Sink?

Discussion in 'General Discussion' started by hpcrank, Nov 19, 2018.

  1. hpcrank

    hpcrank Member

    44
    Feb 4, 2016
    Col. Spgs, Co-Lake Pueblo State Park
    1981 260 Sundancer with rebuilt 454/Mercruiser330-I/O. w/ alum. hard top with front and side wdos
    One rebuilt 330 hp. 454 Chevy
    Greetings

    Just a thought, most how - to articles as well as vendors info., etc. say that the engine well must be sealed off from the cabin part of the boat so any wires or pipes, etc. that pass thru the firewall must also be sealed. If the engine well is sealed off from the remainder of the boat as the USCG requires and given that nearly all the under the water line thru hulls are in the sealed engine well, how could the boat sink?

    hpcrank
     
  2. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    PA
    Various
    Various
    In reality, water will find it's way into the cabin in some way, shape or form. But let's say, for sake of argument, that a cabin area was 100% sealed from the engine area. The bilge is a HUGE area. Water weighs over 60lbs for every 1 cubic foot - think about that for a sec - a box just 12"x12"x12" weighs over 60lbs. Now, imagine how many of those little boxes could fit down in that bilge. I don't even know how many... but I bet it is literally AT LEAST a ton's worth of boxes.

    Let's also eliminate the various "level floatation" or "positive floatation" criteria that certain size/classifications of boats are require to have.

    As the water keeps pouring in, the stern of the boat gets heavier and heavier, with the bow starting to lift. As that happens, the boat gets less buoyant and the stern end sinks faster and faster since the stern end of a boat will not displace as much water as the entire length of the hull. Really, there's two things going on there (and probably more that my feeble mind is not aware of)... increased weight and less displacement. So, to answer your question of "How would the boat sink"... Ass-end first. :)

    FYI... the reason for the USCG requirement to seal any intrusions into the cabin area is to keep engine fumes and CO out of a sleeping area.
     
  3. CliffA

    CliffA Well-Known Member GOLD Sponsor

    Dec 29, 2009
    Lake Norman, NC
    2001 Sea Ray 340DA
    Name: 'Happy Place'
    4.5kW West. Generator
    Purchased Nov. 2014
    Fresh Water Use
    Twin Merc. 6.2L (MPI)
    Raw Water Cooled
    V-Drive Transmissions
    and don't 'assume' that CO will not find its way into the cabin from the ER just because the ER is 'supposed' to be sealed....it will....always keep a functioning CO detector (or two) in the cabin and always run the ER blowers while your genny is running if you have a genny....

    cliff
     
  4. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Are you sure this "sealing" item is a real requirement? On my 340 I was able to very easily fish two sets of 4 gauge wire from the engine room up to the helm through existing wireways below the gunnels, above the fuel tanks. There was nothing remotely "water tight" about it....it wasn't even challenging...
     
  5. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    PA
    Various
    Various
    The requirement deals with the cabin, not the cockpit.
     
  6. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Hmmm....from the helm I was able to continue the fishing of wires into the the starboard cabin closet...unabated....

    All seemed stock on my 340 setup. Very interesting....
     
  7. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    PA
    Various
    Various
    Did you have your 340 since new? If so, has anyone else done wiring work on it besides you? It's possible that the rigging tube (wire ways) you used was originally plugged with silicone (a common practice to meet the requirement), but somewhere along the way the plug was removed.
     
  8. Jon Paul

    Jon Paul Member

    109
    Sep 24, 2013
    Phoenix
    2006 Sundancer 340
    8.1 V drives
    I had to seal mine. Found then same thing when fishing wire.
     
  9. Lazy Daze

    Lazy Daze Well-Known Member TECHNICAL Contributor

    Apr 21, 2009
    PA
    Various
    Various
    One factory worker to another over lunch break: "Oh, is THAT what I was supposed to use that silicone for"?
     
    Stee6043 likes this.
  10. ttmott

    ttmott Well-Known Member

    Apr 3, 2012
    Space Coast Florida
    2006 52 Sedan Bridge
    Cummins QSM11
    The weight of water is only applicable as ballast when water inside the boat is above the water level outside of the boat; that is the delta weight. The weight trying to sink the boat is that mass which is greater than buoyancy in water like the engines.
    Tom
     
  11. MonacoMike

    MonacoMike Well-Known Member PLATINUM Sponsor

    Sep 15, 2009
    Indiana lakes and Lake Michigan
    2000 Cruisers 3870
    97 270 Sundancer
    85 Sea Ray Monaco 197
    8.2 Mercs,
    7.4 BII
    260hp Alpha 1
    I have never been overly impressed with SR sealing off the bulkhead to the cabin from the bilge on the boats I have dealt with. Is it possible it is a dealer responsibility after installing dealer options?

    MM
     
  12. hpcrank

    hpcrank Member

    44
    Feb 4, 2016
    Col. Spgs, Co-Lake Pueblo State Park
    1981 260 Sundancer with rebuilt 454/Mercruiser330-I/O. w/ alum. hard top with front and side wdos
    One rebuilt 330 hp. 454 Chevy
     

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