Sea Rayder F16 Problems

[swally07]

I have a 1997 Sea Ray, Sea Rayder f16 Jet boat.
It has a Mercruiser Sport jet 120XR 175 Hp engine.
My question and problem is it only goes 37 mph.
Does anyone know if this is as fast as it goes, or is something
wrong with my boat. 37 mph seems awfully slow for a 120XR
Any help would be greatly appreciated.
Thank-You
Terry

 

[Alibuma]

I've heard you lose 30% efficiency with a jet drive... - 37mph sounds about right to me. I owned a Four Winns Fling and 35mph was about it.

 

[J.Wilt]

I had the same boat and mine would top out at just shy of 50mph. 37 is to slow, sounds like you need a new jet impeller and shaft.

 

[swally07]

Thank-you for the responses.
I changed the impeller and impeller ring 2 years ago.
Do you think I need to change them again. It didn't help make it faster when I changed them the first time.
Maybe something mechanical
Thanks, Terry

 

[DH175]

What RPM are you getting when wide open?

 

[adamgll]

you can thank me later

 

[truckman]

I have owned a couple of these boats. Do you have
the 120HP engine or the 175HP. You first post indicates a
XR120. The FX16 175XR2 Merc turning 5300 or so RPMs should run about 50, so a
120 HP would be about right at 37MPH. Unless you run in
very shallow water with tons of rocks and sand the wear ring and impeller should be fine. The clearance between the prop and the wear ring should be about 1/16", you should be able to get under the boat and look thru the grate to inspect the clearance or any damage to the blades.