16 ft jon boat made from home milled oak boards

Discussion in 'Boat Design' started by l_henderson, Sep 24, 2011.

  1. l_henderson
    Joined: Sep 2011
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Lucedale, MS

    l_henderson Junior Member

    Anyone have plans for a 16 foot plank and frame jon boat? I want to make a robust boat that will be powered with a 50 hp 2 cylinder evinrude. Plan to have stick steering. Cutting an oak tree now with capability to mill 14 inch wide boards 16 ft long.
     
  2. lewisboats
    Joined: Oct 2002
    Posts: 2,329
    Likes: 129, Points: 0, Legacy Rep: 1603
    Location: Iowa

    lewisboats Obsessed Member

    What kind of oak? Better be Live or White. Red oak is not a wood to plank a boat with. As to the plans...you're building a box basically with a curved bottom. For 16' I would go with a bottom of 4.5 to 5 ft wide and sides around 12" wider, a depth of 16-18" from bottom to shear, 2 seats and a bow deck. Make the seats of plywood, seal them up and fill with foam. Set your aft transom at 1.5" and make the bottom around 5/8" thick, go with 1/2" for the sides and 3/4-7/8" for the bow transom. Deck should be around 5/8". I would go with a lap on the sides for added stiffness. Put your aft transom at a 13-15 deg rake and there you go. I would batten the seams on the inside and outside...the outside providing skid and scrape protection and the inside helping to seal the joint. You will need to put some framing in there to tie the planks together too. I would go with around 2x2" at a 15-16" spacing, running across the bottom and up the sides with gussets at the corners. Also brace the transom with knees in the corners and one from just below the motor mount area to the bottom...with equal legs or the bottom one longer. Double or triple up at the shear or put a scuppered wale in (all those holes are handy spots to tie to).
     
  3. l_henderson
    Joined: Sep 2011
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Lucedale, MS

    l_henderson Junior Member

    Thanks Lewis!!

    There is a lot that I do not know about boat building, the info that you gave is great, just what I was looking for. Transom construction seems crutial. I am planning to use 2 inch plank for transom, but could use more detail on design. Also plan to make sided 21 inches high. Does that change anything from your suggestions?
     
  4. lewisboats
    Joined: Oct 2002
    Posts: 2,329
    Likes: 129, Points: 0, Legacy Rep: 1603
    Location: Iowa

    lewisboats Obsessed Member

    You do realize that the tree you cut today and rough mill won't really be useful until sometime late next year or preferably the spring after. The wood must be allowed to dry and season. It must be properly stacked and stickered (separated by sticks to allow air flow) and allowed to dry down to somewhere in the mid to low teens moisture level.

    Going with 21" side panels...you might want to add about 4 more inches to the beam at the shear...16" wider than the bottom rather than 12. 54" across the bottom and 70" at the shear would be just about right.
     
  5. l_henderson
    Joined: Sep 2011
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Lucedale, MS

    l_henderson Junior Member

    Kind of oak tree

    According to a local expert the tree is a Quercus alba Linnaeus
    Fagaceae aka White Oak. Plan to air dry 3 months. Shrinkage is suppose to be about 6% radial, 10% tangential, and almost none longitudinal. Thanks.
     
  6. philSweet
    Joined: May 2008
    Posts: 2,682
    Likes: 451, Points: 83, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    By all means make the frames out of oak, but plank a jon boat with something else. The oak planks will expand/contract with so much force that the framing would need to be massive to resist it. You could resaw to about 3.5 inches width and work with that, but that is a hard way to build a jon boat. From personal experience, I don't much care for white oak in the tropics; I think it should stay north of the Mason Dixon line where it is less a maintenance headache. I've got this tree so I'm going to build a boat is putting the cart before the horse.
     
  7. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 101, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Oak is not the best planking material due to excessive movement. Usual southern US boatbuilding woods are Live or White Oak for framing and long leaf yellow pine for planking. Don't try to re-invent wooden boatbuilding for your own convenience as the laws of shrinkage and warpage will retaliate.
     
  8. l_henderson
    Joined: Sep 2011
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Lucedale, MS

    l_henderson Junior Member

    I thought that since the oldest commissioned war ship "Old Ironsides" is made from oak it would be a good chouce. I have plenty of Long Leaf Pine trees that I can harvest and mill planks.
     
  9. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 101, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Oak is quite suitable to 8" thick planks on 12"x14" frames but I doubt you want to build your boat that stout. I know a caulker who worked on the CONSTITUTION repair and he said the garboards are 14" thick.
    LLYP is one of the best small work boat planking materials there is. It is hard, very rot resistant, stable and doesn't take up much water when wet. Oak is infamous for crawling around unless it is very well seasoned, out of the sun and quite stout in scantling. Oak makes great planking for warships and large tugs, LLYP more suitable to smaller craft and widely used in the past. Cypress is also good. Whatever you use, season it one year for each inch of thickness. Stack it and stick it for air circulation, paint the ends with paraffin to slow checking, cover the stack from sun with tarpaper stapled on, with a little pitch so rain runs off.
     
  10. l_henderson
    Joined: Sep 2011
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Lucedale, MS

    l_henderson Junior Member

    Lewisboats, you mentioned "lap the sides", how much and which plank goes on top, the higher or lower?
     
  11. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 101, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Plank from bottom up. Lowest, or "garboard" plank first, lap the next about 2 plank thicknesses so if 1/2" plank lap it 1". At ends cut a tapered dado in upper edge of garboard so plank lap disappears at ends, or just keep the lap all the way to the end but this looks clunky and catches on things. If frames are close, not necessary to fasten laps, but if spaced widely put a thin copper rivet through the lap between frames.
    Read this thread about "building a johnboat of lumber" and it should help:
    http://forum.woodenboat.com/showthread.php?107365-Building-a-john-boat-of-lumber
     
  12. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 101, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

  13. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 101, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Passing this along.
     

    Attached Files:

  14. BATAAN
    Joined: Apr 2010
    Posts: 1,614
    Likes: 101, Points: 0, Legacy Rep: 1151
    Location: USA

    BATAAN Senior Member

    Art by Mike Calway-Fagen showing how NOT to do it.
     

    Attached Files:


  15. lewisboats
    Joined: Oct 2002
    Posts: 2,329
    Likes: 129, Points: 0, Legacy Rep: 1603
    Location: Iowa

    lewisboats Obsessed Member

    I think he has a complex...

    Good stuff above...I'da dug similar up if I had time...been rather busy recently...only time to stick my nose in and comment here and there.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.