In an Extendable Draft Platform including a deck, a plurality of buoyancy
columns installed in column wells in the deck for movement from a raised
position to a submerged position, and a heave plate on the bottom of the
columns, each of the columns has an upper portion and a lower portion. A
helical strake having a radial height H is fixed to the lower portion of
each column. The maximum width of the lower column portion is less than
the maximum width of the upper column portion by at least 2H, so that the
strake can pass through a column well having maximum width that is only
slightly greater than that of the upper column portion. A plurality of
guide rails is fixed to the lower portion of each column, each extending
along the outer periphery of the strake from the upper column portion to
the heave plate.