Clamps, clamps and more clamps!
I'll say it again, it is true what it is said about boat building, you can't have enough clamps. It is no surprise that designer Keith Callaghan recommends making simple and inexpensive clamps for planking. Keith provides the drawings for such clamps and it only took a few minutes to make them.
I made my clamps from 2" x 2" x 8' cedar lumber cut at 16" lenghts thus ending with 6 clamp pieces or 3 sets of clamps per 8' stick. I then cut the ends at a 22.5° angle. On each piece I drill a 12 mm hole at about 9.5" from one end.
A 3/8" carriage bolt, 2 washers and a wing nut complete the hardware needed to assemble the clamps. I also cut several 2" x 2" x 0.5" cedar pieces and glue one at each end of a clamp set per drawing specification. I place another piece at the other end without glue (this was not on the drawings) only for storing purposes.
I made my clamps from 2" x 2" x 8' cedar lumber cut at 16" lenghts thus ending with 6 clamp pieces or 3 sets of clamps per 8' stick. I then cut the ends at a 22.5° angle. On each piece I drill a 12 mm hole at about 9.5" from one end.
A 3/8" carriage bolt, 2 washers and a wing nut complete the hardware needed to assemble the clamps. I also cut several 2" x 2" x 0.5" cedar pieces and glue one at each end of a clamp set per drawing specification. I place another piece at the other end without glue (this was not on the drawings) only for storing purposes.
All said and done, I made a total of 12 sets of clamps that I will use during planking. Now wondering... are these enough?
The Jig
The building jig turned out to be a very versatile structure. Made from 2" x 10" dimensional pine lumber, the inside of the jig measures precisely 14' x 33". Outside dimensions are 14'3" x 36".
Earlier, I modified the jig to serve as a temporary work bench. The sliding middle panels allowed me to meet the scarf joints dead center for clamping during bonding. This arrangement worked really well for me.
I removed the temporary boards and sliding panels from the jig and proceeded to add the legs before bringing the jig down from the saw horses. The 6 legs are 18" tall made from 2"x2" cedar lumber.
Once the jig was on the floor, I added a set of crossed strings and squared the frame in 3 dimensions. Fortunately, having straight lumber and a level concrete surface was a good starting point.
Next, I placed the level accross the frame at 11" intervals and confirmed the jig is leveled. I marked the center line on the jig's cross members and marked the stations on the jig's stringers.The Building Frames
Checking things twice and doing things once is a good thing. Placing each bulding frame over their full size drawing, I carefully checked the location of each plank landing, the centerline and the design (DWL).
I then marked the centerline and the design water line (DWL) on both sides of the building frames.
At the bottom of each building frame I screwed a 2" x 2" cedar brace to mount the frames over the jig. I also built a frame to support the transom through the transom holes. I used braces on both sides and the transom hole cutouts as spacers to avoid overtightening and as vertical support to place the transom leveled at the required height from the baseline.
Designer Keith Callaghan's Construction Note #5 states: "The hull is built, inverted, on 7 temporary building frames plus the apron (otherwise known as ‘stem’), and transom. The frame locations are known as stations. 7 frames (numbered 1 to 7) are equally spaced at intervals of 534mm. The forward face of frames 1, 2 , 3, 4 and 5, and the aft faces of frames 6 and 7 are aligned at the station position. The transom is assumed to be 12mm thick, and thus the forward face is located at +4258. when the frames are erected the edges should be protected with PVC adhesive tape to prevent them being inadvertently bonded to the planking."
I placed a certerline string inside the jig and shot a laser along the string to help align the building frames. Then, I mounted the transom as specified, centered it with the laser and squared it with the jig. Once satisfied with the alignment I screwed the transom's frame brace to the jig.
.A front view of construction frames #4 through #7.
Running a centerline string from the transom to the apron, I fine-tuned the alignment of the construction frames across their centerline and the Designed Water Line (DWL). To have unobstructed clearance to run the string, I drilled a 12mm hole at the intersection of the centerline and the DWL on construction frames #1, #2 and #7. The centerboard cutouts on the remaining building frames provide ample clearance to run the string. Extending the centerline and DWL with a simple ruler helped me determine if the string line was centered. Note the support blocks on the aft side of the transom.
One final look and inspection down the centerline string.
I laid the hog over the building frames for the first time. It fit nicely in its place.
The hog over the apron and the bow knee fitted inside the two. The aft face of the apron is precisely at +47mm per the bow profile drawing.
The centerboard case went in through the construction frame slots without any issues despite the fact that I had already bonded the external reinforcements.
A quick snapshot of the centerboard case under the hog, with the bow knee and the apron.Initially I only installed 6 legs on the jig. Later, I added 2 similar legs to the forward section of the jig and 2 more legs to the aft section made from left over 2" x 12" pine lumber.
Next, I'll remove the hog, the bow knee and the centerboard case to brace each building frame square against the jig. I feel better about doing this now knowing that these parts fit and align properly.
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