Posted: Apr 21, 2011 - 04:27 PM
if you want to convert from old shallow/dangerous mast base to the newer, deeper, pin-able system you need to buy and use the whole 5? part kit
this is because the older system, as well as having a semi-dangerous free mast base, was also found have a slightly too thin/weak stainless dolphin-striker rod which would eventually bend or even break, (a broken DS while sailing hard 2up usually results in catastrophic failure of the front beam) 
so when nacra went with the deeper cup on the mast base, (to allow space for a retaining pin to keep the mast on the ball at all angles) they also went for a thicker, and longer, stainless rod for the DS with matching nuts and washers, which in turn meant a slightly bigger nylon ball at the head for the mast to turn on
so there is something like 5? new parts that make up the captive kit and none of them are inter-changeable with the older system......also the older 1.4"? nylon mast balls are no longer made or stocked by nacra
if you trailer the boat to the beach and are raising and lowering the mast often you should really go with the new system for safety
as my 5.2 has mast up beach storage during the season on a small lake i have remained with the older system
the twice a year i am raising or dropping the mast, solo, i simply flip the hulls over on their side and prop it up on some ladders while i connect the stays....i figure if there is no risk of dropping the mast on anyone/anything i don't need to go to the hassle of ordering, importing and fitting the new system
video below shows a few things
http://vimeo.com/5075989?ab
1. it's quite possible to sail the 5.2 solo, easier than the hobie16 for example
2. this is because you can sail it without the 4m2 jib, but be ready to blow the traveller for tacks in strong winds
3. if sailed solo the tramp bar doesn't get in the way as the helm has plenty of space to get under the sail in the tacks/gybes, (it also helps support the 5? times restitched 30 year tramp.....however crew finds it a struggle to cross as the boom comes down to the mast so there is only about 2feet above the bar
4. the long/full bows on the 5.2 don't even look to pitchpole with only 1 up
5. you can go a long way with a few cans of enamel if you have time and an idea