Drive rotation

[Bryan Tuvell 33ZX]

With twins, I have read a bunch on drive rotation, and I am still confused, because most of what I have read are from... Looking for some expert advise please.
Turn "in" or turn "out?"
What is standard if you don't ask for such specific's?
Which raises the bow the most?
Help me out guys as my education continues.
Thanks, Bryan

[Moody Blu']

I think this discussion was on OSO somewhere a while back(like a year ago)

I believe it could go either way depending on the boat.

[MOP]

Most boats are set up to turn outward the reason I believe is you are sucking water from the center of the boat less chance of airing out in turns. I doubt if it changes speed running straight.

[GeneD]

According to Reggie Fountain, when you turn the props in, you will gain 1-2 MPH but will lose docking nimbleness. I had asked him about this a while back (two years ago) and he confirmed what I had been hearing.
When I saw Donzi testing the F2 boat last year, they tried 'in' and 'out'. "In" is slightly faster for them, and though I haven't checked this year, I do believe that they were running "in" last I saw.
Direction of 'in' or 'out' being the rotation from the top of the prop looking from the back of the boat towards the front.

[Shanghied Again]

Turning in on V bottom has a slight edge over out. Step hulls always rotate in.
A Cat is better rotating out for higher speeds but make the boat a handful on top end. The Nor-Tech 36 Cat runs 153 out and 149 in with better control.

[Bryan Tuvell 33ZX]

Thanks for the data guys, several thoughts on this I see, interesting.
RTrip, several things have changed since last night when we spoke, amazing what can happen in a day.
Taking the RH rotating 26ZX out in the morning, hoping to be nimble at the dock for lunch! :)
Off to bed, thanks again.
Bryan

[MOP]

Checked about 80-90 boats rack and land bound inboards all were set up to turn out. Could not find one boat in 5 of the largest marinas out here that turned in. I knew that to begin with having worked on way to many but wanted to see if any manufacurer did anything different.

[z22owner]

Brian,

I just read an article by Bob Teague in Powerboat. He had a reader with a new stepped hull that was running outward props. Bob suggested running inward props to reduce bow rise and increase performance. Just thought I would pass that on.

z22owner

[MOP]

More thoughts! Got to speak with a fellow that I know that has done some racing and hull design. His tilt on prop rotation is that on average and flattish bottom boats don't make a R---- A-- but it make a big difference on Deep performance boats in two ways. According to him when you jump out of the water the first good water feed to the props is the rush off the vee on re entry, with outward rotation it is more immediate, also when thrown into a turn an outward prop will not air out till it reaches a steeper angle. So who knows! He also went on to say look at any OEM setup the all turn outward.

[mjpcowboy]

My 33ZX was set up from the factory to turn in. It was a little harder to back into a dock at first but now it is no problem. Donzi states increase in speed of 2 mph on the 33 however I have no switched and tested myself.

[Bryan Tuvell 33ZX]

Thanks for all the great posts, I now have some first hand factual data on a boat with twin power on the difference, thanks to a pal in Ohio, what a pain to change over for a test! Out of my league. He also achieved better numbers turning "in" with T575's/XR's.

Just curious,
Thanks
Bryan

[Capt. Donzi]

FYI, 28ZX's rotate INBOARD and 28ZX Scorpion's rotate OUTBOARD.