Tutorial on Strip Planking - Overview
The following sections describe the various methods and considerations for applying strips of varying widths and thicknesses to the board.
Clearwood kits are available with options that include Paulownia lumber/strips in addition to frames, such as full kits that arrive with all the materials, components and accessories to complete your project.
The advantage of Paulownia is unmatched strength to weight properties, for building the highest performing, hollow wood surfboard and paddleboard kits available.
Material Milling
Clearwood offers milled Paulownia strips for customers that prefer this convenience, just be sure to confirm this request when you place your order.
However, for those that request Paulownia planks and plan to mill strips at home, we recommend that you consider using your table saw - accounting for the kerf of your blade, which may be 1/8" or more - and creating initial rips of multiple widths that will be rotated 90 degrees and cut further into strips.
Strip Thickness
Planks will arrive 95" x 6" x 27mm (L x W x H). The unusual 95" length is due to small parcel shipping restrictions on overdimensional freight. The unusual 27mm thickness, assuming the kerf of your blade is 1/8", allows for (3) strips per rip that are 1/4" thick.
For the standing portion of the board, as measured from the step in the deck to the tail, strip thickness must be 1/4" to adequately support the weight of the paddler. To optimize board weight and material usage, it is suggested that you mill all remaining strips to 3/16" thickness.
Strip Width
Depending upon the section of the board, strip width may vary between 2" and 3/16".
Installing wide strips saves time. Narrow strips are stronger but heavier, due to the additional gluing surface.
For example, if you choose to add pin lines (i.e. redwood, cedar) along the radius between the deck and rail, strip widths that look sharp are typically 1/4" to 3/16". A "false stringer" that runs on centerline from nose to tail on both the top and bottom of the board may be 1/2".
In contrast, it is not uncommon to use 2" wide strips on the standing portion of the board. On the top of the board forward of the step in the deck, strip widths work well in a range of widths: 1 3/4" adjacent to the false stringer, 1 1/2" further outboard. Strips of this size follow the contour of the deck best.
On longer, flat sections of the board such as the bottom, alternating strip widths makes for an arguably more interesting layout: 1" adjacent to false stringer, 2" further out, 1 3/4" closer to the rail. This flexibility is ideal for utilizing the Paulownia stock with minimal scrap.
Below, pictured, are examples of how contrasting redwood is used to create artistic expression on the Ripper kneeboard, Downwinder SUP, and Exploder shortboard.
The rails require narrower strip width. These can be ripped from wider strips. The tightest radius of the rail necessitates a strip 5/8" to 3/4".
Scarf Joints v Butt Joints
Consider the use of scarf joints to glue (2) narrow strips together, end-to-end, using a tapered, sloping angle at a ratio of approximately 7:1 (length to thickness). This ratio is important to achieve a strong bond. We recommend using scarf joints on rail strips.
Butting strip ends together with the joint centered on the frames is adequate and suggested elsewhere on the board.
Deck Layout
Tutorial on Strip Planking - Getting Started
Add your personal touch. The results are extremely satisfying, such as on the below Cascade SUP. Redwood/Paulownia is a standout combination, in our opinion.
Structural "Skin" or "Shell"
Semi-monocoque or torsion box construction methods, such as those used in the aircraft industry, are incredibly strong and light. Strips epoxied together form this structure.
To join strips:
Good clamping pressure is achieved when excess epoxy squeezes out uniformly along the joined edges, with no air gaps or voids at all. This is a messy, awkward step you will repeat many times. The result is a strong board that will last for generations.
It takes experience to figure out the approach that works best for you to apply equal clamping pressure along the length of glued-up strip. Don't rush, stay loose.
Pro Tips
Safety Tip: Absolutely 100% wear a respirator when working with epoxy, and especially when adding filler into your epoxy. We use the 3M 6100 Half Facepiece and 60923 Respirator Cartridge. It is highly encouraged that you use properly fitting nitrile gloves whenever handling epoxy. No board is worth negatively impacting your long-term health and safety.
Tutorial on Adhesives for Strip Planking
Pro Tip: Because of its strength, we highly recommend using epoxy versus other adhesives. If you disagree for whatever reason (i.e. time), we hear you! Go with whatever you prefer. As long as the glue used to join strips (i.e. Gorilla Glue, Titebond III) does not contaminate the fiberglass lamination process, you are likely good to go. Please be aware that not all adhesives are compatible with epoxy.
We believe that if you are going to spend the time crafting a bespoke, heirloom quality board. . . then take the time. In the long run we think an all epoxy board is the way to go, but other methods can be successful too, for sure. Quality versus speed, we choose quality!
Pro Tip: We are a fan of products such as MAS Cell-O-Fill low density, sag resistant, structural filler to thicken epoxy. . . not sawdust. We avoid using sawdust as filler in order to assure the highest quality results. You will get air gaps and voids if you use sawdust, our opinion.
Squared Edge or "Cove and Bead"
That is the question! Both paths are good. Cove and Bead profiles milled into strip edges produce slightly more surface area and are therefore slightly stronger. However, Cove and Bead has the potential to express a slightly greater glue line.
Pictured below are Cove and Bead router bits, needed to create that particular edge profile.
If choosing the squared edge method, which we personally favor, strip edges must be hand beveled to match the adjoining strip profile using a low angle block plane or sharpened chisel of the appropriate width. Because the bevel varies from nose to tail depending on the angle between mating surfaces, a "rolling" bevel technique is used on the rails for example. The bevel angle is determined by the radius bring wrapped.
Flipping the Board
Tutorial on Strip Planking - Flipping the Board
When the top of the board has been fully strip planked, and a few courses of the rail strips are installed, it is time to flip the board.
Using a Japanese pull saw, such as the Razorsaw 7" Dovetail, separate the board from the assembly table by reaching under and cutting at the top of the rocker tabs. Each cut does not need to be perfectly precise, because in the next step after the board has been flipped and is resting deckside down, you will remove any excess rocker tab material flush from the frame using a low angle block plane and sanding block. See above video example.
It is now OK to remove the individual assembly blocks and rocker tab remnants from the assembly table. Clear any hot glue residue with a stiff scraping blade. When the table is scraped clean, we recommend resting the board on (4) 22" minicell foam blocks such as those used to carry kayaks on some roof-rack configurations. This provides a soft but sturdy base for sanding steps later to come.
Fiberglass Reinforcement
On the interior of the board, under the standing portion specifically, we recommend laminating with fiberglass before installing bottom strips.
Note in the picture below only a portion of each quadrant is reinforced with fiberglass, which is OK. But, if you want a more robust board, reinforce the whole area under foot.
Now that the board is flipped, visit the tutorials on internal blocking and interior sealing.
Please reach out with your questions!
