Can I have Shallow keel and bilge keel together.

Discussion in 'Boat Design' started by alp gulden, Dec 14, 2020.

  1. alp gulden
    Joined: Dec 2020
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    Location: boston

    alp gulden Junior Member

    I have columbia t26 with Shallow keel with a draft of 2.1 inch. To increase the performance and reduce the drag I want to add two twin keels on right and left of the existing keel.
    1. Is this make sense.
    2. Although this sounds good on theory would that create any issues that I don't foresee.
    the displacement is 4225 and with metal keels attached will be go up to 5000.

    3. Any suggestions on the placement of the keels. center, back?
    4. I am planing have 2 holes on the hull and attached the keel custom made metal and metal plate inside the boat with strong bolts. What is your suggestion to have proper water seal on the holes?

    5. Alternatively adding more structure and make a V shape keep at the bottom of my shallow keel can help me for performance?

    Thanks
     
  2. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    Look like draft is 2 feet 1 inch, also written as 2' 1". Columbia T-26 Specifications http://www.columbia-yachts.com/c-26t.html

    Adding two additional keels will increase drag. Skin friction drag will increase. The keel on the upwind side will be close to the surface of the water when the boat heels and will generate waves which will cause drag. And there is likely to be interaction with the center keel which increases drag.

    What aspect of performance do you want to increase?
     
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  3. alp gulden
    Joined: Dec 2020
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    alp gulden Junior Member

    Thanks so much for the response. You are right 2 feet 1 inch. So as far as I understand having a twin keel will be increasing the performance upwind. Since they will be narrow enough I didnt think they will create a drag. The biggest problem is with shallow keel is the drag and instability on upwind.
    I was thinking maybe I can have twin rudder or keel to make it more safe on upwind.
     
  4. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    short answer: no, your boat is basically perfect as is, experts have thought of all that and decided against, for reasons.

    However, if you want to play with parameters consider installing transferable side to side Water Ballast tanks to act as "Rail Meat" to keep the mast more upright and catch more wind. For a boat your size about 8 of thesehttps://www.amazon.com/dp/B087W7XXJV/ref=sspa_dk_detail_2?pd_rd_i=B087W7XXJV&pd_rd_w=j48rj&pf_rd_p=7d37a48b-2b1a-4373-8c1a-bdcc5da66be9&pd_rd_wg=H0M8s&pf_rd_r=J7ZRE3QGJJWESK1ZK9EM&pd_rd_r=ebd131b5-e981-4890-b007-f89013d4c263&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzTlo0QVpDR0dOMjdKJmVuY3J5cHRlZElkPUEwMjQ2NTk2Q0VPWDNIOTJNVFg5JmVuY3J5cHRlZEFkSWQ9QTAzMTUwODE1Q0hWQk44WjRDWlomd2lkZ2V0TmFtZT1zcF9kZXRhaWwmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1, 4 on each side, and some pumps and hoses to transfer 160lbs of water from side to side in about 1 minute. If that doesn't work out you will still have some nice emergency water storage for home or office, and some decent emergency pumping system for the boat.
     
  5. alp gulden
    Joined: Dec 2020
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    Location: boston

    alp gulden Junior Member

    Thanks for the response. Yes i wanted to experiment actually. I am not sure if there are apps for playing these measures.
    Just for me to understand better. These water bottles supposed to be in the boat or hanging outside. What advice i will have with having additional weights. Would adding extra weight on the keel self work?
     
  6. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    I'm thinking inside up high (or just on mattress if no good sturdy way to secure them up high) against the walls, two in the middle bunk area and two in wide rear part of forward Vee berth area.

    I guess on the sides or up on deck (if they clear the boom) could work, too. Main idea is ballast off to one side is much more effective than centered ballast, per weight. Plus, I'm personally scared of smaller keel boats that carry enough weighted solid ballast to sink them straight to the bottom if they get holed. A collection of 1/2 filled big water bottles wont do that and will help buoyancy.

    Yes, adding weight will "work" but what exactly are you trying to do? Sail faster in strong wind?
     
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  7. alp gulden
    Joined: Dec 2020
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    Location: boston

    alp gulden Junior Member

    Here is the problem
    1. sailing upwind is slow and to much drag
    2. on windy conditions I need more stability
    3. finally I am looking to experiment some options. I want to use this boat as protege.
    thanks

    Do you know any other issues shallow keel issues that I dont know.
    thanks again for you time
     
  8. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    Sell the boat and buy something you like more. Yes there were some tripple keeled boats around, but none is a windward wizzard. The only way to make her go higher is by adding a deep foil. That means daggerboard, centreboard or a complete new fixed keel.
    If the boat is tender you need to reef earlier or learn to like sailing at 30°. A water ballast system could help but only if she was designed for railmeat and the structure can take it.
     
  9. alp gulden
    Joined: Dec 2020
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    Location: boston

    alp gulden Junior Member

    Vow that is quiet good. I didnt know there are such thing as triple keel.
    Triple keel https://trident24.com/the-trident-24/triple-keel/
    that is exactly what my plan. I think I would go with plan B : adding a swing centerboard. This is just for fun. is there any app for testing designs online by any chance.
     

  10. Rumars
    Joined: Mar 2013
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    Rumars Senior Member

    I am not aware of any boat design app. You will have to determine the new CLR and CE the old fashioned way.

    Now, before you start cutting holes into the boat (the fun will disappear quickly when you have to cut a slot trough the lead), how old are your sails? The order of changes is not from the keel up, it's from the mast down. That means first you buy a new set of laminate sails with full battens, you change all the rigging to dyneema, and if possible a carbon mast. This will transform how she sails, and if you are still not satisfied you can start thinking about the centerboard.
     
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