[lance]

i am going to purchase a 23 pitch 17 diameter prop for my z235 davanti does that sound about right i have a 23 pitch 14 1/2 diameter and it is spinning the prop when i hammer down do u think this in fact would solve my problem, pushing more water with a bigger diameter

[mikeyt]

I'm not sure if i am reading this right but are you intending to go from a 14 1/2" diam prop to a 17" diameter prop? If so, do you have the clearance to run something that size and possibly more important is whether or not your outdrive is designed to handle the increased load of such a large diameter prop.

If you are looking for some more jump out of the hole you could look at a 21" pitch prop or possibly a 22" - 4 or 5 blade prop. All in, you need to keep your WOT rpm's within the recommended range for your motor. So if your range is 4400 - 4800rpm and you are running at say 4500 at WOT with the current prop then you could drop the pitch slightly and it would increase your rpms along with giving you more bite out of the hole. You do sacrifice some top speed though so everything is a trade-off somewhere.....

[ShabahZ280]

You'll want to increase or decrease your pitch, not the diameter of the prop.

[blockp]

OK. Now I'm confused (easy to do, I know). I thought going from 14.5" to 17" diameter was a bit of a stretch, but I did think that bumping up the diameter would help push more water and give more bite.

Or wouldn't keeping the same pitch and diameter but going to a 4 or 5 blade prop give more bite out of the hole?

[Z 202]

Diameter is another trade off. Larger diameters provided larger surface area, but require more torque to spin them.

Like Mikey stated earlier, the general rule is you drop the pitch a bit when you go to more blades.

[Colin Logie]

Check out " BBlades.com " Great info on props, John had mentioned that the company will send you props to try out for a small fee plus shipping and handling.

[z275st]

Looking at the pics of your boat it looks like you have a bravo1 drive is that correct? A bravo 1 or alpha will not allow for a 17"dia. prop. If it clears at all, it would be only by millimeters. Here is what you need to answer to select a prop.
First of all what is your max RPM with the prop you now have? How do you most often use the boat, water sports, cruising, heavy or lightly loaded, or top speed more important? No single prop will do the best of everything but some come close. I found that a rev-4 that puts you at the high upper limit of the RPM range is a very universal prop. The bravo-1 prop has more blade area and gives more stern lift so it reduces top end more and is more sluggish out of the hole. The mirage-plus 3-blade is better for top end and if you put holes in the vent system it is pretty good out of the hole (not as good as rev-4) but you will lose some fuel economy mid range cruising. If you have a local dealer he may let you try out some props. BBlades.com is the option I used.
Good luck!

[indykoch]

This is all good (and correct) info, but it sounds to me like all you need is a new hub. Your description makes it sound like the drive shaft is turning, but the prop isn't, right? Easy, cheap fix. Then we can analyze the size/pitch prop. I think a 14.5" X 23 is about right for that boat/engine combo. Don't spend the money on a new prop if it's just a worn hub.

[mikeyt]

Now that i go back and re-read the initial post i think Indy is right. It does seem like Lance is trying to say that his hub is spinning when he puts the throttle down hard. If that's the situation then yes, the hub is likely worn and you should be able to simply replace the hub rather than the prop.

[z275st]

Originally Posted by indykoch

This is all good (and correct) info, but it sounds to me like all you need is a new hub. Your description makes it sound like the drive shaft is turning, but the prop isn't, right? Easy, cheap fix. Then we can analyze the size/pitch prop. I think a 14.5" X 23 is about right for that boat/engine combo. Don't spend the money on a new prop if it's just a worn hub.

Man!, SOME people just want to go to the most obvious and simple fix!
Good call Indy, especially if its a flo-torq hub. About $35 will fix it.