Cruising Speed

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J Collins

We are thinking about purchasing a Catalina 350. How well does the boat motor? What rpm do you typically run at and what speed do you make in flat water?
 
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Tim

Cruising Speed in 350

We're still breaking in our 350. Engine RPM's between 2000 and 2500 she motors from the mid 6's to low 7's. Seems like she will idle along at around 3.2 at 1000 rpm's. Very happy with this boat! Big change from my outboard c27!
 
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Mark

Cruising speed of 350

We usually motor out at about 2600RPMs and make 6.5 to 6.8 Knots. At 2000RPM the boat moves along at about 5.5 Knots. Idled back to 1000RPM we seem to move a little slower than Tim and make about 2.5 to 2.8 knots. The engine just sips diesel we have 58 hours on the engine now and have used less than a half a tank of fuel. Most of this has been motoring in and out of the Oakland estuary at 2600RPMs. I had the 50 hour inspection done back in February and the mechanic calibrated the tack, it was off by about 200 RPM. Everything else was in fine shape. Mark
 
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Blair Dehuff

350 Cruising Speed

Just curious what your fuel consumption and speed are like at max RPM's? I used to have a Yanmar diesel which used lots of extra fuel for the last few hundred RPM's, but gave me negligable additional speed. Normal cruising RPM's was 2500 to 2600, and max was 2800. Did you receive an engine manual from Universal which gives fuel consumption curves at various RPM's? Lastly, does anyone happen to know what the theoretical max hull speed is for the 350? Let's see - if I remember right it's something like: Hull Speed = LWL's square root multiplied by 1.32 = ?
 
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Mark

Max Cruise speed

I have not measured fuel consumption as max trottle. It may be in the manual but I have to be truthful and say I have not read it cover to cover with that much depth. I top out as 2800 as you indicated and have come close to hull speed at about 7.2. I believe hull speed is 7.3 Mark
 
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Tom Abbott

Hull speed

Blair, You are close. hull speed is 1.34 times square root of LWL. For the 350, the equation becomes 5.5 (square root of 30.25 LWL) times 1.34 giving us a hull speed of 7.37. Tom C350, #8, Graeagle
 
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Tim

LWL Spec

Tom - I doublechecked the waterline length spec of the 350 and it is shown at 31' 3", so the formula 1.34* (sqrt 31.25) = 7.49
 
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John

Guess the water here near Annapolis is "heavier" because I "only" do 5.25 knots (according to my speed gauge) at 2,800 rpm on my 350 in a straight line with the autopilot sailing the boat. Dealer told us to run it between 2,300 and 2,800 rpms and vary the speed for a while. A diesel engine likes to run, so you really can't hurt it by cranking it up.
 
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Mark

John, What type prop are you using? I haev the 3 bladed cruise prop. Would this make a difference in top speed?
 
R

RonD

Engine RPM, Prop, and Transmission

All three go into what speed you'll achieve. The engine & transmission ratio determine the proper pitch required for your prop, whether 2- or 3-bladed (and, the pitch will be different for 2- or 3-blades for a given engine/transmission ratio combo). Generally, you'll want the prop pitched to achieve hull speed at the engine's recommended cruise RPM in moderate sea conditions & with a clean hull. That allows some so extra RPM to help out in more difficult sea/wind conditions or sea growth on the hull. At idle RPM, you get what you get. Variations noted between boats seem interesting. I'm wondering what a comparison of engine model, transmissions & ratio, and the prop dimensions (diameter, pitch, blade count, type- fixed/folding/feathering) would reveal. --RonD
 
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Tom Abbott

John, I suspect that your knot meter may need calibration. We're also in the Chesapeake and motor at hull speed or close to it at 2700 with a Martec Autostream 3-bladed prop. Tom C350, #8, Graeagle
 
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RonD

Tom has a good point

Try comparing your "paddle wheel" speedo with the GPS Speed Over Ground (SOG) & Velocity Made Good (VMG) readings on a straight course of a 1/2 mile or so.
 
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John

Thanks for the comments. I do have a three-bladed prop. After thinking about my posting, I thought that perhaps I'd see a different speed figure based on the GPS SOG reading. I'll also check the VMG value, and then perhaps talk to the dealer. I have the full autohelm/GPS/radar-chartplotter package, and thought they'd calibrated everything during the shake-down.
 
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Tom Abbott

Dealer Shakedown

I wouldn't depend on the dealer shakedown to get all the instruments calibrated. I had to adjust the depth finder on my boat. The dealer probably is focused on major disconnects in their checkout process. Tom
 
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