c-22 gas mileage

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S

spinny

Just went out to the open ocean to sail and found that because of a lack of a good breeze I had to use my 8 hp outboard a lot. What I found was that it really sucked up the gas. I traveled approx. 20 miles and went through 7 gallons. Almost ran out! Only 3-4 miles per gallon. My hull speed is 7 knots. Is there a formula for sailboats on what kind of gas milage one can get? After all, their designed for sailing and not motoring. chris.
 
Sep 19, 2006
3
Catalina 36 Mid Chesapeake
Something doesn't sound right

I had a C250 with a 9.9 HP Tohatsu outboard. It only used about 1/3 gallon of gas an hour while driving the boat at 5 kts ( probably 1/2 throttle) Trying to drive it at 7 kts would probably need the outboard wound full out - and using much more gas but over a gallon an hour seems excessive.
 
Jun 4, 2004
189
Catalina 30mkIII Elk Rapids, MI.
7 Knot hull speed?

Maybe I am missing something, but I think you need to check all of your figures. I have a C30 with a 25 ft lwl and hull speed is 6.7K How did you figure 7k for a C22? fair winds Dave
 

Bilbo

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Aug 29, 2005
1,265
Catalina 22 Ohio
C-22 hull speed

Hi guys the Catalina 22 has a waterline length of 19' 4" with the formula : Maximum Hull Speed = 1.34 * LWL1/2 that would give the theoretical maximum hull speed of 5.89 knots and not 7kts. Actually 5.89 kts is rather close to 7 MPH. Going any faster requires a seriously increased amount force. If you are using the Catalina recommend 4 to 6 hp outboard size "under usual conditions" your gas useage would be considerably less but I would consider an 8HP 2 cycle on the ocean if I were going out there. Your mileage may be depending upon other factors. If your outboard is running at a good cruising speed and not full throttle, the gas useage would be less. If your boat is heavily loaded, unevenly loaded or you are fighting strong headwinds or high seas your gas mileage would be more. If the hull is not smooth, if you are dragging something (Like a crab pot hooked to the keel), or if the prop isn't set up efficiently. One other thing, I have had situations where the prop thrust isn't in line with the rudder and that would put more drag on the boat. One thing that you can do to increase gas mileage is to "motor sail". Under certain situations, you can run the motor and have the sails up to get more wind past the sails for better efficiency. AS an example, this summer with our "new Style" C22 our top speed (according to our GPS) was 5.6 KTS with sails and with motor sailing was up to 6.1 KTS.
 
Sep 25, 2007
2
- - Catalina Capri 22'
Ready to buy a 9.9 HP Mercury for my Cat 22'

I have a question to add about the others. I have a Catalina Capri 22'. I am about to buy a Mercury 9.9 HP brand new which is a '06 or '07 for $1400. First of all is this a good deal. NExt, can my boat handle this much power or is ot ok to use. If its too much for the boat, what if i just dont crank up the power the whole way but only about 3/4? please write back thanks. joey
 
S

spinny

my GPS gave the reading

Actually, my GPS (Garmin) gave me that speed. Perhaps it's wrong. In any case what I've learned so far from all the responses is that i shouldn't run at full throttle.
 

Bilbo

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Aug 29, 2005
1,265
Catalina 22 Ohio
GPS

can give you a wrong reading on speed. " In any case what I've learned so far from all the responses is that i shouldn't run at full throttle." I would say that with a displacement hull, the amount of power (read Gas) required to go fast increases a lot as you try to exceed hull speed. It is as if you are trying to drive the boat up a hill. Most larger aircraft/boat operators know that there is a maximum speed and then there's an optimum cruising speed. These things affect MPG as well as the durability of the gasoline engine.
 
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