Cruising speed?

Hightower · 13 July 2005, 21:59

When looking at performance figures for new boat packages most manufacurers give a cruising speed. How is this calculated?

Richard B · 13 July 2005, 22:13

Probably maximum speed minus 5 knots I reckon.

Hightower · 13 July 2005, 22:24

Though it might be connected to Engine RPM, like an economic speed where the engine isn't as stressed. Say 4000rpm?

Louise · 13 July 2005, 22:28

That's what I reckon Andy.

to Richard B!

Richard B · 13 July 2005, 22:32

You reckon it's that scientific? Maybe, but then maybe not!

jwalker · 13 July 2005, 22:34

I'm not too sure about outboards but diesels are rated according to their design specification, eg. pleasure, commercial etc. This is typically given as x amount of hours at full throttle in a y time period and, also, an engine speed which can be maintained continuously. For my KAD 300, recommended max rpm -200rpm is the continuous use rating, which, I guess, is the max permissible cruising rpm.
I reckon that's still got to be stressing the engine a bit and I've settled on approx
-900rpm for a balance of performance against longevity for normal use and -500rpm for when I'm in a hurry.

And then, of course, there will be those occasional blasts flat out just cos' I like it. However, I intend not to break it, ever.

For outboards, I reckon cruising at about the max torque rpm wouldn't be a bad thing.

marios · 14 July 2005, 08:52

is the 70 % of maximum rpm, is also the revolutions that the engine can be on for 24 hours as day ...

at least this is what the told me.. lol

pettal · 14 July 2005, 10:42

If you aim for 3/4's of top speed you won't be far off.