pressure

how to find out under water pressure when a boat travel in it?

A boat is usually on the surface of the water, so there is not much pressure to talk about. Furthermore it's a pretty constant value.

Any respectable ship has draught markings on the bow, so you can calculate the pressure at the keel for it.

What exactly is it that you are trying to do?

it is about direction look for pitottube

it is about direction look for pitottube

You're going to have to do better than that in explaining what you are trying to accomplish and why ?

direction look

I have no idea what that means.

i think he wants to calculate speed using delta pitot

how to find out under water pressure when a boat travel in it?

WHY ? If you are trying TO MEASURE BOAT VELOCITY then WHY DON'T YOU JUST SAY SO ?

raschemmel seems to be mixing up the posters...

OP's (uday1921's) original post:

how to find out under water pressure when a boat travel in it?

shooter's response:

it is about direction look for pitottube

To which raschemmel responded (thinking that was from the OP?):

You're going to have to do better than that in explaining what you are trying to accomplish and why ?

Thanks, Jimbo for catching that. Can you go ahead and finish my thought ? (busy on another post at the moment, I hope it's the right one...)

So this guy is telling the other guy to "look for a pitotube " right ? What does he mean by "direction" ? Isn't the tube mounted facing forward like on jets ?

it is about direction look for pitottube

No idea why he's suggesting a pitot tube, but it's possible he's interpreting the OP's very vague question in an out-of-the-box way.

I go with your suggestion "You're going to have to do better than that in explaining what you are trying to accomplish and why ?" even though you directed that at the wrong poster: OP ought to explain more.

As much as it pains me to say it, this guy might be closer to the mark...

Any respectable ship has draught markings on the bow, so you can calculate the pressure at the keel for it.

Or, the OP might mean the effect on the water pressure under the vessel, as it moves past a point?

since we are all taking wild guesses and truly have no clue, maybe the OP wants to know the total flotation of the boat ?

Archimedes says the weight of the water displaced is equal to the lifting force, or some such.

Shpaget had the most obvious wild crystal ball guess.

salt water has one set of pressure and fresh water has a second.

in salt water, a depth of 33 feet or 10 meters equal to 14.7 PSI or 1 bar, or 1 atmosphere. fresh water it is about 34 feet.

to calculate the pressure one has to ask WHERE. the pressure at the lowest point of the keel will be much greater than at the waterline.

Well of OP is on same schedule as yesterday, we'll hear from him or her in an hour or so....

raschemmel: As much as it pains me to say it, this guy might be closer to the mark...

Why are you in pain?

Dave, You are forgetting that salt water has greater density than fresh water. The mass of displaced water is always exactly the same as the mass of the ship. Since the pressure is a function of weight and area, and weight is related to mass, there is only one more thing we have to take into account. That is the area encircled by the water line. If you look at big ships, their horizontal cross sections don't change much around the waterline, so even if immersed slightly deeper or not quite so deep, the area won't change much. Same weight of water over (pretty much) same area produces same pressure at the keel of any particular ship, regardless of the water density.

Hi,

http://en.wikipedia.org/wiki/Waterline

Plimsoll Line.

Tom..... :)

Why are you in pain?

You're the one who said : "that's true" (which wasn't)

when I said :

"no one ever agrees with me..."

It pains me to agree with someone who said no one ever agrees with me....(makes sense, doesn't it ?)

Oh! Are you holding a grudge?

I had hoped it would have been obvious it was a joke. Sorry. (These tenses are killing me.)

I didn't see a :D

I don't have a habit of using them, but here, have some :) :grin: :D :grin:. BTW, where's our OP?