The FX mast is listed at 27' 7" but appears to measure a little over 28'. However, the Blade mast is 28' also. Your comment had to do with mast weight, though. At 230 lbs and 6, I can balance (carefully) the mast with one hand. It doesn't appear all that heavy (I will weigh it.) Possibly you are talking about the mast plus the additional weight of all the accessories? It would interesting to compare the F16 total mast weight with that...
One of the FX One owners at Datchet has tried a Stealth carbon mast on his boat with great success, seems to counter a lot of the problems such as single handers not being able to right the boat and in his opinion seems that it also makes the boat easier to sail. On changing over the masts we measured them against each other with both being almost equal length but the diamonds and spinnaker hoist position being over 400mm higher on the FX one. Weight was the telling stat, over 20 kilos against 13 but more tellingly the FX1 was nearly 10kgs at the tip against 5.5 for the Stealth. Now our scales were only bathroom scales so you could plus or minus that 1/2 kilo probably.
So anybody buying a FX1 should perhaps buy the platform from Hobie and buy a Carbon mast from Stealth marine, bet you would save a lot of money as well.
