Does anyone know what bend a old fibrespar 400 RDM mast might be.
Constant curve, hardtop etc.
I'm using this mast on a 5.4 ka koncept and 5.3 Simmer Apex wave and not sure if it's compatible.

Looks like it depends on which specific Fiberspar 400 you have but for the most part, the 6000 series excepted, Fiberspar run just on the slight hardtop side of CC:

www.peterman.dk/masts-all-imcs01.htm

Looking at that Peterman chart, it seems like some were in the 11 point something range witch would probably be too hardtop. Anything in the 13% -15% range should be fine.

The Koncepts tend to set better on RDM masts witch a bit more soft-top (13.5 to 14.5%) in my practical experience, and tend to set too flat on masts with lower %. Likewise, they set deeper on SDM masts (even with the same % curve) which tends to be better for guys 80Kg and over.

Agree with Andrew..it won't work well.

Thanks guys, I've got a KA 400 SDM so I'll try rigging it on that and see if it rigs a bit deeper.

My fibre spar 400 rdm has radius written on this so possibly an older version. I rigged a 4.7m Simmer apex wave sail on it on the weekend and rigged more like a race sail. Battons above and below boom just touching and floppy leach almost back to above boom.
So the fibre spar obviously doesn't suit the Simmer apex wave sail.