nobody said...nebbian said...IMCS refers to the stiffness, these days it's pretty standard (a 430 is IMCS 21, a 460 is 25, a 490 is 29 etc).
In modern sails, bend curve is more important than IMCS, however most companies don't publish their bend curves, and sometimes they change them without telling anyone 
Luckily there are sites online that have all the lowdown on everything you need to know.
If your sails are older than 2000, then it probably won't make much difference what type of mast you get, just get one that fits!
Yet another reason why the windsurfing industry struggles. If the manufacturers can agree on IMCS, I can't understand why they won't try to do it for bend curve.
Well, it is not quite that simple. The IMCS numbers quoted are pretty nominal. Just because the number on the mast says IMCS 21 does not make that mast exactly IMCS 21 and they usually fall in a range up to a couple of points either side. Not much different to bend curves really............
Because there is often quite a bit of variation between batches, even in the same brand, a snapshot testing of just one or two masts in a given model is still often a bit inconclusive, especially compared with other batches.
Who knows what allowance for variation from spec is considered acceptable by the mast factory?
The only way to really know for sure what you have is to actually test it. A tedious exercise that doesn't help much anyhow as you can't change it anyway. All you can do is try different masts to find what you like best. I admit, I am a bit of a mast collector.........
