I'm sorry. I could not answer before!
Yes, my hakas are standart spineboards. You can get them on ebay or any sanitary equipment shop, emergency shop...
They works fine. You can find more information in another post (pages 26-30):http://www.hobiecat.com/forums/viewtopic.php?f=69&t=37645&start=375
Nohuhu wrote some spineboard adventages:
Low wind and wave profile
Great handles and mounting points built in
Will float up to 250lb ea.
Easy to put neoprene padding on.
All of them are true!!