Ultimately, a yacht designer has to be able to visualize a hull form, produce a 3D surface model or 2D lines plan, and communicate that hull form to a builder in with a table of offsets or full size patterns. Nowadays it is relatively easy for a designer to look at the hull as it is being developed with 3D hull modeling software. However, I believe the best way to visualize the actual hull is with a scale model. A scale model of the hull is a good way of calibrating what the designer imagines the hull form to be with the reality of the actual boat.

I've been using the same method for building basic display models for decades. It was shown to me by Bruce Bingham in 1973. Bruce is an excellent craftsman and his models were perfectly fair and beautifully finished. He also had an aptitude for photography, and he would photograph his hull models in such a way that they looked like a real boat. I don't have Bruce's ability to build and photograph realistic hull models, but I have found his method of model construction to be quite effective for building a hull model in a relatively short period of time.

I built a model of my K-28 design to verify if the sheerline I was thinking of in the design process will be reproduced in the actual boat. The model is of the first iteration of the design, having a rudder attached to the keel to meet the Square Meter Rule requirement and a small cuddy cabin. The design has gone through two more design iterations since the model was built. First, the rudder was moved away from the keel and is now an independent spade rudder. Second, the cabin was removed and the boat now has a flush deck.

Here is the process for building the model:

Step 1. The first thing to do is make paper patterns for the body plan. The patterns can be traced from a lines drawing or plotted from a CAD file. Choose a building baseline above the sheer. All the body plan patterns must have a horizontal edge at the building baseline. Also make patterns for the stem and stern (transom). If the transom is raked and/or curved you will need patterns for the expanded transom and horizontal curve patterns. Make patterns of the hull profile that will fit between the body plan patterns. Assume the body plan station molds are 1/16" thick.

Step 2. Glue the patterns to a piece of illustration board and cut them out with an X-acto knife. The illustration board should be about 1/16" thick. This is the most tedious step of the process and you will go through a lot of X-acto blades.

Step 3. Glue the body plan cutouts (station molds) to a flat piece of hardboard, plywood, or particle board. Glue the stem, stern, and intercostal profile pieces to the station molds. If the model has a curved transom, score the transom piece so it can be bent to the transom curvature over the horizontal curve patterns.

Step 4. Plank the model with 1/16" thick balsa wood strips. A fast drying glue like Ambroid liquid cement works well for this purpose. Glue the strips to the station molds and edge glue them to each other. Alternate the port and starboard sides, starting at the sheer. Use push pins to hold the planking to the station molds while the glue dries. Sand the planking to a fair surface after the hull is completely planked and the glue dries.

Step 5. Sheath the planking with 4 oz/ft^2 fiberglass. I use surfacing resin and apply the sanding coat while the laminate is still tacky. Trim the excess fiberglass after the resin gels. Sand the resin smooth after it cures, then spray on some auto body primer. Final fairing of the hull surface can be done at this stage using a fast-drying hobby filler.

Step 6. Cut the station molds at the deck, cabin, or cockpit line on the pattern. Plank the deck, cabin, and cockpit with 1/16" thick balsa similar to the hull (Step 4).

Step 7. Sheath the deck, cabin, and cockpit with 4 oz/ft^2 similar to the hull (Step 5).