Are full water tanks on the hard bad for the boat?

[Eder]

A US liquid gallon of water weighs about 8.34 pounds or 3.78 kilograms at 62 °F (17 °C), making it about 16.6% lighter than the imperial gallon.”

[NYSail]

So how can it become
Lighter? Is that why us Americans look so big.

[StuM]

Originally Posted by kas_1611

50 GallonsUS of diesel weighs 347.15lbs
125 GallonsUS of water weighs 1045lbs

Total weight of fluid is 1392.15lbs
2.2lbs to the kilo that is 632.8kg

I tip the scales at 74kg (163 lbs) so that is 8 1/2 me's

Weight of diesel 6.9ppg
Weight of freshwater 8.36ppg

The question was whether to empty the water tanks (1045lbs) , not fuel and water.
So that make 6 1/2 yous

[StuM]

Originally Posted by JPA Cate

He did say 175 gallons. 16 lbs per gallon (a pint's a pound, the world around), so approximately 2800 lbs, divided by 150 lbs for the people. Just approximations, but I just ran the numbers again, and my calculator says 18.66666667, so I called it 18. Figured somebody might weigh more than 150 lbs.

Ann

He was asking about the water (125 gallon) not fuel and water.
A US gallon of water weighs 8.35lb, not 16lb

There are not 16 pints in a gallon )

(A pint of pure water weights a pound and a quarter (in much of the world) )

150lb (68kg) is very light. That's way below the standard weight used for calculations such as light aircraft passengers (which are around 85kg for men and 70kg for women) I used 80kgs for the calculation.

[StuM]

Originally Posted by Martkimwat

(1800 lbs =816 kgs = 816 imp. galls)

1800 lbs = 816 kgs = 215 US gallons or 179 Imp gal

[JPA Cate]

Good point, Stu M, the OP did not mean to include the fuel in the calculations.

There are 2 pints to a quart, and 4 quarts to a gallon, so that's where I made my repeated error. Thanks for catching it.

Ann

[TrentePieds]

No need to get all wrapped up in the math. For these kindsa calculations, 2 decimal places tend to amount to spurious accuracy.

A gallon of fresh water weight 8 1/4 lbs close enuff. 125 x 8 = 1,000. Toss in 30 lbs to allow for the 1/4, and Bobs yer uncle. Then there's the 50 gallons aft. 1,000 dived by 5 is 200. 200 x 2 is 400. So what you hull has to carry is the equivalent of five healthy lads forward, a two healthy lads and a small dog aft.

Don't we all carry the answers to those sorts of "good enuff" calculations in our heads, so we don't have to drag out the fancy new-fangled electronic abacuses every time we need such an answer :-)?

TP

[StuM]

Originally Posted by TrentePieds

Don't we all carry the answers to those sorts of "good enuff" calculations in our heads, so we don't have to drag out the fancy new-fangled electronic abacuses every time we need such an answer :-)?

TP

It's much easier if you do it in metric.
If the OP had told us he had a 280 litre (kg) tank forward and a 190 litre (kg) tank aft, it would be obvious that that's about 3 largish men forward and 2 aft.

[minou]

I am pretty sure diesel is about 6.9 pounds imperial gallon.
Not that it makes a lick of difference but if my boat was to fragile to hold a bit of water in the tank on land then that is where I would want it to fail. Not slapped to pieces from the force of the ocean slamming a lot harder than a tank of water just sitting there [emoji16]
Just saying