If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Follow us on Facebook Follow us on Twitter
Results 1 to 1 of 1
  1. #1
    Gold Member Gold Member
    My Boats:
    Phantom 25 (1985) w/Verado 400R
    Join Date
    Oct 2000

    Thumbs up The quest for speed


    This is maybe a impossible question. But its holiday, so I try anyway

    I think I have run my engines too low. I can not use powerlifts, due to the overall balance of the boat (an extra 4-5 inches setback will be too much on my narrow boat).

    I have two Merc 2.5 EFI SS engines with CLE lower units on my Phantom 25. Merc Hi Performance reccommends an engine mounting height of 27,75-28 inches with twins running speeds 85-90 mph. This translates on my engines running the propshafts approx. 0,6-0,8 inches below the bottom (with no setback).

    I have the propshafts mounted 1,2 inches below. The engines also have 2 inches built in setback, so the effective propshaft height should be lower, approx. 1,45 inches.

    If I rise the engines one hole, which is approx. 0,67 inches, the effective propshaft height will be approx. 0,78 inches (measured 0,54 inches below).

    I know that only testing will tell, but how much faster do you think the boat will run with the engines 0,67 inches higher (if I can hold the bow up)?

    The boat runs 87 mph spinning 25 pitch Hydromotive Quad X-O/B props at 7.400 rpms (1:1,87 gears).

    Cheeers! Toffen G
    Attached Images Attached Images

Similar Threads

  1. Quest
    By Yellow_ICC_OK in forum American Offshore
    Replies: 3
    Last Post: 09-06-2008, 09:29 PM
  2. Quest for speed... gear ratio/prop.
    By TomZ in forum General Q & A
    Replies: 12
    Last Post: 05-26-2005, 01:54 PM
  3. Quest for speed... gear ratio/prop.
    By TomZ in forum Prop Talk
    Replies: 3
    Last Post: 04-22-2005, 02:56 PM
  4. Quest ???
    By dyno in forum Powerquest
    Replies: 2
    Last Post: 05-06-2004, 06:02 AM
  5. 272 Quest for speed
    By boatfreak in forum Baja
    Replies: 5
    Last Post: 06-18-2003, 11:13 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
All times are GMT -5. The time now is 12:58 AM.
Powered by vBulletin® Version 4.2.0
Copyright © 2016 vBulletin Solutions, Inc. All rights reserved.
Search Engine Optimization by vBSEO 3.6.1
Original Poster In Postbit provided by Original Poster In Postbit v1.0.0 (Free) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
Copyright 2011 OffShoreOnly. All rights reserved.