Does a stream lined prop dog work

[m4a1usr]

The whole point I am trying to make is that there is quite a bit more turbulence from other areas. Unless you have access somewhere to test for turbulence caused by prop dog/shaft/prop interaction it's all speculation without the data.

I'm with you 100% when it comes down to brass tacks. A tapered drive dog has no value when all of the components are of the same diameter. Its not subject to debate. Water flow is laminar or constant when you have the same components with the same exterior diameters. Doesnt matter if a drive dog is tapered. You WOULDNT NEED a tapered drive dog if all the drive line shared the same exterior dimensions. Water only deflects off surfaces when there are changes in the laminar flow. Its basic 101 hydrodynamics. Very, very simple numerical constants. Doesnt require voodoo, superstition, tossing a virgin into a volcano (well,..........thats a brain teaser) but you get my point. Tapered drive dogs are good when the hub or exterior dimensions of you drive line are dissimilar. The answer? Make them all the same. Then there is no issue.

John

[fatboyelectric]

I'm with you 100% when it comes down to brass tacks. A tapered drive dog has no value when all of the components are of the same diameter. Its not subject to debate. Water flow is laminar or constant when you have the same components with the same exterior diameters. Doesnt matter if a drive dog is tapered. You WOULDNT NEED a tapered drive dog if all the drive line shared the same exterior dimensions. Water only deflects off surfaces when there are changes in the laminar flow. Its basic 101 hydrodynamics. Very, very simple numerical constants. Doesnt require voodoo, superstition, tossing a virgin into a volcano (well,..........thats a brain teaser) but you get my point. Tapered drive dogs are good when the hub or exterior dimensions of you drive line are dissimilar. The answer? Make them all the same. Then there is no issue.

John

Thanks for giving me the scientific explanation as to why stepped mono hulls should be allowed to compete with typical monos. Im not crazy or trying to be sarcastic ...... but dead serious ........ think about it. Oh, sorry, back to the topic.

[TheShaughnessy]

Tapering the front of the drive dog even if it is the same diameter as the strut can make a difference. Because of the gap between the strut and the dog to allow for shaft wind up the water can not completely jump that gap and will reach the flat face of the dog. Any water hitting a blunt surface is going to cause drag.

I have seen tapering the the front of the dog make a 2mph difference in SAW boats.

As for coned prop nuts the only real benefit in my opinon would be on a subsurface drive. On a surface drive most of it is out of the water when the boat is at speed.

Chris

Do you use a lock nut with yours? I've never had a problem with mine, I just like the way the look, never expected there to be a performance gain. I figured the prop made its own cone there anyhow.