Sliver Paddleboards are built with wide planks on the top and bottom skins. Stacking narrow bead-and-cove strips allows us to makes rails with tight curves. In this tutorial I will detail how you can build the rails on your hollow wooden board just like I do.
Your board at the start of “railing” should look similar to the picture above. The ribs are all glued securely with PL Premium or 3m 5200 and the bottom skin should roughly follow the outline of the board. Any more than an inch of material on the bottom plank gets in the way and has more potential to cause cracks in the bottom skin.
Start by checking the height of each bottom rib notch to ensure the outline strip will slide between the rib and the bottom skin. It is better to find out before you have applied the glue.
Tip: Check that the board is centered on the rocker table. You can start six small finishing nails around the perimeter of the bottom skin to stop any side-to-side and front-to-back movement. The nails are NOT nailing in to the bottom skin they are butted against the skin. The board is still pretty flexible at this point and you are just preventing it from moving. It is also a good idea to run a pencil line around the perimeter as a safety measure.
The first Outline Strip (shown in pink) is 1/4″ high x 3/8″ wide. The first strip should be at least the length of the board. All wood-to-wood connections in this tutorial are done with Titebond III. (If you have already sealed the bottom skin use thickened epoxy for the first strip.) Follow the outside of the ribs using your outline on you bottom skin as a reference guide only. The outline template shows the widest part of the rail and NOT the starting point for the first Outline Strip. It is easiest to work from the middle to the ends.
Tip: It helps to have a small length of your Foundation Strip butted against the rib to make sure this strip isn’t pushed too far inward. Hold the Foundation Strip and the Outline Strip that you are gluing in one hand and add clamps with the other. The Outline Strip does not butt against the inside of the notch in the ribs. There should be a small space between the Outline Strip and the rib. This space is there in the unlikely event that water every gets in the finished board you can get it back out.
As the curves tighten near the nose stop and add some steam. You can see how the outline marks on the bottom skin are still visible at this point. This is used as a reference so you can quickly check for fair curves and symmetry. Also note the weight on the board that ensures the board is pressed firmly in the rocker table. Leave all the clamps on the board both for weight and to save you bending down.
It only takes a minute or two with the iron and wet rag to bend the strip around the nose and tail. It is best to work with strips that are 1′ longer than the board. This extra 6″ length at each end can be used as a lever to help the strips bend around the tightening curves. If you are too aggressive bending the strips the narrow strips will snap. Breaking a strip is not a huge problem since the glue is still wet. You have 3 basic options: Remove the broken piece and start with a fresh piece. If the break is past the point where you will be adding solid blocking just leave the broken piece as you will be trimming the strips later when you install solid blocking. The last option is to cut a scarf joint and reuse both sides of the break. Try to add one clamp every 4″ as you move along. One hand flexing the strip and the other applying clamps. You usually only have to steam the first 4 or 5 strips as they are flexed in multiple directions near the nose and tail.
The second strip is the Foundation Strip. I use the same 1/4″ x 3/8″ material but the Foundation Strip has a bead routed on one end.
The rest of the strips will have a bead on one end and a cove on the other. The first 5-7 strips have to be put on one-at-a-time as they have a tendency to want to blowout at the slippery glue joint if you apply multiples at this point. Depending on how tightly the Foundation Strip is touching the ribs you may have to trim the inside edge of the cove. Keep a chisel, utility knife and small hand plane on the board so adjustments can be made as you find them. The infield between the ribs makes a great place to store tools so they are always with in reach.
Tip: Invert the strip on the top of the board with a 2″ spring clamp. The clamp holds the strip vertically allowing you to glue to the cove in a quick and clean fashion.
Once you are past the apex of the curve you can start attaching 2 strips at a time. It is best to use 4″ drainage pipe clamps or homemade bead/cove wedge clamps at this point. It is best to apply every 3rd clamp as spring clamp squeezing the strips sideways. The spring clamp helps keeps the strips aligned and adds a bit more clamping pressure.
Tip: You can start using shorter strips once the rails are above the ribs at the nose and tail.
The last 3 strips can all be put on at once. These strips can be much shorter as the board is much thicker in the middle than at the nose and tail.
When can you stop adding strips? There is no magic number of strips required. Each board shape has a different thickness and rail shape. Use a piece of the “outline” material as a “flex guide”. Hold the stick on the centre and see how easily it bends. If your “flex guide” material is a bit thicker than the top skin you will have a good idea how much you can safely flex the top skin. Remember that the grain of the “flex guide” is likely opposite to the grain on the decking when performing this test. The example above illustrates the minimum number you could do with careful clamping of the deck.