36% slip?
 

took my 2004 magic wizard out for the first time yesterday and only ran 61 mph. that was @ 5000 rpm with a bravo 4 blade 30p prop. any ideas on what i should do. 1.5 ratio xr drive with a sportmaster lower. it would run 55@ 4300. this was at 5400ft of elevation but i think it should still run better. i'm new to the performance boat thing so any help would be great. thx, Tony

I calculate 31-34% slip at either elevation. Something is very wrong here. If these numbers are correct, you will be running a low 20's pitch propeller once the slip is harnessed.

What engine are you running and has the propeller ever been repaired or adjusted?

Brett

it has a 575sci with an intercooler pushing 8lbs of boost. i just bought the boat. it was a repo so i dont have any history. it looks like it has never been repaired but i really dont know.

i tested it several times yesterday. at 5000 rpm max speed on my gps was 61??? i have no clue which direction to go.

The elevation affects make sense and fall within the parameters of change. However, the performance is lack luster. From the little I know about this so far, it seems there may be engine and set up/propeller issues.

I'd try another propeller of smaller pitch and check the results.

Also, is the XR a shorty and how low below the boat bottom is the point of the gear case? Or is it above?

Brett

My guess is that your x dim is way off. I bet that your drive is to high with the shorty. That is why you are spining a 30p at 5000 rpm and only going 61. What is the prop shaft from the bottom of the at now?? You could also try going to a 5 blade but I would guess with that much slip your drive is way to high. IMO Brett will get you going the right way he know his stuff.

i just measured from the middle of the nose cone to the bottom of the boat is right at 6in. what pitch should i try?

He's running sci - shouldn't change w/elevation.

Definitely a problem with setup and/or engine.

An overly high x-dimension could cause major slipage like you're seeing. 6-inches seems high for a Wizard. If you drop the hammer at, say 4000 rpm, are you seeing a quick spin up to 5k? Could be aerating your prop.

Can you double check your prop size?

We had a nice conversation today and we have a game plan.

We'll wait to hear back on some possible water pick up issues. After that there is the propeller and then the engine and then back to the propeller. 1 step at a time.

CC, we are talking 6" below not above. This would be a conservative "X" dimention, not aggresive. Also, sci's are affected by elevation although not as severly as NA's.

Brett

So do we have a pick up that is messing up the water infront for the prop??? 6" sounds low to me. Keep us posted with the out come.