Fuel mileage

[terry]

I hate to ask this question but about how many miles does a full tank of diesl fuel last?  It's a 25 gallon tank and my guess is about 150 miles on a calm day (or about 20 hours).  Can anybody confirm this?

[Stu Jackson]

Approx 1/2 gallon per hour at 5 knots, so, let's do the math --  25 gallons, say use 24 gallons = 48 hours at 5 knots = 240 nm.  No guessing required.   Also dependent, as you say, on a calm day.  Your fuel usage may vary depending on what engine you have.  Our M25 3 cylinder 21 hp uses only  0.423 gallons per hour, measured over almost eight years.  M35 engines use more, say 0.6 gallons per hour.  I wouldn't recommend using all the fuel in your tank, for many reasons:  it could get windy and wavy at the end of your trip, and you wouldn't want to suck air into the fuel lines; you could have gunk in the bottom of your tank, etc.  So, if you use only half of your tank, you get your 120 nm.  Your boat, your choice.

[terry]

A friend of mine has a 36' Catalina and when he first got it he filled up the tank to full and on one of the tacks the fuel leaked up a hose or out of the tank somehow and they had to siphon it out of the bilge.  Anybody have any similar experiences to that on the 34'?

FYI - We just moved our boat from a smaller lake to Lake Michigan and I'm planning to completely fill the tank and probably motor more than usual if the weather doesn't cooperate.  Just wanted to be prepared...

[Stu Jackson]

HOSE CLAMPS

It's not the boat, it's the factory worker.  Some skippers have reported missing and/or loose hose clamps on new boats, C30s, C34s, C350s, C36s, you name 'em.

One of the basic safety issues is to regularly check your hose clamps.  New boat owners think the factory is perfect.  While they should have some reasonable sense of assurance about that, given the big bucks they've just forked over, that simply isn't the case.  Once it becomes YOUR boat, you do have a responsibility to check it thoroughly.  It ain't a car -- because there just aren't mechanics out there.

One of the reasons that I know how much fuel the engine uses is that I keep a log -- engine hours and amount of fuel added.  In case your fuel gage breaks (and many sender units do) it wouldn't hurt for you to keep track of this in your log to confirm what many of us have determined over the years.  Not bad information for your to have for yourself, just in case.

[Ron Hill]

Terry : You seldom go the distance mentioned by Stu (240nm) without being able to roller out the jib and get some help from the wind!!  Even 4 or 5 kts of wind will lower the torque that the engine has to put out - lowering the fuel consumption!

Beside the hose clamps, you need to see how far the hose was pushed on to the barbs.  Also on older boats you might see some cracks on the outside of fuel hose bends.  That tells you it's time for some new hoses. 

Also a C36 has the fuel tank low and is suspectable to salt water corrosion (according to a Mainsheet article)   The C34 tank is much higher and that's NOT a problem.  

[Jack Hutteball]

Terry,
We had a similar problem on our 34 when new.  With a full tank, fuel would flow out the vent with any heel at all.  The vent hose loop was not run high enough to keep the fuel from running out.  Fortunately the vent was securely connected on both ends so none made it to the bilge.  that is probably the case in the C36.  A longer vent hose run as high as possible cured our problem.  This was taken care of by warranty, but during the fix they kinked the hose so the tank would not vent.  I corrected that myself.  No problems since.

Jack

[Ron Hill]

Jack : I wouldn't think that you'd want too long a vent hose.  You could turn it into a "J" trap, just like you have under all of your sinks in your house.  Then NO air would flow when the "J" has some diesel in it!!
A Thought.   

[Jack Hutteball]

Ron,
That what was wrong with it in the first place. It was more like a P trap under the sink and would fill and run out on any angle of heel.  The engine actually starved of fuel on a long motor trip as the vent was full of fuel.  Now that the hose is longer it is routed up as high as possible under the deck behind the port lazeret and is more like a vented loop without the vent.  Fuel can not get to the top on any angle of heel so now it contains air (Vents) only.

Jack

[captran]

.53 GPH average over the entire summer.  Usually run about 1800 to 2000 RPM with a 1997 M35 engine.  Ditto- keep track of your hours and fuel purchases and compute for you individual boat.