Spare Diesel Tanks

[SteveM]

I'm going on a long-ish cruise the last week of August, and I was contemplating bringing three spare 20l diesel fuel cans with me as a safety measure. My fuel gauge always says I have 3/4 of a tank - even last week when I put 200l into it :roll:, so I feel the need for some backup fuel.

I have a custom aluminum roof rack on my R25 that I could lash the full cans onto securely. At about 16 kg a full can (35 lbs), that is an additional 48 kg (105lbs) up there and 64 kg (140 lbs) if I add a can of gasoline for the dinghy. The rack is heavy duty and can easily support the weight, but does anyone have any experience with having substantial weight up on the roof in heavier seas? I am in the Pacific Northwest and going up to Desolation sound. Heavier weather is not unknown in this area.

My other option is a rack I have for my swimgrid. I had to take the rack off though because it gets in the way of my Weaver davits (and generally makes the swim grid less useful for swimming). I could put it back, but that is not my preferred solution.

Thoughts? Am I going to be amplifying rolling seas too much by having a 140 lb pendulum above my head? Or am I overthinking it. The latter is, as my wife will attest, a definite possibility.

 

[tlkenyon]

The analog fuel gauges are kinda worthless, but the engine's fuel consumption meter works great. Fill the tank absolutely full. Set your "software" fuel gauge to full at 80 gallons (or whatever your capacity is). It will keep track of how much you have consumed and left, and I have found it to be accurate to within one gallon, as determined by periodically filling the tank to absolute full. I fill the tank from the supplier hose to within about 3-4 gallons, which is about as far as you are gonna get without making a huge mess. I then fill the remaining amount from a jug, carefully metered. That way I am confident of being absolutely full. As I said, the amount needed to bring the tank to full has always matched the "fuel remaining" on the Garmin display to within a gallon or so.

We are gonna do the Loop starting next month and I am gonna carry a 5-gal can on the swim step. I do not think that having any unnecessary weight up high is a good idea.

TK

 

[Navigator's Son]

It sounds like your concern is more about knowing your fuel level versus availability of fuel once inside Desolation?

As said about the analog gauge, they will always show full until you are stationary and level, and even then they aren't properly calibrated. Use the Garmin if you have it to read real time fuel usage.

I personally wouldn't carry all that extra fuel versus knowing exactly where i can go to get reliable fuel once there

 

[NorthernFocus]

We also have a R25 classic and always carry two 5gal cans of fuel stowed and strapped down in the starboard lazarette locker. It doubles as our heater supply and spare fuel.

 

[knotflying]

SteveM,

There is always fuel available along the way. As others have said, disregard the fuel gauge. The flow meter on the Garmin is very accurate. I have my screen set up so it tells me remaining fuel, my miles per gallon and burn per hour. So far the readouts have been dead accurate. The most important thing is to start off correctly make sure your tank is full, set the Garmin to your proper tank size. Each time you get fuel add the amount of fuel added or if you fill up, hit fill tank. You should never run out of fuel this way.

 

[tlkenyon]

...at least you will never unknowingly run out of fuel.

As I have been taught on this forum, top 50% for routine use. Next 25% for contingency. Bottom 25% for emergency-get-to-a-fueling-spot-now.

TK

 

[SteveM]

Thanks for all the advice! I have the Cummins diesel engine monitor that shows fuel consumption, and it is the fuel gauge in that system that seems to be permanently showing 3/4 full. I have to admit that I have not spent much time looking at how exactly that system is supposed to work, so I may be doing something wrong. I will log my fuel consumption for this trip, compare it to what the Cummins system is telling me and figure out how accurate it is. And despite the assurances, I think I will still be bringing one or two cans of diesel with me. Too many years of being a scout when I was a kid to not over-prepare.

 

[NorthernFocus]

Thanks for all the advice! I have the Cummins diesel engine monitor that shows fuel consumption, and it is the fuel gauge in that system that seems to be permanently showing 3/4 full...

I also have the Cummins, Steve. The system takes its reading from a simple float in the tank. If yours is static consider yourself lucky. It's either stuck(not likely) or someone already dealt with a bad sensor and jumped it out. Much better than getting random alarms.

I'm not sure if the fuel used is measured with a flow device or simply calculated based on the injection rate that the ECM is commanding the engine to do. Either way I've found that indicated fuel usage seems to be more accurate at higher RPM. We tend to putter around a lot at hull speed and I find the indicated fuel used to be anywhere between 18 to 30 percent higher than actual fuel burned. The good news is that it errs on the conservative side, i.e.you have more fuel remaining than indicated. If you haven't yet discovered it you can reset the trip data(i.e.fuel used, miles travelled, etc).

No one really responded to the OP. In the grand scheme of things I doubt that 120 lbs lashed to the roof of the cabin is going to make or break the center of gravity. Though I'd pour it into the tank as soon as there's room to do so.