cavitation?

Answer 1

OK guys, let me try to explain it to you. "Cavitation", not to be confused with VENTILATION !, as pertaining to a boat motor propeller. We all know that water boils at 212 degrees Fahrenheit at normal sea-level atmospheric pressure. But water also boils at room temperature if the atmospheric pressure is low enough. As a shape passes through water at an increasing speed, the pressure that holds the water to the sides and back of the shape is lowered. Depending upon the water temperature, when the pressure reaches a sufficiently low level, boiling (the formation of water vapor) will begin. This occurs most often on a propeller near the leading edge of the blade. When speed is reduced and the pressure goes up, boiling will subside. As the water vapor bubbles move downstream into a high-pressure region that won't sustain boiling, they collapse (condense back to liquid). The collapsing action, or implosion, of the bubbles releases energy that chips away at the blades, causing a "cavitation burn" or erosion of the metal.......The initial cause of the low pressure may be nicks in the leading edge of the blade, too much cup, sharp leading edge corners, improper polishing, or sometimes poor blade design. Massive cavitation by itself is rare, and it usually is caused by a propeller that is severely bent or has had its blade tips broken off resulting in a propeller that is far too small in diameter for the engine. That's what I know, now you do!

Answer 2

The only reason that you have heard about cavitation is most likely because you have a boat that travels faster than 15 knots and you have a transducer near the point of cavitation. Different boats have this problem at different speeds. When you drive most boats at fast speeds, the front usually planes above the water, which means if you had a transducer mounted (the transducer is the device that sends signals through the water to determine the waters depth) in the front of the boat; it would be out of the water! I would say that most if not all, transducers for boats need to have liquid between the bottom surface and the waters bottom. Some transducers are mounted inside the boat and send the signals through the hull. Inside the boat you have to mount a fixture, and then fill it with a liquid that will not evaporate very fast such as vegetable oil and secure the transducer inside this fixture. Since the unit is not sticking through the bottom and does not cause a deflection in the water, you don't have the cavitation problem. The other choice of transducers either mounts to the bow of the boat or you drill a hole through the hull and use a thru-hull transducer. These last two will stop giving you the water depth when the water starts to cavitate around the transducer. You can take a new depth finder and supply it power and hold the transducer in the air over the water and you will most likely get no reading or some very high reading for the water depth. Until the transducer actually hits the water, you get false or no readings. I had a high speed Fairing block (this is a hard molded plastic that you cut to match the angle of the bottom of the boat. Most boats that I installed these units in are "V" shaped and this makes the transducer point straight down even with the angle of the bottom) installed on a boat that could travel approx. 28 knots and as soon as the boat went above 18 knots, the depth finder would quit! The company finally installed a shoot-through unit (installed inside the boat with liquid) and that solved the problem. If you have a faring block with the transducer sticking through the bottom of the boat and if you have not installed it away from the props and away from any item sticking through the bottom of the boat, then when the water starts hitting this device at certain speeds you will get cavitation. This is air bubbles that form around the transducer and then you start getting bad or no readings on your depth finder. I hope this helps!

Answer 3

A descriptive term for massive jolting or jarring.

Edit: It also pertains to the movement of bubbles. I looked up the definition in Wikipedia.

Cavitation is a general term used to describe the behaviour of voids or bubbles in a liquid. Cavitation is usually divided into two classes of behaviour: inertial (or transient) cavitation and non-inertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Such cavitation often occurs in pumps, propellers, impellers, and in the vascular tissues of plants. Non-inertial cavitation is the process where a bubble in a fluid is forced to oscillate in size or shape due to some form of energy input, such as an acoustic field. Such cavitation is often employed in ultrasonic cleaning baths, and will also be observed in pumps, propellers etc.

Answer 4

The noise and vibration are tiny explosions caused by the collapse of the bubbles formed by low-pressure. When the bubbles are exposed to higher pressure again, they collapse and cause a small "sonic boom." While working on bachelor's degree in civil engineer, I worked at my university's water research laboratory. I've witnessed cavitation first-hand in the pipes and pumps that the professors would use in their experiments, and I was blown away by how destructive it can be! The popping can be extremely loud, and the pipelines would often rock violently back and forth. If exposed long enough to cavitation, even the hardest steel will look like Swiss cheese.

Answer 5

Cavitation is when the prop is not securing proper flow of water over its blades . This can be caused by a sudden change of position such as wave action or turning quickly or by excessive torque. The prop spins without grabbing bite to move forward. It can cause turbulance and vibration.

Answer 6

Cavitiation is turbulence caused by flowing gases or liquids across a surface and the bubbles that form from this flowing

Answer 7

it is when the prop spins fast and the air bubbles pop. it can damage the prop and makes nioce.

Answer 8

trim tabs

Answer 9

That's a FANTASTIC question.
Here's my answer.

Nope.

Glad I could help.