Old Spars

O

Owyn in Barnsley

New Member
My spars are pretty old, has anyone noticed them losing some sprininess as they get old? For example, when I let my kicker off it doesn't go all the way off when my mates with a new boat does (the kickers are the same length).
It got me thinking that a spar that is easy to bend would give less leach tension than a stiff one, this is obviously the only thing stopping me from winning the olympics.
 
If you want to test this it would be easy to do so.

Method 1
Get a fish scale see how much pull is required to pull in a given amount of line on both boats. If yours is easy to pull relative to his and they have the same vang system then your mast is not as stiff (assuming the same vang and sail of equal age and condition).

Method 2
The other way (a better way because it eliminates all the variables besides the mast) would be to place the two masts over saw horses and put a weight at the tip and measure the deflection. If yours is softer it will deflect more.

I only have old stuff so I have no idea if they degrade with age. I would think that they would work harden and become stiffer (more easily broken because they are now brittle) a question that should be answered by someone more involved in metalergy than I.



PS Congratulations on the upcoming Olympic gold.
 
157800 said:
Spars actually get stiffer with old age. Maybe your spars are bent?
Click to expand...

that actually makes sense now that i think about it... case hardening.

not uncommon for the top section to be benta little.
 
I thought case hardening was when steel was raised to a locally very high temperature in a carbon monoxide atmosphere then quenched after, hence super saturating the steel with carbon, which makes the outside of the steel hard (it's case) often used in rollers where the part must be resiliant but have a hard surface.
 
ok.. i am no metalsmith and i believe what you say , but i believe that aluminium, does get stiffer when bent back & forth... to a degree... then it breaks.
Also, as I recall hard anodized aluminium is significantly stiffer than otherwise.
My term was incorrect.
 
Though the spars are aluminum and harden with age, the vanguard spars will permanently bend a little when used in over 12 or so knots. The euros won't. Call it whatever you want, but I have a 30-year old spar and it gets a lot more permanent bend in it than a new spar gets.
 
I did a little looking in an old Eng. text of mine and have found that in aluminum case hardening is not what happens. It is referred to in the text I have as "Work hardening" or if it is done artificially it is called "artificial ageing"
 
I sound like a right know it all but work hardening only occurs when something is loaded beyond it's yield point, i.e. try bending a coat hanger, it's very difficult to get it to bend back in the same place, if your spars are to stay straight then no work hardening will occur as all the deformation is elastic.

there is a process in aluminium called age hardening, this can be done artificially by elevating it's temperature for about a day in a high carbon environment.

I was thinking that as a spar (particularly a laser one) gets bent back and forth that some fatigue could be occuring and the growing cracks limiting the amount of material available to take the stress and therefore being easier to bend (before they break!)

Perhaps I should just buy some new ones!
 
A dye penetrant test would be cheaper than new spars and would reveal any cracks - but presumably you could economise still further by finding out if spars fail and where they fail.

Russell
 
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