Saturday, December 31, 2011

Planking












Planking can be the most fun of all boat building tasks. While there are thirty steps or so to the making of each strake, it is a task that settles into a smooth rhythm. On a carvel boat the work starts at sheer and keel so there are four places to work at any given time until the shutter planks are reached. Work never stops while waiting for a steamed plank to set or for a glued scarph to dry. At the moment of this writing there the fourth plank from the sheer on the port side is spiled. The third plank from the sheer on port is being fastened. The third plank from the keel on starboard is being final fitted, soon to receive a caulking bevel, and the third plank from the keel on port has just been steamed to take the twist in the forward end and is about to be scarphed. So it will go until the boat is closed in and we are ready to fair and caulk.
Silent Maid's topsides are to be finished bright as the original's were in 1924. Since we were unable to find Atlantic White Cedar of sufficient quality for such a treatment Western Red Cedar is being used. This is some beautiful stuff, some of it 33' long and 24' wide. The garboards and broad strakes are full length and the rest of the planks will have one joint each rather than the two or three the shorter white cedar might require. We are scarphing the planks together partly to offer a better appearance when varnished and partly to get all the rigidity we can out of each strake. More full length planks might be gotten out of this wood pile but as we move away from the sheer and keel the strakes develop more curvature and joints are preferable to the cross grain that would result from a full length plank.
 The planking is being riveted to the frames wherever possible. The rivets pull the kerfed frames together as well as securing the planks. This is the most durable fastening method of them all. To save time and produce rivet heads of even quality a pneumatic hammer is used to head over the rivets. When done this way it only takes a little longer to rivet than to screw fasten, rivets inaccessible to a ball peen hammer can be done, and the framing is not marked up with the missed hits of a ball peen hammer.
Take Care, Be Accurate, Move Quickly
  1. Layout spiling batten on frames taking care to avoid edge set
  2. Draw lines at each frame
  3. Swing arcs with a compass defining width at each frame.
  4. Move batten
  5. Pick up bevels of adjacent plank at each frame.
  6. Make patterns of the hollow on the inboard face of the plank  
  7. Select plank stock. The hollowing patterns dictate thickness and, “The inside of the tree is the outside of the boat”
  8. Position spiling batten on the stock taking care to avoid imperfections and looking for a good sweep of grain over the entire plank.
  9. Draw Frame Lines.
  10. Swing compass arcs.
  11. Add bevels.
  12. Clamp a batten through the marks and draw a line.
  13. Band saw, leaving the line.
  14. Plane square.
  15. Using this plank as a pattern draw a mirror image on another piece of stock for the opposite side of the boat that way steps 1 through 12 only have to be done once for each pair of planks.
  16. Plane the bevel to match the adjacent plank.
  17. Layout the scarph joints. This is a 12 to 1 ratio scarph with the inside edge lined up with a frame edge. Scarphs in adjacent planks will be 5 frames apart and no joint shall happen on the same frame for three planks. Use common sense though nothing is so uncommon.
  18. Cut scarph.
  19. Glue scarph, usually this happens on the boat.
  20. Back out the plank if necessary using the patterns made in step 6.
  21. Trial fit, scribe edge for a precise fit and plane.
  22. Trial fit again until perfect.
  23. Plane caulking bevel.
  24. Final clamp up. Remember polysulfide at transom, cotton wicking if you’re all traditional.
  25. Drill for fasteners.
  26. Drive screws and nails.
  27. Place roves, clip nails and head over,
  28. Remove clamps and complete fasteners.
  29. Do it all again and again until the boat is planked up.
    Boat building is all about the short term goals, the ones between the drawing of plans and the sailing of a complete vessel. Those goals keep us going in the near term but they have a treachery all their own. When a boat is fully planked there is a sense of wholeness to her, she is a potential vessel for the first time. But after the shutter is in there is fairing with hand planes, then fairing with the aptly named torture boards, long sanding boards. Then there is a progression through finer grits, all by hand. In between the initial planing and the torture boards all those thousands of fasteners are bunged. When the fairing is done there are thirty seams to caulk. It is not daunting with enough hands but on the slow days this can all seem eternal. As the shutter goes in there is a bit of a party atmosphere but it takes character to push through all the work that was finished in the minds eye on the day the last plank was fastened in. It is a long haul across a dusty desert between the shutter plank and turning the finished hull upright but damn that hull looks good.


1 comment:

  1. Fantastic!... Beautiful design!... Perfect construction!...

    ReplyDelete