Prop Slip

Motoxxxloak · Jun 26, 2017

I am sure there is more info/testing needed and if so, I will do it this weekend.

I ran some numbers on the Merc app and this is what it came up with. I did some research as well and it appears there could possibly be some hub slip? Aaron (Absolute) suggested I get a new hub kit when he gave me some props to try but I have not done that yet.

Current prop is a 30p Merc, 540 quad rotor motor.

gmnhra · Jun 26, 2017

Is that the prop that was on the boat when you bought it??
I thought it was a 32 non labbed...
as I recall...3200 rpm was right at 55 mph...
As I am sure you know...the less the slip...the more stress on the drive...the more opportunity for drive failure...

hope to see you on the water one of these days...
look for the old guy on the pontoon...no new "fun boat" yet...

Motoxxxloak · Jun 26, 2017

gmnhra said:
Is that the prop that was on the boat when you bought it??
I thought it was a 32 non labbed...
as I recall...3200 rpm was right at 55 mph...
As I am sure you know...the less the slip...the more stress on the drive...the more opportunity for drive failure...

hope to see you on the water one of these days...
look for the old guy on the pontoon...no new "fun boat" yet...

No, I took the 32 off as it did not really work when there was 6 people and full fuel.

I feel it should be around 14% to 17%. I will be out there this weekend. Will keep an eye out for you

MooreMoney · Jun 26, 2017

Go to Gibbs propeller and have them work the prop. They will want a top end speed number and rpm to dial it in. They do great work.

Motoxxxloak · Jun 26, 2017

MooreMoney said:
Go to Gibbs propeller and have them work the prop. They will want a top end speed number and rpm to dial it in. They do great work.

I just had it worked by Auggie at Cutting Edge. The slip numbers didn't change at all.

I think I may need to try another prop. It is great once I get on plane but am still having some issues getting on plane. I was told to stay away from the 5 blades as the drive will not like it. Any other ideas?

RiverDave · Jun 26, 2017

The slip #'s are going to be high at slower cruising speeds. Generally people tend to dial them in at WOT. If you are looking at more efficiency going slower than I'd go to a larger diameter prop, or a 5 blade, and be gentle with the throttle.

RD

Don Johnson · Jun 26, 2017

Your cruise speed prop slip does not look that bad for a 4 blade IMHO. I bet if you measure the slip at 75-80 MPH, when the boat is freed up, the prop slip % goes down fast. A 5 blade would definitely help you but the trade off is they are harder on the drive for sure due to the reduced slip.

My boat for example with #6 drives, twins and 5 blades I see prop slip in the 20% range until the boat frees up after 70 MPH, then prop slip progressively goes down to single digits. I can play around with the trim at low speeds and get the props to bite much harder by burying the prop but cats need positive trim at slower speeds to work right so it is a tradeoff.

boatnam2 · Jun 27, 2017

I have everyone stand by the dash when coming on plane, illegal for sure but night and day for popping the boat up without propping down or hammering drive.

LargeOrangeFont · Jun 27, 2017

boatnam2 said:
I have everyone stand by the dash when coming on plane, illegal for sure but night and day for popping the boat up without propping down or hammering drive.

Unsafe savage!!

stokerwhore · Jun 27, 2017

boatnam2 said:
I have everyone stand by the dash when coming on plane, illegal for sure but night and day for popping the boat up without propping down or hammering drive.

Pirate status!

boatnam2 · Jun 27, 2017

Capt morgan shuffle.

wzuber · Jun 27, 2017

boatnam2 said:
I have everyone stand by the dash when coming on plane, illegal for sure but night and day for popping the boat up without propping down or hammering drive.

http://www.riverdavesplace.com/forums/images/smilies/yikesj.gif

that's comical, when I was a kid we used to have to do that in our pos. 16' glasspar out board, used to annoy the chit outa me. To think of having to do that in a high dollar, hi h.p. super bling boat is just incomprehensible to me.
Maybe try a different impeller? lol

Runs2rch · Jun 27, 2017

wzuber said:
http://www.riverdavesplace.com/forums/images/smilies/yikesj.gif

that's comical, when I was a kid we used to have to do that in our pos. 16' glasspar out board, used to annoy the chit outa me. To think of having to do that in a high dollar, hi h.p. super bling boat is just incomprehensible to me.
Maybe try a different impeller? lol

Hahaha right? A little tab to get her over?

gmnhra · Jun 27, 2017

A great resource in Havasu for setup and prop/x dimension/etc. is Thane at Nordic....
don't hold me to it but folklore says he assisted, or was responsible for, the tooling of the 25 Daytona..

He is a wealth of info on tunnels

Having played with that setup for many years...the result was adding some cup to the 32 pitch prop (hull actually likes a bit of stern lift and likes to run "flat"...not nose up). this also helps with reducing bow rise on take off.
my launch routine was
bury the tunnel tab
bury the drive
throttle to approx. 3k rpm
boat would start to roll over ...add throttle to "edge of prop blow out"
boat would roll over..
raise tabs to full up
raise drive to about +3
adjust throttle for 50 mph cruise..
raise throttle to 60 mph cruise to get the boat to free up a little (more aero lift)

for higher speed runs...I would typically lower the drive a bit to "0" to let the boat run flat...

Hope this helps

For comparison:
pontoon:
turn on stereo
have a refreshment in cup holder
push throttle forward
recline captains chair for comfort
cruise at a blistering 35 mph down the lake

GM

BDMar · Jun 27, 2017

Just FYI. XR drives are 1.35:1 That improves your slip numbers by almost 2%

As already stated, your slip numbers will decrease dramatically as the speed increases and drag is reduced.

At 60 mph I am about 25% depending on which props are on and how many people are in the boat. At speeds not mentioned my slip drops to somewhere around 10% depending on people and props. Adding 3 people to the boat increases the slip a surprising amount.

fishing fool · Jun 27, 2017

How do I find out what gears I have in my bravo outdrive???
496mag eliminator 220eagle

LargeOrangeFont · Jun 27, 2017

fishing fool said:
How do I find out what gears I have in my bravo outdrive???
496mag eliminator 220eagle

Probably 1.5.

It will be on the drive sticker. The big blocks got 1.5 ratio drives typically, the small block got 1.65 ratio drives for the most part.

Although on the port side mine says SEE OTHER SIDE and the ratio is stamped on the starboard side of the sticker on the drive.

fishing fool · Jun 27, 2017

Is 13.9% good?? I did it on two different sites and 14% was it.
23 pitch
3200rpm
1.5 gear
40mph

LargeOrangeFont · Jun 27, 2017

fishing fool said:
Is 13.9% good?? I did it on two different sites and 14% was it.
23 pitch
3200rpm
1.5 gear
40mph

Yea. For us low powered boats, that is good.

What is your slip on the top end? single digit to mid teens is good.

I'm at 10% slip in optimal conditions for my top end.

@ 50 MPH my slip is 14%

24 pitch
1.65 ratio
4200 RPM
50 MPH
14% slip.

fishing fool · Jun 27, 2017

I don't run wot much so I am not too sure on the speed but here is what I think it is with this prop
23 revolution. I'm on the limiter with throttle left.

23 prop
1.5 gear
4800rmp
65mph
7 slip

LargeOrangeFont · Jun 27, 2017

fishing fool said:
I don't run wot much so I am not too sure on the speed but here is what I think it is with this prop
23 revolution. I'm on the limiter with throttle left.

23 prop
1.5 gear
4800rmp
65mph
7 slip

When I ran the Rev 23 I think my prop slip is down to 8 or 9%. I still need to really test it to get an exact GPS speed. The B1 24 definitely has more prop slip almost everywhere in the rev range.

boatnam2 · Jun 27, 2017

wzuber said:
http://www.riverdavesplace.com/forums/images/smilies/yikesj.gif

that's comical, when I was a kid we used to have to do that in our pos. 16' glasspar out board, used to annoy the chit outa me. To think of having to do that in a high dollar, hi h.p. super bling boat is just incomprehensible to me.
Maybe try a different impeller? lol

Yea its only for a second, the other option is not a get a ride in boat lol.

Motoxxxloak · Jun 28, 2017

boatnam2 said:
I have everyone stand by the dash when coming on plane, illegal for sure but night and day for popping the boat up without propping down or hammering drive.

I do the same thing. It just becomes a hassle at times but takes 5 seconds to accomplish what I need

Motoxxxloak · Jun 28, 2017

gmnhra said:
A great resource in Havasu for setup and prop/x dimension/etc. is Thane at Nordic....
don't hold me to it but folklore says he assisted, or was responsible for, the tooling of the 25 Daytona..

He is a wealth of info on tunnels

Having played with that setup for many years...the result was adding some cup to the 32 pitch prop (hull actually likes a bit of stern lift and likes to run "flat"...not nose up). this also helps with reducing bow rise on take off.
my launch routine was
bury the tunnel tab
bury the drive
throttle to approx. 3k rpm
boat would start to roll over ...add throttle to "edge of prop blow out"
boat would roll over..
raise tabs to full up
raise drive to about +3
adjust throttle for 50 mph cruise..
raise throttle to 60 mph cruise to get the boat to free up a little (more aero lift)

for higher speed runs...I would typically lower the drive a bit to "0" to let the boat run flat...

Hope this helps

For comparison:
pontoon:
turn on stereo
have a refreshment in cup holder
push throttle forward
recline captains chair for comfort
cruise at a blistering 35 mph down the lake

GM

I am going to give this a whirl. I've been doing it slightly different!!!!

boatnam2 · Jun 28, 2017

I ran the merc slip deal, says i running 128 mph, so not to sure about acuracy.

Bigbore500r · Jun 28, 2017

boatnam2 said:
I ran the merc slip deal, says i running 128 mph, so not to sure about acuracy.

Must be using the 2FF slip calculator!

fishing fool · Jun 28, 2017

boatnam2 said:
I ran the merc slip deal, says i running 128 mph, so not to sure about acuracy.

How does it say you are running that? How do you know the slip???? You put in all the other factors and it came up with the speed?

LargeOrangeFont · Jun 28, 2017

fishing fool said:
How does it say you are running that? How do you know the slip???? You put in all the other factors and it came up with the speed?

He probably put in 0 slip and got the max theoretical speed

boatnam2 · Jun 28, 2017

Looks like Im running a slip factor of 11 or so, 31p 1.5 drive at 5900.

Bigbore500r · Jun 28, 2017

I ran the numbers for my boat, looks like at 35-40mph Im at 25 % slip, and when running 68 im down to 13 percent. Normal?

Don Johnson · Jun 28, 2017

yes sir, that's looks in line. Your boat is just getting freed up at 68 and the slip numbers would keep going down with more speed

You at the river house next week? If so we will be on and off the water all week and will rattle the windows a few times.

Runs2rch · Jun 28, 2017

Don Johnson said:
yes sir, that's looks in line. Your boat is just getting freed up at 68 and the slip numbers would keep going down with more speed

You at the river house next week? If so we will be on and off the water all week and will rattle the windows a few times.

We have a 335 hallett. used the calculator. With 5 blades is 7-10 percent slip possible?

Don Johnson · Jun 28, 2017

Runs2rch said:
We have a 335 hallett. used the calculator. With 5 blades is 7-10 percent slip possible?

As a rule of thumb twins run less slip. That said, 7-10% slip at higher speeds is certainly possible, especially with 5 blades.

boatnam2 · Jun 28, 2017

Don Johnson said:
As a rule of thumb twins run less slip. That said, 7-10% slip at higher speeds is certainly possible, especially with 5 blades.

So what is the slip telling us? Say if were turning max RPM at WOT throttle with a 4 blade, is it possible to have better low end slip numbers or more driver friendly(plane better) at low speed and still have max RPM at WOT with a prop change? This is on a single engine cat.

Boat 405 · Jun 28, 2017

25 Daytona, imco -2 lower, xr drive, imco standoff box

28pitch prop

5900 rpm

96 mph

1.5 gear

8 % slip

That was bone stock 28p prop. Just sent it in to get cleaned up, labbed and detailed. We will see the difference if any soon.

Don Johnson · Jun 28, 2017

boatnam2 said:
So what is the slip telling us? Say if were turning max RPM at WOT throttle with a 4 blade, is it possible to have better low end slip numbers or more driver friendly(plane better) at low speed and still have max RPM at WOT with a prop change?

As a rule of thumb you want to prop a boat to run WOT in alignment with its power band, which with Mercury's is the rev limiter. So in tuning/propping the boat there is always give and take. Prop the boat to capably pull the WOT RPM you want and is aligned with the boats power band, and still be able to be driver friendly out of the hole and cruise speed.

That all said, minimizing slip is always a great goal but IMHO people tend to get too caught up in making that their only goal. I am of the opinion that some slip is good for lots of reasons, hole shot and acceleration are just a few of them. It really is a trade off/ give and take to balance the performance of a boat and any bravo powered boat that has WOT slip in the low teens is a good balanced boat. It really comes down to how a person wants to use their boat. If out of hole and mid range cruise speed is the real goal, a 5 blade is best. It extracting every last MPH is the goal, a 4 blade tends to be faster due to 1 less blade creating drag, the trade off being more slip. I am no prop or boat setup expert and these elements are best directed to a prop expert whom will take all your input and suggest a prop that meets your goal and boats specific needs.

boatnam2 · Jun 28, 2017

Don Johnson said:
As a rule of thumb you want to prop a boat to run WOT in alignment with its power band, which with Mercury's is the rev limiter. So in tuning/propping the boat there is always give and take. Prop the boat to capably pull the WOT RPM you want and is aligned with the boats power band, and still be able to be driver friendly out of the hole and cruise speed.

That all said, minimizing slip is always a great goal but IMHO people tend to get too caught up in making that their only goal. I am of the opinion that some slip is good for lots of reasons, hole shot and acceleration are just a few of them. It really is a trade off/ give and take to balance the performance of a boat and any bravo powered boat that has WOT slip in the low teens is a good balanced boat. It really comes down to how a person wants to use their boat. If out of hole and mid range cruise speed is the real goal, a 5 blade is best. It extracting every last MPH is the goal, a 4 blade tends to be faster due to 1 less blade creating drag, the trade off being more slip. I am no prop or boat setup expert and these elements are best directed to a prop expert whom will take all your input and suggest a prop that meets your goal and boats specific needs.

Thanks for the info, here is my set my set up, a lavey 27 sabre, teague 800, teague drive, no tabs, spinning a worked 31 4 blade 5900 rpm not sure speed i never look down and rarley hold it wide open to let it build to max sped, i like the 40 to 80 mph speed currently, but just cruising boat probably 85% of the time( girlfriend not really into hauling ass) it really lags, i would like to improve that, so i may try a few different props, boat was set up almost 15 years ago so Im guessing there may be something that could work better then current set up.

Bigbore500r · Jun 28, 2017

Don Johnson said:
yes sir, that's looks in line. Your boat is just getting freed up at 68 and the slip numbers would keep going down with more speed

You at the river house next week? If so we will be on and off the water all week and will rattle the windows a few times.

No Sir, we wont be back up there till Labor Day! Got some other trips planned, this summer is kinda hit and miss in July / Aug

Prop Slip

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

In it to win it

Don Johnson

Well-Known Member

We aren't happy until you aren't happy

aka bordsmnj

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

B & D Marine

Well-Known Member

We aren't happy until you aren't happy

Well-Known Member

We aren't happy until you aren't happy

Well-Known Member

We aren't happy until you aren't happy

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

We aren't happy until you aren't happy

Well-Known Member

Well-Known Member

Don Johnson

Well-Known Member

Don Johnson

Well-Known Member

Well-Known Member

Don Johnson

Well-Known Member

Well-Known Member