Ok I read the porposing post that Jetboatunderground posted. I am having issues with this thing above 75MPH (78.9MPH to be exact). It scares me that I have to get out of it. I know this boat will do 85MPH if I stay in it but I can't it slaps so bad it wants to throw me out of the boat. It rides dead smooth at about 4000 RPMs but when I hit the go pedal it screams to 6k and I can only stay in it for about 3 seconds and that is it. By the way when I do this it sounds like a screaming cat.

Here is my set up.
A violent BBC EFI 8-71 dynoed at 730HP at 6100 RPM. Nordic bubble deck, full stringer. Berk JG, stainless A impeller, no droop, 4 degree wedge up, manual new style place diverter (set in middle for my runs). Rideplate set at 2 degrees up. Jetboat Performance loader set right exactly at zero at the keel.

Please help, if I can just get this thing to settle and ride smooth I would not be so scared of it.
I want to keep the bow up and keep the boat aired out, I guess I want my cake and eat it too.
Thanks.
T.J.

TJ...

Having driven white water boats for nearly a decade, let me tell you that what you are experiencing is very dangerous, so please be careful...

Now that that is out of the way.......

I would try eliminating the wedge for now (you can  put two wedges 180* out from each other), giving you 0* down and "zero" the ride plate. This is your starting point. You should be able to get a little more Diverter out of it at this point. On a hull like yours, i would say optimum rooster height would be about 6' high( but may take more/less depending on the center of gravity.

The droop being down with a raised rideplate is more than likely causing a rocking chair effect and is very scary...

I have probably already seen pictures of it, but do you have an early or late Diverter design? the early ones cannot be used with a droop, the later ones have a flat ride surface on them that works very well with the droop...

Good luck and stay after it, it sounds like that thing is going to be stupid fast....be careful...

GT

take out the intake grate. to long of ramps, you are probably over charging the pump, try a old fashion angle grate on it. how deep of shoe are you running?

The biggest problem with the late 70's Nordics are usually the bottom. Orville popped the boats out of the mold to soon and most of them have bad hooks in them. I just blue printed one this last winter. No matter what I did the boat would just porpose. At one point I put the ride plate 2 degrees below the keel, The boat rode awesome until about 70 then it would just slap violently like what your describing. It was fukin scary, but after we straightened out the bottom is rides smooth as glass. I dont know if you have ever looked at the bottom of your boat but it might be part of your problem. I one we did was hooked on one side and a huge rocker on the other. We build the bottom of the boat up an inch on one side.
Matt

TJ heres an extreme "hook" example that were dealing with right now on a Miller to give you an idea

TJ its actually a 3/8 drill , its some of the worst (and longest ) we've seen its mostly surrounding the areas that the outer "shorty bunks" set on (worse on right than left) , a few have speculated the boat was maybe "green"  when set on the trailer Tom