My boat tracks OK and doesn't pull but I noticed yesterday that at top speed if I ease right I pick up a few tenths mph. I thought it may just be the gps playing tricks or the prop torque. What do ya think is happening?
Printable View
My boat tracks OK and doesn't pull but I noticed yesterday that at top speed if I ease right I pick up a few tenths mph. I thought it may just be the gps playing tricks or the prop torque. What do ya think is happening?
The propeller becomes more efficient, according to the Masters thesis I've been reading.
Agree with ya. Thing is ya pushing weight and water drag friction, and sometimes the prop will start to slip as it can't push no faster. Move around a bit and grabs better. Hell, I dunno, but seems to make sense?Quote:
Originally Posted by transomstand
That's tha way I learned how ta drive my first Allison. Just lettin' it slightly "drift" right..........From there it didn't take long ta go straight.
I did the same with my first Hydrostream. Prop walk is wantiing to make the boat turn right so when you let it do what it wants it runs a tick faster.
Rock
It's like adding the same effect as a torque tab. Hooks the prop back in against the propwalk.
I've been looking at that thesis. The guy obviously has previous experience that pushed him to look in that direction. I have to wonder if increasing torque tab and maintaining a straight orientation would not be more efficient. Seems to me like steering right counteracts paddlewheel to keep the prop engaged. His data only showed the effect of the skew, not the reason for increased efficiency, other than better water flow which could be the result of countering paddlewheel effect, unless the skew exposes more blade area. A crabbing lower may produce a gain in prop efficiency, but also creates drag. He put a lot of research into his thesis, but IMO you still have to rely on "seat of the pants" trial and error. Not looking for an argument, but his findings didn't reveal anything we don't already know from experience.Quote:
Originally Posted by transomstand
That? in bold? Not gonna happen, torque tab adjust. Just more drag, and if out the water on plane?..useless anyway. And bet boats would all be faster if we did the old school racing.."always left turns", and with a rotating RH prop? Do clockwise! Or simple a new gearcase, with a LH prop rotating? I had a 26 foot I/O, VP OD, LH rotater prop. Damn, could I slip it easy! Nuff thinking me..back to drinking!:rolleyes::cheers::thumbsup:Quote:
Originally Posted by frederick55
What are you thinking? My skeg mounted tab is (usually) never out of the water when on plane.Quote:
Originally Posted by Robby321
Think increasing skeg mounted torque tab is more drag than crabbing the whole lower unit? Last I heard, starboard was a right hand turn, and obviously faster. Guess Nascar dictated racing direction. Said I wasn't looking to argue, but some people... better go back to drinking......me too. LOL :cheers:
Dude, ya must be young. Don't get me wrong, as I know where ya talking. BUT? :rolleyes: tab still in the water on plane? Have any clue what I run? SURFACE PROPS! Ya fast boats owned, and still do.Quote:
Originally Posted by frederick55
Tried to help ya, but ya get bitchy me, 60 plus years wet? (And FU very much..on "Nascar". SUCKS!) And I was M/C flat tracking, circle boats, when you were in diapers. And I'm still a drag racer.;):D:thumbsup:
Oh yeah, for the clueless in a boat? Right/Left? THINK the amount letters.."Starboard is right, and green. Port? red and left.
Tired messing ya...in person me, be a diff story...not what typed..in person ya would understand...
You're focused on 10th's of a GPS MPH? Come on home slice. Just sayin.............:rolleyes:Quote:
Originally Posted by Stumpalump
Dude, back me in the 70's. (and MOST efficient prop would be 0ne blade also) Ran a XS with a 2 b Cupped 14x24. Trim tab? HA!
Attachment 301368
Bingo here! ;):D:thumbsup:Quote:
Originally Posted by Greg G
Yes, I have heard that it can be more efficient straightening out the boat and lower unit using a tab on the skeg vs just steering into it, crabbing the boat which loads turns the skeg more and more out of being straight.Quote:
I have to wonder if increasing torque tab and maintaining a straight orientation would not be more efficient.
Without a tab the boat turns sideways making more ero drag. Without tab the lower unit also is creating more drag (surface area) not going straight.
The xs case I'm building now has a tab, it will be interesting to see how it handles.
Robby, I don't think you are on the same page. He is not talking about the normal torque tab anode under the cav plate.
I believe this is MR D's pic. Should get you on the same page.
C