Reducing bottom frame angle add skeg

Discussion in 'Wooden Boat Building and Restoration' started by rasorinc, Dec 6, 2010.

  1. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    Due to money constraints, I'm changing my mind and using the lumber on this
    plan. https://www.boatdesigns.com/products.asp?dept=735

    `Im adding 2 frames at 32" oc rather then re-spacing frames and plans allow that. So starting at the transom then frames 1,1a,1b,2, 3,4 . 5 on and on all
    of these frames the V is 4/12--18 1/2* . I want to change frame 1b to 3/12,
    frame 1a to 2/12 frame 1 to 1/12 and the transom to 0/12 and then add a sheg from frame 2 to frame 1 to carry the 4/12 V to the rear. The skeg will not be deeper then the forward V 4/12 frames but stop at frame 1 so a jet can be installed between frame 1 and the transom. All Frames to the rear of the stem are 32" oc. I know I will need trim tabs but hoping the skeg will keep it going straight. All comments greatly appreciated. Not really concerned with weights and balance. Thanks
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I can't really see how you are going to install a skeg and a jet at the same time. Also, why you need it. However, if you are not really concerned with weights and balance, go for it. You are saying that the handling and behaviour of the boat are not important to you. In another thread you started, it says you have no knowledge of wood. It may not be wise to make major structural modifications.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Keeping it going straight isn't going to be your problem with a jet. I'm not sure what you're trying to do, though it does sound like you're attempting lengthen the design, but using an unconventional method. I don't think your method will work, though I admit I've having difficulty picturing your revisions. Slow down and be more specific Stan, so us slower folks can catch up.
     
  4. rasorinc
    Joined: Nov 2007
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    rasorinc Senior Member

    Will try again. Gonzo, if I said I have no knowledge of wood I must of eaten a poison mushroom. The one thing I do know a lot about is wood, lumber, and the structural properties of species. So I must have been really screwed up if I said that. I have over 40 years experience in the lumber field. When I said no concerns about weights and balance I should have said "At this time I'm not going to address the weights and balance issues because I need to address the lengthening and bottom angle issues first". I will certainly want to make sure those issues are studied and corrections, if needed, are made.

    The boat is 24'-1" in length. Bottom and side frames are 32" OC until you reach the stem.
    I am wanting to add 2 more duplicate frames or 64". The bottom frame angle is 18 1/2*
    or 4/12. I'm trying to flatten out the rear so I could consider a jet or if I use a V drive the prop will be up higher and protected somewhat. The transom bottom will be 1/2"/12. Frame # 1 will be 1/12. Frame 1A will be 2/12. Frame 1B going forward will be 3/12 and Frame #2
    will be 4/12. All other frames continuing forward are 4/12 until you reach the stem where they are steeper angled. So I'm curving up frames slowly to, an almost flat area, between frame #1 and the transom. Glen-L instruction say add extra frame rather then re-space frames so I'm keeping the 32" OC. From frame #2 thru frame 1B and 1A ending at frame #1
    I want to add a skeg keeping a 4/12 pitch going aft so the keel line is as it was originally.
    I hope I did better on this description this time as my scanner is out. Thanks much, Stan PS I really value your opinion PAR and GONZO
     
  5. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    I apologize if I confused this post with another. Jet drives steer with the nozzle. I think that a skeg will probably impair steering. The main problem with a jet, is that you will need a flat area in the bottom. That means a complete re-design of the hull. By the way, are you willing to share some of them mushrooms?
     
  6. Tad
    Joined: Mar 2002
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    Location: Flattop Islands

    Tad Boat Designer

    Probably easier to just cut the tip off the vee wide enough to take the jet intake. The jet manufacturers will say no to any hull protuberance (skeg) forward of the intake....if you have directional problems install small directional fins (similar to surfboard) well outboard (say...2/6ths of the total beam out from centerline) alongside the jet intake but far enough away there is no chance of introducing eddies or bubbles even when the boat is sliding sideways.

    Cut the vee off horizontally (parallel to waterline/centerline) forward from the transom to the leading edge of the intake. Then cut forward with a shallow downward slope until you intersect the centerline. Slope should be no more than 5 degrees...hopefully less. You end up with a vee shaped panel with its pointy tip at forward centerline. This cuts away volume which you make up for by not flattening the bottom......
     

  7. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    The Wallypower jet drive boats use a pair of fins aft and outboard. The fins are about rudder size. You can see them in the photo just aft of the red lifting sling. Sorry about the bad picture.
     

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