My boat is 1976 Catalina 30 with 3 blade Indigo prop. At the start of the season I was able to get 1900 RPM at full throttle and slightly over 5kts boat speed. Towards the end of the season few issues have developed:
1. I could barely make more than 3 kts at full throttle.
2. There was noticeable vibration when I increased RPM, which seemed to come from under the cockpit.
3. Tachometer stopped working: its jumping between 0 and reasonable RPM, while staying mostly around zero. I don't think issue is related to the first 2, but just adding it here for completeness. I suspect this is just the case of bad connection... But because of this I don't know what was the engine exact RPM.
So, long story short the boat was hauled out this weekend and I was curious to see the state of the prop (hopefully a big garbage bag wrapped over it). There was some barnacle on the blades and some on the shaft. The later was behind the strat and kinda asymmetric. But I don't think this could explain such a loss of boat speed. The hull was mostly clean. I check the prop shaft for play and did not find any. So, obviously I will have to wait until next season to see what my boat speed will be with clean prop. But in the mean time I wanted to ask few questions:
1. Should I expect to see higher RPM with Indigo prop. I think max 2300 is advertised.
2. What else should I check in spring to explain loss of speed? Could it be ignition timing, for example, or anything else?
3. Can growth on shaft case vibration? What else should I check? Engine mounts, alignment come to mind as obvious candidates.
Any advise would be greatly appreciated.
1. I could barely make more than 3 kts at full throttle.
2. There was noticeable vibration when I increased RPM, which seemed to come from under the cockpit.
3. Tachometer stopped working: its jumping between 0 and reasonable RPM, while staying mostly around zero. I don't think issue is related to the first 2, but just adding it here for completeness. I suspect this is just the case of bad connection... But because of this I don't know what was the engine exact RPM.
So, long story short the boat was hauled out this weekend and I was curious to see the state of the prop (hopefully a big garbage bag wrapped over it). There was some barnacle on the blades and some on the shaft. The later was behind the strat and kinda asymmetric. But I don't think this could explain such a loss of boat speed. The hull was mostly clean. I check the prop shaft for play and did not find any. So, obviously I will have to wait until next season to see what my boat speed will be with clean prop. But in the mean time I wanted to ask few questions:
1. Should I expect to see higher RPM with Indigo prop. I think max 2300 is advertised.
2. What else should I check in spring to explain loss of speed? Could it be ignition timing, for example, or anything else?
3. Can growth on shaft case vibration? What else should I check? Engine mounts, alignment come to mind as obvious candidates.
Any advise would be greatly appreciated.
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