Extending a keel/ engine rudder install

Discussion in 'Boatbuilding' started by Tjason27, Oct 3, 2015.

  1. Tjason27
    Joined: Oct 2015
    Posts: 1
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    Location: Mass

    Tjason27 New Member

    Hi looking for help regarding extending the keel on my 27 downeast, 27 Terry Jason. I completely gutted this boat and stretched it out 2ft.. So I am at the point now where I need to figure out where to place the engine.. how to achieve about a 7 degree shaft angle, prop clearances etc..

    Right now.. I just put a template of the engine/gear in the boat and the old 8ftx1.5" shaft into the boat to see what things looked like.. if I extend the keel back say 18" have about a 10 degree angle.. im looking to reduce this.. as for the method of extension of the keel I was thinking of cutting the dead wood off the back of the keel and then glassing in/ fairing in a FRP tube ..as I look at these pictures I am wondering if cutting the deadwood off and thus being able to lift the shaft up a bit will help me out or not.. I want to extend the keel to compensate for the added bouyancy that the stretch gave me.. some say I should just leave the running gear where it was.. some say move it back..

    im here to listen to opinions.. very much appreciate the info
     

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  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 476, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    Yeah, I'll climb into the move it back camp. You've gained a fair bit of additional volume, so you'll want to move some mass aft a tad. As to the angle, the simple way is how you're doing it. Make a template or jig to hold the old shaft at 7 degrees (good choice BTW) and see where this has the stuffing box fall. This will force your hand in regard to the engine placement too.

    Given you've effectively moved the wheel forward 2' with the stretch, you really do want it as far aft as practical, assuming the rudder will remain in its stock location (assumed just forward of the transom). That boat has more than enough keel hanging down to do it's job, so don't worry about adding to it. You'll just be adding to the volume you've added with the stretch and no performance advantage will be gained either. This will leave the shaft hanging in space, but at the lower angle, it'll tuck in behind the keel neatly, protecting it. You'll need a strut to keep the thing from whipping, but I'm assuming you figured this out already. You could build up the shaft area, like on that one image, but it's not necessary, unless you can guarantee this addition, will eliminate the need for a strut (a really, really stout laminate would be necessary).

    In the end, you can cut the keel if you want, but only to get the angle where you want it. The U shaped bites around the shaft exit will not do much for you, if the shaft is sticking out 24" past the keel. Also consider a metal skid plate, possibly from the keel bottom to the bottom of the rudder, to further protect the wheel and rudder.
     
  3. kapnD
    Joined: Jan 2003
    Posts: 716
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    Location: hawaii, usa

    kapnD Senior Member

    How did the boat ride before surgery?
    Did it need a lot of tab to plane, or was it bow heavy?
    Was your decision to extend it performance related?
    A two foot extension is not going to make a giant difference in the boats performance, so why not leave the running gear as was and save yourself a lot of money and headache.
    Also, having the running gear tucked back under the transom can be a real asset in many types of fishing, if that is what you do.
     
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