will a severely barnacled hull prevent engine from reving up to full speed?

Discussion in 'Propulsion' started by sdowney717, Oct 7, 2012.

  1. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    The hull of my 37 foot boat is loaded with big barnacles which has hurt our forward speed.

    I found out yesterday on the water that the engines wont rev past 2500 rpm doing a WOT test. I remember years ago they would rev slightly past 3000 rpm.
    They dont miss overheat and run smoothly with good fuel. so was wondering if dirty hull has effect on engine top rpm? This past summer we dove on boat and supposedly props are clean. It really does not concern me much as I mostly operate the boat in the 1000 to 1500 rpm range.
     
  2. keysdisease
    Joined: Mar 2006
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    Location: South Florida USA

    keysdisease Senior Member

    Yes


    Will a severely barnacled hull prevent engine from reving up to full speed?
     
  3. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    Even at 1000 rpm, it is also hurting your fuel economy.
     
  4. tunnels

    tunnels Previous Member

    Bit of a silly question !!
    its like having a bag of sand tied around you waste and the trying to run !!
    Any growth of any sort is going to kill any boat speed and rpms . :confused::D:p:p
     
  5. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    With the engine warmed up and engine in Neutral, see if the engine will go to 3000rpm for a few seconds.
     
  6. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    yes it does, easily revs to 4000.
    not much power needed to rev up in neutral.
    Engines are V8.
    My thinking had been the barnacles slow down the boat but do barnacles slow down the prop?

    I thought the props were not influenced by the hull, but maybe if boat hull cant get going faster, then neither can the props spin up faster?
    So if the hull is clean then the props take less power to spin?
     
  7. Frosty

    Frosty Previous Member

    Too much thought and thinking going on here . I thought you were told to clean the hull I think this is your answer. I thought you understood this?

    If you put a sheet of 8x 4 ply on the front of your car will it go as fast -- well no it wont --well why ---why don't the wheels go round just as fast.
     
  8. tunnels

    tunnels Previous Member

    clean it man !! everything !!! and anti foul will make a big differance !! :mad::p
     
  9. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    In summer we scraped off from waterline about a foot down. And that did help a little.

    With winter coming up so plan to haul it next spring. I envy those of you with large tides. Our tidal range is so small about 3 feet or less we have to haul to work on the bottom.

    Some of the barnacles are very large about an inch by inch sized.
    How big do these get? They are not goose, just look like volcanoes.

    Do barnacles grow on top of other barnacles?
     
  10. Frosty

    Frosty Previous Member

    Might get a few green lip mussels deeper down . boiled up and eaten with vinigar and bread and butter,--lovely jubbly.
     
  11. keysdisease
    Joined: Mar 2006
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    Location: South Florida USA

    keysdisease Senior Member

    Hire a diver to clean your bottom, might get you through the season.

    My thinking had been the barnacles slow down the boat but do barnacles slow down the prop?

    YES

    I thought the props were not influenced by the hull,

    WRONG


    but maybe if boat hull cant get going faster, then neither can the props spin up faster?


    CORRECT


    So if the hull is clean then the props take less power to spin?

    AND YOU MOVE THROUGH THE WATER FASTER USING LESS FUEL WITH LESS STRESS ON THE DRIVE TRAIN AND ENGINE

    Steve:cool:
     
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  12. Frosty

    Frosty Previous Member

    I think hes got it!!

    Imagine shoveling sand with a clean shiny stainless steel shovel. Then your next door nieghour borrows it to mix cement. He does'nt clean it off at all and it comes back with cement all over it big blobs here and there.

    Will you still be able to cut and slide into that sand??

    Can you swim faster with clothes on or off.
     
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  13. tunnels

    tunnels Previous Member

    take off the prop with everything attached and give it a good boil up . throw the prop away and eat the soup . :D:p
     
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  14. WestVanHan
    Joined: Aug 2009
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    Location: Vancouver

    WestVanHan Not a Senior Member

    All great answers,but this one shows best...

    There was a story going around my area years ago-may be an urban legend- apparently some guy and his wife bought a new boat,and were disappointed with the top speed and handling.So they took it back to the dock and phoned the dealer.
    He came down and noticed the trailer was still attached.

    At the risk of sounding rude...how does someone get 144 rep points on 238 posts by being helpful- yet wonders how 1" barnacles will slow him down??
     

  15. tunnels

    tunnels Previous Member

    He is a interlectual !!! He is taught how and never had to think why !! unfortunatly the world is overloaded and top heavy with these kinds of non thinkers !! :eek::confused::?:
     
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