Changed prop & everything seems funny

[lekslk]

I was running a Raker 20 x 14 1/2 raker on a 1987 stratos 181P w/ a 2000 Johnson 150. The RPMs were 58-5900 speedo around 59-60 and nice & smoothe. I know put a 22 x 14 1/2 Raker on & motor sounds different almost rough, rpms around 5500, speedo around 61-62 & props breaks loose or slips whenever Motor is trimmed up part way, & my 20 Raker very seldom slipped. My prop shaft is about 34 1/2" below the pad & boat weighs around 2400 plus or minus. It is just me & the way it is set up, or could a prop be bad. This was a used proip but it looks good & strait. Any help would be greatly appreciated.

 

[Dhadley]

Re: Changed prop & everything seems funny

There are (at least) 3 styles of Raker props. The first generation had no name on the hub and came with small vent holes. Gen 2 had slightly larger vent holes. The latest version, Raker II, has the name cast into the barrel. The Raker II is not made by the same folks who made the first version. The first generation had the most bite and lift.

Or if the 22 Raker has been reconditioned by someone who didn't have the proper pitch blocks they may have turned it into an SST II.

However, you lost 300-400 rpm and gained 2-4 mph. That says the new prop has less slip, which is what we'd expect going up in pitch. As for the slipping in the trim range that may have to do with blade shape (especially if it's been rebuilt) or condition or tip cup.

As for the motor acting different, it may vibrate if the blades are unbalanced, could that be the rough running?

 

[lekslk]

Re: Changed prop & everything seems funny

I looked at the props & both have RAKER stamped on the barrel & they have 3 5/16 or so holes on the barrel (are these the vent holes). The biggest thing I noticed right off was When I say it sounds funny, I think the exhaust sounds different, there may have been some vibration on the prop I don't know everything just seemed. off. when I gave it full throttle with motor almost all the way down, it just blew out (or slipped?). The old prop never did this. My wife said she did not like how it sounds now allot different for her to notice (lol). If I was to put the 20 back on would that be to fast to run 5900 rpm on a 2001 Johnson 150. Could it be my jack plate is to high for this prop? My prop shaft center is 3 1/2" below the pad. Thanks allot