Ontario Whitehall Rowboat Project Online Builders' Manual

 

SECTION ONE: PREPARATIONS

CHAPTER 1

BUILDING the STRONGBACK


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Once completed, the STRONGBACK is really just a long and skinny worktable to which the station molds will be attached.

And, over the molds, the HULL will be created. 

 What is important is taking the time to make this item as accurately as possible. The simple truth is that a bad boat can be built on a good mold but a good boat cannot be built on a bad mold. Take the time to get this foundation piece done well; it is a good way to start this project.

With the photo above as a visual guide to what is to be constructed, it is time to purchase the basic materials and to begin.

MATERIALS LIST for the STRONGBACK:

(a) 2- MANUFACTURED WOOD I-Beams

approximatly 9 1/2 " tall x 14' 4" (see note below )

(these are used as floor joists in house construction)

(b) 3- pieces of 2" x 6"-- six feet long

(c) 1- sheet 4' x 8' good one face PLYWOOD

(d) 16- carriage bolts - 1/4" x 3 1/2" with nuts and washers

(e) 4 levelling 'legs' (often found under stoves to 'level' to your floor)

I have found them in Home Depot loose hardware section; get the package with the T-nut insert

(f) 1 package of deck screws #10 x 3 1/2"

(g) 1 box (approx 500 pcs ) drywall screws #6 X 2"

You will need a pair of level sawhorses to do the building of the strongback.

 

PROCEDURES:

CUTTING THE STOCK

(1)    The two I-Beams are likely a standard length perhaps 16 feet; yours need to be cut square to be 14' 4" long.

(2)    The 2 x 6 stock needs to produce a total of 8 pieces: these are all used to make the support legs. Cut these as perfectly square as you can. Make four at 24”, another 2 at 36” and the final 2 at 16 7/8".

(3)  If your lumber yard has a panel saw, have them rip two 16"x 8' panels from the sheet of ¾” thick  plywood. These will be the top plates of the strongback. The remaining piece will be used to make 8 GUSSETS.

 

SEQUENCE OF ASSEMBLING the STRONGBACK:

  

      Set up the sawhorses and lay the two I-beam pieces so they are upright; clamp together side-by-side with the ends squarely aligned. In this position, you will be laying out a series of 8 lines used to position both the GUSSETS and SUPPORT LEGS.

On both sides of the MID POINT LINE, mark out four further lines 6" then 44" then 54" and then a final pair 4" from the ends. While the I-beams are still clamped together, use a small square to draw vertical lines down the outside of the beams. These side lines will guide the drilling for connecting the gussets.

       Unclamp and separate the two I- beams so they are 12" apart. Take some time to level the beams both from side to side and from end to end. You may have to use thin cardboard shims to get this to work out.

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Next, prepare the EIGHT gussets from the plywood left over from making the two top plates.

The gussets-in this case- measure 9 1/2" x 12". Your 9 1/2" dimension may vary depending on the actual size of the I-beam. In other words, they have to be 12" wide x height of the I-beam.

The gussets fit inside the I-beam to join the two together and to keep the beams in a straight line.

It is important that these pieces have SQUARE CORNERS. Notice in the image that all 4 corners of each gusset has a square notch cut out. The size of the notch is determined by the size of the top and bottom rail of the I-beam.

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Slip all 8 gussets between the I-beams such that each is centered on the 8 lines drawn earlier. Use as many clamps as you can muster to hold the whole unit together.  You will likely need to loosen and adjust your clamps as you use your small square and a small level to confirm that the gussets are plumb and square to the beams.

It is preferable to begin at the ends and work inwards particularly if you only have a few clamps. Once you have the gussets in place and centered on the lines drawn earlier, use a small pilot drill (1/8") and drill through the side of the I- beam and on into the gusset—three holes per position. Then drive in a #6 x 2" drywall screw. Continue until all 8 gussets have been secured inside the I- beams.

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The TOP PLATES are the next pieces to be dealt with.

In total we need to have the combined length of the two panels total only 15' 9 5/8" so 2 3/8" has to be cut off one piece.

(Look at the top sheet of your plans).

.

 Then, to make building the actual boat easier, cut a taper at one end of this shorter panel.

It will start 17 5/8" from the end and will narrow down to a final 1" width; or, 1/2" either side of the mid line.

Save the two long triangles created by the cutting.

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To align the plates on the I-beams, you will need to make 10 small blocks of wood ¾" x 1" x 4"- (the one inch dimension is the really important one). Flip the plywood panels over so the POOR face is up. Use even spacing as you clamp six of these blocks to the outside edge of the longer panel and four to the shorter. The 1" dimension is to face outward. In the photo below, the clamps but not the blocks are visible.

Flip the panels back over so the good side is up with the guide blocks below snugged up tight to the top rail of the I- beams.

Be sure the bow and stern ends are positioned in your shop so you will have comfortable working space.

 Your top plates are now aligned and extend 1 inch beyond the I-beams.

This 1" overhang becomes significant in CHAPTER 2 when the mold cross blocks are attached.

  At the TRANSOM end, be sure the top plate is even with the ends of the I-beams.

Next, you will be screwing the top plates to the rails of the beams.

In the photo above, you can see long blue chalk lines. We used chalk so it would show; a combination square and pencil would do a fine job—just draw the lines 1 ¾" in from the edge. You may need to adjust this measurement if your rails are a different size.

The whole idea is to get the screws into the center of the rail.)  At 6" intervals along both lines, drill 1/8" pilot holes then add a small countersink to make certain that the screw heads will be below the surface. Then drive down the 2" drywall screws. You could run glue as well but the screws are plenty strong.

Remove the clamps and guide blocks; their work is done.

With some help (the thing is getting heavy!) turn the unit upside down on the saw horses and relevel if necessary.

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The SUPPORT LEGS are next to go into place.

From the collection of 2 x 6 pieces, take the four which are 24" long. Double check that all four are the same length and have nice square ends. These four will stand upright starting on the underside of the top plates and positioned 49" from the middle of the beam and thus centered between the gusset pairs attached earlier. Clamp all four in place.

Again, use your square and level to ensure that all four are correctly positioned. The legs will be attached to the I-beams with the CARRIAGE BOLTS. Mark out and drill four holes through the 2 x 6 and through the rails of the I-beam using a ¼" drill bit. Insert the bolts; secure well with washers and nuts.

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The two pieces of 2 x 6 x 16 7/8" complete the leg structure. They sit ON TOP of the vertical parts just attached and are held in place with the #10 x 3 ½" deck screws (great hold in end grain).  Pre drill with a 5/32" bit.

The final parts of the strongback legs will be the horizontal floor levelers. These are the 2 pieces of 2 x 6 x 36". Mark the centre point (18") and draw a centre line on all four sides of these parts.

If you take a few minutes to round over the upper corners, perhaps on a band saw, your ankles are less likely to get bruised as you walk by while building.

Along the bottom (the 36" length), draw a line ½" from the edge.

Next, hold these two leveling feet together and turn them so the 36" length is up. Clamp together in a vise and use a spirit level to ensure they are level!

Drill 3/8" holes four inches from the ends and centered on the work piece. These holes need to be 1 ½" deep. Hammer in the T –nuts.

Insert the threaded portion and turn these down until fully inserted into the T-nuts.

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With the strongback still upside down, clamp the horizontal floor levelers to the leg unit along the ½" line just drawn a few minutes ago; the 1/2" extension makes it easier to level the strongback since it will rest only on the four levelers. Ensure that these pieces are centered on the midline.

Once again, use your square and level to be sure these final two pieces are square to the beam and level along the horizontal. Use another four of the #10 x 3 ½" deck screws to attach these parts to the 16 7/8" leg base.

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And, finally, take the two long triangular parts cut earlier when you tapered the top plate. Glue and screw these together and then use the 2” drywall screws to attach these to the underside of the top plate. Some screws go through the end gusset and, when the box is turned over, a few more from the top. These triangles add support to the BOW END of the boat as it is built.

The completed strongback can now be turned upright! It is ready!

This one was painted white (2 coats of left over latex from another job) because it looks neater and, when lines are drawn (next chapter), they will be easier to see.

At a minimum, it would be a good plan to paint at least the top plate surface in white.

 Remove the sawhorses; make a decision where the building will take place (leave some butt room !) and get it leveled (side-to-side and end-to-end) using the small leveling feet inserted in the horizontal floor leveling board.


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