I looked up the Dragoon specs found them on :
http://www.hobiecat.nu/html/batar/dragoon.htmlassumed a luff of 3,75 mtr. for the jib based on the ratio's between mainsail luff and jib luff of other boats.
Punched in the numbers in the Texel calculator found at :
http://www.geocities.com/kustzeilen/excel/tr_calculator_2002.xlsAnd arrived at a Texel (estimate) of 142 for a spi less dragoon and 138 for a dragoon with spi.
A hobie 16 has 116. But better would be to calculate the D-pn for the dragoon by taking the Prindle 16 D-PN.
So the D-pn estimate for the dragoon becomes
138 / 119 * 77,8 = 90,2 for the spi dragoon and
142 / 119 * 77,8 = 92,8 for the spiLESS dragoon.
Hope this helps. It may be wise to check the dragoon input data I've used as these may differ from webpage to webpage.
www.google.com and typing "Hobie dragoon" should work well
Wouter