gear change vs. prop change

[nodigg]

So help me out. What are the advantages, if any, of a gear change vs. a prop size increase. If running say a 30 bravo 4 blade and bumping the rev limiter hard with stock Bravo one gearing, would I benefit best from a gear change or a prop increase?? Or is it irrelevant? What is the difference between going to a 1:36 vs. increasing to a 32 prop for instance?:confused:

[Infomaniac]

Changing gears keeps you in the more common less expensive prop pitches most of the time.
Just my opinion.

[nodigg]

Any mathmeticians out there with a formula handy for the gear/vs. prop change?

[cstraub]

Going to a 1.36 from a 1.50 really loads the drive and the engine. I would only recommend it if you have a light boat and serious power. Kinda like taking off in 3rd gear with a 1.36. Go props.
Chris

[superdave013]

threads like this make me really happy to be a v drive guy.
One gear swap comming up. Be done in under 15 min. :)

[nodigg]

Originally posted by cstraub69
Going to a 1.36 from a 1.50 really loads the drive and the engine. I would only recommend it if you have a light boat and serious power. Kinda like taking off in 3rd gear with a 1.36. Go props.
Chris
Makes sense but would it not be the same if a larger prop is used??

[nodigg]

Originally posted by superdave013
threads like this make me really happy to be a v drive guy.
One gear swap comming up. Be done in under 15 min. :)
???

[Turbojack]

If you are running a 30 pitch prop now just go up in pitch. The gear change is equal to about 3" of pitch. I would not change gears unless you have to go to a 34 or bigger. Plus change props is cheaper than changing gears.

[DogHouse]

Come on Rick, you know that deckboat only does 35! What are you talking about, prop/gear change... ;)
I'd say try a new prop. That way if you like it you can sell me your 30 for a really good price! :D
I would try to borrow a prop first and see how it works, then decide. If it still comes on plane easily, will cruise slow without too much slip, and gives you the top end bump you're looking for, then you're good to go. That way you also end up with a spare prop. Bob will sell Bravo four blades to his customers for about 400 bucks. If you find that you are getting too much slip at low speed with the big prop, then you could consider the gear change for more $$$.
-brian

[celeb1]

Most boats tend to have a little better top end with a larger pitch prop but I guess it would mostly depend on the power band on your motor. I dropped down my gear ration and went with a smaller prop and lost about 2 MPH.

[nodigg]

Originally posted by Turbojack
If you are running a 30 pitch prop now just go up in pitch. The gear change is equal to about 3" of pitch. I would not change gears unless you have to go to a 34 or bigger. Plus change props is cheaper than changing gears.
That's good info on the gear change being equal to 3" prop change. Thanks

[nodigg]

Originally posted by DogHouse
Come on Rick, you know that deckboat only does 35! What are you talking about, prop/gear change... ;)
I'd say try a new prop. That way if you like it you can sell me your 30 for a really good price! :D
I would try to borrow a prop first and see how it works, then decide. If it still comes on plane easily, will cruise slow without too much slip, and gives you the top end bump you're looking for, then you're good to go. That way you also end up with a spare prop. Bob will sell Bravo four blades to his customers for about 400 bucks. If you find that you are getting too much slip at low speed with the big prop, then you could consider the gear change for more $$$.
-brian
EXCUUUUUSE MEEEEE BRIAN! But I am doing 37.5 MPH now! ;)
Actually, Richard suggested cupping the lab 30 first lst night and it yielded .2 mph more on top but with 200 less rpm. He is going to loan me a lab 32 this afternoon then its back on the water for a new gps reading. He called this morning and says he sold my old 26 and may trade the 32 for my old 28.
:D :D
Should see 38 MPH tonight with any luck! Thanks for the input!

[jackpunx]

I don’t know all the reasoning behind this.. But when I did the work on my motor.. (GT performance) .. we upgraded the drive.. Gary T said it would be best to run lower gears VS going to a 34 .. At least in my size boat.. Plus.. if you ding your prop its highly unlikely that you will be able to find a replacement (for that weekend) if your pitch is out of the high or out of the norm..
FYI.. I did run a 32 .. my boat acted a lot different.. I like the attitude of the boat with the 30. and my trim points were different too..

[HP350SC]

One commonly held belief which makes sense is it takes a certain amount of power (due to frictional losses) just to spin the prop in the water. so you lose a little speed when spinning a smaller pitch prop faster. Of course it depends on the application too. Bumping the rev limiter w/ 1.5 gears and a 25 prop would make sense to prop up. Hitting rev limiter w/32 prop and 1.32's may be better off going to 1.24-1.26's.
It is interesting to punch in variables on the prop calculators on Bammarine or Bronsonpropeller websites.

[jackpunx]

Originally posted by HP350SC
One commonly held belief which makes sense is it takes a certain amount of power (due to frictional losses) just to spin the prop in the water. so you lose a little speed when spinning a smaller pitch prop faster. Of course it depends on the application too. Bumping the rev limiter w/ 1.5 gears and a 25 prop would make sense to prop up. Hitting rev limiter w/32 prop and 1.32's may be better off going to 1.24-1.26's.
It is interesting to punch in variables on the prop calculators on Bammarine or Bronsonpropeller websites.
the only problem there.. is your slip changes with different props

[HP350SC]

Yeah that's true....nobody said it was easy:D

[nodigg]

Thanks for the input fellas.
I ran the 32 lab and gained a few miles per hour over the lab 30 and it comes out of the hole okay also. I DO like the way the boat feels a little better with the 30 however. It took a bit longer of course to get to the top end. Now I just gotta loose some slip. Anyone have any experience with nose cone changes?