In regards to how to construct a model boat hull the same considerations must be processed as if you were building a full size boat. But the best solutions to how to make it are quite different due to size. This points that must be considered are shape, assembly, and sealing.

The options available for shape include making the hull out of one piece, constructing out of multiple shaped pieces, or construction out of multiple flat pieces. For the size we are working in the ultimately superior method would be to make a single piece that is exactly the size a shape we need. This bypasses the need for assembly and sealing entirely. However we could not use this method because we did not have the proper resources to make a piece to the specifications that we needed, so, since we could abundantly make flat pieces that was the method we were somewhat forced into.

Now the real challenges of boat building: assembly and sealing. Assembly is perhaps the part of construction that has the most options, and those options have many sub-options. Speaking of acrylic alone there is bolting, welding, taping, locking, and gluing. Let’s look at each of these and why I choose to use or not use each.

Bolting: the principle of bolting is to connect two pieces by putting a nail or such through them. This is perhaps the sturdiest option but was ultimately not even under considerations because since the pieces we were connecting were small and at angles with each other this would maximize the stress concentrations and would like likely break the pieces with no time to fabricate new ones. Also who wants to punch holes in the bottom of a boat? Not me.

Welding: plastic welding is a great way to connect pieces of acrylic together. A strip of plastic is placed in the interconnecting crevice and a large amount of heat is applied to melt the strip to the pieces. This forms a strong permanent bond that is smooth and easily seal-able. It is, however, relatively dangerous because of burns. But I am fairly experienced in this so that is not likely to be an issue. We were going to be using this method, but we were not able to procure a heat gun in time for construction so we had to switch.

Taping: the principle of taping is very simple; a thin strip of polymer is applied with an adhesive. This strip is then placed across the crevice attaching the pieces together. This method has numerous shortcomings however. The seal is very hard to make tight and is also prone to deterioration in a matter of days. This is great for temporarily and quickly attaching things but not for the work we are doing.

Locking: locking requires no eternal attachment to construct; the geometry of the bodies is simply designed to interconnect. This method generally makes loose connections that are still quite sturdy. However complicating geometry both makes sealing impossible and fabrication a complex endeavor.

Gluing: an adhesive is applied to the surfaces which will attach them. This method is extremely simple mechanically. There are thousands of glues available that can do anything from drying in seconds to holding literally multiple tons of weight. We chose this method because it caused the least complication with sealing and could create a very strong bond.

Sealing our hull is important because we a holding quite a lot of expensive electronics in it. The simply best way of sealing a crevice is to apply a silicone based gel that expands to fill the crack to form a water proof bond. The glue that we will be using is a marine epoxy rated for underwater use, however we will still be applying silicone because you are better safe than sorry.

package of epoxy

William Cooper