Building the Ultimate Expedition Kayak

Constructing the 30-minute Strongback

The 30-minute strongback, built from two 16-feet 2 x 8 boards and two 8-feet 1 x 6 boards, along with a couple of 2 x 4 boards for the legs.

A lot of kayak builders and master boat-craftsmen will tell you it is vitally important to have a flawless strongback on which to build your kayak. From a certain point of view, I suppose this makes sense. After all, won't any boat built on an imperfect foundation turn out imperfect as a result? Well, honestly, the answer is no. True, aligning and plumbing the stations will be somewhat easier and quicker after you've spent several painstaking hours building the "perfect" strongback for your foundation. However, a quick glance at the detailed, tedious steps which many kayak-building handbooks provide for building strongbacks will expose the rest of the truth: that you'll almost certainly end up wasting more time than you save. In the end, even if your strongback is less-than-perfect, you can achieve perfect results when building your boat. How? Well, it actually boils down to simple geometry. It sounds unbelievable, perhaps, but regardless of how mis-aligned your strongback may be, as long as you plumb all of the stations carefully with a level and a stringline, they will end up level and perfectly aligned no matter how twisted the thing is that is holding them up. Period. So unless you're going into the boat-building business and you need a strongback that will last without warping or twisting for years to come, you can save yourself a lot of hassle by building a simpler, less labor-intensive strongback that will still serve its purpose without any compromises to the quality of your finished kayak.

Having decided I didn't need to waste hours building a "perfect" strongback, I went to the lumber store and bought two 2 x 8 boards 16 feet long, and two 1 x 6 boards 8 feet long. Since I didn't want to make the strongback any more imprecise than necessary, I spent some time searching through the lumber bins to find the straightest boards I could. For the 2 x 8 boards, I sighted along the narrow edge to make sure this edge of each board was as flat and straight as possible. A little curvature to the left or right was acceptable, but the narrow edge needed to be as flat as possible. Also, there could be no "twist" in the board, as this would distort the flatness of the narrow edges as well. For the 1 x 6 boards, I sighted down the wide face of the boards to make sure this face was, again, as flat and straight as possible. Again, some curvature to the left or right was acceptable, as long as the wide face of each board was relatively flat. Of course, following my own logic that the strongback need not be "perfect," even these precautions are partly unnecessary. However, a substantially twisted or warped board will restore the "hassle" to the strongback-building process, so it's best to at least begin with the straightest boards you can find after a quick glance through the lumber bins.

Having gathered all of the necessary boards (plus a couple of 2 x 4 boards for making the strongback legs), I took my lumber home and prepared to build the strongback. Here, it probably bears mentioning that many carpenters and wood-workers recommend storing the lumber in your garage or workshop for up to four weeks in order to let the wood acclimate to its new home before you use it. This practice helps ensure that the wood will not significantly warp or twist later. Alternatively, if you have access to old lumber in usable condition, it should have finished settling long ago, and the potential for warping shouldn't really be an issue. It is not absolutely imperative that you follow either of these recommendations (I didn't), but be aware that the wood in the strongback can "settle" after you've built it. Again, following my logic that an inaccurate strongback is not the problem popular wisdom has made it out to be, the issue of "settling" wood is only a problem after you have set up your riser blocks and stations. Then, the warping or twisting will not just affect the strongback but everything else attached to it, meaning that your stations will be rotated or twisted out of alignment to a greater or lesser degree. In this case, inaccuracies will be introduced to the finished kayak if you don't notice and correct the problem before you build. Since I stripped my hull to completion within two days of building the strongback, settling was not really an issue for me. However, if you let your strongback sit for several weeks before building, wait to set up your stations until the day before you actually begin laying strips.

Determined to get the boat-building process underway, I set my strongback up as follows:

Set both 16-feet 2 x 8 boards up on their narrow edge and lay them parallel to each other.
Place temporary 2 x 4 spacer blocks between the 2 x 8 boards to maintain a constant spacing of two inches along their full 16-feet length. Note: The spacing will not be exactly two inches because a standard 2 x 4 is not actually two inches thick, but is cut slightly smaller. This is fine. We want the spacing to be identical to the thickness of a 2 x 4 board.
Lay the two 1 x 6 boards end to end, on top of the 2 x 8 boards, effectively creating a three-sided box with the 1 x 6 boards as the "top" of the box. (See picture above)
Screw down the 1 x 6 boards into the supporting 2 x 8 boards. Place a screw every ten inches along the full sixteen feet. Note: Since the 1 x 6 boards will overhang the placement of the 2 x 8 boards, use care to screw far enough in from the edges of the 1 x 6 so that your screws actually sink into the 2 x 8 boards.
Snap a chalkline to create an arbitrary centerline down the top face of the strongback (the face of the 1 x 6 boards that comprise the "top" of the strongback). Use a straight edge and trace this chalkline in pencil to make it more visible and permanent. Note: The placement of the line is not wholly crucial; that is, it need not be exactly down the center of the strongback face, as long as it is perfectly straight and stretches from one end to the other.
Measure along the centerline and, starting from the middle of the strongback (the seam between the two 1 x 6 boards), mark off the spacing for the riser blocks and stations.
Square each riser block off of the centerline. This ensures everything will be straight and squared, regardless of any left or right curvature to the strongback itself.
Build three legs for the strongback. Each leg should have a vertical 2 x 4 support post that will fit into the gap which you spaced into the underside of your strongback in Step Two. Be sure to make the legs as sturdy as possible so they won't wiggle later. Ensuring the legs stand perfectly vertical and level will be convenient later, but not absolutely imperative. Do not permanently attach the legs to the strongback yet.
Set up the strongback where you plan to build the boat and use a level to level the strongback along its full length, parallel to the centerline you created in Step Five. If you built your strongback legs out of 2 x 4 boards, the legs should slide up into the gap between the 2 x 8 boards (underneath the "top" created by the 1 x 6 boards). Adjust the height of the legs by sliding them up or down inside the gap. When you find the correct height, screw through the side of one of the 2 x 8 boards straight into the top of each leg to hold it at the desired height and keep the strongback in the now-leveled position. Waiting until now to attach the legs allows you to compensate for any flaws, dips, or irregularities in the floor of your building location and ensures a nice, level strongback.
Now level perpendicular to the centerline on your strongback to get it as perfectly level as possible. Start at each end, then level the center. Shim under the legs as needed to get the strongback level. If there is some "twist" along the length of the strongback, much of it can be taken out by removing the leg at or near the problem-area and having someone twist the strongback back into alignment while you reattach the leg. Normally, the reattached leg will be sufficient to pull out the twist in this manner, but some shimming may again be necessary.
Go back over the strongback with a level to double-check everything. Again, absolute perfection is not necessary, but getting it close (without obsessing over it) will make things go more conveniently when you set up the stations. When it all looks tolerable to you, stand back and breathe a sigh of satisfaction.

Congratulations! You've built a 30-minute strongback! It may have taken you slightly longer than 30 minutes once you factor in the time required to build the legs, but rest assured you've saved yourself a lot of tedious measuring and gluing and whatever else is suggested by popular wisdom on this subject. The only downside is that your 30-minute strongback won't look quite as lovely hanging over your mantle when you're done, but I'm doubting you would hang it there anyway.

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