twarner4574
Seaman Apprentice
- Joined
- Jul 17, 2013
- Messages
- 34
Ahoy mates! I have been dealing with a long standing issue with poor top speed at WOT on my Nova 23 (Not XL). It was originally propped with a 14.5 x 19 3-Blade, and it was only achieving about 4000, maybe 4100 RPM with a top speed of 36 MPH. The motor was dog slow for a bit when putting down the throttle also. Since then, I've repowered the boat with a single reman Mercruiser 260 HP 5.7L, which was what it originally had (old one blew). The Quadrajet was also rebuilt 2 years ago, but I don't know how old it is. The gear ratio is 1.47 as it is an Alpha one out drive. I tried the 19P for a while on the reman engine, but it was still slow to plane and top speed wasn't great either. So, I added smart tabs to the boat, and I also changed props from the 14.5 x 19 3-Blade to a 15 x 17P 3 blade to try and up the RPMs. Now, my RPM's are STILL at about 4100, and I've lost 1 or 2 MPH. I know that's probably due to the drop in prop pitch, but I had hoped that smaller pitch = more RPM = more top end horse power. Now I've heard from many on these forums that many boats my make, year and LOA average about 50 MPH on the water with two people on board. The boat weighs 4000 lbs empty and it holds 80 gallons of fuel. The bottom is coated with CC ablative paint. Maybe a throttle cable adjustment would help??? Can anyone help me with ways to improve the boats top speed without buying a different boat? (please spare me the jokes) I understand this is not a speed boat, but if what other forum posters are saying that my WOT speed on this should be about 50 or so, I can use some help here. Thanks everyone!
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