Measure the length of your mast. The standard Hobie 18 has a mast length of 28' 1". The 18SX has a mast length of 29'7". Chances are your 1984 boat still has the original standard length mast that it came with ifrom the factory. That said, you should still check because it would have been easy enough for a previous owner to upgrade the rig to an 18SX. "Magnum" simply refers to a style of wing seats Hobie offered. These are the more commonly found shorter wing seats that don't extend fore and aft beyond the front and rear crossbars.
Use two screwdrivers, one in each end, on the thimble or fork hole of the shroud and measure from the outside of each screwdriver. This is the best way to determine what you need in a shroud.
If you are using a shop to make the shrouds, take a picture if you can of the end measurement and send it to them.
Edited by klozhald on Nov 15, 2012 - 12:06 PM.
-- Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA --