Finding Apex Line

[Dubb]

Knowing the rabbet and bearding lines, I'd like to find the apex line on a stem. I was shown a method awhile back, but can't recall the whole process. I remember drawing a line perpendicular to the rabbet then using the mid-point of a piece of planking stock (say 1/2 inch think and 1 inch wide) to find the apex line. Obviously, I'm missing a few steps. Can anyone help? Thanks.

[Bob Cleek]

I'm not going to give you a whole dissertation on this, but... You have your rabet (outside of plank) line and your bearding lines (inside of plank). You take a piece of planking stock, maybe six inches or whatever by an inch or so, and as thick as the designed finished thickness of the planking. (Remember that your planking stock will be thicker to begin with to permit backing out.) This is called a "fid (fit) stick." Take the angles that the planking will run into the rabet off your lofting at various points all along the rabet and then holding your fid stick at the appropriate angle at each respective point along the rabet will show you the angles the sides of the rabet should be. Chisel the angles at each point, using the fid stick held at the proper angle as a pattern. When it lays fair and fills the rabbet between the bearding and rabet lines, you've got it. Once they are all done (a bunch of notches), then cut out the rabet between each, keeping the angles fair. (Sort of "connect the dots.") Don't worry where the apex or midline or whatever you want to call it ends up. If you have the fit stick laying in the rabet fair like the plank would be, and you connect the notches all up, the apex line will take care of itself.

[ 08-23-2004, 10:10 PM: Message edited by: Bob Cleek ]

[landlocked sailor]

The CLEEK lives!!!! Rick :eek:

[nedL]

I saw this morning & was wondering when someone was going to comment. Hey Bob, You've been missed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Think you might be stopping in occationally? I hope all is well with you out there on the west coast. :D :D :D

[Jon Etheredge]

Okay, so you've got a line drawn perpendicular to the rabbet line at some point on the stem. Now you just need to know what shape the surface of the plank is at that point so you can use your planking fid to find the apex.

The perp that you have drawn will cross one or more waterlines. You need to lay out the half-breadth of the boat at each of these intersections. Draw lines that are perpendicular to your first line at each intersection. Now carry that intersection up (or down) to the half-breadth view and pick up the half-breadth dimension. Carry that dimension back to the profile view and mark in the half-breadth. After you do this for each intersection, you can connect the dots and you will have a picture of the surface of the plank. Now you can lay your fid in to find the location of the apex.

If my crude attempt to explain this doesn't jog your memory, try to lay your hands on a book like Rossel's <U>Small Boat Building</U>. You will find diagrams that illustrate how to do this much more clearly that I can try to explain it.

[r stevens]

Take a square piece of wood that is the plank thickness by any length (say 6"). It is square so you don't have to think about which face to use, they are all representative of plank thickness. Cut both ends square, same reason.Now draw a line square to rabbet line. Don't worry about its relation to the bearding line. Put one corner of the stick on the point where this square line hits the rabbet. Now pivot the stick until the opposite face crosses the intersection of the square line and the bearding line. Trace the square angle this creates between the rabbet and bearding line. The point of this angle is the apex line and the depth. Imagine in your mind rotating this angle 90 degrees.
Now connect a number of these apexs. Set your circular saw to the minimum depth( minus a scooch if you are anal) of the apex line in this area and cut the line. Now you have the apex line and its depth.
You will know your depth of your apex is correct if you lay your plank stock piece on the back rabbet, I think its called, after you've cut down to it and a straight edge laid on top will meet your rabbet line.If it goes outside it your apex is too shallow.If your chisel is square laying it on edge on the back rabbet and striking it means when the corner hits the apex the cutting edge will hit the rabbet.
Two other things, in the fore foot and and keel/stern post area don't cut all the way to your bearding line. Planks don't like to bend as easily as lofting battens here. They usually straigten out from your last frame to the hood end. Also put your stopwaters in between the apex line and the rabbet where the caulking will come in contact with them before you cut out your rabbet.
I hope this is clear. Most boatbuilding tricks are designed to eliminate the need to think. Rob