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Table Of Half Breadth/heights
I purchased this really nice book the other day (at a substatially enflated price, should have bought it from NOAH's) called CANOECRAFT by Tom Moore. Now this book goes into extensive detail about building the cedar strip canoe. As informative and appealing as this book may seem, when I got to the 8 designs that they offer with "the purchase of the book" my first thought was "WHAT ARE THESE GUYS SMOKING"??? I am not, I repeat NOT a rocket scientist nor do I play one on TV. If somebody could please decipher these tables for me in a manner that is consistent with a ROOKIE BUILDER I would be forever grateful. I'm trying to transfer these things to grafting paper and would appreciate any advice you could give (NO , DON'T EVEN SUGGEST ME BUYING THE MOLDS, THIS IS WAR)
I hope you enjoyed my review of this book
I even got my copy of the book out to see if I could help.
I've built a few boats, but I couldn't understand the butts and WL's, either.
I have a friend that used these tables though, I will touch base with him.
The book Canoecraft will be most valuble once you get the tables sorted out.
It saved my butt more than once.
table of offsets: help is out there
I know this is an old post, but I just got here. Just in case this might be useful to someone:
An excellent source on lofting (I've found it both highly useful and easy to understand) is "Lofting" by Allan H. Vaites, published by Woodenboat Publications. It made all the difference on my first lofting project, a 17 foot sailboat. Because I only had a small scale lines drawing and no offsets, I had to draw out the lines full size. In the process I developed a table of offsets, an experience which has helped me when working in the other direction (from a table of offsets in "Canoecraft") to lay out accurate station and stem molds.
"Lofting" is only about 140 pages long, clearly written and generously illustrated, and costs about $20.
I will say that lofting is a complicated skill and even after two projects, I'm far from expert, but this book made things clear enough to me that so far I have been able, notwithstanding the odd bump in the road, to get where I've needed to go.
Well it ain’t quite rocket science.
For station moulds tape some heavy construction paper to a piece of MDF. Make sure one corner of the paper aligns exactly with the edges on one corner of the MDF.
Useing a carpenters framing square, not a tape measure, draw a vertical centerline on one side of the paper, being sure to allow enough horizontal space for half the station mould.
Mark off the horizontal distances (half breadths’) from the centerline on the bottom edge of the sheet. Traditional tables of offsets use 1/16” to denote fractions so 2.8 or 2 8/16 means 2 1/2”
Mark the 0 or waterline on the centerline high enough so you can add the below waterline points. Make this an even inch or mm as you will be measuring up and down from this point.
Place one arm of the square against the bottom edge of the MDF, the vertical arm should be parallel with the centerline.
Place the vertical edge of the square on the horizontal reference point (half breadth) for the waterline. Using the graduations on the square, measure up to the vertical reference point for the waterline. If you measured up 6” for the waterline mark on the centerline then 6” is waterline mark on the ½ breadth. Mark this point with a pencil.
Continue adding vertical and horizontal reference points until you have a series of dots that look like half a station mould.
Drive a 1 ½” finishing nail about ½”into each point, make sure the nail is straight.
Make a batten of straight grain wood thin enough to bend around the points. Untapered sail batten works well too, whatever you use needs to bend with an even curve, no kinks. Place the edge of the batten on paper and bend around the outside of the nails. You can use a spring clamp to hold the batten to the top nail. The batten should touch every nail evenly, no gaps or kinks. If you have nails out of place recheck the measurements. Mistakes in the tables are not unheard of so if everything checks out and you still have one out of line blame the designer. Do not force the batten into an unnatural curve unless it is required by the design.
Mark a line on the inside of the batten between nails, pull the nails and cut the cut the paper ½ station on the line with a razor knife or scissors.
Tack or tape the ½ station onto the MDF and mark around the edge, mark the water line points on the MDF at the edge of the paper. flip the pattern over, match up the waterline marks and draw the other half. Lay a straightedge across both waterlines before lifting the pattern to make sure both halves are aligned.
The same principal can be scaled up to any size boat although it is usually easier to draw both sides directly on the bulkhead or mould frame for larger hulls.
Or you can save the hassle and get Noah’s to do it on our CNC machine.