the deep

iTrader: (8)

What is the terminal velocity of a Bravo 1 lower . From what I'm seeing I guess around 85mph . Can anyone tell me for sure ? Does this vary a little from boat to boat or is it a given that at xx mph you are now outrunning the drive ?

professor_speed

Actual prop height and type of prop will play a big role. Plenty of boats run well past 85 but they have high prop height.

Smarty

These are standard Bravo's (came with the 502/415 motors) with 1" prop shafts, low water pick-ups, boat runs 90-92 mph. This same engine -drive package were put in a 30' Eliminator cat that reportedly ran 100 mph, so the drive is hydro-dynamically sound enough to run 100 mph.

The drives pictured below are fairly high, spin 34" Bravo props.


PS Clarification the boat did not run 90-92 mph with the Mercury 502cu.in./415 hp, it does runs 90-92 mph with 540cu.in./520hp but with the same outdrive(s).

the deep

iTrader: (8)

With the vast amount of knowledge that is OSO can no one give me a more definitive answer . Looking for single engine applications . High or deep prop shaft heights really , in my mind , should have no effect on terminal velocity . Trying to find out , in reality , just how fast a stock Bravo lower can be pushed before the prop starts eating air . Surely someone has this info . Thank you to the two guys that did answer , just looking for something more precise if it even exists .

abones

I know this won't be the info you need ,but I have seen a bravo 1 boat that runs around the lake by me that will run over 115mph. Sorry Deep but can't give you any other info on it cause I never talked to the guy.

professor_speed

Prop height is directly proportional to drag, i.e. directly proportional to terminal velocity. Also if the drive is at terminal velocity another drive with equal force (hp) would not allow for a speed increase. ( think one sky diver vs two separate divers, same speed its still terminal velocity twice as much mass but also twice as much drag)Terminal velocity is when an increase in force results in an equal increase in drag, and thus no speed increase. The force required to get to terminal velocity would cause drive failure, well before drag was high enough to completely stop acceleration.

glassdave

iTrader: (1)

i believe the E Ticket cat ran 130ish on Bravo drives. Not sure derivative but they were some sort of Bravo drive



Terminal velocity may be the wrong term for what you are looking for. Maybe upper boundary? There are so many variables its difficult to nail it down.

the deep

iTrader: (8)

Then it may be assumed that a nose cone or switch to an Imco or Sportmaster lower may not be necessary to run into triple digits . It's more a case or combination of setup and prop . Thanks guys for these answers .

Cobra100+

iTrader: (3)

Thats a fact in my case, well into triples with standard XR lowers.

the deep

iTrader: (8)

What props are you using ? Wondering if a cleaver style prop would be a better choice over a Bravo1 four blade . Single engine cat .