The yorker class5 mast that I have and is used by most people here in NZ for class5
was designed in the UK by Mike Hampton I believe and has as its lower section scaffold tube Are the matierials for this type of mast no longer available over there ?
It is made up of
48.6 OD scaffold tube for lower section
44.5 OD x3mm wall tube
38.2 OD X3mm wall tube
31.7 OD x3mm wall tube for top section
Send me a PM if you want a drawing and you can find the necessary sections
The metric dimensions are probably imperial conversions we have moved on in that department here about 50 years ago

Hiko - PM on it's way in a bit. It's frustrating as I know it's got to be doable from whats available but finding it is hard. The metric thing! Argh! I grew up at the supposed crossover - 1973? 1 minute feet and inches, next minute centimeters (then dropped for meters and mm's). I talk to people older than me in imperial, and younger in metric. I did an engineering apprenticeship in imperial after learning metric at school. I designed buildings in mm's built with imperial steelwork and 4" thick bricks. Should of swapped and forced the issue. I could go on....I fact I think I just have Those sizes look findable though 7g and inches!
Landyacht - 2nd hand masts seem to be 370,400,430 in the UK and RDM (worked that one out), all 'buyer collects', fetch decent prices, and on the South coast. In fact, just chatting to the missus, we both haven't seen more than 4 or 5 windsurfers in 10 years despite heading to the coast regularly. Must all be in Devon, Cornwall and Wales. Thats a min 400 mile round trip with petrol at Aus $2.20/L . Hence the original question. I'm struggling for ideas to keep the budget well down.

Cheers Col

(Got SDM, but CMS has drawn a blank - in my climbing days it meant Chronic Mountain Sickness)