get a feel for what the spar looks like from them.
 

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Re: Top section

PS I believe there are a set of these spars getting a work out in Australia right now though I think they are on the East Coast.
 
Re: Top section

Recently there a more and more reports of broken top sections of the Laser mast and many anticipate a move towards a carbon fibre top section.

Reminder: the carbon top section (if approved) will only go with the radial rigs.
 
Re: Top section

Reminder: the carbon top section (if approved) will only go with the radial rigs.

And 4.7s.

But... it is certainly worth debating whether or not these composite spars (they are only 5% carbon so don't deserve the label "carbon spar" in my book) might be the answer to the aluminum top mast problems.

Just throwing that out there to see what people think.
 
Re: Top section

Perhaps it helps to state the problems ?

1. Inconsistent sections resulting in changes in stiffness - IIRC this is caused by both material spec and the dies producing a thicker section the more they are used..

2. Breaking at the collar caused by the hole thru the spar for the rivet.

3. Perm. bends caused by both mis-use and inconsistent material


Anything else ?


IMHO, The class should fix #2 right now, that doesn't need a change to a composite spar, I believe there was a proposal for a change that would eliminate having to drill the section. Any progress on that ?

I don't see #1 and #3 getting solved if we stay with aluminum.
 
Re: Top section

IMHO, The class should fix #2 right now, that doesn't need a change to a composite spar, I believe there was a proposal for a change that would eliminate having to drill the section. Any progress on that ?

I have heard two proposals for this:
1) glue the collar to the mast instead of using a rivet. The WC has been told that this has been investigated but that there is not a reliable adhesive that would work as effectively as the rivet.

2) Develop a mast insert to replace the collar. If I understand correctly, there are several issues but the primary problem is the combination of tolerance (e.g. the variation in inner diameter of the bottom section) versus strength. There was a very serious investigation of this just a few years ago.
 
Re: Top section

Couple of thoughts:

Problem 4 is the knuckle-type bend at the joint, that causes the sail to look so bad in some photos.

A boom type sleeve could be used to both stiffen the stress point, and maybe help with 4. At little cost and hardly causing any obsolesence to old rigs. If someone wants to risk the bend/break to have the de-power effect, then that's their choice. The sleeve could be sliced or taper cut to spread the stress point out, instead of just moving the knuckle up.

I also think that the rivet could be moved to the bottom half of the collar. I'd bet this would eliminate any break passing thru the rivet hole. Bending type failure might be the same, but we all know a bend is better than a break, as it saves the sail, makes getting home easier, and it allows the spar to be straightened/reversed. This one change is a no-brainer in my mind.

Since the "Cf" spar is being aimed at lightweights/depowering, then what's gonna happen when a 180 lb master goes out in 25+?

Al
 
Re: Top section

Thanks for update - amazing that with all the adhesives the aerospace guys are cranking out that we can't bond aluminum and plastic.. back to the mixing pail
 
Re: Top section

The boom sleeve isn't a snug fit in the tube- there's about a 16th to an 8th of an inch of clearance. I just added a sleeve this summer, and was a little concerned about the space. The sleeve doesn't even start to help until you're vanged hard. I don't see a sleeve as helping that much, unless it was four or five feet long.
 
Re: Top section

The boom sleeve isn't a snug fit in the tube- there's about a 16th to an 8th of an inch of clearance. I just added a sleeve this summer, and was a little concerned about the space. The sleeve doesn't even start to help until you're vanged hard. I don't see a sleeve as helping that much, unless it was four or five feet long.

which would add a good bit of weight aloft, and possibly hurt righting movement
 
Re: Top section

And 4.7s.

But... it is certainly worth debating whether or not these composite spars (they are only 5% carbon so don't deserve the label "carbon spar" in my book) might be the answer to the aluminum top mast problems.

Just throwing that out there to see what people think.

Hi Tracy,

In the past you've mentioned that the class seems to be extremely resistant to any sail cut or material change that would represent a "game changing" difference.

The sail costs $500+ and wears out relatively quickly (depending on who you ask)

The upper mast section costs about $200, and breaks less frequently (depending on who you ask.)

Personally, I'd vote for both changes. But if we can't sell the class on a more durable sail, the relatively decreased cost/benefit of an upper section seems like a tough sell to me.

The only difference is the catastrophic, sudden unexpected failure of a top section can cause people to lose what otherwise would have been a fine showing in a regatta. So I can see folks to whom that has happened voting for a more durable section to keep it from happening again.
 
Re: Top section

The only difference is the catastrophic, sudden unexpected failure of a top section can cause people to lose what otherwise would have been a fine showing in a regatta. So I can see folks to whom that has happened voting for a more durable section to keep it from happening again.

I'd go for a composite section, even though I've not lost a major regatta due to a failure.
Like a lot of people though, I've saved my pennies for a new sail, only to have the top section snap on one of the first few outings, rendering that nice pretty sail totally poked!This wouldn't bug me so much if it had been 30 knots, but considering that sail had barely been worn in, it was kinda annoying!

Anything that might help preserve the racing life of a new sail would be good in my books. If it was marginally stiffer than the ali one, it might even prevent some of those ugly creases which get blamed on the joint! Or at least it might stop the arguments! ;)
 
Re: Top section

I am sailing in country Western Australia and I am out there by myself regularly in 20 knots+ offshore and I do not feel comfy with that top section. The overall length of the common shark here is about 2 feet longer than my Laser.

If someone fits a sleeve to their boom and it is not a snug fit, they chose the wrong sleeve, my factory sleeve in my boom sits snugly.

I am currently on the road, when I get home I will put a sleeve in and will report back to anyone interested. Should I not be able to find a sleeve that fits perfectly I will say sorry to comuteroman2.

Same with the glue. Do not abandon a good idea because of hearsay that it is not possible.
 
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.
 
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.
 
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.
 
Re: Top section

I have some questions for the "cf" top section advocates:
  1. how much stronger/resilient is a "cf" section than an aluminium one?
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.

(bearing in mind the exhorbitant mark up on "class legal" sails etc) how much might a "cf" section cost?

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.
 
Re: Top section

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

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

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

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