Catalina - Capri - 25s International Assocaition Logo(2006)  
Assn Members Area · Join
Association Forum
Association Forum
Home | Profile | Register | Active Topics | Forum Users | Search | FAQ
Username:
Password:
Save Password
Forgot your Password?

 All Forums
 Catalina/Capri 25/250 Sailor's Forums
 Catalina 25 Specific Forum
 Engine & speed/fuel economy
 New Topic  Reply to Topic
 Printer Friendly
Author Previous Topic Topic Next Topic  

Erik Cornelison
Navigator

Member Avatar

USA
113 Posts

Initially Posted - 09/04/2018 :  15:41:50  Show Profile  Reply with Quote
Hey all, our family is having fun with the boat this summer. Itís new to us. I was just wondering how fast are your motors pushing you?

I can consistently sail 1-1.5 knots faster (some times even more) than my 9.9 Mercury Bigfoot will push me at full throttle, but I figure Iím at 7,800 ft elevation and lose some hp.

Also, anyone have a best speed-to-economy for GPH for a modern 9.9? I donít think brand matters much.

Iím guessing around 4kts, hoping for 6 mpg.

Reason asking is we are planning a trip to Lake Powell, Utah this fall and I would like to get a guesstimate for fuel needed to head down the lake., and back.

If you know Lake Powell you know you may not be able to always sail it, hence the motor.



Love the boat, it performs better than expected.

Erik Cornelison
6th Generation Professional Sailor, First Gen Submarine Sailor.
1986 Standard Rig SW. #5234

Edited by - Erik Cornelison on 09/04/2018 15:43:11

islander
Master Marine Consultant

Members Avatar

USA
3303 Posts

Response Posted - 09/04/2018 :  16:25:04  Show Profile  Reply with Quote
Full throttle Back it down there big boy. With a 9.9 about half to three quarters should push you along in the 4.5 to 5.5 range and is where most of use cruise along at. Full throttle is just a wast of fuel and the boat will try to climb it's own bow wake and the stern will just squat down with little speed increase compared the the extra fuel your burning. Your also just beating the motor up and the noise level has to be annoying.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound



Edited by - islander on 09/04/2018 16:44:39
Go to Top of Page

glivs
Admiral

Members Avatar

USA
654 Posts

Response Posted - 09/04/2018 :  18:02:37  Show Profile  Reply with Quote
I agree with Scott. I'm going on memory here and only have a few observations but my Mercury 9.9 w/ four-blade prop running at 1900 rpm (about half throttle) pushes me along on flat water with no wind at 5 to 5.2 kn and about 4.5 kn with a headwind of 5-10 kn. I haven't made any long trips since purchasing this motor so have no quantitative observations on fuel economy although a 2.5 gal tank lasts much of the summer (little boat time these past few years).

Gerry & Leslie; Malletts Bay, VT
"Great Escape" C-25 SR/WK #5972
Go to Top of Page

Erik Cornelison
Navigator

Members Avatar

USA
113 Posts

Response Posted - 09/04/2018 :  18:36:51  Show Profile  Reply with Quote
quote:
Originally posted by islander

Full throttle Back it down there big boy. With a 9.9 about half to three quarters should push you along in the 4.5 to 5.5 range and is where most of use cruise along at. Full throttle is just a wast of fuel and the boat will try to climb it's own bow wake and the stern will just squat down with little speed increase compared the the extra fuel your burning. Your also just beating the motor up and the noise level has to be annoying.



Please read my post before replying, you didn't answer either question, instead you assume I'm being annoying to others and beating up my motor.

I was asking how fast others motor pushes their boat with a similar HP to compare and guess on how much fuel is used. Really annoying to get these kind of responses online.




Erik Cornelison
6th Generation Professional Sailor, First Gen Submarine Sailor.
1986 Standard Rig SW. #5234
Go to Top of Page

Erik Cornelison
Navigator

Members Avatar

USA
113 Posts

Response Posted - 09/04/2018 :  18:40:32  Show Profile  Reply with Quote
quote:
Originally posted by glivs

I agree with Scott. I'm going on memory here and only have a few observations but my Mercury 9.9 w/ four-blade prop running at 1900 rpm (about half throttle) pushes me along on flat water with no wind at 5 to 5.2 kn and about 4.5 kn with a headwind of 5-10 kn. I haven't made any long trips since purchasing this motor so have no quantitative observations on fuel economy although a 2.5 gal tank lasts much of the summer (little boat time these past few years).



Thanks, that helps. I've used about four gallons this summer, but its only going in and out of the marina, we are sailing a lot and the lake is really small so no motoring.

Erik Cornelison
6th Generation Professional Sailor, First Gen Submarine Sailor.
1986 Standard Rig SW. #5234
Go to Top of Page

glivs
Admiral

Members Avatar

USA
654 Posts

Response Posted - 09/04/2018 :  19:25:43  Show Profile  Reply with Quote
Eric...Slow down. Scott did largely answer your questions if you grasped what he was saying and he did so in a friendly tone. He easily could have noted that your questions have been addressed many times over on this forum - use the search option above. This forum, however, is the product of a largely friendly community and is based on sharing individual experiences whether they or their interpretations are the same or not as yours.

Gerry & Leslie; Malletts Bay, VT
"Great Escape" C-25 SR/WK #5972
Go to Top of Page

Voyager
Master Marine Consultant

Members Avatar

USA
4094 Posts

Response Posted - 09/04/2018 :  20:10:54  Show Profile  Reply with Quote
Eric,
I have Honda 8 HP engine and although itís not a Merc, itís an outboard. And an 8HP is just a 9.9 thatís been detuned.

FWIW: My experience has been as follows:
The engine runs well at 3/4 throttle and doesnít go significantly faster at full throttle. Maybe 5.5 vs 5.2 kts.

You did say something that I wonder about:
quote:
I can consistently sail 1-1.5 knots faster (some times even more) than my 9.9 Mercury Bigfoot will push me at full throttle, but I figure Iím at 7,800 ft elevation and lose some hp.

This tells me that your max speed using your engine is 1.0-1.5 kts less than about 5.2 kts. That means your engine achieves something like 3.7-4.2kts at full throttle.
Is this an accurate interpretation?
If so, something is radically wrong with this picture, even at altitude, since a carburetor adjustment would probably fix this.

My mileage varies with throttle setting, but if I run at 3/4 throttle I burn about 1 gallon for 75 minutes. Using 60DST equation I get:
75/60*5.2 = 6.5 nm on a gallon. Converting, 6.5nm*1.151=7.5 statute miles per gallon.

In previous discussions among the regulars here, these results are not unusual for 8.0s and 9.9s. Others who have a 9.9 HP Mercury outboard may have similar results.

If you get significantly less performance, you might want to check your spark plugs, carburetor, engine timing or choke settings.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain Stratford & Milford, CT

Edited by - Voyager on 09/04/2018 20:19:24
Go to Top of Page

sethp001
Mainsheet C-25 Tech Editor

Members Avatar

727 Posts

Response Posted - 09/04/2018 :  20:50:34  Show Profile  Reply with Quote
quote:
Originally posted by Erik Cornelison

Hey all, our family is having fun with the boat this summer. Itís new to us. I was just wondering how fast are your motors pushing you?

I can consistently sail 1-1.5 knots faster (some times even more) than my 9.9 Mercury Bigfoot will push me at full throttle, but I figure Iím at 7,800 ft elevation and lose some hp.

Also, anyone have a best speed-to-economy for GPH for a modern 9.9? I donít think brand matters much.

Iím guessing around 4kts, hoping for 6 mpg.



I get 6.5 knots at full throttle with my 15hp Johnson. I rarely do that because I'm just wasting fuel when a third throttle will push me along at 4.5 knots.

Of course you know that motoring at less than full throttle will yield better fuel economy. But it's interesting that your motor, which should be more than powerful enough to push your boat along at hull speed, pushes the boat along slower than you can sail.



Seth
"Outlier" 1987 Catalina 25 SR/SK/Traditional Interior #5541
"Zoo" 1977 Morgan Out Island 30
"Nomad" 1980 Prindle 16
"Lost" 1988 Catalina Capri 14.2
"Marine Tex 1" Unknown Origin POS 8' Fiberglass Dinghy
http://whichsailboat.com/2015/08/22/catalina-22-review/
Go to Top of Page

keats
1st Mate

Members Avatar

USA
55 Posts

Response Posted - 09/04/2018 :  21:40:41  Show Profile  Reply with Quote
quote:
Originally posted by Erik Cornelison

Hey all, our family is having fun with the boat this summer. Itís new to us. I was just wondering how fast are your motors pushing you?

I can consistently sail 1-1.5 knots faster (some times even more) than my 9.9 Mercury Bigfoot will push me at full throttle, but I figure Iím at 7,800 ft elevation and lose some hp.

Also, anyone have a best speed-to-economy for GPH for a modern 9.9? I donít think brand matters much.

Iím guessing around 4kts, hoping for 6 mpg.



I think 6 mpg is a fair estimate. (I think I've owned cars that did that!) It purports well with data I've heard that a 9.9 will burn 1 gallon per hour at WOT. I've pencilled out 7-8 mpg in my limited calcs on my boat and I'm light on the throttle as it usually means we're steaming in and I'm in no rush.

That is a pretty good elevation and I wonder if your carb has been rejetted for that altitude?

At 800 feet, we hit hull speed at a little less than 3/4 throttle. That's in relatively calm conditions.

Have a great trip, it's no fun without some risk!

Tim Keating
1985 C-25 TR/FK #4940
Midsummer
Lake Don Pedro, CA
Go to Top of Page

islander
Master Marine Consultant

Members Avatar

USA
3303 Posts

Response Posted - 09/05/2018 :  05:26:58  Show Profile  Reply with Quote
Erik, Sorry if you misinterpreted my answer but I did try to answer your questions.
you asked
I was just wondering how fast are your motors pushing you?
I said With a 9.9 about half to three quarters should push you along in the 4.5 to 5.5 range and is where most of us cruise along at.

You asked
Also, anyone have a best speed-to-economy for GPH for a modern 9.9? I donít think brand matters much.

Iím guessing around 4kts, hoping for 6 mpg.
I said With a 9.9 about half to three quarters should push you along in the 4.5 to 5.5 range and is where most of us cruise along at.
I didn't answer GPH for a modern 9.9?
I didn't answer this because I have not traveled long distance with my boat so I don't know, I have a brand new 9.8 and there are many variables in how much fuel you will burn, Head into the wind, With the wind, Motor sailing, Current if any, Throttle setting and in fresh water you might have more drag because the boat sits lower than in salt water. Not sure of that. The rule of thumb for fuel is, One third out, One third back and one third reserve. That said I would use one gal. per hour as a good safe guess and should leave you with plenty reserve.
I would also add that I did not mean that your question or you were annoying. I was referring to the noise level of a motor at full throttle for long periods of time. This is a friendly Forum and as you know you will get many answers to a question. Some relevant and some not and none of use are experts, Just fellow sailors trying to help.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound



Edited by - islander on 09/05/2018 05:30:28
Go to Top of Page

HerdOfTurtles
1st Mate

Members Avatar

USA
45 Posts

Response Posted - 09/05/2018 :  13:57:51  Show Profile  Visit HerdOfTurtles's Homepage  Reply with Quote
I have a 6hp Tohatsu 4 stroke and get between 4-5 kts at 3/4 throttle depending on wind and sea state. I don't know the exact fuel burn as I have never run the engine for an extended period. I have read by searching here of folks attaining 4 kts speed and 1/3 gallon per hour fuel burn, so 12 mpg. Personally, I would err on the side of caution and estimate 8 mpg until I had enough time with my own boat and motor to plan for better economy. However, the 12 mpg claimed economy *sounds* about right.

I also routinely sail 1-1.5 kts faster than I motor.

Edit: Oh, wow 7800 ft elevation. I'm at 0 elevation and brackish water. I'm not exactly sure what being so high in elevation would do to your fuel economy but I imagine full throttle for you would be equivalent to about 3/4 throttle at sea level. And when I say equivalent I mean exactly the same. Same rpm, same noise, same fuel burn(though you probably have to use different main and idle carb jets) as if you were at sea level running 3/4 throttle.

1978 Standard Rig
Fin Keel
L-Dinette

Edited by - HerdOfTurtles on 09/05/2018 14:16:37
Go to Top of Page

GaryB
Master Marine Consultant

Members Avatar

USA
3989 Posts

Response Posted - 09/05/2018 :  16:25:55  Show Profile  Reply with Quote
Guys, need to remember he said he was at 7,800 MSL. In a normally aspirated airplane at 7-8,000' the best you will get is approx. 75% of the power you would at sea level. To get 75% you have to use full throttle.

Eric - How fast do you go at full throttle at your altitude?


Sorry Herd... I didn't read your whole post before I posted. Didn't mean to be repetitive guys.


Association Member

GaryB
Andiamo
'89 SR/WK #5862
Kemah,TX

Edited by - GaryB on 09/05/2018 16:31:12
Go to Top of Page

RichardG
Admiral

Members Avatar

USA
967 Posts

Response Posted - 09/06/2018 :  16:41:24  Show Profile  Reply with Quote
I usually go about 5.5 knots with the Tohatsu 6 (with high thrust prop) unless it's especially choppy. Even a little beam wind can help push it to 6 knots. It pretty much knows only two throttle settings - full and idle. I often go on 20 mile runs with little or no wind, and get about 8 miles(nautical)/gal.



RichardG 81 FK/SR #2657
Terminal Island, CA
Go to Top of Page

Stinkpotter
Master Marine Consultant

Members Avatar

Djibouti
7943 Posts

Response Posted - 09/06/2018 :  18:18:51  Show Profile  Reply with Quote
The good news is Powell is less than half your elevation and probably closer to ďourĒ average. With (now Bruceís) Honda 8, I figured a gallon per hour at about 5 knots (5.75 mph), so around 6 mpgóbut that was pretty conservative in my experience. Mine would cruise cmfortably above 5 kts at around 2/3 throttle. Full throttle would approach 6 kts, but the transom would squat adding wake and drag (and noise). Thatís at zero altitude, but I donít think motors are optimized for zero feet. 6.3 kts is the theoretical limit for the C-25, but approaching that requires an exponential increase in thrust and gas.

So why not a 6hp? Pushing into wind and 3-4í Long Island Sound chop.

(BTW Bruce, yours isnít a ďdetuned 9.9Ēóaccording to a factory rep, itís cammed for more torque for diaplacement hulls and therefore the better choice for a sailboatóand thatís from the company that makes more money on the identical but more expensive 9.9.)

Dave Bristle
Association "Port Captain" for Mystic, CT
PO of 1985 C-25 SR/FK #5032 Passage
Now on Eastern 27 Sarge (but still sailing when I can).

Passage, Mystic, and Sarge--click to enlarge.

Edited by - Stinkpotter on 09/06/2018 20:03:23
Go to Top of Page

Voyager
Master Marine Consultant

Members Avatar

USA
4094 Posts

Response Posted - 09/06/2018 :  20:10:24  Show Profile  Reply with Quote
quote:
Originally posted by Stinkpotter

(BTW Bruce, yours isnít a ďdetuned 9.9Ēóaccording to a factory rep, itís cammed for more torque for diaplacement hulls and therefore the better choice for a sailboatóand thatís from the company that makes more money on the identical but more expensive 9.9.)


Dave, thanks for the update on the Honda engine. There are any number of brands that twiddle their performance so they can rate their 9.9s as 8s for regulatory reasons or for branding reasons. Getting into the cam and valve timing and compression across the combustion cycle is a very clever approach.

Erik, Thinking about your situation, while youíre on a smaller lake at altitude, would you need a 15 HP engine to get enough torque to push your boat at 5.0-5.5 kts? You should be pleasantly surprised by your current engine out on Lake Powell.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain Stratford & Milford, CT

Edited by - Voyager on 09/06/2018 20:12:08
Go to Top of Page

AlMo
1st Mate

Members Avatar

USA
31 Posts

Response Posted - 09/07/2018 :  20:50:18  Show Profile  Reply with Quote
Density altitude is a pilot concept, I've rarely seen it used in sailing, but then Tahoe and even Powell are high enough altitude lakes to bring that into play. So here's the "wonky stuff" needed to calculate engine performance at higher than sea level: https://www.experimentalaircraft.info/flight-planning/aircraft-performance-3.php. I am making the assumption air-cooled (airplane) and water-cooled (sailboat) engines follow roughly the same curve. Don't know if this addresses either of Erick's original questions or not.

I do know this is a friendly board, with relatively "troll free" discussions, hope we keep it that way!

1978 C25 "X Lives" #1035
SR/SK
Go to Top of Page

JohnP
Master Marine Consultant

Members Avatar

1480 Posts

Response Posted - 09/10/2018 :  12:33:26  Show Profile  Reply with Quote
I have motored a little more than 40 miles with my Honda 9.9hp motor (into a 3-5 knot breeze) with a 5 gallon gas tank and have fuel left at the end. That's about 8 MPG.

JohnP
1978 C25 SR/FK "Gypsy"
Mill Creek off the Magothy River, Chesapeake Bay
Port Captain, northern Chesapeake Bay
Go to Top of Page

jerlim
Master Marine Consultant

Members Avatar

USA
1466 Posts

Response Posted - 09/12/2018 :  05:38:04  Show Profile  Reply with Quote
We get about 4 mpg with our 8 hp Merc, as averaged in varying conditions.

Jerry
Whisper
C-25, #1672,'80, SR/SK
S. Jamesport, NY
Go to Top of Page

WesAllen
Navigator

Members Avatar

USA
222 Posts

Response Posted - 09/12/2018 :  07:55:28  Show Profile  Reply with Quote
9.9 Merc Big Foot on mine and use 9 gals to go from Key West to Everglade City. Roughly 10 mpg but was ideal conditions (flat seas).(3/4 throttle) But that was the best, usually not quit that good. 8-7 mpg would be more realistic.

Wesley Allen
"Breaking Wind"
1982 C-25 SR/TR/SK #2773
Hemlock, MI
Go to Top of Page

Frank Law
Navigator

Members Avatar

USA
155 Posts

Response Posted - 09/12/2018 :  11:45:55  Show Profile  Reply with Quote
Relating to altitude while driving a car? While driving a 1967 V W camper we were on a level stretch of road ,at an altitude of 10,000 / 11,000 ft?? (higher) and the camper would go no faster than 35 mph . This was in Colorado near Leadville . They use different carbs for this reason.

Frank Law
Ex C-25 owner
Go to Top of Page

sailboat
Navigator

Members Avatar

USA
143 Posts

Response Posted - 09/12/2018 :  22:24:27  Show Profile  Reply with Quote
I think a gasoline engine loses 3 percent power for each 1000 feet of altitude. So at 7800 feet the earlier figure of 75% power available and that at full throttle is pretty accurate. Speed and efficiency unknown.

Mike
Chariots of Fire
1981 Cat-25. sail number 2230
SR/SK Dinette Version
Go to Top of Page

Voyager
Master Marine Consultant

Members Avatar

USA
4094 Posts

Response Posted - 09/13/2018 :  18:49:52  Show Profile  Reply with Quote
So if I rent a car in Denver at 5000ft, does that mean the car will drive like a dog? Iíve never noticed any performance degradation while driving around Denver and Iíve driven there a lot. Does the computer just compensate for altitude without anybody having to think about it?
Iíve even driven up at elevation in the hills outside of Boulder and the car ran like a champ.

Bruce Ross
Passage ~ SR-FK ~ C25 #5032

Port Captain Stratford & Milford, CT

Edited by - Voyager on 09/13/2018 18:51:26
Go to Top of Page

GaryB
Master Marine Consultant

Members Avatar

USA
3989 Posts

Response Posted - 09/13/2018 :  18:56:44  Show Profile  Reply with Quote
quote:
Originally posted by Voyager

So if I rent a car in Denver at 5000ft, does that mean the car will drive like a dog? Iíve never noticed any performance degradation while driving around Denver and Iíve driven there a lot. Does the computer just compensate for altitude without anybody having to think about it?
Iíve even driven up at elevation in the hills outside of Boulder and the car ran like a champ.


Up to a point. Go up to Pikes Peak and it will probably be gasping for air as much as you. LOL

Maybe cars shipped to the Denver area have the computer and fuel system setup for the higher altitude?


Association Member

GaryB
Andiamo
'89 SR/WK #5862
Kemah,TX
Go to Top of Page

Stinkpotter
Master Marine Consultant

Members Avatar

Djibouti
7943 Posts

Response Posted - 09/14/2018 :  12:06:49  Show Profile  Reply with Quote
The consensus I've seen is the EFI system automatically leans out the mixture to compensate for the thinner air, so to get the same power, you'll push the peddle down a little more. And "peddle to the metal" won't give you as much as it did at sea level, if that's a concern.

Dave Bristle
Association "Port Captain" for Mystic, CT
PO of 1985 C-25 SR/FK #5032 Passage
Now on Eastern 27 Sarge (but still sailing when I can).

Passage, Mystic, and Sarge--click to enlarge.
Go to Top of Page
  Previous Topic Topic Next Topic  
 New Topic  Reply to Topic
 Printer Friendly
Jump To:
Association Forum © since 1999 Catalina Capri 25s International Association Go To Top Of Page
Powered By: Snitz Forums 2000 Version 3.4.06
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.