Verbi69,
I have a 2000 280 silencer with a 502. It came with a 24 p bravo I. My boat will blow out a little bit just as it rolls onto plane. (It does that only as it coming onto plane, never any time else.)
I believe the X dimension is pretty high on the 280's. I was going to try a 5 blade some time, or may eventually try a 1" spacer. For now, I like the way it runs. I am used to the slight blow out on take off and it is not a problem.

hey guys theres two ways to measure 1 is make sure your drive is level with the bottom of the boat then check from bottom to prop shaft deep drives are ones 6'' or deeper 7 or 8''. 4 1/2'' to 5 1/2'' middle and 4'' to 1'' high side. also your x is measured by center of gimbal pins are to bottom newer boats with steps seem to be 17'' or higher or if you have a box or notched transom. my baja hit a wall at 76mph for years then I but a 2'' shortie on and picked up 8mph with a carb change too. so figure 4 or 5 with shortie. boat ran flatter in rough to and mid 80s. so if you guys post some numbers I can give you some info on other boats that I know the heights of. my new ride is a SABER 28 WITH A KONRAD drive going on with a box. factory was around 7 5/8 or 8'' it was slow then the owner picked up 2 or 3mph with a 2'' shortie. since I am running a box and the performance lower we are starting with a 3'' high or 17 1/2'' X. with big power hope to break a 100.

when your getting on plane are you trimed all the way down and put your tabs down? if you nail it and send the nose to the moon you will slip any boat plus put a lot of strain on your drive. my boat was 7'' deep on the prop shaft and I blew a prop and also the coupler the 1st year I owned the boat with 330hp from not using my k planes trimming in and nailing the throttle. I mostly throttle it up to 3000rpm and as it falls over on plane pull back and throttle it again with a stock b1 drive for 10yrs with 600hp plus and before with 400hp plus for 4 yrs, then went to a newer b1 with a shortie for 2 yrs until it was stolen. if I can help anyone pm or post back here . and with the spacers you are putting the drive deeper = less performance mostly. so if your cavitating a lot it could be the prop ,there are different 4 blades out there some bow lifting and others transom lifting which will give you cavitation on the wrong hull.

Air Time I could only wish to run 100. Good luck and have fun with that!!
Murf, my 280 blows out exactly like yours...I have to back off the throttle for a second as it rolls over....then throttle up again as it flattens...its the only time I blow out.
What I would like to do is add an extension box to raise the prop shaft height and hopefully pick up some speed....
My boat has a single stepped hull with the notched transom.
Thanks guys,
Mike.

I am super gentle on my boat getting on plane. It ALWAYS blows out as it starts to roll over. It goes again but I think it is always slipping. I can literally rev up the engine while cruising with minimal increase in speed. I feel it is always slipping. 3500 rpm is 40 mph for me. Top speed is 74 gps at 4900. (496ho with 3.5 boost procharger 28 bravo 1 4 blade) I am thinking a spacer will get the prop in cleaner water and help with cruise speed and top end. I am trying to find a couple different sizes to borrow before I spend $400 a crack to try.

Hey Verbie, what kind of speeds are you seeing with your power? Top end and cruising?

SpecialK, if memory serves me correct I think my cruising speed is similar to yours give or take a couple hundred rpm.
I'm running a BBlades labbed 26 Bravo 1 with maximum cup, spinning 5250-5300 rpm ( yes re-mapped ecu).
With this prop, 4 adults and full fuel I have seen 74.0 mph on the gps, the speedo at that speed is only 1 mph off.
Most of the time it is a constant 73 ish.
This spring I will try a labbed 28 with less cup as my 26 to keep the rpm up to where I need to be. Also in the plan is to get rid of the stock exhaust and run headers. I was thinking with an extension box there might be additional mph to be gained as well.

Oh and the only time the boat will blow out is as it rolls over....does not matter if the tabs are down or not.
I can hammer the throttle from a dead stop without blowing out the prop....as the boat rolls onto plane then it blows out...I simply back out of the throttle for a second then I can give it the full throttle again ....and off to the races we go.

I have a labbed 26 bravo so I think you guys with 100-150 more hp are way under propped, you can borrow props from any of the guys that sell them.

I dont have any blow out issues, I was saying the previous owner had issues before the 1" spacer.

I have tried about 5 different props. I could not turn any rpm with a 30. I did not have access to a five blade. It will never be the fastest around, but I was trying to pick up some cruising mph to help with the gallons per minute burned. Of course I would love to see upper 70 mph range even though you can never go out and do that on lake michigan with a 28 footer on most days.

Trying to find the right prop can take some time and requires patience thats for sure.
Not Right, maximum rpm plays an important role in prop pitch selection.
I was able to keep the 26 Bravo 1 I was running before the increase in hp because the engine went from max rpm of 4900 to the now new max rpm of 5350. I also had alot of cup added to the prop which brings down rpm.
That being said I think a labbed Bravo 1 28 pitch with little to no cup would be a good fit and keep me in the rpm range and give me more mph.
Thanks my thinking anyway....