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  1. #1
    Join Date
    Dec 2017
    Posts
    34

    Default Princess 35 flybridge prop spec

    Hey guys I have a princess 35 flybridge 1988 with tamd41a 200hp on shafts with 20x22 3 blade props I am thinking of changing to 4 blade props is there anyone running 4 blade props with similar spec and if so what performances are you getting my boat Wright is around 8ton most of the time.

    Regards
    Marty

  2. #2
    Join Date
    Jan 2011
    Location
    Dorset
    Posts
    477

    Default Re: Princess 35 flybridge prop spec

    Only change if you can get up to max rpm, if not then you will spend money for nothing and lose performance plus the engines will have to work harder. Assuming you can get to max rpm a three blade prop will give you more speed compared to a four blade so perhaps better to consider getting the props re-pitched to get more speed for less cost. There are a few sites that allow one to input data and get a prop design.
    Best option would be to try them all and see what comes out.
    My guess is you could re-pitch to 20 x 24 and get a couple more knots.
    I have been through this loop with my boat and am now slightly over-propped! What the hell, I don't travel flat out anyway! Next year knock an inch off the pitch perhaps.
    Broom owners club..... www.broomowners.com

  3. #3
    Join Date
    Dec 2017
    Posts
    34

    Default Re: Princess 35 flybridge prop spec

    I get full revs to 3800 rpm at 24knots but I never do that, can you recommend sites to do this.

  4. #4
    Join Date
    Jan 2011
    Location
    Dorset
    Posts
    477

    Default Re: Princess 35 flybridge prop spec

    From what you say your props sound correct.
    I googled prop design and a few sites popped up, I do not have that info any more.
    Broom owners club..... www.broomowners.com

  5. #5
    Join Date
    Mar 2016
    Posts
    930

    Default Re: Princess 35 flybridge prop spec

    Hi there.
    Interested in your post here. Our P385 was changed to 4 blades before we got her. She is maybe over propped now I think.
    She will lurch forward at an alarming pace when put into gear at idle rpm. Will do about 6 knots anyway at tick over almost.

    Do you need to change props ? Sounds like you are perfectly set up with your numbers. Thatís great going. Generally 3 blades are far more efficient compared to 4 blades. 4 blades help get up and go compared to 3 blade (of the same pitch) but generally will loose top end pace. They do tend to keep a boat on plane at lower rpm though. Generally speaking.

  6. #6
    Join Date
    Nov 2001
    Location
    Medway
    Posts
    19,485

    Default Re: Princess 35 flybridge prop spec

    My my, you must be made of money. .
    What are you trying to achieve. ?
    The top speed of a P35 with sparkly shiney new everything and a perfectly clean bum was 24 knots and you can bet Princess made sure there was no junk aboard whatsover on the test.
    Probably no dinghy or davits either .
    Its 35 years later with a couple of not 200HP engines and lord knows how much extra bits and pieces added over the years, like 20 miles of redundant copper wire that appears to do nothing very much.
    You should in the real world get around 22 (ish) knots in calm water, any chop will reduce this.
    Stick to your 3 blade props, changing to four blade will not give you any increase in speed if your existing props are pitched correctly.
    That extra blade will raise purchase price considerably.
    My 3 blade props on a 1991 boat are 20" x 26P.
    We have a spare set that are 20" x 24P .
    Performance is virtually identical, except that finer pitched pair gives about 150 rpm more at WOT.
    See my previous posts about skippers forking out £1000s changing from 3 to 4 blade props and achieving zilch.
    Have half a dozen very similar boats on our moorings ie. Princess 35/Princess 330/ Corniche 31, all powered by the 41B and 2.63 MS4B gearbox , not one single boat has the same props,all vary in size and pitch.
    Good Luck.
    Last edited by oldgit; 17-05-19 at 07:20.

  7. #7
    Join Date
    Dec 2017
    Posts
    34

    Default Re: Princess 35 flybridge prop spec

    I achieved 24knots on my princess with half fuel and half water and It was calm day going with the tide and I don’t carry a lot on my boat just the basics and this was with a gps I recorded speed. As regards to speed I’m not trying to gain speed I’m looking to see If anyone getting better efficiency with 4 blade props or 3 blade prop but different pitch.

  8. #8
    Join Date
    Nov 2001
    Location
    Medway
    Posts
    19,485

    Default Re: Princess 35 flybridge prop spec

    Suspect Princess will have originally invested considerable time and effort calculating the most efficient way of getting 200HP to the props, also with a regard to longevity of engine and gearboxes.
    Pretty sure the P35 came with 3 blade props as standard. ?
    The diameter of the prop(s) would also have to be smaller to compensate for the extra blade area ?
    It would seem that bigger capacity engines with lower revs favour 4 blade.

  9. #9
    Join Date
    Dec 2017
    Posts
    34

    Default Re: Princess 35 flybridge prop spec

    Yeah most 4 blade props I’ve seen have lower revd engines.

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