Conex dumbbell

This basic idea was purposed in the structure designs book, with supplementals added here.

A single-spar column consisting of a modified CONEX shipping container. With the possible addition of a top deck, and/or expanded buoyancy at the bottom of the spar.

Google Sketchup model of a CONEX Sea Spar

   * Safety
         o Probably only safe in fair to moderate weather as corrugated steel is not meant for high pressure.
   * Comfort
         o Cramped living conditions
         o Few amenities
   * Cost - cheep-ish, probably <$25,000
   * Pretty - Ugly.
   * Modular
         o CONEX units are designed to lock together during transit.  Spars made from them should be able to connect with relative ease and security as long as the units do not sport any top decks or other protuberances along the formerly 'top' or 'bottom' sides.  However, units could only take advantage of this design feature to connect in a single line; not to make larger square areas.
         o Units with uniform decks may be connected also, though with somewhat less ease, and more flexible geometry.          
   * Cargo - As each unit is for only one (or a few) individuals the load requirements are much smaller then with larger designs.  By devoting one entire floor to cargo storage, and a second, smaller floor devoted to liquid tank storage, there should be enough room to supply the spar for several months worth of provisions
   * Free Floating - Yes
   * Scalable - CONEX cans are available in several sizes from 20' to 56'.  Multiple units could be welded alongside each other to increase the footprint from 8' x 8.5' with no practical limit except cost on the number of units joined together.
   * Standards
   * Mobile - Yes, although slow b/c large wetted area. May be able to shape spar and/or lower hull as teardrops to reduce drag.
   * Draft - Would be difficult to draft lower then ~25', but could run deeper depending on the spar configuration.