In the last post on model testing the Almaguin utility runabouts, I left off at the joining of the side panels and the bulkheads. Today, I'll describe the next steps in the construction process: adding the panels that form the double V of the running surface, and fairing the whole thing smooth.
The V panels, having been cut to match the scaled plans, can now be glued to the relatively rigid backbone/bulkhead/side assembly. As the 1/8" fibreboard won't take screws, these panels are first glued to the edges of the transom and the aft two bulkheads, then temporarily taped in place. Once that glue is dry, they can be bent around the forward bulkheads and zip-tied to the stem.
The chines have been filleted with thickened epoxy. In the full-size boat, there are narrow plywood panels at each chine. To verify that they fit and bend correctly, paper templates are made from the scaled plans and are laid in place on the model's chines. Not surprisingly, the edges line up exactly as they should.
At this point, the model starts looking pretty ugly. That's because, with the hull essentially complete, it's time to fair everything to a smooth finish in the proper shape. Epoxy thickened with microballoons is the ideal material for fairing; it's easy to work with, waterproof, sticks to all the materials being used, and sands nicely once cured. But it doesn't do much for appearances, at least until it's sanded and painted.
Fairing compound, or "mud", should be laid on just a hair thicker than is actually necessary. The smooth finish will come from sanding this once it's cured. The inner chines are of particular concern here; when lightly loaded and moving fast, the Almaguin rides on the inner V, while the outer V is clear of the water. That means the water needs to break cleanly away from the inner chine. Fairing these chines correctly is critical to achieving the boat's full performance potential. The sides and transom, of course, are clear of the water when under way- fairing them is purely a matter of appearance (and, in the model's case, waterproofing).
The model, at least for now, lacks the protruding spray rail seen at the outer chine of the full-size Almaguin. This will make no appreciable difference in performance (the rail does provide a small amount of planing lift at low speeds when heavily loaded), but it does mean the model will ship a bit more spray than the full-size boat.
Up next in this series: Sanding and painting the model, then towing it on the lake beside Sunset Chaser for a qualitative assessment of its performance.