Scribe-fitting Difficult Profiles
Ever have to scribe fit a kitchen cabinet to fit a wavy and out-of-plumb wall? How about fitting a bulkhead or partition-wall panel into the inside hull of a yacht or ship? Can you scribe fit a curve as high as 7 feet and as deep as 3 feet? And in a space where nothing is square, little is plumb and level changes constantly with payload and wind? Welcome to the world of interior ship joinery sans lasers and computers, and file away another handy but simple, old-time skill for when you may need it.
I took a half hour and got out some scaled-down panels, sticks and battens to answer a question on how to build bunkbeds into the inside curve of a yacht hull. Now there are plenty of yachts sufficiently slab-sided for simple scribe fitting to work. But not this one. This one is a 180-ton ocean-going tug being converted to a family liveaboard. The space in question is around 7 feet high with a bulge in the outside wall around three feet deep. Time to get out some ticking sticks.
First some old-time jargon. Woodworkers “make” or “build” objects and their components. Boatbuilders and shipwrights “get out” parts as components of a boat or vessel. What y’all call a “ceiling” in a house isn’t the same thing in a boat. Boats have “overheads” instead. “Ceilings” in boats are the interior lining of the hull, in this one softwood planks. “Floors” in boats are framing members similar to the joists above your house foundation. What you walk on in a boat is it “sole”.
A vertical template is clamped temporarily next to the curve in the ceiling your new panel has to fit. Find a distance that fits both curve and template and mark it on the ticking stick. Here I’m using 16 1/2″. Draw the line and distance from several points on the curve to the template. For more complicated profiles you can use multiple distances and even make your ticking sticks from wooden yardsticks.
Remove the template to your work area, align it to your bulkhead or bunk panel and simply transfer line and distance to marks.
Connect the marks fairly using a flexible batten and ice picks or nails. Draw a line, cut the profile, and fit it to the ceiling.
The hardest part often is indexing the template if the boat isn’t gutted and you don’t have beams and floors to clamp it to. Be prepared to screw temporary blocks to the sole and overhead to fix it in place 90 degrees to the sole. The template can be positioned at any angle to the ceiling, but is always best placed along the line the panel will lay, usually athwartships along a line equidistant from the stem, and the profile scribed is the outside of any bevel required.
Luan doorskin for templates is inexpensive. Ticking sticks and flexible battens can be got out of any straight-grained softwood like the Doug Fir you see here. Using sticks, size and depth don’t matter. Get that template aligned and plumb, and with very little practice it’s mark, cut, bevel if necessary and fasten regardless of size. Run the beltsander lightly over your template and run your sticks and batten thru the planer to erase the marks for the next installation. Buy a box of art gum erasers if you don’t have those tools yet. View Image
“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think…that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ –John Ruskin.
Replies
Another excellent tutorial Bob. It's good to bring some of those boatbuilder's skill to the rest of the woodworkers isn't it?
Now THERE'S a trick I can't wait to try out, even if it is on dry land!
Mike Hennessy
Pittsburgh, PA
I scribe stuff this way all too often, though on dry land. I just think the framers and drywall hangers/plasterers were drunk when they did their work.
The tick stick method was described in FHB, and it works well. I did a mantel top that fit into a spot that used to have a window...when fitted, the edge of the mantel shelf that abutted the wall looked a lot like the coastline of California...
I remember reading of the technique in Wooden Boat a long time ago. They called them "Jogglesticks" the article described a stick with a random zig zag edge that after marking was duplicated by matching the zig zag pattern later during the layout. Your method is simpler in that you don't have to make the special ticking sticks.
Edited 10/8/2007 4:34 am by QCInspector
Another trick is to notch your stick in 2 places, incase one runs off your board.
Good tip!
Thanks for passing along some of the old world knowledge. I could have used some of your experience a couple of weeks ago.
I'm in the process of finnishing a 15 ft Rangeley and installing the brackets for the seats was alot more effort than I had imagined. The two seats need to be positioned correctly and accurately and are mounted to the hull side where it is curved in two directions. Add to this the need to have the tops of the brackets paralell with each other so that there is even bearing for the seats. Three seperate levels, string lines, large drafting triangles, framing square, clamps and temporary support framing all came into play just to get the position right. Then I had to hand shape each of the four brackets to fit the compond curves.
They're in, fit right, and I think they'll take the loads (butt and rowing) but I'll bet you would have had a good belly laugh at the procedure and how long it took to do it.
Thx.... Ric
Yours could be done in stages like you did....get the inner hull vertical curve using ticking sticks....bevel the edge to match the fore-and-aft curve...then draw and cut the seat rests.
But sometimes you have to "loft" complicated shapes that can't be scribed. Lofting is drawing the boat and its components full-sized or to scale using the table of offsets in the plans that define the curves or making your own table from a scale model.
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We use these heavy work punts for underwater log recovery, and the design is so simple a seperate lofting stage during construction isn't required. Until you try to get out that heavy, cambered 3" X 5" bow stiffener to fit between the three bevels on those 2X3 bent chines in the corners that is. After failing to make a satisfactory pattern from the actual boat, I lofted that area after the fact and drew the two sections I needed rather than risk ruining the nice stick of old-growth Doug Fir I has selected for the stiffener.
Here's what a table of offsets looks like:
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“When we build, let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us for; and let us think...that a time is to come when those (heirlooms) will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, ‘See! This our father did for us.’ “ --John Ruskin.
Bob
I know you must flip thru Wooden Boat from time to time?? I saw your quote. That boat designer had his .... together.
Dan
Thanks Bob and I applogize for the late post.
I have been reading Geo Buehler's book and having a great time with it. He does a good job of explaining the lofting process. My boat is strip built and the inside has no reference points except the stem, inner keel, and transom. And the keel is slightly hogged. The designer told me that the position of the seats needed to be accurate, I presume so that the boat will row the best it can. So I leveled the boat as best I could (with a hogged bottom longitudinal level is relative) pulled a string line from stem to tramsom and tried to get perpendicular from that. I would have liked something a little more accurate.
If I had been thinking ahead (like Beuhler says) I would have left a mark when the hull was still on the formers. I knew level and station position excately then.
Attached is a pic of the boat still on the formers. I should have the seats in and the oar blocks on this weekend and I'll post a pic.
Ric
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