Quote:
Originally Posted by Dave R
I have a 25 foot boat, with a single-stepped hull, 24 degrees of deadrise at the transom, and terrible weight distribution due to the big block engine option. It's obviously a pretty bad combination for slow speed planing, but it'll easily plane out at 19 MPH with the tabs down, and 24 MPH (speeds measured with GPS, not the OEM speedometer) with the tabs retracted. I have a Bravo 3 drive, so I suppose that helps a lot, but I find it hard to believe there's many boats out there that really won't plane at 25 MPH.
Mine does get substantially better gas mileage from 28 MPH to 40 MPH compared to 25 MPH though (as measured with a Lowrance LMF-200). Literally, 40% better.
|
Dave...
That Bravo 3 Dual prop drive is the key.... it pushes alot of water very efficiently at lower speeds.... nothing pops a boat on plane better or quicker than the Merc Bravo 3 or Volvo Duoprop setup...
But like everything... there is a tradeoff to be made!
The dual props become less efficient at higher speeds... thats alot of blade area to spin and it requires sustantially more HP to spin the faster it goes... and water does not compress. All things being equal thats why the huge difference in gasoline consumption.
A high performance boat such as my 26' Donzi is setup (weighted, balanced, propped) to go fast... 67-69 MPH. But like everything else there is a tradeoff. The boat doesnt like 25 MPH... even with the tabs down! The propeller is cavitating, the stern squatting and the nose is high.. and the wake rivals a Carver! I am sure its compounded on the larger heavier high performance boats.
Its funny but everything settles down smoothly at 30-32 MPH. You wouldnt think 5-6 MPH would make a big difference but it does.
For the record.. I seriously doubt the MP is going to pull you over for going 30 MPH... but you never know.
Woodsy