There has been a bit of discussion regarding prop slip on this site and others recently stemming from the introduction of Mercury's 400R outboard. Being pretty new at HP boat stuff, I am trying to get a better understanding of the real forces on hulls, props, etc. After taking Tres Martin's HP Boating course, I was amazed at what I intuitively new about boat dynamics, but did not put the physics into play like Tres so well presents. It was pretty eye opening for me! It also made me a much safer boater by understanding and anticipating the "badstuff' that can happen hopefully before it does hopefully at least.

I know that there are people on this site that know a lot more that I do. As I said, I am learning the boat stuff. I spent most of my life tuning motorcycle engines and more importantly suspensions to allow me to be a competitive racer and some of my later life tuning and racing road race cars. I have an abundance of very well written books regarding the engineering, tuning and set-up for road race cars that I have used as my bible in the past, but I have not been able to find much on HP boating written.

Back to the prop slip discussion. Some have stated that they have achieved very low slip numbers with their boats, as low as zero slip. So I tried to do some on-line research. Below is an article that explains some of the physics of propellers and why slip is critical for a boat to have thrust. I welcome some conversation regarding this issue, not to cast doubt on anyone, but to try to flush out real world experiences and gain a better understanding. Thanks!

https://www.vicprop.com/propeller101.htm

Mine is 8%