10x

Just put a "new" pair of Mercury CNC'd 18x35 5 blades on the boat. Running a 1.50 drive ratio, dry sump VI's. Figure I've got around 20% slippage. Tried a pr a Herring's 18x35's and it was worst 29%.

Last year, I ran 18x32 5 blade plain Mercury props, not the CNC'd ones. Boat ran 5850 rpm, 103-104 mph, on GPS, non salt water. Now there's another 150+ hp per side, so they tell me to run a 34/35 pitch prop.
Tried a set of Herrings, 18x35's in salt water, boat ran 103 @ 6200 rpm. Terrible !!!
Got a new pr of CNC'd 18x35's from Mercury, and the boat runs, 62/63 @ 4K rpm, 74 @ 4500, and 85 @ 5000 rpm. At 6150/6200 rpm I've seen 108, and possibly might've climbed to 109/110 if I would've stayed in the throttles another minute or 2. It took about 10-15 seconds to go from 107 to 108.

Now, according to my calculations, these props have around 20 % slippage. Last year when I ran the plain 18 x 32's, it would run about 62/63 mph @ 3700/3750 rpm, and at WOT (5850) it ran 103 tickling 104, and I figured I had about 12 % slip.

Now another set of "new" Merc CNC'd props that are 17.5 x 38 5 bladers run 111 mph @ 5750 rpm. That too, shows about 20 % slip too. What the he!! is wrong with mercury props lately??? I can't believe that 2 brand new sets of props, have 20 % slip in them, and my old 32's have 12 %. Are all these new props that bad??? I never seen nothin like this in my life, and now, where do I go from here ?????

Just plain phuckin frustrated !!!!!

Frank

RunninHotRacing163.1

Frank let me know what ya find out i spent a bunch of Bretts time on the phone this week and was gonna order a set of Merc 17 X 38s and the new Mercs are suppose to be the Cats azz ..... When we tried them before against the herings we gained 3 mph with the Herings ... Are you tradin the new ones back in or gonna sell them ?????????? u got my # BIG Daddy

bbladesprops

No the new Merc props are not bad. You do see a 9% better slip number with the Mercs over the Herings.

The old Mercs would actually be 33 pitch propellers and the slip would be in the 15+% range.

What current HP and rake angle propeller are you using from Mercury?

10x

Mercury told me that on a V-bottom, the rake angle does'nt make a difference, only on a cat. The hp is 1150, compared to 975 last year. They say to run one # bigger in pitch when using the Herrings, but the Herrings that I tried had about 29 % slip.
Brett, we called you twice today, and the girl told us you were in the back shop. If you could call me back, anytime, I'd like to see what your opinion is, and if there's anything you could do to help this situation.

I remember the props have a # on them and they say 850 hp. I'm gonna go in the shop and write down all the #'s off the boxes, now.

My cell # is 708-870-2572, thanks alot for your time, Frank.

10x

Just looked at the box, it says, 15* CNC lab finish 850 hp.
pt # 48-8M0003465, and there's another # on it also # 91048.

Still at 15% slip, that's better than 20.

P Offshore

Wipe the grease off maybe they will quit slipping......

10x

Thanks Eric. I knew I forgot to do something before I put them on. I guess I figured that for how much they charge for them things, that Mercury woulda wiped them off for me. So much for me figurin.