Bung Placement

Discussion in 'Boat Design' started by Katoh, Apr 25, 2011.

  1. Katoh
    Joined: May 2010
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    Katoh Senior Member

    Colleagues
    I want to add a couple of drainage bungs to my motor well, the boat was built and designed without these and after the years a huge amount of sludge diesel oil ect has accumulated in the bottom of the well. My thoughts if there were a couple of holes would be great for a wash down after use or after oil changes ect. The problem being there is no room at the transom to put them in. can you put them through hull or is this inadvisable? The Photos will tell you more, please don't think there is an orientation problem with the photos, The boat is actually sitting on its side and undergoing a full rebuild.
    Thanks
    Katoh
     

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  2. Katoh
    Joined: May 2010
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    Katoh Senior Member

    I am thinking of using two of these http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=200598260814&ssPageName=STRK:MEWAX:IT
    through the hull at the front of the motor well, one on either side of the keel bar. That would place them around a meter forward of the transom around 40mm up either side of the keel line. The plugs would be put in from the motor well not the hull bottom.
    These bungs would protrude around 10mm lower than the hull, therefor there would be two 50mm dia circles hanging 10mm out of the bottom.
    will this effect the boat? or is this a bad idea? were else could I put the drains?
    Katoh
     
  3. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Weld-Glue or bolt a conopy type deflector in front of each to streamline the flow around and over the pertruding drain plugs. Search around some thru hulls come with the deflectors as part of the unit. In your case it would have to be in alum. or stainless. Wouldn't advise plastic too sustible to being damaged.-Geo

    P.S. You make it sound like oil accumilation is a problem-where is all the oil coming from- normally oil in the bilges is very rare and if so should be properly absorbed by an absorbtion pad often referred to as a sock and not flushed out. Flushing oil out whether on land or at sea is a big no-no and usually results in public reporting and big fines.
     
  4. Katoh
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    Katoh Senior Member

    Viking North
    I can see the benefit of a deflector in front of the bungs. I could even make some up and weld them on. This is a project boat I recently acquired and am restoring,
    Just looking at the amount of grime in the well is not good a thing probably mixed in with diesel from fuel filter changers oil changes ect. I like to rinse my boats down after pulling them from the water, this includes motor and well, but there is nowhere for this rinse water to drain too, such the reason for the bungs.
    The motor has been removed and will be rebuilt in time, Its not so much a oil problem but a grimy muck that accumulates in the well, it can be seen clearly as a dirty black smear in the photos. I believe this to be 20 years of rubbish as there was no possible way to clean and drain the well, this is the problem I want to resolve. There was no oil leak from the motor.
    I would like to try and keep these things clean, the more muck the more chance of corrosion both to Aluminum and steel, the cleaner the dryer the better.
    Going back to the question at hand, if the bottom of the bung ended up being flush with the hull would it still need a deflector on the front?
    Cheers
    Katoh
     
  5. Frosty

    Frosty Previous Member

    What you are talking about is bilges. A well is the slop shelf just inboard of an outboard motor usually self draining.

    You do not normally make unnecessary holes in the hull under the water line.

    How will you access these under the engine. If you mean the plug would be from under the hull this would be most irregular and not advisable.

    You can but an adaptor for the 'bilge' pump to suck out almost dry.
     
  6. Katoh
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    Katoh Senior Member

    Frosty
    I have 4" of clear space from the front of the motor to the front of (dare I say The Bilge or motor compartment) I have very good access there. There is a pump in there already, you can see it in the photo, but I don't think whatever you put there is going to do a decent job of anything, due to all the bars and stringers involved, I am going to replace the pump, but it would still be nice to drain all that rubbish away. The only other way I can see this working without drains is to run two 3/4" aluminum tubes to either side of the keel bar, have them almost touching the hull plate, and bring both of them up to a larger self priming pump, that can handle a bit of dirt. With the keel bar there that is possibly the only way to remove all the water after cleaning.
     
  7. viking north
    Joined: Dec 2010
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    viking north VINLAND

    If the screw in plugs once screwed in end up fairley flush with the hull's skin really no need for a deflector. Most runabouts have drain plugs in or near the transom. However and Frosty will attest to this also, we want the first report on the panic moment you launch the boat and she's leaking like hell because you forgot to screw the plugs in. :) Something you might think about, If you could install them in the transom, you can use them as an emergency pump in case of heavy rain or taking a wave. Simply run at about 1/4 to 1/2 speed minimum and unscrew a plug. The suction will drain the boat in no time. We often do this on our open fishing boats in Newfoundland after or during a heavy rain at sea or if they are left on the collar(morred off)and accumilate rain water. Geo.
     
  8. Katoh
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    Katoh Senior Member

    The big problem with the transom mount is the amount of room needed. Refer to the photo 1. that black line is the seal for the Volvo out drive, once that's on the transom you only have about 1" clearance to the hull bottom, the other problem is inside the bilge, its not just a single plate, there is a 1.1/2" x 2.1/2" stiffener beam welded across the bottom, this is a hollow beam. There is no way of placing these drains on the transom.
    I have two consolations I gather with my bilge, if ever the plugs are not put in and the boat launched, firstly it is a totally sealed bilge so water may flood in to about halve the height of the motor, the floor sits 6" above water line and there is another 5" riser above that that covers the bilge, At least I wont sink. The other I plan to fit a large Auto bilge pump in the bilge, may give me me enough chance or warning to put the plugs in.
    I thought more about using just a pump, but with the amount of rubbish I see in the bilge it would just be a matter of time before the pump gets fowled.
    For a cover for the plugs if they are through hull, could I not use a piece of angle cut in a wedge shape and welded either side, like a stiffening rod on the outer hull only much shorter. Will that not create a vacuum behind it also when underway?
    Thanks
    Katoh
     
  9. Frosty

    Frosty Previous Member

    These 'bungs" are only 1 inch OD it looks like you would get one in.
     
  10. Katoh
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    Katoh Senior Member

    Frosty
    I still have the problem of the hollow beam welded inside the bilge, If put in two really small plugs there, they are just going to go into the beam not the bilge, then I could possible drill to holes into the beam from the bilge side, so it would drain from the bilge into the beam then out through the transom. For some reason I can see myself looking at future trouble, as the beam fills up with dirt salt and whatever, also may be a point were corrosion could start.
    Its still a thought.
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Cut a weep hole in the centerline stringer, as close to the transom as you can. This will let water pass from one side to the other, then install a flush fitting garboard drain. Another solution would be to weld an 1/8" plate to the underside of the hull, where you intend your drain. Drill a 1" hole through both the hull and the plate, then tap it for a 1" plug. This will let all the water drain out with only an 1/8" protuberance on the exterior of the hull. The leading edge of the plate could be beveled out so the impact to the flow would be minimal. The plate only needs to be big enough (thick) to permit a few threads in it.

    If it was me, I'd cut the hole slightly over size, say 1.125", then butt weld the inside of the hole, where the hull and plate meet. Then drill this clean and tap. Harder to describe then to do.
     
  12. Katoh
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    Katoh Senior Member

    PAR
    I think your on the money, the garboard drain looks nice. Nearly exactly what I was looking at. I might even make something up out of some plate along the same lines, brilliant thinking and so simple to cut a little hole in keel bar, I think at times when we look for solutions we tend to overlook the obvious and make things harder then what they should be. Have to say we are looking at shooting solution here, one hole custom made piece welded in and out with a screw plug all finishing flush with the hull. problem solved.
    Many Thanks Again
    Katoh
     
  13. viking north
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    viking north VINLAND

    The magic of the forum works again. For years I'd sit alone in my shop ponder a problem and allow the voices in my head give their input. Just to be sure i got enough input(voices) I'd sip on a bottle of rum. Most times the voices did not solve the problem it was the demon rum taking my mind off it's locked in approach and usually in the morning hangover and all a new approach solved the problem. There are times in this world of computers I miss the good old days.

    A yacht is not defined by the vessel but by the care and love of her owner.
     

  14. Katoh
    Joined: May 2010
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    Katoh Senior Member

    Viking North
    I understand totally! In my case, years gone past many a problem was solved through a bottle of fermented grape juice and warped stick of inhaled nicotine goodness, but those days have passed and one has become uncertain of his decisions:confused:. The grape juice has been put on rash-ions, the warped sticks have been made contraband in his household, and he is left to the pitiful, sole cleansing ale ever now and then, and the odd scotch and soda when no one is looking to try and work through ones dilemmas. Oh dear, what have we come too!
    I have to honestly say, thank goodness we have this means of technology to give our opinions on the subjects we want to talk about so easily and freely, its nice to converse with others with the same interests and help out when we can. I am new to boat building and designing, but if not for people like you and others on this forum I would not be attempting the things I am today.
    Three cheers to all!!!
    Katoh
     
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