Need help from Ron Hill!!

**omcstratos** · 08-14-2013

Ive been testing my 11.25 x 18 Yamaha style cleaver and have had a little difficulty. I don't know how low is too low for this style prop to run but I am having a pretty rough time getting the prop to grab the water. First off, Looking at some of these pictures, I am worried that I am getting some exhaust to come around the thru hub and ventilating in the blades. My past experience with thru hub surfacing props are that they don't slip until the boat is about to break over and plane off. This one seems to slip immediately like an over the hub prop when throttle is added.

Secondly, this may be due to me not spending quite enough time playing around with setup but I don't feel like I have gotten 100% hook up from the prop when on plane. I can be cruising along for a while and back off the throttle and the prop finally bites in. I'll ease back on the throttle and immediately lose bite, and do this back and forth all day.

I've tried this with the prop completely submerged and the cav plate 2.5 in out of the water. I get slip and can't plane off at all with the prop submerged and with it raised it only improves a little.

I know cleavers like running high, but I thought it was odd that I couldn't plane off at all with the prop submerged. Any help???

**Ron Hill** · 08-14-2013

Sounds like too small of a prop in both pitch and diameter.

What is the horsepower of your motor?

This prop usually planes easy!

**omcstratos** · 08-14-2013

50hp OMC. I know I thought this prop wouldn't have much problems planneing!

**Ron Hill** · 08-14-2013

See if you can figure out the gear ratio. Some of those Nitro gearcases can swing 12 1/4 X 20-24.....

This is the 12 1/4 diameter....

**omcstratos** · 08-14-2013

After running it today my best numbers was 18pitch prop turning at 6200rpm and I only could get 34mph out of it. I don't know what the ratio is but its the small gearcase for the 2cyls

**omcstratos** · 08-14-2013

apparently the gear ratio for this motor is 2.42

**Ron Hill** · 08-14-2013

Keep the hub kit, I'll send you a 12 1/4 by 22.

**omcstratos** · 08-14-2013

Ok. Hmm I'm curious about going up 4 inches in pitch. How many rpm's does that normally drop? You certainly know more than me so I won't doubt your advice!! I'm still learning about surfacing props haha.

**Ron Hill** · 08-14-2013

Clearly the 11.25 X 18 is too small. When a prop just slips, no way of telling how much an inch or two will effect the RPM's. General rule of thumb is 2" of pitch is 400 RPM's...