Water Displacement

[Craigy boy]

Hi guys. Im getting very lost with calculations on water displacement. So many different websites out there and they all come back with different figures.

Can somebody please tell me the water displacement of my boat. Its 28ft long 9ft wide 11ft high and weighs 3.5t

Thank you very much

Craig

 

[sailorman]

She displaces 3.5T of water

One short (US) ton (2,000 pounds) of water equates to about 32 cubic feet
http://www.montecitowater.com/how_many_gallons_of_water_in_a_c.htm

Hi guys. Im getting very lost with calculations on water displacement. So many different websites out there and they all come back with different figures.

Can somebody please tell me the water displacement of my boat. Its 28ft long 9ft wide 11ft high and weighs 3.5t

Thank you very much

Craig

 

[ianj99]

If it weighs 3.5t it will displace that mass of water which is also 3.5 cu metres.

 

[knuterikt]

what ton?

She displaces 3.5T of water

One short (US) ton (2,000 pounds) of water equates to about 32 cubic feet
http://www.montecitowater.com/how_many_gallons_of_water_in_a_c.htm

Don't you use metric ton in UK?

Short ton (US) 2000 lb / 907.1847 kg
Long ton (UK) 2240 lb / 1016.047 kg
Metric ton 2204.623 lb / 1000 kg

Density of freshwater is (approximately) 1000 kg/m3 (999.8395 at 0°C, the highest density is 999.9720 at +4°C)
Density of saltwater is a little bit more 1020 to 1029 kg/m3

Volume of water displaced depends of the salinity (and temperature of the water), the weight of displaced water is always the same (with same boat&load)

That is the reason cargo ships have different load lines marked, if loaded to F when i fresh water it will float at S when in salt water.
S – Summer Temperate Seawater
F – Fresh Water

 

[Tranona]

Hi guys. Im getting very lost with calculations on water displacement. So many different websites out there and they all come back with different figures.

Can somebody please tell me the water displacement of my boat. Its 28ft long 9ft wide 11ft high and weighs 3.5t

Thank you very much

Craig

Size and shape are irrelevant. It is only weight that matters. However establishing that accurately is difficult. The designer may well have calculated it, but the builder may not have built it to that weight. Then as soon as it goes into use weight is added by fuel, water, gear, stores tc. This can easily come to an extra ton. Then the weight can be in pounds or tons (2240 lbs) or more commonly now kilogram and 1000 of those is a so called metric tons or 2200lbs.

The only way of finding out for certain is to weigh your boat and that will be the weight of water it displaces.

 

[reeac]

Why do you need to know the volume of water displaced anyway? Does some marina charge according to that figure?

 

[TimBennet]

The only way of finding out for certain is to weigh your boat

And weighing doesn't mean quoting what the crane driver or travel lift operator reads off from his 'gauge' when you're lifted.

A good guess is more accurate.

A lift using a calibrated load cell (or on a trailer at a weighbridge) is the only accurate method of weighing a boat.