Overpowering question

[DesertAlbin736]

One reason I log fuel use is that the logbooks I use from Evergreen Pacific Publishing have a fuel log section with a format for noting date, engine hours, gallons pumped, cost, location, and remarks. Second and most important reason is to get a good idea of how many gallons to expect to need at various fuel gauge levels (mechanical float gauge) & engine hours since last fill up. Important to avoid surprise overfilling & spills coming out of the tank vent while at a fuel dock. Had that happen once while refueling a charter sailboat that had an inaccurate fuel gauge at the end of a 7 day charter. We were told the engine used about 1 GPH when it turned out it used much less. After 22 hours on the meter expected it to take 22 gallons, but actually took much less & a small amount of fuel backed out of the vent when I wasn't expecting it. Luckily the dock attendant was standing by with a pad & caught it, but scared the crap out of me. Ever since then I want to know how about much to expect to need & slow up nozzle flow rate when I know it's getting close to full. Also I listen closely for the change in pitch of the gurgling sound as it nears full.

[Bob Noodat]

Accurate fuel gauges should be cheap and easy to find, specifically ultrasonic ones that would be fine with diesel. But they don't seem to be. Amazon list some

https://www.amazon.com/s?k=ultrasonic+t ... _sb_noss_1

But either they are expensive, or suitable only for water tanks, or are poorly rated. Various companies sell industrial ones, but the fact that you are asked to contact them for a "quote on your project" merely adds zeroes to the price you are likely to pay. Since the technology has been around for at least 20 years, this should be a $20 item, connectable to a standard analogue fuel gauge, or a $100 item with an included digital gauge.

[jerridsc]

I’ve read of a whistling device, installed in the vent line near the fuel tank that you can hear while fueling. When the whistle sound stops you know tank is full. Haven’t used one yet but I’ll be giving it a try soon. Should help prevent over filling.

[Bob Noodat]

I’ve read of a whistling device, installed in the vent line near the fuel tank that you can hear while fueling. When the whistle sound stops you know tank is full. Haven’t used one yet but I’ll be giving it a try soon. Should help prevent over filling.

My Kubota L5740 tractor has a beeper that speeds up as you fill, then the noise goes constant at the fill point. Yes it is useful, but a full time accurate gauge is what you need on a boat.

[DesertAlbin736]

My gauge is accurate as far as that goes, same kind as on a portable outboard gas tank. Purely mechanical, read by (using a flashlight) looking through a hole in the floorboard over the tank. The thing is, as we all know the A25 fuel tank is not strictly rectangular but has a sloped bottom to follow the curve of the hull. In our case the guage float is not over the deepest part of the tank. So 'half' is not really half and 'empty' is not really empty. At 1/4 tank gauge reading it takes about 9 gallons to fill out of total 20 gallon capacity. So in practice besides knowing about how much to expect to fill, while I'm pumping fuel the Admiral watches the guage & calls out readings as it gets close to full. Diesel is not like gasoline where a few drops spilled in the water evaporates right away.
That said, if I were to let my fuel level get down to an empty reading I'd know that I'm not actually out of fuel yet but "on reserve". Beyond that without knowing how many hours run since last fill I'd have no idea how much fuel I actually had left once the gauge went below "empty". In practice I never let it get below a 1/4 reading and sometimes not even that low depending on how far away we are from the nearest fuel dock. Also I keep a cruising log journal for each day we're out on the water & besides logging location of where each day started and ended, what we did & saw, beginning & ending engine hours, also include starting and ending fuel gauge reads. I'm now on my 3rd Evergreen Pacific log book. So I can look back & tell where we were, where we went, & what we did for every day on the water, even if just out for a spin on the lake going back to when we first got the boat.

That practice goes back even beyond my sailing days of 1998 to 2012 all the way to my years of skydiving & the 400 jumps made between September 1978 and March 1984. I can pull those logbooks out & reminisce about those good old days.

[Bob Noodat]

Is there such a thing as a digital flow meter that could be placed between tank and engine? Most new vehicles seem to have something of the sort built in. That would probably be the most useful information.

[DesertAlbin736]

Digital flow meter? I suppose so. I'm fine with KISS. It's not like these boats guzzle fuel at 18 GPH.

[Bob Noodat]

Digital flow meter? I suppose so. I'm fine with KISS. It's not like these boats guzzle fuel at 18 GPH.

Tsk tsk.... with a digital flow meter, if it was wireless, you could then have an APP! Why, you could be lolling around in the aft cabin watching the flat screen TV, with the boat on autopilot, and be able to check your fuel consumption on your smart phone! What could possibly be better than that!?

[hetek]

I had a dual engine Floscan gauge on my 27' Seasport Pilot with twin Volvo gas I/O's. Each engine had a fuel flow sensor in the fuel line to the carburetor that would send data to the gauge.

Basically, it told me that a one-hour long circumnavigation of Shelter Island, NY cost me $60 in gas.

$1 a minute.

[Bob Noodat]

I had a dual engine Floscan gauge on my 27' Seasport Pilot with twin Volvo gas I/O's. Each engine had a fuel flow sensor in the fuel line to the carburetor that would send data to the gauge.

Basically, it told me that a one-hour long circumnavigation of Shelter Island, NY cost me $60 in gas.

$1 a minute.

The only reason you really need to buy an A25! We had friends on Orcas Island 30 years ago with a big cabin cruiser with twin 454s (7.4 litres each). He said that he never even looked at what he paid for fuel. He didn't want to know.

[DesertAlbin736]

Hmm, let's see, in round numbers assume fuel dock prices at $US3.50/gallon (much higher in Canada even after correcting for US-CAD exchange rate) consumption rate 0.45 GPH @ 6.5 knots. That's 14.4 nautical MPG = 24c per NM or 2.6c per minute.

Except your 1 hour circumnavigation would have taken 3 or 4 in an A25. As they say, speed costs, how fast do you want to go?

[Bob Noodat]

Hmm, let's see, in round numbers assume fuel dock prices at $US3.50/gallon (much higher in Canada even after correcting for US-CAD exchange rate) consumption rate 0.45 GPH @ 6.5 knots. That's 14.4 nautical MPG = 24c per NM or 2.6c per minute.

Except your 1 hour circumnavigation would have taken 3 or 4 in an A25. As they say, speed costs, how fast do you want to go?

Slow and cheap, that's me.

The only good news from Covid: putting 1800 litres of clear (undyed) diesel in my bulk tank just cost me $1450. Canadian. X 0.7 to convert that to US$$$, so $1015 for 474 US gallons, or US$2.14 per gallon. I cannot remember when it was last that cheap. What's diesel down there?

So, it'll be really cheap to go nowhere for the next little while!

[DesertAlbin736]

At the road taxed filling station pump #2 diesel is currently $2.79/gal ($0.73/L US, $1.06 CAD).
When at home & going out on the lake I have to fill up on land because the marina fuel dock doesn't sell diesel. According to my fuel log last time we filled up at a fuel dock in Canada was July18, 2019 at Poets Cove, S. Pender Island, BC, $1.69/L CAD. Translated to gallons & US $ that was $4.85/gal or $1.26/L. On that same cruise we refueled at Friday Harbor in the San Juans in WA on June 22nd for $3.66/gal including sales tax.
Starting with a near full tank with 3.5 hours on the engine since previous fill up & launching from Blaine, WA on June 16th, running down to the San Juans & up into the Gulf Islands as far north as Ladysmith & back ending on July 27th we purchased a grand total of 26.5 gallons, or 102 litres & came back with a 3/8th read on the tank left. Total expense in US$109.25.

Our 2019 course track. Yes, all that for 41 days worth of cruising on 26 gallons.

sj route map 2019.jpg

[ssrig]

Keep in mind too that a US gallon is smaller than an imperial gallon, nearly 1 litre difference?

[Bob Noodat]

Canadians have a curious relationship with gallons. Although in theory Imperial gallons (at 4.55 litres) are meant by the word "gallon" in Canada, you cannot buy anything in gallons, only litres up here. On the other hand things like jerry cans often are marked as gallons, but always US gallons at 3.8 litres. Canadians also tend to talk about "miles per gallon" in vehicles, and by that they mean Imperial gallons, but really none of them have any idea what they mean by that! Further to confuse the issue is distance which is universally given in km, but the whole western side of Canada is neatly divided up into square miles on the same grid system of townships and ranges as found in the US. Don't even go near supermarket purchase of meat and produce, always given in dollars per kg, but advertised in flyers as "This Week Only Chuck Steak $4.99 per pound!". And construction!! Every carpenter and framer and roofer is still working in 64ths and 16ths of an inch! Buy plumbing, still inches and fractions, but buy culvert and you'll be getting a 20 foot length of 450mm diameter.