MPH for 2001 380 Sundancer w/ 7.4 L Horizon MPIs at WOT?

[shooker320]

I Just bought a 2001 380 SD. It has the 7.4 Horizons MPI. I just had a valve job and engine alignment done based on a survey when buying the boat. I have reviewed the boat test done on a boat with the 8.1s and the MPH at WOT was much higher than the 26 MPH top end that I am getting at 4600 RPM. Is this consistent with other boats with the 7.4s? PS..Love the boat

 

[RollerCoastr]

No, that's slow!

 

[RollerCoastr]

I only need 3500-3600 RPM to hit 26 mph, depending on load and conditions.

Are you using a GPS for speed data? If you're really only doing 26 MPH (not knots) at those RPM's, then I'd say she's significantly under-propped.

 

[shooker320]

I Just bought a 2001 380 SD. It has the 7.4 Horizons MPI. I just had a valve job and engine alignment done based on a survey when buying the boat. I have reviewed the boat test done on a boat with the 8.1s and the MPH at WOT was much higher than the 26 MPH top end that I am getting at 4600 RPM. Is this consistent with other boats with the 7.4s? PS..Love the boat

Thanks for the response. The GPS and speed transducer data match. I still need to check to make sure that they are not both set to knots. I have a friend with a 400 and will be able to check speed against his boat. I think I need to start looking at replacement props when I take her out for the winter in 2-weeks. That way I can compare what is currently on it. Any suggestions for props would be greatly appreciated. Thanks

 

[RollerCoastr]

Even 26 knots / 30 MPH is on the slow side, but if it's reading knots, that might explain why no-one at the seatrial said "what the heck is wrong with this thing??"

It's not likely that you need new props. It's common to tune props to match the dynamics of the boat. I'd reach out to a Propscan shop like Wolverine. Prop tuning is an interesting mix of science and art, but they'll at least have a baseline of what the props should look like on a 380DA. (in SeaRay speak, SD refers to Sundeck)

Congrats on the new boat btw!