mercrusier rpm guage

[lazy grady]

8/18/23 my 2014 mercrusier 350 mag ect will run my 1994 gw 245 explorer (4500 lbs) 38 mph at full throtle. the rpm guage only shows 3800. is the guage bad?

 

[seasick]

Can't tell. perhaps you are only making 3800 revs.
The gauge could be bad but without knowing what type and model it is, I can't recommend how to test.

 

[Coastboater]

Is the bottom clean?

 

[DennisG01]

The engine is 10 years old... has this been going on for 10 years?

Are you trimming up till just before ventilation?

Need more info.