would this cause a boat to porpoise??

[fs5]

would this cause a boat to porpoise ????? my boat is an slt boat with a 55hp merc.either way i will be fitting a new crush tube.
http://www.youtube.com/watch?v=89vcs4Nyrmk&feature=player_embedded

[Detroit Whitey]

I have had a long list of things cause this style of boat to porpoise.Will need more info at what speed?how many people in the boat?what did you change that made it start to porpoise? so if i say what will cause my boat to blow over i wonder what response i would get!!!!!!

[fs5]

it seems to only do it when i run cleaver's,i have ran numerous small choppers around 18/19p and the boat runs fine .i also have a pitched up 15p trophy sport that runs like its on rails.although i have tried a couple of new 12x20 and 12x22p merc cleavers and they ran fine.
i'm currently running one of rons 11x18p 4 blade cleavers,the boat runs fine up to about 45mph and then start to porpoise.triming it in helped.
i usually run 1up with about 30kg of ballast in a tub i tie in,the boat always runs better with a copilot when i can get some one to jump in.
speeds are mid to high 50's with the choppers and trophy,and mid50'sto low 60's with the cleavers.