01-07-2012, 10:18 AM
After a couple of nasty colds, and various other December distractions, I am back to looking at the Super Skipjack model I am trying to build. The instructions say to cut a notch 17 3/8 " from the stem tip, where the deck panel will sit. Unfortunately, I did not cut my stem quite right. So I wanted to see in the drawings how long the notch itself should be. But that info was not available. I had to calculate it.
The starting point is that the stem post is cut from "nominal 1x12" stock, often 11+1/4", but this can vary". It is cut at a 39 degree angle, and then a tip piece is added, which is supposed to have a top edge 9" long. So, if I calculated right, the length should be (w / sin 39) + 9" . I make this to be 11.25 / 0.6293 + 9 = 26.88", or 683mm, (but this can vary). Of that I am to subtract the 17 3/8": 26.88 - 17.375 = 9.50" or, 683 - 441 = 242 mm, (but this can vary). Not that hard to sort out, and pointed out that my model of the 1x12 plank had varied more than real-life wood probably would, and in the unlikely direction of being too wide.
But I am left wondering. Why did I have to calculate at all? Why isn't this visible in the drawings. Why is it measured from the most unreliable point in the assembly, the tip? If I am not mistaken, this is an important measurement, since it will fix the position of the deck, and with that, the angle of the forward bulkhead, and the mast box, and the rake of the mast itself. Is there a subtle reason to do it this way that I have missed? Or am I just being too much of an engineer here?
When I get to the point of installing the deck, I think I will keep a good eye on getting the fwd bulkhead at the indicated 93 degree angle. Which in the drawings seems to be 93 degrees to the bottom panel, which isn't level or even straight at that point...
The starting point is that the stem post is cut from "nominal 1x12" stock, often 11+1/4", but this can vary". It is cut at a 39 degree angle, and then a tip piece is added, which is supposed to have a top edge 9" long. So, if I calculated right, the length should be (w / sin 39) + 9" . I make this to be 11.25 / 0.6293 + 9 = 26.88", or 683mm, (but this can vary). Of that I am to subtract the 17 3/8": 26.88 - 17.375 = 9.50" or, 683 - 441 = 242 mm, (but this can vary). Not that hard to sort out, and pointed out that my model of the 1x12 plank had varied more than real-life wood probably would, and in the unlikely direction of being too wide.
But I am left wondering. Why did I have to calculate at all? Why isn't this visible in the drawings. Why is it measured from the most unreliable point in the assembly, the tip? If I am not mistaken, this is an important measurement, since it will fix the position of the deck, and with that, the angle of the forward bulkhead, and the mast box, and the rake of the mast itself. Is there a subtle reason to do it this way that I have missed? Or am I just being too much of an engineer here?
When I get to the point of installing the deck, I think I will keep a good eye on getting the fwd bulkhead at the indicated 93 degree angle. Which in the drawings seems to be 93 degrees to the bottom panel, which isn't level or even straight at that point...