Page 2 of 3 FirstFirst 1 2 3 LastLast
Results 16 to 30 of 38

Thread: 22 Classic - Prop advice

  1. #16
    Join Date
    Jun 2012
    Posts
    12
    Rep Power
    0
    Quote Originally Posted by Carl C View Post
    All props are not equal in pitch rating. The Bravo 1 is over-rated by at least one pitch number. I spin a BBlades labbed 30p Bravo 1 behind a stock 525, also with Bravo XR/Imco -2" lower. The 525 usually dynos around 540 hp. I bump the rev limiter at 5,400 rpm in ideal conditions. It sounds like your hp numbers are a little optimistic.
    Could be, as the engine was not dynoed. I think my problem is prop slip though. I had a good run yesterday with the same old 28p Hydromotive 3 blade as the Bravo 4 blade hasn't arrived yet. Ran 78 GPS @ 5,400 rpm bumping the limiter again, 3 people 1/2 fuel, trimmed 1/2 out. I calculate that as 18.3% prop slip, which is a lot.

    I have to admit, at that speed it's a bit of a handful and I'm starting to think about hydraulic dual ram steering. Carl, you the same XR/IMCO setup, what steering do you have?

  2. #17
    Join Date
    Oct 2012
    Posts
    498
    Rep Power
    0

    70-73mph

    Quote Originally Posted by John B View Post
    I'm still waiting for the 28p Bravo 1 to arrive to test.
    In the meantime roadtrips numbers are starting to make sense to me. With 9-10% slip 28p could be too much. I made a handy HP, Speed, Pitch calculator in excel, seems I'd need about 750 hp to turn that wheel properly at 5,400 then I'd be going 87 mph. I would link it here, but the forum doesn't accept excel files. If anyone would like it PM me your email

    Pat - good input. I wonder how the new Mercury racing Max5 would work?
    http://mercuryracing.com/boat-propel...erndrive/max5/

    Attachment 86112
    My boat will run 70mph GPS at 4800rpm with full load of fuel and 4 people. 73mph at 5000 rpm with just me and light on fuel. With the Rev 4, I can trim away any porpus at any speed; with my Mirage 3 blade the handling is not nearly as good.

    A stock 28p Bravo is more like 26.5" pitch. Like I said, I don't like them on old school deep V boats. I did have good success with a BBlades modified 28P on my 97 24' Superboat.
    Thanks, Patrick


    1996 22' Classic

  3. #18
    Join Date
    Mar 2017
    Posts
    4
    Rep Power
    0

    Minx 20 with New Imco 2" Shortie

    Hi. Saw some of these past posts and wanted to ask if anyone had issues when they put the 2" shortie on your Donzi classic. I am getting major slippage/cavitation since I put the shortie on. I have a small supercharger on a 350 SBC. Should be making around 400hp but still questioning that. I tried a Mirage 21p and a Rev 4 blade 19p and both where very bad. Boat handled real sloppy too. I do have a Rev 23p that I could try but wondering if something else is wrong. Appreciate any info you have on this..

  4. #19
    Join Date
    Oct 2012
    Posts
    498
    Rep Power
    0
    Quote Originally Posted by MinxRaider View Post
    Hi. Saw some of these past posts and wanted to ask if anyone had issues when they put the 2" shortie on your Donzi classic. I am getting major slippage/cavitation since I put the shortie on. I have a small supercharger on a 350 SBC. Should be making around 400hp but still questioning that. I tried a Mirage 21p and a Rev 4 blade 19p and both where very bad. Boat handled real sloppy too. I do have a Rev 23p that I could try but wondering if something else is wrong. Appreciate any info you have on this..
    How far below the bottom is the prop shaft?
    Are you running an Alpha SS or did you switch to a Bravo?

    On my 22' the prop is 7" below with standard Bravo. Guys run 2" shorty with great success.
    I owned a 20' Minx with 350 Alpha drive but never checked how deep or if a SS would work.

    I think about 5" below the round bottom is a good spot for these boats.
    Thanks, Patrick


    1996 22' Classic

  5. #20
    Join Date
    May 2004
    Posts
    2,852
    Rep Power
    16
    I had a Minx with with an Alpha S/S....gained zero.

    I don't know how much shorter a Imco -2 shortie on a Bravo upper is over the S/S, but I know the S/S didn't work for me.

    Ken

  6. #21
    Join Date
    Mar 2017
    Posts
    4
    Rep Power
    0
    I am running a Bravo drive with the 2" shortie (replaced the original Alpha at the same height). The standard Bravo was close to 8" below the bottom so I assume I should be around 6" now. Unfortunately didn't get a measurement before the boat went in the water. Just seems to have a real bad effect overall and not sure a prop can fix it.. Putting tabs down made things much worse..

  7. #22
    Join Date
    Jun 2012
    Posts
    12
    Rep Power
    0
    I just tried the stock 28p Bravo from BBlades yesterday and immediately felt the difference. The boat came up on plane much easier and at lower rpm, now about 2,200 rpm vs about 3,000 with the 3 blade 28p Hydromotive. It handled better in turns at cruising speeds and generally felt more stable. Max speed on this run was 80 mph GPS at 5,200 rpm with three people and 1/4 fuel. I only trimmed it out 1/2 way as it felt a little different than before, maybe more torque steer and I didn't want to push it with passengers on board. The boat likes the 4 blade with the shorty and I'm getting close to where I wanted to be but that's still more prop slip than I expected, I calculate 13%. I'd like to see RPMs up to 5,400. But I'll do another test solo and trim it out more before I try to reduce pitch.

  8. #23
    Join Date
    Jun 2012
    Posts
    12
    Rep Power
    0
    Quote Originally Posted by MinxRaider View Post
    I am running a Bravo drive with the 2" shortie (replaced the original Alpha at the same height). The standard Bravo was close to 8" below the bottom so I assume I should be around 6" now. Unfortunately didn't get a measurement before the boat went in the water. Just seems to have a real bad effect overall and not sure a prop can fix it.. Putting tabs down made things much worse..
    Minx, I didn't like the feel of the shorty on my 22C at first. It took more patience on the throttle to get it up on plane and required the use of tabs, which it didn't before. As I learned how to "Tickle" it up on plane patiently I got used to it. I just put a 4 blade prop on and it's now much better (see post above). I'm now a full shorty convert. My prop is 5" below the V at the transom with neutral trim.

  9. #24
    Join Date
    Aug 2005
    Posts
    7,788
    Rep Power
    21
    Good news! Hopefully you can squeeze out a few more rpm and mph.
    Lake St. Clair, Lake Huron, Lake Erie, Lake Oakland

  10. #25
    Join Date
    Oct 2012
    Posts
    498
    Rep Power
    0
    Quote Originally Posted by John B View Post
    I just tried the stock 28p Bravo from BBlades yesterday and immediately felt the difference. The boat came up on plane much easier and at lower rpm, now about 2,200 rpm vs about 3,000 with the 3 blade 28p Hydromotive. It handled better in turns at cruising speeds and generally felt more stable. Max speed on this run was 80 mph GPS at 5,200 rpm with three people and 1/4 fuel. I only trimmed it out 1/2 way as it felt a little different than before, maybe more torque steer and I didn't want to push it with passengers on board. The boat likes the 4 blade with the shorty and I'm getting close to where I wanted to be but that's still more prop slip than I expected, I calculate 13%. I'd like to see RPMs up to 5,400. But I'll do another test solo and trim it out more before I try to reduce pitch.
    Good News!
    Test her solo with the B1 28p and record numbers at just on plane, mid range 3400ish, and WOT. You may choose to go for a 30p if planning to lab. BBlades has a good formula to lab/modify B1 props for more bow lift and that's what these boats need.
    You may also want to test a round ear Hydro 4 blade and a 5 blade prior to labbing...

    My 24' Superboat ran 78mph at 5000rpm with BBlades labbed 28p B1.
    Thanks, Patrick


    1996 22' Classic

  11. #26
    Join Date
    Oct 2012
    Posts
    498
    Rep Power
    0

    check drive alignment and 1" spacer

    Quote Originally Posted by MinxRaider View Post
    I am running a Bravo drive with the 2" shortie (replaced the original Alpha at the same height). The standard Bravo was close to 8" below the bottom so I assume I should be around 6" now. Unfortunately didn't get a measurement before the boat went in the water. Just seems to have a real bad effect overall and not sure a prop can fix it.. Putting tabs down made things much worse..
    A Bravo drive is a little longer than an Alpha and I'm guessing that a Bravo with 2" shorty is similar to an Alpha SS in length.

    I would not think 6" below is too high but you could try a 1" spacer.
    I would check drive alignment and make sure your steering is tight/not sloppy.
    Thanks, Patrick


    1996 22' Classic

  12. #27
    Join Date
    Sep 2005
    Posts
    5,498
    Rep Power
    0
    Quote Originally Posted by John B View Post
    I just tried the stock 28p Bravo from BBlades yesterday and immediately felt the difference. Max speed on this run was 80 mph GPS at 5,200 rpm with three people and 1/4 fuel. I only trimmed it out 1/2 way. The boat likes the 4 blade with the shorty.
    You can get a Revolution 4 "XP" in 25.5 pitch. Might be worth asking Bblades about testing one out as a comparison as they run a touch stiff.
    1972 16 OB - C16B-63 - "Surface Tension" Resto Project
    1974 16 OB - DMR16106017-B - "The Mule"

  13. #28
    Join Date
    Nov 2015
    Posts
    255
    Rep Power
    0
    I'm running a 4 blade 26 pitch Bravo that has been labbed by BBlades

    still breaking motor in and hopefully just worked out some carb issues I'll find out this weekend hopefully

    so far it seems to get up okay and at about 4300 rpm just starting to trim it up it's hitting 65 so I am anxious to see what she will turn

  14. #29
    Join Date
    Jul 2016
    Posts
    1
    Rep Power
    0
    Quote Originally Posted by John B View Post
    Minx, I didn't like the feel of the shorty on my 22C at first. It took more patience on the throttle to get it up on plane and required the use of tabs, which it didn't before. As I learned how to "Tickle" it up on plane patiently I got used to it. I just put a 4 blade prop on and it's now much better (see post above). I'm now a full shorty convert. My prop is 5" below the V at the transom with neutral trim.
    As has been said before.......Each 22C is different to some degree.
    I installed an IMCO -2" shorty on my Bravo 1X and the boat is better in every aspect. Handles much better, mid range porpoise is reduced, gained almost 5 MPH on top end and get's on plane just as easily as with the stock lower unit. My prop shaft is now about 5 1/4" below the bottom.
    Was running a Bravo 1 26P and decided to try a 28P. The boat handles better with the 28, get's on plane effortlessly, and is 2 MPH faster on top end. I've tried several 3 and 4 blade props, and the Bravo 1 is hands down the best prop on MY boat.
    Stock 496 non-HO with whipple reprogram, runs 72 MPH @ 2000' msl. with 2 people and 1/2 fuel.

  15. #30
    Join Date
    Oct 2012
    Posts
    498
    Rep Power
    0

    want to buy shorty?

    I want one, but not for $4500. Anyone know where to buy good used or new in $2000 range?
    Thanks, Patrick


    1996 22' Classic

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •