Snapping a top mast section.

3

3nbellc

New Member
Hi all,

I went out training for a morning in a good force 4 and then i went in for lunch. When i came out to afternoon club racing my top section suddenly snapped and ripped my sail (yes it hurt:() . Is this a common thing that happens in the laser?
 
It happens, especially if your mast is older and the mast collar rivet wasn't aligned properly. Do a search on broken masts, mast collars, aligning rivets etc. as there has been a lot of discussion on this topic.

Look at the break and see if some of the metal looks corroded (often looks darker or duller along the tear) -- that's a good sign that this was waiting to happen. In fact the masts that I have broken didn't break in heavy air, they waited until the next day and broke in light air. . . and when I looked carefully at the break there was usually signs that the rivet hole had been starting to go for awhile.

You can cut down the remaining big piece to make a new boom (search the forum again) and you can use the small piece as a drinking goblet to help drown your sorrows over your torn sail and broken mast. ;-)
 
Thats exactly what happened. Around the rivet it was corroded and this simply made the rest of the mast snap cleanly. Thanks for the help.

I think i might make a lot of drinking goblets, i have been doin a paper round for ages to save up for a new sail and the third time i take it out. SNAP
 
Don't be too discouraged, when you get a new top section make sure to always keep the rivet pointing to the back and that should help a lot.
 
can someone explain the rivet on the back concept. it seems like it would get the least compression and release on the side. :confused:
 
I don't actualy remember how to correctly set up the laser masts, but lasermasts tend to have an arrow on the top mast and one on the bottom and those are suposed to point towards eachother or something =p
 
jealou5 said:
can someone explain the rivet on the back concept. it seems like it would get the least compression and release on the side. :confused:
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My understanding is that you want the rivet to be in compression, not to avoid it. If the hole is in the front or sides the bending of the mast can cause the aluminum to start to tear at the rivet hole. Once that happens then it's just a matter of time before the mast breaks. Therefore you always want to have the rivet and hole in compression when sailing; that way the forces at work on the mast are trying to smoosh the hole shut but because the rivet is in there nothing is happening.

If that's not accurate, perhaps some engineering type can set us straight.
 
Why is it that we as a class continue to allow this? There is no way to know when it's going to fail, but rest assured, sooner or later it will. I see this as a major design flaw, and the dealer is only making more money from replacement top sections and sails. I've been back into the class for 6 months and I've broken one, and have seen two others. It's very frustrating considering the cost. The collar can be glued, and then they won't break.
 
I'm sure I saw a design/suggestion somewhere for a 1 piece plastic collar, i.e. the bottom plug and collar joined by a thin tube - fits over the mast but not as thick as the bottom plug so its just as easy to insert the top section. Again you wouldn't have to drill the rivet hole and wouldn't be worried by glue giving way under the collar. The tube would automatically set the collar at the correct position too.
Looks like a simple solution - anyone know if it is being considered ?
Anyone tried buying a bare mast from a supplier ? You could claim to have the old fittings and want to re-install them on a new mast tube - esp when your top section breaks after only 15months (like mine did) and they are still like new.
 
Ross B said:
my answer to this is a one piece mast
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that's an idea... but Laser is really into being practical. This will mean that the mast will be more expensive, and people will need multiple full masts for each type of sail. Also, making the masts mobile would be tougher... it's an idea, though. Do you guys think that just making the rivet point back would fix this problem for everyone??? At one point they'll just get old and it'll happen anyway. Masts don't always break at the rivet, but it seems to be most of the time?
 
I understand where you're coming from, there would have to be 3 mast sizes, but you gotta remember there are a lot more dinghy's that have one piece masts, so it obviously works, and if we went one piece, it cold open up sail design, and we could possibly get rid of the stupid sail sock
 
Hmm yes it is a meddling little peice of red/white/blue cloth isnt it. Well I usually roll my sail around the mast anyway. It's quick, you know, when you're gonna sail every day in a week or something. On another note: Do you think that flaking a sail is better/worse than rolling? Logic tells me rolling is better.
 
if its a multiple day regatta, I just roll around the mast at the end of the day

other than that, my race sail is rolled around a tube

all my other sails are folded and flaked, I can't afford 10 tubes and Colie sail bags!
 
My approach to rivet position is to put the rivet on the side on the neutral axis which is the position of least stress. I alternate sides between race days, starboard one day, port the next etc. I believe this extends the fatigue life. I also suggest that the mast is end for ended about every two seasons.
 
In the really old days, when masts had two rivets in the collar, I used to have them in each side. the first one I broke was coming out of a nice roll tack in light winds!! yes, it was a bit corroded too. the replacement had just 1 rivet, and by keeping it at the back it lasted until I sold the boat about 3 years later.
These days I still keep the rivet at the back, but as Clive says above, swap ends every two seasons or so. I have to straighten it out a bit to meet the rules!
 
Yes, a lot of the failures I have seen were due to corrosion. It is really important to wash out salt water after sailing with a high pressure water jet. Also if you get to re-assemble the joint yourself - say when you end to end the section, use a corrosion inhibitor like duralac between the rivet and the mast.
 
Wouldn't all of these problems be solved with a carbon top section or sikaflexing the plastic join instead of riveting?
 
abenn said:
I'm sure I saw a design/suggestion somewhere for a 1 piece plastic collar, i.e. the bottom plug and collar joined by a thin tube - fits over the mast but not as thick as the bottom plug so its just as easy to insert the top section. Again you wouldn't have to drill the rivet hole and wouldn't be worried by glue giving way under the collar. The tube would automatically set the collar at the correct position too.
Looks like a simple solution - anyone know if it is being considered ?
Anyone tried buying a bare mast from a supplier ? You could claim to have the old fittings and want to re-install them on a new mast tube - esp when your top section breaks after only 15months (like mine did) and they are still like new.
Click to expand...

This seems like a sensible solution. I personally have never broken a top section sailing Laser and I weigh 240 right now. I have never paid any attention to the rivets either. I am currently using a top section with the one rivet and blue collar. I have a spare that is older and has two rivets and a black collar. I think that a carbon fiber top section or one peice will make the boats go from 5k to 6k to purchase.
 
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