Speed on a C-Dory

E

El and Bill

New member
We were just asked a good question about the speed we traveled over the years on our C-Dory, and thought our experience (with good engine servicing and two sets if Honda 40 engines) would be useful for others.

Our speed: Probably 5-10% above 15 knots, 55% 10 to 15 knots, and 35-40% below 10 knots.

Hope this (rough) answer is of interest. We are rarely in a hurry in life (usually we went fast to escape a storm or clean engines), cruising we stayed near hull speed for economy, and looking at wildlife or shores we chugged slowly. Our engines served us well with this type of use, and still do.

El and Bill


 

 
 
When we bought our C-Dory, we expected to run above 15 knots all the time. And, we kinda did at first. Then, you discover the comfort and economy of running at or around displacement speed (usually doubles the mpg). These days, our speed depends as much on where we're cruising as anything else: slow when we aren't trying to make a destination or we're out day tripping. Faster when we want to get somewhere or we're trying to make the best of tide/current and weather. That's one of the nice things about these boats: the ability and comfort to run fast or slow.

You two and Halcyon have shown many of us the adaptability of these fine boats. Someone is going to get a well cared for boat and a piece of C-Dory history when Halcyon goes to a new home. Wishing you all the best with the sale and your upcoming European travels.

Best wishes,
Jim
 
We agree. As relative newcomers to c-dorys we have found that we tend to go slower in order to enjoy the ride. With the tomcat, however, we sometimes do increase speed in order to smooth out the ride. That seems counterintuitive but it's true. Most of all, however, we enjoy the ability to go slow, brisk, or fast.
 
Our first four years it was at least 95% at 10 to 15 knots, then on our 2007   Southeast Alaska cruise we discovered the various benefits of displacement speed & it changed to about 50/50.  Upon retiring  in 2010 & that years Alaska cruise it  changed again to  75% displacement & for this years 856 miles so far it's been at least 95% displacement.  Have only gone to two motors to avoid tides against the wind, outside waters with big swells & wind & for better  boat control  in certain circumstances.  Very seldom do I even get the urge anymore to go above displacement speed.

Jay
 
I do a lot of slow cruising, (I get 10MPG @ 5 MPH!)and I noticed when reading the owner's manual for my Suzuki 90A, that more frequent oil changes are required for"extended trolling use". They don't specify a schedule, any comments on extended slow speed use maintenence?
Thanks
Roger
 
rogerar":274s51pa said:
I do a lot of slow cruising, (I get 10MPG @ 5 MPH!)and I noticed when reading the owner's manual for my Suzuki 90A, that more frequent oil changes are required for"extended trolling use". They don't specify a schedule, any comments on extended slow speed use maintenence?
Thanks
Roger
Click to expand...

I suspect that type of operation doesn't heat the oil enough to reliably evaporate accumulated water out of the oil. Boating in Florida should be less problematic this way vs. boating in Alaskan waters.
A quick and dirty crackle test can be done at home to test for water contamination in oil. Note, I'm not vouching for the accuracy of this test.
http://ezinearticles.com/?Motor-Oil-Analysis-Testing-on-the-Cheap---Water-Ingression-Test&id=2897412
Professional oil analysis obviously would be more accurate. Question is, does a professional test cost as much as an oil change?
 
FTI............

I pulled my oil dipstick on my 90hp Honda. The oil looked like globby butterscotch pudding on the stick.

Turned out to be a stuck thermostat and trolling alot causing the water in the oil to not evaporate as the motor was always cold.

A new thermostat and an oil change solved the problem.
 
Water in the oil is not "normal"--even with extended trolling etc. I would look at the head gasket or other sources of water intrusion. Normally there is no water in the oil.

Running at 5 to 7 knots is not "extended trolling" and would not justify more frequent oil changes. As long as the engien gets up operating temp, then the wear will be normal.
 
Bob,

Moisture occurs in the oil from condensation due to the cold water environment and accumulates in the oil. No evaporation was occurring. THe engine block was cold and the cooling water barely tepid while trolling at 600 rpm for hours. Replacing the thermostat and an oil change was all that was done. Since then the engine has several hundred more hours on it w/o anymore problem.

Happy Memorial Day

Jack
 
Do you all still change oil every 100 hours when you're cruising at displacement speeds?

I'd like to cruise at 1800RPM (5-6 knots) and save gas. It's easy with the autopilot. But that means changing the oil every 500-600 nautical miles, which is a pain, and expensive if the boat has to get hauled for the lower unit oil.
 
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