Hello all, glad to have found this forum. I bought new a 1977 four winns 24.5 sundowner w 7.4g 300 hp Volva Penta outdrive. With gps and speedometer ran 52-53 miles per hour with a few people. All factory including the prop. 14-1/4 x 21 omc Alum #3850302. We added trim tabs. Boat ran great. I can't remember exactly how long ago but the outdrive blew out, a lot of noise we were able to put it on a trailer. The marina had the lower unit repaired. We got the boat back in the water and were now experiencing a top speed of 42-43 miles an hour a huge drop. We didn't think of the obvious for a long time. We tried a new prop, tune up's ect. We were still getting rpm's around the high 4000's. The dealer who had sold us the boat had a real lack of mechanic talents. We have no paper work as to what new gears were installed. The boat did take off well as and had a great top end until the lower unit repair. Any ideas or help as to what ratio of gears would get us back to where we were originally. We ocassionally leave the boat in the water but only trailered it during these years so you can rule out taking in water into the glass. This was a sudden change. Thank you for you help.
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