Goody76

Has anyone used with a positive gain as far as speed, handling and lower slip than four-blade. I have a single cat with prop in the tunnel turnning a 4-blade merc that seems to be slipping at 22-24% which is much to high.

cobra marty

I would try to fix your boat first rather than try a 5 blade. What hull, drive, engine, X or propshaft to bottom of sponsons, center pod, weight? What props have you tried?

Thunder Roy

I HAVE A PAIR OF 28 PITCH HERRINGS FOR SALE

BillR

I'm game; how much?

Goody76

cobra marty- The hull is a 28 profile cat with a center pod stepped bottom. The drive is a 1.50 imco xr with a standard imco lower. The bullet of the nose cone sits about 4 inches lower than the center pod. The engine is a whippled 500hp/efi. Boat weight is about 4650lbs. I am currently running a labbed 34 four blade merc bravo1 spinning it up to 5600 and running 98mph. Beginning of the season I was spinning this prop @ 5400, 1.50 gears and was seeing 106 gps.

Tbonepmp

HHHHMMMMmmmm HOW MUCH?????

Thunder Roy

2000.00 FOR THE PAIR. THEY ARE FOR BRAVO ONE SMALL SHAFT

Tinkerer

If you know someone with a 1:36 ( I think that is the ratio ) or lower ratio drive I would try it with a lower pitch prop and spin the prop faster with the same engine RPM.

cobra marty

Interesting. What changed between the two runs? Fuel load, passengers, anchor, beer chest? Is the prop nicked or bent? By labbing it the ears are thinner and easier to bend. The bend in pitch might not be visible to the eye. Do you boat on water with a current? A 2-4 mph current will make a difference like you describe. I would try a box stock 34" and start again. I am surprised at the speed with 700hp and that hull with a center pod. I didn't think that the Profile was that fast. Your X sounds pretty low, do you have access to a 2" shorter lower unit? I don't know if a 5 blade will help you.

Goody76

Cobra marty- I am going to try a 2 inch shortie on the lower and was going to try a 5-blade since I am raising the prop higher to the surface to get more blade area in the water for getting on plane and for stability at higher speeds. I talked with Bob's son Jim @ Herring and sounded very confident about making a prop for me that would only slip 6-8% and that if they didn't get it right the first time that they would have no problem in trying until I was satisfied. On my current 34 that I sent out to Dennis Cavanaugh @ Merc. to lab I did hit a piece of wood at high speed in the bay one night and put a slight fold the size of a nickle in one of the ears. I brought it to a local prop guy to fix so I would be out in time for the weekend and I am starting to think this is where I went wrong. Not being a Merc prop guy he did what he did to it not thinking in terms of it being a high performance application, possibly taking out some cup or altering the balance of it!