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Notches for Jig and Structure Assembly

With or without dimensions.

Notches in stringers and frames make the assembly easier and self-aligning.

In some cases, we show the notches location and depth on the plans but those dimensions are not necessary.
The builder can very easily mark the notches on the parts himself.
Here is how it goes in case the plans do not show the notches.

First, locate the notches on the frames.
The plans always show the stringers spacing. Look more closely and you will see that there is a note on the plans that says from which side of the stringers that distance is measured.

For example, let's say that we have a set of stringers at 12" from the centerline, measured from the inside of the stringer.
Draw a line on the frame at 12" from the center.
Now, look for the thickness of the stringers. If it is made of two layers of 3/8" plywood, the total thickness = 3/4".
Draw a second line 3/4" away from the first one.

Now, let's decide that we will make all notches in the stringers 3" deep. Look at the picture above (3" is marked as 76 mm). That shows us how deep our notch is going to be on the frame: the full length of the line minus the 3".Mark that point and cut the notch.
We cut with the saw blade outside of the line, it gives us a little bit of play for the assembly.

Mark and cut all other frames the same way.

Next, mark the stringers.
The procedure is the same but lengthwise this time.
The plans show the spacing of the frames, usually from the lower corner of the transom. Draw those lines on the stringers.
Check from which side that distance is measured. Look for the thickness of the frames and mark that second line on the stringer.

If we follow the example above, all the notches in the stringers will be 3" (76 mm) deep. Cut them outside of the line again.

That's all: the structure will go together as a puzzle.


  • Close to the bow, the stringers will not be as high and you may want to cut shallower notches. Use the same system but cut notches only 1 or 2" deep.
  • Precise adjustments can be made by pushing little wedges in the notches between the parts. The goal is have the stringers and frames flush on the hull side.
  • If major differences appear, check the level of the floor first. It is probably due to molds (frames) that are too high or to low on an uneven floor. If you use a jig with strongbacks, check your molds level: that is probably where the mistake is.
    This is one of the advantages of the notches: mistakes appear immediately and can be corrected before materials are wasted.

It is not necessary to use notches but they make the assembly faster, easier and fool proof.

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