Hmmm, I'll try to be objective. I have a 430 and 460 80% SDM (drop shape). Great masts considering price although the 430 cracked at the ferrule after second use (it was taped at the joint, so no, there was no gap between the joint). The broken section was replaced promptly but compared to the better named masts on the market (from experience - Severne & Tushingham) their production quality appears slightly inferior and weight significantly heavier than above mentioned masts. Irrespective of how they look though, I have found them to be great for the sailing I do (open ocean) and now believe I just got an unlucky mast initially.
From a technical aspect, ensure your boom can fit snuggly onto the slightly smaller diameter (but not quite RDM diameter) as a RDM shim wont work e.g. a maui SDM boom head can't get a tight enough grip onto Sunshine Mast and the RDM adapter is too small.
I have a Sunshine drops 80% 460 and it broke on Friday morning. I always tape the join and I do not use a winch for downhauling. The spigot or ferrule broke and the bottom end of the mast top also expanded.
Herb, Maybe it wasn't just "an unlucky mast". That's basically what happened to mine. I resleeved the ferrule with a tip off an old mast and took about 5 mm off the damaged end of the top section. Seems to work okay but don't count on it being in my quiver much longer but I still have the replacement bottom section.
I'm wondering if the tape might be the problem. There can be quite a bit of force pulling the two sections apart when rigging up some sails, possibly more than the tape can handle if it doesnt stick very well. I never tape my masts but before I apply downhaul I run my finger along the mast sleeve to feel for the joint. Even if the sections are a millimeter apart you can feel the gap through the luff sleeve. Sometimes the two sections can be 1 or 2 cm apart, even after I went to some trouble to keep them together. I then push the two sections together and I only apply downhaul when I can't feel any gap between the mast sections. If you can't feel where the joint is then you can take it that the two sections are together perfectly. If you tape the sections together, this will probably make it difficult to detect any gap between the mast sections.
spend the extra dollars and get an Ezzy or Severne mast,they are both popular here in Geraldton because they can handle the conditions."If you buy cheap you buy twice"
I have a Sunshine 430 that I got with my first rig a few years ago that is still going strong. It has been my most used mast, surviving numerous catapults, crashes and bashes. I always tape the joins as the ferrule is quite tight and can be a pain if sand gets into it.
Same story as Sausage, 430 Sunshine Infinity, btoke at the mast join after a few sails, was actually just lying on the grass before use when it went, it was also taped together so no gap issues. Lower half was replaced on warranty promptly and has had no problems (1 year since). Nice mast to use but I'll go to KA masts next time round.
havent had a problem with my 80% 400 rdm mast had a few big wipe outs, like landing upside down from big endo forwards, but mainly use it for freestyle
