slip??

[wyoboat]

I've read a lot about this and i think i know what it is just want to be sure what it is. So will some one please tell me what this means.

 

[fishrdan]

Re: slip??

It's either the thingy women wear under their dresses,,, or a permanent place to park your boat on the water, like a parking spot.

Which on were you referring to

 

[Frozen]

Re: slip??

It's either the thingy women wear under their dresses,,, or a permanent place to park your boat on the water, like a parking spot.

Which on were you referring to

i think neither in this case, since it posted on the prop section. I think he's asking about prop slip and I don't know exactly what it is besides the prop slipping on the shaft. This is calculated by boat weight, prop size, engine rpm and actual speed.

 

[craze1cars]

Re: slip??

LOL...I'm sure he's asking about neither...and it has nothing to do with propeller slipping on the shaft either. It has to do with the propeller slipping thru the water.

Propeller slip defined: The difference between the theoretical distance the propeller should travel in one revolution, and the actual distance the vessel travels.

A true 19 pitch prop should travel exactly 19" forward per revolution, assuming zero slip. All props slip some, however. So if this 19" pitch prop travelled only 18" in one revolution, it lost an inch of forward movement due to slip. This means the prop had 5.26% slip (1 divided by 19"). If it only travelled 17" in one revolution, it lost 2 inches of forward movement to slip. This means the prop had 10.52% slip (2 divided by 19").

Slip is simply a measurement of efficiency of a propeller. The more efficient the propeller, the less movement is lost to slip, and the more engine power is actually transferred directly into forward movement. All things being equal, in propeller terms, everyone is striving for the least amount of slip possible...

We use propeller slip calculators like this one to help determine a prop's performance, relative to other props: http://go-fast.com/Prop_Slip_Calculator.htm

Keep in mind this is NOT an exact science, and oftentimes input figures must be changed and estimated to get accurate numbers (especially with regard to pitch input...you do NOT always enter "19" into the pitch field just because the prop is labeled a 19 pitch. If it's aggressively raked/cupped you should probably enter a 20. And if it's a 4 blade you should probably enter a 20. And if it's an aggressively cupped 4 blade you might want to enter 20.5. Plus, almost no propellers that are labeled a given pitch, are actually that EXACT pitch. So keep in mind that cup and rake wreak havoc on prop slip comparisons, as can more or less blade count, and different types of hulls, etc. So the math in the calculators can be a good guide/tool to use, but it is far from a failproof catch-all, and the mathematical results can be VERY easy to misinterpret when comparing props and boats of different syles, sizes, etc....

 

[dragginanchor]

Re: slip??

I don't think he means a spun hub on a prop (prop slipping on the shaft), or splines sheared off the prop shaft / hub.
I would guess he's talking about the difference between the theoretical speed the prop should deliver and the actual speed it goes, measured in %.. prop slip.
Things that would effect the actual speed- nicked/damaged prop, dirty hull, motor height, trim angle, excessive weight, and all sorts of other problems.

 

[fishrdan]

Re: slip??

i think neither in this case, since it posted on the prop section.

Ooops, :redface: didn't notice it was in the prop section

Carry on...

 

[wyoboat]

Re: slip??

thanks guys, craze1cars knows what I'm getting at, Just trying to dial-in what prop to buy. thanks again to everyone on this site. read a lot on here.