Is a boat pushed or pulled by the prop.......that is the question

[tlandauer]

I guess i may have said it wrong initially:

Should have said, is the prop "boring/biting" into the water in front of it, drawing water in towards it......................"pulling" itself into the undisturbed water ahead of it.......................I wasnt actually referring to where it was on the boat.

Like Darin just said, how the prop moves itself thru the water..................which is how the boat is propelled by being attatched to the hull 'somewhere'.

It was just a physics question.

Actually, that's how I understood from your first question, also the drawing was clear. I think the subject matter made an unexpected "left" turn due to some unknown forces "pulling" it or shall I say "pushing" it.. Hence my analogy of pushing/pulling the car.

[Doug Smock]

in fact Newton's laws have nothing to do with the questions why the boats wants to go forward or an helipcopter wants to go upwards
Newton's laws explain why a boat has torque roll or make it necessary for an helicopter to have a tailrotor( or an other solution like contra rotating props)

I think Mr.Newton and Bernoulli would both agree that a boat is being pushed.

Propel your toy boats however you want fellas.

[iop65]

with all due respect ; they will not

[tlandauer]

Hmmm......
PADDLE WHELL....... Torque roll?

Sent from my D6708 using Tapatalk

[Make-a-Wake]

This results in a pressure differential between the two sides of the blade: a positive pressure, or pushing effect, on the underside and a negative pressure, or PULLING EFFECT, on the top side. This action, of course, occurs on all the blades around the fall circle of rotation as the engine rotates the propeller. So the propeller is both pushing and being pulled through the water.

So there is some pulling involved..............and pushing...........and pressure difference.............which all equals thrust the way I take it.

[Make-a-Wake]

Actually, that's how I understood from your first question, also the drawing was clear.

That's what I thought..........

[SweetAccord]

One reason that surfacing propellers are "faster" is because they create a low pressure 'vacuum' area in front of the prop, this is well documented. The result of the pressure differential is strong forward movement.



.

Right, and in addition, the "faster" is also due to the drag factor is one of the reasons why surface piercing propellers are very efficient. One or more blade(s) is always out of the water causing less drag. They are also designed to run with the water line at hub level which keeps the majority of the blade area clear of the water and this reduces drag to a minimum and propulsion at maximum.

[SweetAccord]

That SweetAccord guy has all the answers, very fine explanation!!

Thank you. You are very kind.

[dasboata]

boats are being pushed by Props,, not pulled,,, front wheel drive cars pull cars,, as rear wheel drives push the car pretty simple

[tlandauer]

boats are being pushed by Props,, not pulled,,, front wheel drive cars pull cars,, as rear wheel drives push the car pretty simple

That is correct, but I am afraid my insurance adjuster will tell me that the part ahead ( i.e. front over hang part) of the front axle is still being pushed by the front driving wheels. lol.....

[Make-a-Wake]

boats are being pushed by Props,, not pulled,,, front wheel drive cars pull cars,, as rear wheel drives push the car pretty simple

I am perfectly aware of where the prop is on a boat.

I am talking about the prop boring into the water ahead of it "pulling itself" thru the water thus moving the boat

Hopefully everyone now understands that my question was much more in depth than where the prop is.....................

[eric-paul]

http://www.merriam-webster.com/dictionary/propel

http://en.wikipedia.org/wiki/Propeller_(disambiguation)

http://en.wikipedia.org/wiki/Propeller#Theory_of_operation

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

[SweetAccord]

I am perfectly aware of where the prop is on a boat.

I am talking about the prop boring into the water ahead of it "pulling itself" thru the water thus moving the boat

Hopefully everyone now understands that my question was much more in depth than where the prop is.....................

Your question IS deeper than most are going to understand. I for one actually enjoyed your question. Most will try to think inside or outside the box, while others make the BOX!

[ray schrauwen]

A prop in itself is pulling through the water. In order to propel a model boat as the ones we talk about in this forum it is most efficient imo, to attatch it to the rear of a boat for best performance, in doing so the boat is pushed forward by theprop pulling through the water.
DaT sound good enough?:-)

[markwithak]

Wow I must be bored trying to do some searching for my own stuff and info but stumbled on this mess.

Really, common sense rule in affect depends on location of motor. If motor or driving force of shaft is in front of propeller or impeller or turbine, boat or aircraft its pushing. if motor is behind its pulling. This should be as simple as what the shaft that spins the prop feels and if shaft is in front of propeller it sees force as pushing. If shaft is behind prop it sees it at pull. For general RC boats if it did not push forward you would not need any gap on your flex cables...