User Tag List

Results 1 to 14 of 14
  1. #1
    Join Date
    Apr 2001
    Location
    MILWAUKEE WI.
    Posts
    317
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Prop calculation chart

    Does anybody know if there is a chart for calculating props with RPM and slippage. Or is there just a formula?



  2. #2
    Join Date
    Apr 2001
    Location
    Georgia
    Posts
    16,973
    Thanks (Given)
    2
    Thanks (Received)
    38
    Likes (Given)
    46
    Likes (Received)
    174
    Mentioned
    1 Post(s)
    Tagged
    7 Thread(s)
    This is my favorite:

    http://www.rbbi.com/folders/prop/propcalc.htm

    I have it saved in my favorites. It sure beats gettin' out the calculator. For gear ratio, just type in the first number. Example, for 1.87:1 as in Mercs, just type in 1.87
    Membership upgrade options: http://www.screamandfly.com/payments.php

  3. #3
    Join Date
    Apr 2001
    Location
    MILWAUKEE WI.
    Posts
    317
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks it could become a favorite of mine also.



  4. #4
    Join Date
    Apr 2001
    Location
    Long Island NY
    Posts
    4,885
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    4
    Mentioned
    4 Post(s)
    Tagged
    1 Thread(s)
    I have that in my favorites too. 1 thing I noticed though, if you want to figure out your slip at anything over 100mph, it cant calculate it for some reason.
    Helmut
    slow boats

  5. #5
    Join Date
    Aug 2002
    Location
    Lowell,IN
    Posts
    2,548
    Thanks (Given)
    0
    Thanks (Received)
    10
    Likes (Given)
    57
    Likes (Received)
    43
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    I use this one

    But it has the same problem as what stvhelm was saying.
    http://hillpropellers.com/propcalc.html

    upon further review. They look very similar to each other. HEHEHE. Oh well you have more boat sites you can go to now.
    Lata
    Travis
    Last edited by outboards4life; 05-10-2003 at 01:07 AM.

  6. #6
    Join Date
    Apr 2001
    Location
    Daytona Fl.
    Posts
    10,562
    Thanks (Given)
    5
    Thanks (Received)
    240
    Likes (Given)
    2
    Likes (Received)
    2245
    Mentioned
    7 Post(s)
    Tagged
    2 Thread(s)
    This is the one I've always used-- Gear ratio, If you've got 1.87-----1 divided by 1.87=.535 x .000946 x pitch x rpm = mph with no slip. you can take 10% off for slip normally. An example is my yellow flamer: .535 x .000946 x 32 x 8300 = 134.34 mph. My actual speed on GPS was 124 mph. to calculate slip, divide 134 by 124 = 1.08. The slip is 8%
    " IT'S NOT HOW FAST YOU ARE, IT'S HOW COOL YOU LOOK!!! "

    Check out my new website. liberatorpowerboats.com
    Boat Delivery available













    Things owned. NOTHING!!
    Ain't got no toyz, Ain't got no money! I is jus a poor Florida boy!

    Visit My Liberator Boats Website

  7. #7
    Join Date
    Feb 2003
    Location
    St. Pete Bch., FL
    Posts
    9,755
    Thanks (Given)
    8
    Thanks (Received)
    8
    Likes (Given)
    95
    Likes (Received)
    42
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    thanks everyone...

    Thanks for the links and formula, that is really helpful.

    96' STV Euro

    Smarta$$ of the
    Sunshine Syndicate,

    How to upload pics (click here)


    Quote Originally Posted by jphii View Post
    Well then, give her a $50 bottle of booze and don't let her know about the hookers, or what you spend on them
    Quote Originally Posted by 1BadAction View Post
    oh no. i just realized I am the voice of reason on a thread. i am so done, RIP 1Bad.

  8. #8
    Join Date
    Apr 2001
    Location
    Home
    Posts
    4,749
    Thanks (Given)
    0
    Thanks (Received)
    2
    Likes (Given)
    0
    Likes (Received)
    4
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If you want a real good one http://www.aeromarineresearch.com has an excellent one. You have to buy it but does all the crap without back and forth stuff. Change pitch or rpm or slip ratio what ever without refilling the boxes. Change anyone and all the others change to the new speed.


    There is one thing about the calculators, they generally have one peice of garbage info (garbage in garbage out.) The prop is a guestimate of it's pitch, also the style changes the amount of slip that is "good".
    Don't get carried away with them just use em as a rough reference, and forget about slip. High slip is sometimes the fastest props. Figured from emperical evidence.
    Any prop comparision, same boat many props and styles will result in a very wide unreasonable slew of results. The props are a variable that can't be predicted with a number. The slip that results changes the speed that you get so it aint exact.
    Slip can be ~14% - ~5 % Try both extremes and you'll see a big change.

    The formula is actually a short hand version of the real thing. Rpms are measured in minutes and MPH in miles and hours, prop in inches. Convert the thing to the same units (miles and hours) and you can do it without the .000946 number- which is a conversion of those.
    '90 STV
    '96 260
    under construction

    for far too long

  9. Likes Jimboat liked this post
  10. #9
    Join Date
    Nov 2001
    Location
    Lake Charles, Louisiana
    Posts
    11,959
    Thanks (Given)
    956
    Thanks (Received)
    591
    Likes (Given)
    17340
    Likes (Received)
    6167
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    -----------------------
    93 STV Mod VP/MERC 2.5 200
    -----
    The Bible is life's instruction manual.

    Proverbs 4:18-20

    " For a nation that is afraid to let its people judge the truth and falsehood in an open market is a nation that is afraid of its people."
    -- John F. Kennedy 1962

  11. #10
    Join Date
    Apr 2001
    Location
    Long Island NY
    Posts
    4,885
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    4
    Mentioned
    4 Post(s)
    Tagged
    1 Thread(s)
    damn, that one stops at 31pitch and 120mph
    Helmut
    slow boats

  12. #11
    Join Date
    Apr 2001
    Location
    Johnstown, NY
    Posts
    10,063
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    3
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    Hydrostream Registry

    That board has a download for the best I've seen.

    http://www.hydrostream.org/Prop.htm

    David

  13. #12
    Join Date
    Feb 2003
    Location
    Bellingham, WA
    Posts
    6,079
    Thanks (Given)
    11
    Thanks (Received)
    17
    Likes (Given)
    213
    Likes (Received)
    98
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    That is the one

    The one on the Hydrostream site is the one I like too

  14. #13
    Join Date
    Apr 2001
    Location
    MILWAUKEE WI.
    Posts
    317
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I want to thank all you guys for your help. All these sites are really cool. Thanks again Dave



  15. #14
    Join Date
    Mar 2002
    Location
    Vero Beach Florida
    Posts
    47
    Thanks (Given)
    0
    Thanks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    prop slippage

    can any 1 tell me if the same formula applies when twin motors are used
    thanks
    paul

Posting Permissions

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