Prop clearance
 

Hey guy's , does any one know the minimum clearance between the cavitation plate and the blade ? I think its 1/8" but could be wrong

Depends on the boat and HP you are running.
Props flex a lot more than one might think.
I remember when we developed the Maximus prop and the 2" short Sportmaster ITS drive unit. (these were at close time frames)
Upon removing the prop from the drive after the first test, we noticed the flattened tips of the Maximus blades. They were very uniformed in their damage. Next, you guessed it, we looked at the drive and found the slot cut on the underside of the cav plate caused by the prop. This set up had about 1/8" clearance on a 38 Powerquest with 500EFI's.

I like to see 3/8" in most performance set ups.

Brett

Thanks Brett I tried a Hydromotive 15 1/2 dia. 22 pitch on my 26 Outlaw 496 HO (425 HP) and was just a little worried , but ran her good and nothing but did it bring that boat to life. I think we chatted last year about this and finally got around to try it. It is closer to the thickness of your thumb.

Dave

Sounds good.

I do think a little less diameter for your hull is a good idea. Especially with a Hydro Q4.

Brett

Brett if we went smaller in diameter I would have to go up in pitch as we are right on 5000 and just a shade of trim to almost middle of gauge pushes me over 5 then rev limiter kicks in about 51 or just over . So I guess that 15 with 23p might be the ticket or just going to cup the tips a shade to drop 100 rpm and gain a little more bite. Our worry is tweaking it a tad to much, but I will let you know how we make out.
Dave

Ok,

sounds good.
I think you would be happier at 15" diameter.

Brett

If I can't get the one I tried then I will call and see what we can work out.
Thanks Dave

Hey Dave,
I agree that less diameter and more pitch will work well for you in the Quad IV. We go with 23" pitch and 14 3/4"-14 7/8" diameter, on your application.

Thom

Hi Thom to late Todd figures 22p 15 D Quad 1V X is the ticket but he could be wrong I will see this weekend. If this performs like the one I had or a little better I won't touch it , but thanks for the advise that both you and Brett have given.
Dave

Thom it didn't work out to good so going to 15 1/2 23p so I may have to get it labbed but it is real close to what I tried and had success.
Dave