slow speed

Question
I have a Wellcraft 1999 2400 marinique - mercruser 5.7 litre 430 hours.
It is going slowly max speed is around 25mph at 5000 rpm 4700 around 20mph 4000 rpm off plane. Doesn't seem to fouled up leg is right down engine seems fine.
Any ideas please

Many thanks

Answer
Hi Nigel...Sorry for the delay in responding to your question.

It sounds like you may need a different pitch/diameter of prop. Record the part no. on the hub of your prop and ask a MerCruiser dealer to identify its size, etc. Based on that info, they can recommend what would be more appropriate to meet your needs.

Alternatively, the prop could be slipping on the prop shaft and needs to be properly secured.

Safe Boating
Ron