1999 450 voyager slow speed

I bought a 99 450 last sept. we brought it 700 miles home. No problems, ran great. According to the factory and 5 other 450 owners I know, this boat should run 29 mph at 2600 rpm. Mine does 20 mph at 2600 rpm. Runs great, no smoke, but only 20. Drop it to 2350 cruise and it does 17. Bottom is pretty clean and trim tabs work fine. Any thoughts on where to go from here.

They do have the same engines and gears. Mine is all stock other than personal gear so I would say the load is average. I am getting the speeds from 2 separate iPhones, an Ipad and a chartplotter so I'm sure it is right. I have a diver going down to determine the prop size, hopefully, and then I will know more. According to the original parts list, the boat was delivered with 30 34 props so I will see if that is what it still has.

I just talked to carver. This boat is hull #1. They have test data on it. It did 28 in the test. I've rav the boat about 1000 miles since I bought it. It has always been at the speed it is now. No change.

Well I dove beneath the boat with a flashlight and dive mask. Believe it or not I was able to read the prop stamp. 28 30. Carver said the boat was built with 2 to 1 gears and 28 30 props. 1 year in it was changer to 2.476 to 1 gears and 28 33 props and that is what it should have now. I checked and it does have the 2.476 gear but as I saint it has 28 30 props. That doesn't mean the props weren't re pitched. I will have to pull and scan the props to know for sure. All that said it looks like I should need 28 33 props but it is running at the correct WOT so if I change props that would lower the rpm below the ideal speed and the fact they want $8700 for a set of props that might not help so, I'm guessing I may just have a 20 mph voyager unless I figure something else out. I am going to have a diver clean the bottom next week and see if that makes a difference. I'll let everyone know the progress and any ideas would be appreciated.

I would agree except wot with no load is 2870 so I would think that is where the governors are set at.

I am the 3rd owner. When I talked to carver, they were very helpful, they told me this boat I'd hull #1. They said it could be heavier than the others because the mold was made off this hull. I thought that was the problem so I did some work. I measured gunnel to water at 4 spots. Found 4 other 450's and measured at the same spots. 1 was 2 inches higher, I was one inch higher, one was the exact same and I was 2 inches lower. So I believe weight isn't the problem. Carver also told me the speed numbers were taken from my boat, after they changed the gears and props so back to the drawing board.

Actually the 2 inches was across the board front to back. Of all 4 I measured , weather it was higher or lower than mine, it was pretty well the same front and back.