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Thread: "ALMA" a 1891 scow schooner

  1. #91
    Join Date
    Jun 2007
    7 miles north of Phelan, CA


    Skipjack was in the tank today.
    Everything works as it is suppose to.
    Like the slower RPM control.

    After removing weight by modifying motor to a smaller physical size and removing 2 servos and steel shafts, I think I have the new additional ballast, correct.
    I do still have an issue.
    But before I start chasing it, I need to get the boat in a bigger tank or pond.
    With my tank full of water, the boat touches the bottom with about 1/4" of the sail above the water surface.

    The issue I need to chase is a balance issue.
    Surfaces, the boat is stern heavy. . . not very much. Maybe 3/8" from level waterline.
    Submerges, the boat is stern light. . . again, not very much. Maybe 1/2" but this is hard to tell as I think the bow is sitting on the bottom of the tank.

    I am not going to try and fix this for this Saturdays gathering.
    I will open up the boat tomorrow and charge the battery.
    I am going to move the batter forward about 1/2" and the ballast tank back 1/2" if I can.
    Test it again.

    After Saturday, I plan to modify the electronics tray.
    With the smaller motor and two servos gone, I can cut the electronic tray just behind the motor and remove 3/4" to 1".
    Shorting the tray will give me about 1" to move the ballast tank and battery back from the front.
    More weight location adjustment will be possible.

    I also think the auto leveler will correct the stern position with a little forward motion.
    In the tank, I can see the rear planes moving to push the stern to level.
    SSBN 598 - blue/nuke trained IC/forward

  2. #92
    Join Date
    Jun 2007
    7 miles north of Phelan, CA


    Skipjack status report. . . . .

    Batteries all charged.
    New ballast tank balloons. (replace before every run.. at about 10 cents a piece, why not)
    Gathered up a small assortment of tools, nylon ties, silicone grease jar and a rag for water cleanup.
    Skipjack is now in it's transport box and buttoned up for the trip.
    Tx and tools in 2 gallon bucket sitting by front door so I don't forget it in the morning.
    Gassed up the truck while in town earlier today.
    Even washed the dust off the truck.
    (I live on a dirt road and the truck usually gets washed when it rains)
    Had to. The front window was bug splattered to the point I would not be able to see if I had to use the window wipes.

    I think I am ready to go.
    Still got time to think about it in case I am forgetting something.
    SSBN 598 - blue/nuke trained IC/forward

  3. #93
    Join Date
    Jun 2007
    7 miles north of Phelan, CA


    After the run report.
    I put new ballast balloons in as always.
    Forgot to blow them up to expand the rubber.
    By not doing this, the water pump has to fight the balloon to inflate.

    Brought the boat in and opened up the cylinder.
    Put air in the balloon and squeezed to to stretch the balloon out some.
    This help a lot.

    As I expected, I had trim issues.
    Stern down on surface and stern up submerged.
    The night before the run, I was thinking about what I needed to take and what I might have forgotten.
    Then a thought hit me.

    In my rush to trim the boat, I was working on the ballast Effect instead of the Cause.
    This resulted i my putting ballast weight farther stern and moving the ballast tank aft.

    The result of doing this caused the surface Center of Gravity to move aft and the submerged Center of Gravity to move forward.
    This made the distance between the two CG farther apart.
    Just the opposite of what it should be.
    I did get the new ballast weight correct.
    After removing the original main motor and two servos and through cap shafts, I calculated the weigh difference to be 800 grains.
    It was close as it turned out to be about 825 grains.

    I have some more changes to make.
    The new motor is smaller and lighter.
    It also has a slower RPM.
    I can see the propeller turns at slow speed. (still running about 40% fromt he Tx.

    Also the changes will include rebuilding the electronics tray.
    The new motor is about 1" shorter and I can shorten the tray that much allowing me to move the ballast tank towards the rear. (more to the center of the boat)
    The extra weigh I added was put in as a temporary fix and will come out easily to be moved.

    It will have to wait.
    I have another sub project on the bench.
    Should be completed in a few days.
    Currently doing the electronics wiring.

    Still making small standing rig parts for the ALMA.
    These are the metal parts on the mast and booms that all the lines go to, plus the blocks. (double and triple blocks)
    These things are crazy small so I make one or two at a time.

    I tried the small wooden parts made by the company in Spain.
    Problem is the Spanish blocks are for looks and will not take a load.
    So, I of course am making them out of plastic sheet.

    Just this morning, I had to make a special bolt for my small drill press table vise.
    I took an Allen screw and put in the drill press and used my Dremel to grind the middle of the screw down.
    Then cut the end off.
    This screw goes in the vice moving jaw and hold the jack screw from coming out of the jaw.
    The threaded part of the screw is about 1/4" long and the tip is about 3/16" long which goes in to a groove on the end of the jack screw in the jaw.
    If I think of it, I will take a photo of this part.
    SSBN 598 - blue/nuke trained IC/forward

  4. #94
    Join Date
    Jun 2007
    7 miles north of Phelan, CA


    Photo of the drill press vise screw holding screw.
    New screw is on Allen wrench end.
    SSBN 598 - blue/nuke trained IC/forward

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