Performance Information on C-Dory WebSite

[Rain]

I have been wondering about the Performance Information shown on the C-Dory WebSite. Of course, we shouldn't expect to attain the results shown there except under ideal conditions, if at all, but hopefully, the information is good at least for comparison of different models, etc.

I am curious why C-Dory chose to provide Performance Information attained using the maximum HP allowed on the Venture 23' (150), while for most of the other models they chose to post results attained using the recommended HP, which for the Venture 23 is 115 and what is on my boat. I notice they did deviate again from their own recommendation (albeit in the opposite direction) when they tested the 22" Cruiser by recommending 90HP and testing 75HP. A little consistency would be nice!

Any opinions regarding how actual results with a 115HP will compare with results with 150HP?

Also, top speed is shown at 42.5 MPH. That sounds too fast - maybe a typo???

 

[Will-C]

We had a 2008 C-Dory 23' with a 150 HP Yamaha with a Permatrim. We showed 42 mph on the GPS. The boat at that speed is not all that stable. We went with the 150 hp unit as it was only 65 pounds heavier than a 115 hp. We got around 3 mpg or a little better loaded moderately . Cruising speeds were 20 to 30 mph if you were in a hurry. We never seemed to need to run engine wide open. We could do 29 mph on Yellowstone Lake which is at around 8000 foot elevation using the same prop.
D.D.

 

[South of Heaven]

Will-C,
I was just checking out your photos. You have an amazing boat and have done some epic cruising. I saw you've been to Block Island several times. Have you ever continued on all the way to Cape Cod before? M.V or Nantucket?

 

[Will-C]

We at one time were supposed to do a Martha Vineyard Run but weather and one of the other cruisers that were in our pack caused the cruise to be shortened to start from Block Island. Our Friends had a place in Rhode Island near Charlestown and belonged to a small yacht club at a place they called Quaunny (sic) short for some indian name. Anyway From their marina where we launched it was only about 8 miles over to Block and from there we headed over to Montauk and on down to Shelter Island and on to Greenport. We also did a Narragansett bay week long cruise and ended up in Westerlyand then ran the thirty miles over to Block Island and spent the July 4th weekend there. Block Island gets so crazy at that time of year. Good fireworks on July 3rd if I remember correctly. So we have been to Martha's Vineyard and Nantucket but never on our boat. Maybe someday.

 

[NORO LIM]

I have been wondering about the Performance Information shown on the C-Dory WebSite. Of course, we shouldn't expect to attain the results shown there except under ideal conditions, if at all, but hopefully, the information is good at least for comparison of different models, etc.

. . . A little consistency would be nice!

Any opinions regarding how actual results with a 115HP will compare with results with 150HP?
. . .

A couple of observations about your general question: Various iterations of these boats' manufacturers have tested some of the models at different times. As far as I know, no recent comprehensive testing using consistent methodology has been done on all of the models. In the real world, load, balance, propping, engine mounting, and trim, not to mention water conditions and operator preferences and skills, are likely to be the more significant variables in determining the performance of any one model. The experiences of owners on this forum may be your best resource for performance data.

With respect to your specific question: I ran a Venture 23 for 6 years with 100hp (twin Yamaha 50's) and then for 2 years with 140 hp (twin Yamaha 70's). I used Permatrims, but not trim tabs. I did a lot of long range, very heavily loaded cruising. Not surprisingly, the bigger engines pushed the boat faster. WOT speed was roughly 28 mph versus 36 mph with a heavy boat on flat water. Somewhat unexpectedly, on the other hand, I think I got slightly better mileage at my normal cruise speed of 21-23 mph, with the bigger engines. (BUT - I also raised the engines one notch when I installed the 70's and of course the gearing and propping were different - all variables other than hp itself.) On three separate 2,000+ mile Inside Passage trips (two with the 50's, one with the 70's) I averaged about 3.4 mpg on each trip. Those trips included a very wide range of conditions.

These are great boats! I hope you get as much joy out of yours as I did out of mine. :thup

 

[thataway]

Performance Information shown on the C-Dory WebSite

Un-hijacking the thread--There have been a number of owners of the C Dory name in the last 15 years. Sometimes they have relied on past testing, (Current PDF comes from Fluid Marine ownership) Sometimes on the tests done at "Battiest.com" Obviously the BoatTest.com is a bit higher than the average boater gets, because the test boat is light. Often fuel is half, no water, and only two people, no gear or many extras (such as lots of electronics, a dinghy on the top, a cruiser back etc which would all decrease speed. Thus there have been many different results--and the current owner may choose what they want for the web site. (Often a poor source of statistics, such as hull weight, unfortunately)

BoatTest uses a radar gun for speed, in line sensitive fuel flow meters for fuel consumption etc. They often do two way runs to get the true speed to eliminate effect of current. Thus BoatTest is going to be faster and better

The best source of information is owners--and David verified that you can get 42 mph with a 150, but that seems to be more engine than a fairly light boat at sea level needs.

I know that I have found that over 30 mph the light C Dory 22 can get a bit squirrelly.

 

[Rain]

I have come to expect nothing less than great responses. Thanks!

 

[Foggy]

I have been wondering about the Performance Information shown on the C-Dory WebSite. Of course, we shouldn't expect to attain the results shown there except under ideal conditions, if at all, but hopefully, the information is good at least for comparison of different models, etc.

. . . A little consistency would be nice!

Any opinions regarding how actual results with a 115HP will compare with results with 150HP?
. . .

SNIP Somewhat unexpectedly, on the other hand, I think I got slightly better mileage at my normal cruise speed of 21-23 mph, with the bigger engines. SNIP

Better MPG at cruise speed with larger engine(s) is my experience; may be
coincidence due to many variables.

With a given load, trim, and boat, a larger engine does not work as hard as a
smaller one to attain modest performance resulting in less fuel consumption.

Aye.

 

[williwaw]

We have an Etec 115 on our 23 and it's a good size match most of the time. It has good low end torque and typically that's what you want for a heavy boat. For motors using the same block, like the Honda 135 and 150, you won't even see those extra HP until you wind the engine up.

I haven't done any rigorous testing but at 1800 RPM we make 5-6 knots at 6 nMPG. At 4200 RPM we typically make 26-28 knots which is comfortable and yields around 3 MPG. For trip planning I usually use 3 nMPG and find I've got plenty of reserve when we reach our destination.

 

[Rain]

That is very useful information. Thanks to all!

Someday, I hope to have my own data from which to work.

 

[hardee]

Hi Rain, It will come and it 'll be fun.

Yesterday was my first day out since the 1000 hour check and tune for the twin 40 Yamis. Also with the new SeaStar cylinder and the OB's were both raise 1 inch to get them up where they should have been all along.

At 6000 RPM on each I was hitting and maintaining 20 knots on very flat calm water with no tidal drift, but to make sure I ran the course both ways twice. (OK, yeh I know but it's that twins and redundancy duplication thing :wink:

I will be working on some prop changes as 6 grand is max WOT.

Harvey
SleepyC

 

[NORO LIM]

. . . For trip planning I usually use 3 nMPG and find I've got plenty of reserve when we reach our destination.

Precisely. That's how I planned every trip. (Actually, I was even a little more cautious since I used statute miles for calculations.) In perfect conditions, at hull speed, 6+ mpg was not unrealistic. At WOT in good conditions, or at constantly changing rpms in significant wind and steep waves, something south of 2 mpg was likely. Overall, however, a long trip with a mix of speeds and conditions almost always averaged out to 3.3 - 3.4 mpg, which is about what I would get at my best planing speed of 21 - 23 mph. YMMV.

Regarding Foggy's comment on engine size and mileage: I agree that (within reason) bigger engines may get better mileage at cruising speeds because they don't work as hard. A 40 percent increase in hp, like going from 100 hp to 140 hp, may well entail an increase in engine displacement. The reason I'm cautious about endorsing that theory in my case is that the Yami 70's are built on the same block as the 50's - hence my reference to other factors that differ between the two set-ups I had. Gearing and propping differences between the 50's and 70's may have accounted for a slightly lower rpm requirement for the "sweet spot" cruising speed, but if I had to guess, I think raising the engines a bit may have been the biggest factor in improving performance at cruise speed. As several others have noted, many of these boats may have been set up with the engines mounted a little low. I would encourage anyone looking at performance questions to investigate engine height. After I raised mine, the Permatrims looked EXACTLY as they are supposed to when the boat is planing, i.e., there is just the thinnest film of water running over the top of the plate.

Bill

 

[Easyvictor.14]

I have an 08 23 Venture with a Suzuki 150, 9.9 kicker, radar, AC, Honda 2K generator, and various gear on board.
Half tanks, two adults,
3800RPM= 21-23 mph on GPS.
3.5-4.5 MPG