Thanks Thanks:  0
Likes Likes:  0
Page 1 of 12 123456789101112 LastLast
Results 1 to 10 of 116

Thread: Max Speed Attainable with These Fgures

  1. #1
    phillnjack
    Guest

    Default Max Speed Attainable with These Fgures

    hi folks
    can somebody on here please state the maximum attainable speed with the figures below
    lets say for example with a zero amount of slip (yeah i know) and lets say the boat is the best possible
    for speed and drag etc.

    revs 5500.
    gear ratio..2.09 to 1
    propeller 13 inches of pitch
    diameter 10 inches.


    this is not a joke its a serious question


    phill
    Last edited by Ron Hill; 11-17-2013 at 10:29 PM.

  2. #2
    phillnjack
    Guest

    Default

    wow im shocked that nobody reading these cannot answer a simple question like this.

    come on prop guru's...put down your answers...

    and dont forget its miles per hour not kilometers per hour or knotts. mph is what i want.
    it can then help settle a dispute.

  3. #3
    Team Member capnzee's Avatar
    Join Date
    Nov 2004
    Location
    manhattan beach
    Posts
    344
    Post Thanks / Like

    Default

    Quote Originally Posted by phillnjack View Post
    wow im shocked that nobody reading these cannot answer a simple question like this.

    come on prop guru's...put down your answers...

    and dont forget its miles per hour not kilometers per hour or knotts. mph is what i want.
    it can then help settle a dispute.
    @my guess is about 34 mph, @ 100% not much pitch and no rrrrr,s @2.9:1 Lucky to get 30mph on a boat Rod

  4. #4
    Team Member ima75man's Avatar
    Join Date
    Jun 2007
    Posts
    467
    Post Thanks / Like

    Default

    o.k. i like trick question. 29.8 mph at 8 % slip.. u might have faster water than we got over here.. or 32.1 at .01 % slip..
    out front again

  5. #5
    phillnjack
    Guest

    Default

    These are exactly the answer i was expecting .

    its just a guy on this very forum with these exact figures says his boat is doing 39. ??mph
    i said its impossible with that ratio,that revs and that prop.

    others have chimed in and also say 40 is easy with that set up !!!!!!!!!
    i think a touch of the niagra falls would be needed ha ha

    but im glad that someone else sees it as around the 30mph mark and not me going mad

    thansk guys


    phill

  6. #6
    Team Member ima75man's Avatar
    Join Date
    Jun 2007
    Posts
    467
    Post Thanks / Like

    Default

    a lesson i learned early in life,never bet against the man making the bet.he knows something u don't.
    out front again

  7. #7
    phillnjack
    Guest

    Default

    ima75man
    what would you call realy good slip figures for a race boat ?
    and any idea what the average speedboat slip would be ?

  8. #8
    Team Member ima75man's Avatar
    Join Date
    Jun 2007
    Posts
    467
    Post Thanks / Like

    Default

    on a good race boat just a quess 6 to 10 % maybe 8 %.on a speed boat don't know to many varible to consider. just one person opinion
    out front again

  9. #9
    Team Member zul8tr's Avatar
    Join Date
    Oct 2008
    Location
    Orlando, Fla
    Posts
    575
    Post Thanks / Like

    Default

    Quote Originally Posted by phillnjack View Post
    hi folks
    can somebody on here please state the maximum attainable speed with the figures below
    lets say for example with a zero amount of slip (yeah i know) and lets say the boat is the best possible
    for speed and drag etc.

    revs 5500.
    gear ratio..2.09 to 1
    propeller 13 inches of pitch
    diameter 10 inches.


    this is not a joke its a serious question


    phill
    Max speed zero slip = pitch x engine rpm / (1056 x gear ratio) = 13 x 5500/ (1056 x 2.09) = 32.5 mph
    If slip was 10% speed = 32.5 (.90) = 29.3mph.

    For other data including slip use this

    http://continuouswave.com/cgi-bin/propcalc.pl

  10. #10
    phillnjack
    Guest

    Default

    these were the same speeds i got when i calculated it, and i also used the continuous wave gizmo as well to verify.
    its juts that on another part of this forum someone said they have these very figures and the boat goes to 40mph on his gps !!!!!
    i said its impossible with these figures and people have jumped on me saying its easy done and ofcourse its possible.

    now being the stated engine and props figures etc the only thing i could see to make it possible was it being
    measured in kilometers per hour and not miles per hour by the guys gps.
    but he claimes his gps is 100% accurate etc and definitely miles per hour !!!!!!.
    now a few other people chimed in and said i was totaly wrong, and with these figures 40mph is not uncommon,
    and mathmatics is nothing compared to a gps reading ha ha ha

    to my mind, everything speed related has to be a mathmatical piece to even get the speed, and a turning propellor at a given pitch and revs can only achive a certain maximum speed.

    i know im from england and many things between our language can easily be mis-interpreted, but im glad that the guys
    who do know their stuff agree that its only a possible 32.5 at best with these figures.

    the boat is on this site and from the usa by the way,not in england, we have slow water.
    thanks for all the input on this one,
    youve all cheered me up and helped me re-gain a little bit of sanity


    phill

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. need more speed
    By deejaycee_2000 in forum Mini Boats and Mini Boats History
    Replies: 9
    Last Post: 02-04-2008, 03:38 PM
  2. Power Cat Speed
    By Dago Fast in forum Technical Discussion
    Replies: 16
    Last Post: 02-03-2007, 09:39 PM
  3. Top Speed
    By SEAHORSE50 in forum Technical Discussion
    Replies: 21
    Last Post: 12-16-2005, 09:52 PM

Bookmarks

Posting Permissions

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