Reply With QuoteI have an Ultra 247 with an HO and run a 26.5P labbed Bravo 4 blade. I run 79 mph on GPS. But, I do need the trim tabs when going that fast.
Hey all. Was just trying to pick some brains here. I have a '06 247 genesis with a 496 HO runnin I belive a 4 blade 24p prop. I have 30 hours on the motor and I have gotten the boat up to 78mph on the speedo.( save it I know this is off because a regular speedo isn't accurate.) I was at 75mph before at about 20hrs. Is this thing gonna wake up even more? Oh by the way the way I am hitting 4800 rpm trimmed out. Oh the other question. If I changed out props what would give me better top speed? and what does labbing do. and what does it mean? thanks in advance. One more question. If Merc says that the optimal rpm range is 4600 to 5000 does that mean that I cannot exceed this range?.....thanks again.
I have an Ultra 247 with an HO and run a 26.5P labbed Bravo 4 blade. I run 79 mph on GPS. But, I do need the trim tabs when going that fast.
I have an Ultra 247 with an HO and run a 26.5P labbed Bravo 4 blade. I run 79 mph on GPS. But, I do need the trim tabs when going that fast.
thor I wasn't quite sure. But is the 247 genesis the mold form Ultra? I know they aquired it from someone just wasn't sure exactly who. What are you rpm wise. And what did it cost ya for the prop? When you ran that fast what where the boat conditions. Alone? gas at what level?...I know what you mean. When i ran that fast the boat started to walk on me. Was thinking about gettin some tabs from Eddies marine.
It's not possible to go over 73mph with a 24 pitch prop at 4800rpm. That is the max speed with 0% prop slip.
At 10% prop slip your speed would be 66mph at 4800 rpm's.
It's not possible to go over 73mph with a 24 pitch prop at 4800rpm. That is the max speed with 0% prop slip.
At 10% prop slip your speed would be 66mph at 4800 rpm's.
So the speedo is that far off? I swear the damn thing said 78. at 4800 rpm. Sorry for the ignorance but what is prop slip?
Sorry for the ignorance but what is prop slip?
Here:
http://sites.mercurymarine.com/porta..._schema=PORTAL
So the speedo is that far off? I swear the damn thing said 78. at 4800 rpm. Sorry for the ignorance but what is prop slip?
I don't know all the calculations for prop slip and all that. If you do a search you should find it. What I do know is you may be mistaken about your RPM or you got a bum deal and paid for an HO and only got a 496 Mag. Max RPM on the 496 Mag is 4800 whereas the HO max RPM is 5300 I believe.
So the speedo is that far off? I swear the damn thing said 78. at 4800 rpm. Sorry for the ignorance but what is prop slip?
In a perfect world for every revolution of your prop your boat will move forward 24 inches. That doesn't happen. Your prop will slip and you won't move forward a full 24 inches. The less slip, the more effecient your prop and set up is. Mathematically your boat can only go so fast at a given rpm with different sized props.
Unless your speedo is gps it could have very well said 78.
I don't know all the calculations for prop slip and all that. If you do a search you should find it. What I do know is you may be mistaken about your RPM or you got a bum deal and paid for an HO and only got a 496 Mag. Max RPM on the 496 Mag is 4800 whereas the HO max RPM is 5300 I believe.
I think the HO is 5150.
Here:
http://sites.mercurymarine.com/porta..._schema=PORTAL
Nice link.
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