Hello Brad,
And welcome to the C36 owners website. I just bought my 1994 C36 MK1.75 in June and love it. I don't think you can get a better boat in that size for the money. And this site and the people on it are just amazing. I can't imagine a stronger more helpful group. The boat is worth buying just for that!! To answer your question log on to "Practical Sailor" (the mag)and look up Catalina 36. (You might have to be a member to get access)
There's a good review they did of the MKII back in 2001. So it should be applicable to the boat you're looking at. They say their test boat (Universal 35B engine) used .8 Gal/hr at 2200rpm.
I've found that I can get as good as .5 gal/hr in moderate wind with some sail assitance. Our last trip against 15kt head winds and 3 ft waves with no sails, I measured .7 gal/hr at 2200 rpm over about 7 hours. My boat has the 30hp, Universal M35.
Good luck.
Sam

Hi Blair,
I have 1999 C36 MKII with Universal 35B ( that is 35 HP). I estimate that it uses about 3/4 of a Gallon Per hour at about 2000 RPM. Everything is stock including the propeller. It has - I think 25 Gallon fuel tank. I have never used more than 1/2 tank on any trip. I spent over a year comparing sailboats and there is nothing with a better combination of everything, Examples are - keel stepped mast, keel, engine, batteries, wood construction, the shape and placement of the spreaders. It is a a very good looking boat. There is a very large number of owners here and you can get friendly advice from many professionals. It also keeps its value and you can get you money back when you are ready to sell it. It is an excellent stable coastal cruiser.

0.8 US gallons per hour is about right for my 2002. I cruise the M35B engine (35 hp) typically about 2500 rpm, at maybe 5.5 kts or a little more.

I think if you go with 1.2 MPG, with the M35, no sail assist, it will be pretty accurate.
I believe that is also what I read in the manual. If in doubt, call Kent at Catalina Yachts in California.
Rich

Rich, that's way too much fuel burn. You're talking Bayliner stats there. With a full 25 US gallon tank that would take you only 30 miles. If an M35B burns one US gallon per hour (and it doesn't use that much) at 5 to 6 knots, that's 5 miles per gallon at least, and a range of over 125 miles.

(Could you have meant gallons per hour, not miles per gallon? Or maybe miles per liter, eh?)

My experience is somewhere between .5 to .7 GPH at a cruising speed of 5 and a half knots under average conditions. With headwind or current, I go with .7 to .8 GPH. M35B engine.
John Meyer

Sorry!
Yes it is 1.2 gallons per hour. (Max)

Here is a copy of a diagram I copied from the spec page of the engine. Shows HP, Torque and fuel consumption per RPM.

Interesting that they just graph it to RPM regardless of load.

It looks to me that at a steady 2300 or 2400 rpm you are going to get about 1 gal. per hour. If you spend a certain amount of time like I do just idling and at slower rpm when in the marina and docking, then your average will go down. I seem to average around .8 gal/hr which includes some longish trips. I have an Autoprop which seems to be somewhat more efficient.