Loading ...
Sorry, an error occurred while loading the content.

Centerboard Raising Mod

Expand Messages
  • eo_ant
    I got the following responce from Chris when I ask him some questions about his centerboard raising modification and he gave me his permission to share it
    Message 1 of 3 , Oct 6, 2005
    • 0 Attachment
      I got the following responce from Chris when I ask him some questions
      about his centerboard raising modification and he gave me his
      permission to share it here. Here is what he had to say.


      The specific thing I did for my centerboard mod was to drill a hole in
      the rearmost top part of the centerboard trunk and insert a thru-hull
      into that. Unfortunately, that area will still go in and then out of
      the ballast tank so I was worried at first when doing this. A tube of
      3M-5200 and Plumber's Goop as well put my fears to rest as it doesn't
      leak and it's solidly in place. The thru-hull was inserted so it
      angles back to target a hole in the front section of the cockpit
      floor. I used an upside down 45-degree rail fitting for cockpit floor
      hole. The whole thing was tied together with either 1 1/8 or 1 1/4
      sanitation hose and covered by two layers of PVC pipe halves for
      strength.

      The centerboard I had needed some serous repairing from the prior
      owner cranking it on the trailer axle. I remove it and fixed all of
      that. Before I put it back in, I enlarge the pivot hole to accept a
      1/2" centerboard bolt for added strength. I also added 2lbs of lead
      to the back section for improving the speed of centerboard deployment.
      Lastly, I added a cam-cleat to the rear area of the cockpit floor for
      the centerboard cable securing.

      I really like the mod for the following reasons: I can adjust the
      centerboard from the cockpit which was something I liked when I had my
      26X. Also, I can completely pull the centerboard into the trunk when
      the boat is out of the water so that it doesn't rest of the trailer
      cross-member and gouge it on its resting spot. Additionally, the
      centerboard will drop quickly and assertively.

      The things I didn't like about it is you need to have the centerboard
      all of the way up when motoring fast (you supposed to anyhow) or water
      will come into the cockpit floor. Also, the tube the cable runs
      through to get to the cockpit will block some access to the rear
      berth, but it's not so bad. Additionally, you will now have a
      cam-cleat and 5ft+ of centerboard line to step on in the cockpit.
      Overall, I like the mod and would recommend it to anyone
      single-handling their boat like me.

      For your endpoint of adding lead to the centerboard, you are correct
      the stock Mac19 centerboard raising system just won't cut it and I
      personally believe it's marginal to begin with as the centerboard
      needs to rest on the trailer when out of the water. I could envision
      you adding some weight to the centerboard along with a deployment
      system similar to mine and having success there. The question would be
      the limit of the weight added as you might need to use a larger
      cable/rope than what I use (being the standard jib/mainsheet size and
      is also used on the 26X's centerboard system). Also, the cable
      attachment point may need to be fortified to prevent breakage there.

      Somebody on the 26X board did add lead to their boat's centerboard and
      reported improved sailing characteristics and increased stability. You
      might want to do a search there for at least two threads pertaining to
      that. The one thing to keep in mind is the 26X is really tender and
      anything done to improve its stability might have a greater effect
      than for our more stable Mac19s. The physics involved is to imagine a
      pivot point for when the boat rocks from side to side and calculate
      the leverage arm for the added lead to the centerboard. The righting
      moment force will change as the boat heels more and is close to zero
      when the boat is level in the water. Obviously from this, you will
      get the most benefit by biasing the lead in the rear end section of
      the centerboard.

      Good luck with the project and let me know how it goes!
      -Chris
    • fischer@optidynamic.com
      Something caught my attention when reading this post. I spoke with Bill at the mac factory sometime ago when I had questions about keel repairs I was doing and
      Message 2 of 3 , Oct 7, 2005
      • 0 Attachment
        Something caught my attention when reading this post. I spoke with Bill at
        the mac factory sometime ago when I had questions about keel repairs I was
        doing and I mentioned to him that my keel pivot hole was much larger than
        the 1/2" pivot bolt. He said they where designed that way so the load on
        the keel underway was placed on the trunk walls and not on the bolt. It
        should have enough slop in it to allow the keel to swing side to side and
        wedge itself into the trunk. The hole in the keel is 5/8" and the pivot
        bolt is 1/2".
        Thought I would throw that out there for concideration.

        fischead



        > I got the following responce from Chris when I ask him some questions
        > about his centerboard raising modification and he gave me his
        > permission to share it here. Here is what he had to say.
        >
        >
        > The specific thing I did for my centerboard mod was to drill a hole in
        > the rearmost top part of the centerboard trunk and insert a thru-hull
        > into that. Unfortunately, that area will still go in and then out of
        > the ballast tank so I was worried at first when doing this. A tube of
        > 3M-5200 and Plumber's Goop as well put my fears to rest as it doesn't
        > leak and it's solidly in place. The thru-hull was inserted so it
        > angles back to target a hole in the front section of the cockpit
        > floor. I used an upside down 45-degree rail fitting for cockpit floor
        > hole. The whole thing was tied together with either 1 1/8 or 1 1/4
        > sanitation hose and covered by two layers of PVC pipe halves for
        > strength.
        >
        > The centerboard I had needed some serous repairing from the prior
        > owner cranking it on the trailer axle. I remove it and fixed all of
        > that. Before I put it back in, I enlarge the pivot hole to accept a
        > 1/2" centerboard bolt for added strength. I also added 2lbs of lead
        > to the back section for improving the speed of centerboard deployment.
        > Lastly, I added a cam-cleat to the rear area of the cockpit floor for
        > the centerboard cable securing.
        >
        > I really like the mod for the following reasons: I can adjust the
        > centerboard from the cockpit which was something I liked when I had my
        > 26X. Also, I can completely pull the centerboard into the trunk when
        > the boat is out of the water so that it doesn't rest of the trailer
        > cross-member and gouge it on its resting spot. Additionally, the
        > centerboard will drop quickly and assertively.
        >
        > The things I didn't like about it is you need to have the centerboard
        > all of the way up when motoring fast (you supposed to anyhow) or water
        > will come into the cockpit floor. Also, the tube the cable runs
        > through to get to the cockpit will block some access to the rear
        > berth, but it's not so bad. Additionally, you will now have a
        > cam-cleat and 5ft+ of centerboard line to step on in the cockpit.
        > Overall, I like the mod and would recommend it to anyone
        > single-handling their boat like me.
        >
        > For your endpoint of adding lead to the centerboard, you are correct
        > the stock Mac19 centerboard raising system just won't cut it and I
        > personally believe it's marginal to begin with as the centerboard
        > needs to rest on the trailer when out of the water. I could envision
        > you adding some weight to the centerboard along with a deployment
        > system similar to mine and having success there. The question would be
        > the limit of the weight added as you might need to use a larger
        > cable/rope than what I use (being the standard jib/mainsheet size and
        > is also used on the 26X's centerboard system). Also, the cable
        > attachment point may need to be fortified to prevent breakage there.
        >
        > Somebody on the 26X board did add lead to their boat's centerboard and
        > reported improved sailing characteristics and increased stability. You
        > might want to do a search there for at least two threads pertaining to
        > that. The one thing to keep in mind is the 26X is really tender and
        > anything done to improve its stability might have a greater effect
        > than for our more stable Mac19s. The physics involved is to imagine a
        > pivot point for when the boat rocks from side to side and calculate
        > the leverage arm for the added lead to the centerboard. The righting
        > moment force will change as the boat heels more and is close to zero
        > when the boat is level in the water. Obviously from this, you will
        > get the most benefit by biasing the lead in the rear end section of
        > the centerboard.
        >
        > Good luck with the project and let me know how it goes!
        > -Chris
        >
        >
        >
        >
        >
        >
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
        >
        >
        >
        >
        >
      • eo_ant
        Fischead, Thanks for sharing that tidbit. Seems like an odd design plan to have the CB swinging side to side to wedge into position in the trunk, but it sounds
        Message 3 of 3 , Oct 10, 2005
        • 0 Attachment
          Fischead,

          Thanks for sharing that tidbit. Seems like an odd design plan to have
          the CB swinging side to side to wedge into position in the trunk, but
          it sounds like the info came from a reliable source.

          Eric



          > Something caught my attention when reading this post. I spoke with
          Bill at
          > the mac factory sometime ago when I had questions about keel repairs
          I was
          > doing and I mentioned to him that my keel pivot hole was much larger
          than
          > the 1/2" pivot bolt. He said they where designed that way so the load on
          > the keel underway was placed on the trunk walls and not on the bolt. It
          > should have enough slop in it to allow the keel to swing side to
          side and
          > wedge itself into the trunk. The hole in the keel is 5/8" and the pivot
          > bolt is 1/2".
          > Thought I would throw that out there for concideration.
          >
          > fischead
          >
        Your message has been successfully submitted and would be delivered to recipients shortly.