Notes for Joaquin

• I would recommend looking at the information below to catch up with the progress so far
• Also the calculation spreadsheet is in
• The main tasks that still need to be done:
  • Design the actual shape of the keel (this needs to meet the volume target in the spreadsheet) - ideal shape uses elliptical cross section at the front and then tapers to a pont at the end apparently
  • Design the mold to cast the bulb (using something like the process in either of these videos https://www.youtube.com/watch?v=reXc0vZ47N4&t=235s, https://www.youtube.com/watch?v=KvxxCl1UJII&t=332s
  • Notes: I think the method in the second video might work best, except using epoxy and lead shot slurry instead of molten lead. I don’t want to have to use a mold and mold release when it is not strictly necessary (also there were air bubbles and stuff)
  • Figure out where the keel needs to be placed front to back (we know roughly how far down and how much weight now. However the wingsail counterbalance has not been added yet so that may change CG
  • Figure out how keel will be mounted to hull (right now I am thinking slap a piece of alumninum extrusion on the bottom using the existing holes and cut a slot in it and drill some holes to attach the steel fin)

Design Requirements

• Limits heeling to 20 degrees with winds at 25km/h
• Waterline should be in a certain spot (needs to be determined)
• Low hydrodynamic drag on fore/aft axis
• High hyrodynamic drag on port/starboard axis
• Hull attachment points are waterproof
• Keel can be detached and reattached to the hull

Constraints

• Uses existing 1/4” threaded rods with existing spacing to attach to hull

Considerations

• Math to figure out how heavy and how far down the keel needs to be
• Lead is ideal material, but molten lead is difficult to work with
• One solution is using small lead scrap (will need to find/buy somewhere) and an epoxy mold - https://www.youtube.com/watch?v=reXc0vZ47N4
• Ideal hydrodynamic shape looks something like a teardrop for the bulb, maybe it is a good idea to put an acrylic plate between the threaded rods to increase drag side-to-side (do we need to worry about an airfoil shape here as well?)
• Need a good order of operations for manufacturing
• Attachment points to hull currently (using 1/4” nuts on either side of the aluminum extrusion substructure) not waterproof (water can leak in where the threaded rod exits the hull, need to figure out how to seal while still allowing keel to be removed. Or maybe we just attach the keel permanently?