Re: Engine power loss
Speters,
In my opinion the 5.7 will not get your 55-60mph top speed requirements under load in any configuration in that large of a boat.
The answers to the next couple of questions would change the advice available.
1.) Did the boat ever go 55+mph with a full load when new?
2.) Did the dealer work with you after first purchasing the boat to be sure the pitch matched what you wanted the boat to do?
3.) Did the performance behavior change dramatically after the water-intrusion-induced service?
There are many pitch ranges for the those props, thus there is no "standard" setup from the manufacturer. In general, for any given engine, larger boats will require a drop in pitch when compared to smaller boats. It is part of the dealer's responsibility, in my opinion, to be sure the boat is propped for what the buyer needs. The dealer should have stock available to be able to re-prop as needed. In your case dropping down a pitch or two may be what is needed. That is a large boat and borderlines on needing two drives or at least a big block single drive.
It is difficult to predict if a pitch change would help or not without knowing what you have on there now, and what the rpm is at the reported top speed attained.
With 53 mph being reported at light load I would say the engine has plenty of power. That also makes it sound like an F7 pitch. Dropping down to F6's or F5's would drop your top speed potential but the boat would plane much faster and accelerate better under load.
Trading boats may be your only option, I'm just sayin'.....
