Building and Sailing Thlaloca Dos

Building

Before the start of any building process many preliminaries have to be considered with great thought. In this regard it is past experience which helps immeasurably to arrive at some conclusion faster than anyone with none. This, of course, is fundamental to anyone faced with any task. In our case there were several basic requirements, not necessary in the order presented:

Large enough vessel to live aboard comfortably for long period of time
Proven design for seaworthiness and being sea kindly
Ample Engine Power
Large engine room to access vital components without acrobatics
Perhaps because we are romantics, the vessel had to be aesthetically pleasing–and not only to our eyes !

Now to the nitty-gritty's:

As a builder in love with wood, creating our future craft in wood was the only material I felt comfortable with. In considering the type of planking, I concluded that cold-molded assured us being the lightest but strongest hull sheeting, outside of metal. In this type of construction, the scantlings are bend over a "network" of longitudinal stringers spaced appropriately. Now, these individual stringers are potential water traps and cause rot. A much better solution is strip-planking the first layer. The advantage is a smooth inner hull, and a good foundation to fasten the diagonals--the second layer. As a bonding agent between layers we used epoxy glue and monel ring-nails as fasteners throughout. The third layer is carvel, why? Because no matter how careful the outer layer is finished, the normal contraction and expansion of wood will show under certain light condition even through two layers of Vectra cloth, we put as final layers for additional strength, and guarding against water absorption and worms. Meaning to say that carvel appearance is more the natural print and less obtrusive. Also, having strip planking as the inner layer, the outer layer of carvel makes matching seems less likely. To make absolutely certain there will not be any moisture penetration, we bonded the last layer with polysulphide to one foot above the waterline. The thickness of the individual layers are: Strip planking 1-1/8", diagonals 1/4", carvel 3/8" There are 10 full or partial bulkheads. One thing about Vectra cloth it is very strong, and compared to fiberglass superior in strength and abrasion resistance. It is perfectly alright to use polyester resin for bonding, but the real advantage of Vectra is gained by using epoxy resin. Because polyester brittles with time whereas epoxy retains elasticity. We don't have a single failure after 26 years. But nothing is perfect. Vectra is a "bitch" to finish; and can only be accomplished by way of careful sanding. Because, once a mechanical sander hits the cloth it sort of melts and fusses and the only way to repair it is by applying more epoxy filler. In short, from the outset, the hull should be pasted with a thick layer of fairing compound, epoxy in our case, in order to have enough "meat" to prevent cut-ins. The hull was built upside down, therefore provided the huge advantage not having to "pump iron" (sanding overhead). This type of hull construction is labor intensive, and building up-side-down is the only way to significantly lighten the load. Nice would be a roller contraption used primarily in steel construction, that would immensely facilitate building and handling of the hull. But, like everything else in life, there are trade-offs; and in boat building particularly so.

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