thanks prairie tuber,
"Double check the hub prop to make sure it is not spun. This is far and away the most likely problem." - not sure what to look for, is the hub what holds the prop on? how would i distinguish whether it was 'spun'?
i should have mentioned that i have a ply floor, not air deck.
as a newbie i am trying to get as much information out of the older posts as humanely possible, without nagging you experienced guys with things that have been covered a number of times. though many of the threads are just a little short on the info i need personally. i am determined to get my bearings around SIB's, how they work, what impedes their performances, what enhances it, maintenance, outboard basics etc.....