In case you don't frequent the old forum, here is a post by Bill Roberts in regard to your question:
Posted by Bill Roberts from 216.76.180.23 on August 01, 19103 at 08:53:56:
Hello New Forum User,
My password stopped working today on the 'new forum',
so here's a source for the mast you need....Check with Tom Haberman at Aquarius Sails, Aquarius-Sail.com web site. He makes masts for C and D class catamarans and RC27s and RC30s etc. The carbon laminate and overall mast length can be tailored to your needs.
Good Sailing,
Bill