I just had a 2000 280ss surveyed. It is a fresh water boat with 40 Hrs on her. She was not used at all this year, just sat in the water. Prior to seatrial bottom was powerwashed. She was supposed to be a 56-59 mph with 4900-5000 rpm (twin 350 Horizon Mags/ B3 OD an 26pitch props undefinedundefinedall original stock never tampered with), but they only did 46.2 @ 4200rpm each. The engines were maintained up to spec and look brand new.
Can it be the old fuel or is there something more? Should I stay away or will some TLC and running her on new fuel help?

is the bottom spotless? If it had a beared then I am guessing that the bottom still needs some work even after the power wash. Bad gas will not help but I would just have them hook up the computer and read for any codes.

Jon

I believe the 350's are rated to 4200 rpm max. B3 with 26" props, it would seem that they are as big as you might go anyway with a 28' boat w/350's.

Don't overlook the props also.
In my experience the B3 will only give you 100% when the props are spotless !

S.

Thanx for the info. Just what I was looking for!

I have a single engine B3 running 26 pitch props. I run 57 at 4600 rpm so the high 50s at 5000 would be correct. Boat sitting in water could take on a lot of water weight. To lose 10 mph, you have lost the equivalent of 130 to 150 hp of the 600 or so the boat originally had.

What about the valve springs? It is p[ossible after sitting for a year under constant load that they have set. If your RPMs are not coming up, change out the valve springs.

Thanx for all your help. She needed a good powerwashing, dry gas, injector cleaner and fresh gas. Ran 59mph @ 5100rpm.

Never put dry gas in a boat. Your fuel line will collapse from the inside. Wont appear anything is wrong.

Hyper Baja,
How did the dry gas collapse your fuel lines?