GPH vs Miles help??

[Vandeusen]

Just a quick question to see if somebody can help me figure this out since I'm learning about gallons per hour versus gallons per mile

If I have 100 gallons on board assuming I only use 80 to leave 10 gallons on the bottom of each tank and I average 1.8 gallons per hour how far would I be able to go on 80 gallons? Thank you

 

[Srbenda]

The speed at which you are traveling is an important component to solve this equation...

 

[SteveK]

At a constant 1.8 you can go 44.44444444444444 hours with 80 gallons.
How far can only be calculated if the speed is known while burning 1.8 GPH

 

[Bmarler]

80 plus 10 is 90. are we leaving 10 for empty space in this math problem?

 

[SteveK]

80 plus 10 is 90. are we leaving 10 for empty space in this math problem?

2 tanks, 10 each left

 

[Bmarler]

2 tanks, 10 each left

didn't catch the dual tanks. 50 each is pretty small.

 

[Vandeusen]

Yes so 100 gallons is what I carry 50 gallons per tank I'm only going to run 40 gallons out of each tank

 

[Vandeusen]

Cruising speed of 9 mph

 

[Vandeusen]

It used to have hundred gallon tanks to Total 200 but they removed the metal 100 gallon tanks and replaced them with 50 gallon plastic giving me 100 gallons

 

[hollywood8118]

1.8 GHP @ what speed?


HW

 

[Vandeusen]

9 mph

 

[SteveK]

400 miles

 

[SteveK]

That was fun, can we do if two boats 1000 miles apart each leave at the same time to rendezvous, one at 8 knots the other at 9 knots how far will each travel before they meet.

 

[Vandeusen]

I'm too dumb for that lol but 400 miles that is a lot better than my Silverton 34C where 80 gallons would have got me 80 miles lol

 

[SteveK]

OK a hint. One boat will arrive at the destination and wait 30.6+/- hours for the other to arrive because it used all the fuel except the reserves.

 

[Vandeusen]

I'm 50 gal tanks leaving 10 gallons remaining per tank is that pretty standardish I'm not worried about corrosion type stuff because they're plastic tanks

 

[SteveK]

I have two 170 G tanks and run them in the middle third. Seldom below bottom 1/3 and only occasional top 1/3. That is standard for me.
I do not know if there is a standard, but planning to leave 10 out of 50 seems too close to running out before fuel barge if you use running hours and do not allow for current and weather.

 

[Vandeusen]

I guess no mathematicians wanted to partake LOL

 

[Vandeusen]

For emergency I will probably keep three or four five gallon fuel jugs on board but I figured I would be okay with 20 gallons total remaining plus my emergency reserve

 

[tiltrider1]

No discussion of current or wind. Some one is going to be scratching their head when they run out of fuel before they reach their destination.

 

[Vandeusen]

LOL it's not to be quoted LOL it's just to get a generalized idea the more I learn the Trawler the more I would have a better idea

 

[twistedtree]

Just to be clear since this has been a bit confused from the start.... is that 1.8 gph per engine,or is that the combined total for both engines? I ask because getting over 4 mpg at a speed of 9mph is pretty darn good. Almost unheard of, save for some specialized boats.

 

[Bmarler]

20% is a fine reserve once you factor in weather and sea state. personally though, i rarely let my tanks reach the halfway mark. only if i'm planning a specific trip and have my fuel stops all planned out. then i use that 20% as the absolute minimum.

 

[Bmarler]

Just to be clear since this has been a bit confused from the start.... is that 1.8 gph per engine,or is that the combined total for both engines? I ask because getting over 4 mpg at a speed of 9mph is pretty darn good. Almost unheard of, save for some specialized boats.

i get pretty darn close to that. i cruise at 1700 rpm, get about 7.25 to 7.5 knots depending on the bottom growth. 7.5 knots would be 8.6 mph.
my theoretical burn at 1700 is 1.5 gph, but it's a little higher than that. probably in the 17. to 1.8 range. i have yet to measure it accurately but it's close.

 

[SteveK]

I was burning ~0.5 litres an hour on my 30 sailboat. IIRC I had a 15 gal tank. WE went to desolation and back without refill until back in Nanaimo. It is all relative to boat and engines.

I think the purpose of this thread was mathematical calcs based on fixed amounts. real or imagined then does not matter, nor does it matter single or twins, style of boat, etc. Just a theoretical calculation without current, wind or zig zag steering.

 

[twistedtree]

i get pretty darn close to that. i cruise at 1700 rpm, get about 7.25 to 7.5 knots depending on the bottom growth. 7.5 knots would be 8.6 mph.

my theoretical burn at 1700 is 1.5 gph, but it's a little higher than that. probably in the 17. to 1.8 range. i have yet to measure it accurately but it's close.

Fair enough. I was thinking that 9mph was faster than it is. Speed of course makes a huge difference.

 

[Benthic2]

80 Gallons / 1.8 Gal/hour = 44.44 hours.

44.44 hours x 9 Miles/Hour = 400 miles.

That's pretty basic math. God forbid you ever had to triangulate a distance measurement.

 

[SteveK]

80 Gallons / 1.8 Gal/hour = 44.44 hours.

44.44 hours x 9 Miles/Hour = 400 miles.

That's pretty basic math. God forbid you ever had to triangulate a distance measurement.

Did you mean triangulate your position? If not give an example of why I would want to T a distance.

 

[High Wire]

Merry Christmas everyone!

 

[Benthic2]

Did you mean triangulate your position? If not give an example of why I would want to T a distance.

If you want to get to a point that is 10 miles north and 10 miles west you would want to know the straight line distance between those points.