Oh my aching head!

Those tricky V's

The primary purpose of this blog was to set out for those interested in designing their own small boat how to go about it. It has also become a way for me to record methods that I don't use very often and then when I come to do them again I have to learn how from scratch. So it has been with developing panels for V-bottom boats. I could not for the life of me remember how I had done it when designing Vole.

Vole is a small kayak-ish boat based upon the mouse boat. Here is the one I built for my Grandson, The plans are free on my website, here.

Vole has a V-bottom and I was going to use it to show how to develop the panels and so for the past two days I have been racking my brain to figure out how I had done it as I never wrote it down. However now I've got it again and so I will write it down.

Here are the lines for Vole,

To get the length of the panel we'll draw a baseline and then take the distance between stations, starting from station 5 and working fore and aft, from the profile drawing along the keel and mark that along the baseline as we did with the side panel in the previous post. We then draw a vertical line at station 5 upwards from the baseline.

We know that to get rocker in a V-bottom the panels, as they are laid flat, must diverge from the midpoint of the bottom otherwise you will have a straight line much like folding a piece of paper in half. The question is how to determine the amount of divergence at each station? To do it you need a second line parallel to the baseline much like the second waterline when we developed the side panels for sampram however that line cannot be parallel to the line of the keel in plan. What to do?

Any line which is a 90 degrees to station 5 in the section drawing will be parallel to the baseline. Here I must digress.

I have been referring to station 5 throughout the last few posts, that is a bit of shorthand for the point at the greatest amount of curve in either the keel, chine or what ever line you are using to establish your baseline. In most cases it will be station 5, if the greatest amount of curve is elsewhere you will need to draw in new station lines from a vertical line through that point of greatest curve.

Back to our panel.

In this case I have drawn a line from the intersection of the gunwale and bow transom at 90 degrees to station 4 in the section drawing which just happens to be, in this case, the same angle as station 5. I then mirrored that line into the other side of the drawing establishing a line at 90 degrees to station 5 and parallel to the baseline but not parallel to the line of the keel. For want of a better term let's call it a diagonal.

We then transfer the diagonal from the section drawing to the profile drawing using the techniques we have discussed previously.

We take the distance along station 5 to the diagonal to determine the height of the diagonal above the baseline.

And then transfer that distance to our vertical line from the baseline and draw a line through that point parallel to the baseline. Transfer the distances between stations on the profile drawing along the diagonal to the line we have just drawn.

Join the station marks,

and then, as we did for the panels in the previous post, transfer the distances above and below the diagonal to the panel drawing, here is the above,

 

 and join the intersection with a smooth curve. You should note that the distances at the bow and stern are taken from the developed transoms not the section drawing

When drawing the curve for the keel line be very aware that some of the section distances are only minutely different than the distance between the baseline and the diagonal, not taking this into account will affect the shape of the developed panel.

Erase all unnecessary lines and there is your developed panel.

 

Once I remember how to do twisted panels I'll post again. Oh my aching head!