Much depends on the availability of resources; Cocos is a long way from anywhere...
A proper frame for any
boat is by nature an at least semi-custom endeavor.
To build either a jinker or
cradle basically requires the same information; where to place the supports, and how many to use.
If you can get hold of a detailed drawing similar to this, with these projections, the job is easy,
measure where the bulkheads you want to support are, determine where that spot is located on the drawing and place the support at the proper height and distance from centerline (as determined from the drawing) on the ladder frame.
If you can't find drawings (I looked on line for about a half hour to no avail)
you can get pretty close measurements by securing the
boat over a flat part of the bay and taking measurements at the appropriate places. This is of course aided by your location...scuba
gear will speed things, but if you're a good snorkeler, that would
work too.
The
keel can rest on the ground (in the case of a cradle) or a cross beam made into the frame of the jinker (in which case it should be able to support the weight of the boat, in your case about 6 tons).
The supports should be stiffened with appropriately spaced, angled and sized braces in two dimensions, especially with a jinker, as it has to bear the added stresses of movement.
It should be kept in mind that
wood can be used for this purpose as well, or a combination of
wood and metal. Rollers can be used instead of wheels, depending of your traction
power and substrate you may be able to just 'grease the ways' and skid the thing into place...
A good, experienced
builder should be able to be found on the island to assist, he need not be a formal
engineer...but he should have good
references.
And finally, if this is not to be permanent, since the archipelago is only about 10 x 7 miles, might an investment in some extra good ground tackle and keeping an eye on any approaching storms to find the best lie make more sense?
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