Riegfrghtl
Petty Officer 3rd Class
- Joined
- Jul 7, 2008
- Messages
- 77
Hey guys, I am not sure if this is a prop or engine problem. I have a 1972 Cruisers, Inc 21 Foot Bonanza. It has a mercruiser 888 (188 hp) motor with about 1100 hrs. Total weight of boat with fuel, people, gear is around 3900 lbs. Last week I was out with the family and struck a submerged object. I was at idle when it happen but it dinged up the prop around the edges. The prop is a michigan wheel 15 1/2 X 19 3 blade alum. I was able to make it back to the marina where I keep the boat with no problem. Basically just idled back. The next day I took the prop off and had the marina send it out to be fixed. Prior to this mishap I was able to reach 4150 rpms and go about 41 to 42 mph (gps). Mercruiser rpm range is 3800 to 4200 rpm. While my prop was being fixed the marina let me try out a michigan 4 blade vortex 14 1/2 X 18 prop. I put it on and tried it out but the performance was less than spectacular. The boat would hit 4100 rpms (eventually) but would go only 34 mph. It also took forever to plane. Between 2200 to 3000 rpms it felt like there was alot of cavitation. Almost like a muscle car smoking its tires before getting traction. Today I got my 3 blade prop back and its doing the same thing as the 4 blade prop. It came back looking like brand new and they also said the hub was fine. I also now notice a vibration at 2100 to 2200 rpm which goes away as rpms goes up. I don't know if I am dealing with a prop issue, motor issue, or stern drive issue. Any recommendations or ideas would be greatly appreciated. Thanks fellows!! Tim