Adjusting lead ballast in a full keel

Discussion in 'Sailboats' started by dhornsey, Jan 12, 2009.

  1. dhornsey
    Joined: Jan 2009
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    Location: vancouver, bc

    dhornsey Junior Member

    Hi All,

    2 years ago we purchased a 1978 Pacific Seacraft Mariah 31. It has 6000 lbs of internal lead poured into its full keel. The previous owner told us they made a mistake when pouring the ballast, and so she has always sat 5 or 6 inches too high in the stern. We estimate it would take around 500 pounds of weight in the rear to get her to sit properly.

    Its something I'd like to remedy, but I'm not sure of my options. If you have the answer to any of these questions I'd really appreciate it:

    1. Is it possible to cut out some of the ballast from forward and to move it back? How would this be done?

    2. If we wanted to add ballast aft, what is the best way to do so? Could we use a mixture of lead shot and epoxy to hold it in place?

    3. Any other ideas?

    Thanks!
     
  2. TeddyDiver
    Joined: Dec 2007
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    TeddyDiver Gollywobbler

    That's a lot...
    1. Drilling or/with chisel
    2. best? make a pattern => mold => pour. With a pattern it's easy get it done in a foundry too
     
  3. dhornsey
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    dhornsey Junior Member

    How would I make a pattern? There is a big empty space at that aft end of my bilge where I would theoretically add ballast - is there some way to take a cast of that space in order to create a chunk of ballast that will fit exactly?

    Thanks.
     
  4. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    Casting lead shot or other scrap metal into resin seems to be a fairly common technique.

    To cut some of the existing ballast out would likely involve paying the guys at the boatyard a fair chunk of change to get in there with air chisels and hack it out bit by bit, to be repoured in the proper spot. I'm somewhat amazed that the boat's original owner didn't insist on it being fixed back in 1978.... or maybe he tried and failed?

    Or, you could just keep a lot of your heavy gear and stores... water, fuel, etc... well aft in the boat, and pretend there's no problem.
     
  5. dhornsey
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    dhornsey Junior Member

    We bought the boat from the original owner. He told us the story of the ballast matter of factly, I didn't think to ask at the time why he didn't have it fixed - maybe they gave him a steep discount or something.

    I just found a website where the guy gets lead ignots, and cuts each of them to fit, Fills the voids with lead shot and epoxy, then glasses the whole thing in. Seems like it might be a decent solution.

    http://www.glen-l.com/weblettr/webletters-9/wl68-keel.html

    Thanks.
     
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Before making changes to the ballast, you should be sure your not getting a load of crap from someone trying to hide another issue, with BS about a bad ballast pour, which isn't especially common. 5 - 6 inches high at the stern means the ballast is off a lot, this type of mistake may not be possible, given how the keel sump is filled. Basically they pour to the line and move on. You can be off by a little, but that amount of trim difference suggest something else.

    Now it could be that you have a Mark I, which has a different ballast location then the Mark II. PSC recognized they needed to shift the ballast. They also changed the rig to address weather helm. The visible difference between a Mark I and a Mark II is the sprit is about a foot longer on the Mark II.

    The very first thing I would do is completely empty the boat. I mean completely, everything that isn't nailed to something comes off the boat. Cushions, anchors, that old 300 yards of anchor rode, those extra engine parts living in that rust filled locker, everything. Now look at your boat's profile from quite a distance back, say at least 50 yards. Take pictures. Compare these to others of your boat and Pacific Seacraft Mariah 31's you can find. See if you can get Bill Crealock (760/434-3253) to send you the freeboard dimensions for your boat. This will determine if you boat is floating where it's supposed to or not, nor the ratings of amateurs or former owners' who's sole purpose in life is to sell the boat.
     
  7. dhornsey
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    dhornsey Junior Member

    The mark I mark II thing is definitely is a factor here. It is my understanding that ours was the very last mark I to be produced. They added 1000 pounds of ballast to the Mark II. We were told that this extra 1000 pounds was also added to our hull as an afterthought, which is where they went wrong in the first place. I do trust the previous owner, for what it's worth, but I guess you always have to question. Supposedly they made a mistake in adding this extra weight.

    Crealock didn't design the Mariah, it was Henry Mohrschladt. I'll see if I can get in touch with him, thanks for the advice.
     
  8. PortTacker
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    PortTacker Junior Member

     
  9. dhornsey
    Joined: Jan 2009
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    dhornsey Junior Member

    Our Mariah is definitely sitting differently from others we have seen. It causes a few issues internally - there are various places where internal water runs forward, rather than back towards the bilge and the bilge pump. I am quite sure it was not designed to sit like it is.

    Thanks for the advice regarding not adding weight to fix the problem. I'll try to consult with an expert before doing anything. I looked around online for the contact information of the designer Henry Mohrschladt, but haven't had any luck so far.

    I guess another option is to add some weight in a non permanent fashion to judge its affect?
     
  10. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I'm not in your area, but I'm very sure I could sort out the difficulties in short order. Most often boats trim differently because of accumulated gear, stores and equipment that have been forgotten.

    Create a "base line" for all evaluations, empty the boat. I'm not kidding about everything. Picture this as taking possession of a bare bones boat directly from the manufacture, without previous owner influence. You should be able to literally flip the boat upside down and nothing will jingle or fall out.

    This is your base line which to compare others against. You may simply have a LWL painted on incorrectly (it wouldn't be the first time). Check freeboard measurement from other 31's.

    If a 1/2 a ton of ballast was added, it was likely concrete and can be fairly easily removed with a chipping hammer and lots of buckets full over the side. It's a tedious job, but not that uncommon.

    You're much better off rearranging weight then adding weight. Removing volume from the front of a casting and placing at the tail end is the usual method. This make incremental changes in the distribution and trim can be adjusted finely. The further away from the CG you place additional weight, the bigger affect you'll have on trim, but this comes with negative side effects in sailing qualities in most cases. In other words, you can place a surprisingly small amount of weight in sand bags on the aft deck and it will quickly effect trim, but it will also be about the worst place to have extra weight. Keep it (any additional ballast) concentrated near the original castings.
     

  11. Omeron
    Joined: Feb 2007
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    Omeron Senior Member

    Sounds like your problem is not lack of weight aft, but rather too much weight forward. Before worrying about how to add weight aft, i would consider how to shave weight off the front,to begin with, which should be an easier task than adding weight anyway.
    Once you get an even trim by taking ballast out, if you think she is riding higher than she should,then you can add ballast, but this time evenly across without worrying about ruining the trim again.
     
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