High Performance MPX Foil/Self-righting Trimaran-The Test Model

Discussion in 'Multihulls' started by Doug Lord, Dec 28, 2010.

  1. sigurd
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    sigurd Pompuous Pangolin

    Thanks. What's with the bow, intended to resurface easier, or is it some sort of "hullspeed trick"?
    Looking forward to see the planing ama.
     
  2. Doug Lord
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    Doug Lord Flight Ready

    --------------------------
    Intended to go thru small waves easily-and I think it looks good. It also reduces the size (and weight) of the deck for a given waterline length.
    I'm going to test the planing ama for the MPX-12(see that thread) and I'm testing another version of planing ama for the SRT: designed to rarely contact the water at any speed so shape is optimized for momentary contact.
    Of course, coupled with the "curved pieces", both have substantial buoyancy.

    MPX-12 thread: http://www.boatdesign.net/forums/multihulls/mpx-11-very-small-high-power-trimaran-33686-15.html

    Pictures: two views of the MPX-12 planing ama with "curved piece" which is simply an attachment system designed to create "emergency" buoyancy when coupled with the ama.
     

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  3. Doug Lord
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    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    These pictures are just before the deck is added. Have to carbon all the vertical tubes after making a fillet around the base. The big tubes are the vertical supports for the cross arms. They needed to be vertical because the cross arm will slide on and off for transport and the cross will be able to be raised /lowered as appears necessary in testing. The tube diameter is equivalent to a 4" OD tube fullsize. The boat is about 1.22 times as wide as it is long and the cross tubes have a fair amount of "dihedral" as well as forward sweep-the tubes are not 90 degrees to the centerline. Everything is either adjustable or one saw cut away from adjustability.
    The mast step tubes intersect a thin glass piece(center picture, below) and after the deck is installed-up to the glass piece but not over it-a carbon tube will be carboned in place to serve as the actual mast step. The mast will be adjustable fore and aft about the distance you see. The target position is about 3/4" from the back end with a lot of mast rake.
    After the series of tedious small carbon jobs-The Deck!

    click on image:
     

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  4. rapscallion
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    rapscallion Senior Member

    That is so damned good looking!!
     
  5. Doug Lord
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    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    -----------
    Thank you!
     
  6. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    Got the carbon tubes carboned in and the mast step reinforced. Next step :The Deck.
    Did a weight check after the carbon work: 2.125lb! Excellent. Target-main hull only-not incl rig, foils, cross arms ,amas= 3.858lb. Piece of cake....


    click on image:
     

    Attached Files:

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  7. rapscallion
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    rapscallion Senior Member

    Keep the Pics coming Doug! The boat looks great!
     
  8. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    High Performance Self-Righting Tri Experimental Test Model

    -------------------
    Thanks-should have the deck on soon-pictures immediately....
     
  9. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    Half a deck! Need to install the curved aft portion of the raised front deck and then plank the front deck, then carbonize....

    click on image:
     

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  10. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    The deck is roughed in and will be detailed and prepared for carbonation shortly:

    -click on image-
     

    Attached Files:

  11. rapscallion
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    rapscallion Senior Member

  12. Doug Lord
    Joined: May 2009
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    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

    ===============
    Thanks!
     
  13. Doug Lord
    Joined: May 2009
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    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    Here is the deck with 1 layer 5.7oz carbon just after carbonation-still needs grinding and some limited cosmetic attention. Next: amas, "curved pieces", curved foil and trunk mold and parts, mainfoil and daggerboard, rudder and gantry.
    Weight today before grinding 3.4 lb(target hull only 3.9lb).

    Coming very soon pictures in the water ballasted to her final weight!

    click on image:
     

    Attached Files:

  14. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model

    Here are a couple of shots of the bow before and after decking and carbonating:
     

    Attached Files:


  15. Doug Lord
    Joined: May 2009
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    Location: Cocoa Beach, Florida

    Doug Lord Flight Ready

    High Performance Self-Righting Trimaran: The Test Model-FLOAT TEST

    FLOAT TEST
    ------------------------
    Conditions were poor for photographing the boat-I could barely see the screen on the camera. The wind was offshore and quite strong which meant that the boat wanted to go-only had a few seconds to get the camera and shoot. Excuses aside she floated perfectly! I knew that the original hull floated on her lines but this was the first test of the modified hull which had the bow changed, CB moved forward and length extended.
    The first test today was equivalent to the full size boat at 750lb-which includes the crew and keel ballast(for self righting). The second test was minus the ballast.
    The setup: in both tests the boat had a 4.625lb piece of lead duct taped to the bottom for added stability. To figure out the exact test weight first the buoyancy of the daggerboard, ballast bulb, main foil rudder and rudder foil was calculated. Since these were not on the the boat their buoyancy(saltwater) would be subtracted from the all up 16.688 lb model weight. But because the lead piece was strapped to the bottom a correction had to be done for its buoyancy which was subtracted from the total for the foils. The net adjustment to the total weight was -.88lb making the test weight(MAX) 15.8lb.. The second test was removal of the ballast( 3.9lb). Pounds per quarter inch immersion for the full size boat was calculated at 58lb. The boat at MAX weight was slightly bow down with the center of the transom slightly above water. I couldn't see well enough to take close up pictures of the transom and bow-the one I did take did not show the detail apparent with the naked eye.
    What was learned:
    1) boat floats perfectly for the designed maximum displacement of 750lb.,
    2) The center of buoyancy was in the right place allowing latitude for the crew to move aft as wind increases, if required, and it appears that extreme light air wetted surface can be reduced with the crew forward and the boat heeled slightly.
    3) The unballasted test showed the knuckle of the bow slightly out of the water and the center of the transom slightly out of the water.
    4) It was great to get these excellent results even though I "knew" I would. The fact is you never know for sure until the boat hits the water. She did well!


    Pictures, L to R, 1&2: test with max weight including keel ballast, 2&3: test minus keel ballast-

    click on image for best detail:
     

    Attached Files:

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