300 SLX Cruise RPM & Trim Angle

[Mike Francis]

Just bought a 2008 Sea Ray 300SLX with twin 350 MAG's and Bravo III's,. We're trying to determine the "best" cruise RPM's for the boat. I've seen several boat tests which shows 3500rpm is the most efficient (most range), but I'm wondering about engine longevity. Our previous boat, 280 CC with twin 5.7L's, seemed to be very happy at 3000rpm - 3200rpm, new boat seems to be happier at higher rpm's but I'm worried about engine longevity. What do others with similar engines cruise at?

Also I'm wondering what outdrive trim angle do others use with their 300 SLX or 290? We're noticing the trim doesn't seem to make much difference with the speed of our boat, unlike previous boats, just a slight reduction in vibration.

 

[sheehyjo]

I have a 2014 and cruise at 3400 rpms, where I get 29-31 MPH depending on the conditions. As far as trim, my boat likes to be trimmed just a tap or two up from all the way down. BTW, where did you find the speed vs. MPG comparison? Can you post a link?

 

[Mike Francis]

I have a 2014 and cruise at 3400 rpms, where I get 29-31 MPH depending on the conditions. As far as trim, my boat likes to be trimmed just a tap or two up from all the way down. BTW, where did you find the speed vs. MPG comparison? Can you post a link?

Thanks! That's about what I've noticed with trim too, just a nudge so the vibration goes down.

I haven't been able to find a link for a test with twin engines and a Bravo III, but this is one for the Bravo I with my engines and a 290 Select EX. The closest I've been able to find. http://www.boattest.com/oem/32/boats/160/0/

 

[Cincy Aquaholic]

I have the 290 SS version. Same engines with bravo 1s. Seems to be very happy 3200-3500. I only use a tad bit of trim if cruising a long way on flat water. Just a bump or 2 to get the bow up a little. Too much and the props will break loose easily.