04 Sep 22:
We cut and fit the keel, and per plan neither the top or bottom of the keel is straight from bow to stern. I wondered for a bit on how to mark our not-so-cheap piece of sapele mahogany so as to get an accurate cut line and optimize the amount of lumber left over. An expensive way to do it would be to cut a piece with plenty of excess along the cut lines, and scribe the top of that piece to the.....anyway, ask 7 boat builders how they do it and grab some coffee, you'll be there a while listening to 7 x infinity answers.
What I did was find a long stick and marked out 4 inch increments to scale to represent "stations." Once the marks were made we basically have a scale ruler, and I laid the measuring/marking stick on the plans. The stick was placed on the 2 high points of the keel drawing at the bow transom and stern transom. Station Zero we'll call it, was the mark that touched the bow edge of the keel drawing, and stations were numbered by inches then feet, so 0, 4, 8, 1, 4, 8, 2, 4, 8, 3... Confusing? Yes it was. To make things even better, the stick was numbered right to left.
Here's a photo of the stick. That clears things up, right? A wider, flat stick would have been better, but this is what I had. And for this photo I took it later and the Station Zero tick mark, shown on the lower face of the stick to the far right, is not touching the uppermost bow end of the keel drawing. FYI, it was when I took the measurements. And there a lot of lines there, the top and bottom of the bottom plank lines, the tip of the keel, and the top and bottom lines of the chafing strip. The first bit of error can be introduced by using scaled plans vs full size patterns (which are not offered) but it's all part of the so much fun of messing about with boat building. Actually the first bit of error was to begin building a boat at all, if prescribe to Capn R. D. "Pete" Culler's philosophy (he was a serial boat designer and builder). Pete prefaces that belief with the wisdom that boat building was simply about correcting one mistake after another, with the first mistake being in beginning at all. "But oh what fun." He also advises that experience starts when you begin.
Oops, I wandered off there. The scale for these plas is 3" = 1'. Each mark on the stick represents 4 inches. It would have reduced my confusion if I had marked the stick using the Feet-Inches-Eighths convention. See how there are two four inch marks on the lower face of the stick? The one to the right is at zero feet, four inches, zero eighths, it's mark would be 0-4-0. Since we're reading measurements right to left, the four mark to the left is at 1-4-0, or one foot, four inches, zero eighths. These "Station" marks go out to almost 6 feet, and the problem with my lazy scheme is that I left a lot of fours and eights hanging in space with confusing context.
Still with me? My plan was to now take my 2 foot folding carpenter rule, which is marked in inches and eighths, place the rule on the plans below the stick and then take measurements down from the stick to find the top and bottom measurements of the keel per plan. Then we'll transfer those measurements to the full size piece of mahogany, with our baselines being the straight edge of the stick and a straight line on the mahogany. So at Station Zero, the tip of the keel, those measurements are 0 inches to the top of the keel and 0 inches to the bottom of the keel, those numbers are barely legible on my soon to be patented Keel Stick 2000. These points become Sharpie dots on the mahogany. At 4 inches aft of the keel tip, the top of of the keel is 1 1/4 inches down from Keel Stick baseline and the bottom is 2 1/4 inches. A 8 inches aft of the keel tip, top of keel is 2 inches down and bottom is 3 inches.
When WE, yes, you are in this with me now, no escaping...When WE get further to the left on Keel Stick v1.0, around 4 feet, numbers get confusing. Does that 4 mean 4 feet or is it 4 feet 4 inches? Here's where the Feet-Inches-Eighths numbering would come in handy.
Should we talk about Introduced Error now? Sure. Those lines on the plan are at least 1/8 inch wide when you scale them up, and the lines on the ruler are about the same. Plus what if the plan line falls between a mark on the ruler? Then you can use you best guess and add +/- to the measurement, example 0-3-4(-). Once the cut lines are drawn on the work piece, use judgment to decide how much slop to leave when you cut to the line, or in other words, don't cut exactly to both cut lines. For our butchery that day we cut outside the top-o-the-keel line first, not To the line, and left plenty of reserve wood on the keel bottom cut line.
Zoom in on this photo of the keel and you may see the Sharpie mark of 4-8. It is nowhere near where the keel ended up being cut, the mark is at least 1/2 inch (+) off the final cut.
Once we got the measurements on the stick we transferred those measurements to the expensive mahogany with a Sharpie dot, with the only measurement and Sharpie dot that we certain of being the Station Zero measurement and marking. Then we connect the dots using a batten to get a mostly fair curve, and make the first cut outside of the top-o-the-keel cut lines. At one point you have to cut of excessive lengths and widths of the lumber, leaving enough wiggle room for the scribing and fitting to come.
Did we get pictures of the Sharpie points before the battening and first cuts? No. Did we get photos of placing the rough cut keel on the bottom for scribing? No. But for our first scribe we were almost an inch off in one area, because we accepted that variance in measuring and rough cutting. I scribed the bottom to the keel, cut to that line and actually got close enough that thickened epoxy could have filled the small gaps we had in 2 areas, less than 1/8th inch. Still no pictures. I made the second scribe cut to the line and had a nice fit, so we were done with the top-o-the keel fitting.
Since I was remiss in my photog duties, here's a picture of a turtle.
Next we marked the keel bottom points, drew the cut line with a batten and a Sharpie and cut outside that squiggly line with a jigsaw. We faired the bottom of the keel to a pleasing curve with 40 grit belts on a belt sander, backyard boatbuilding at its best.
Voila, the keel is cut! This is how most blogs explain these complicated maneuvers at the late stages of construction.
"Next, we need to make the keel..."
"The keel is attached!"
So we offer our method to you so you follow us down this trail, or you can decide we are crazy and blaze your own trail.
Some folks amy ask, what did the Nutshell Pram Build Guide offer in the way of keel cutting instructions? The answer is nothing, as the Guide is written for those assembling the precut kit for the rowboat version, and the keel comes precut. There are however, detailed instructions and photos for making the sailing version spars, daggerboard trunk, daggerboard and rudder.
Once again I apologize for dropping the ball on getting photos of the cutting, scribing and fitting. So here is a consolation photo of Skipper's Drascombe Lugger ONKAHYE outbound on East Bay. Taken from inside the air conditioned and well provisioned house on the bay with high speed wi-fi, by the crew who were told we were shoving off at 0900.
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