I picture it this way:

Say your boat's turtling, right at that moment, whatever forces are acting to turtle it are able to overcome the bouyancy of the top third of your mast, driving it into the drink. The deeper your mast goes, the more bouyancy is being overcome.



So the top third has a certain definite volume; and displaces that much seawater upwards. It's got weight too, but as we add flotation, that flotation is near enough to weightless so that we can consider the weight of the entire mast, with and without flotation, to be (darn near) constant. So you add some flotation, ie, volume. How much volume, compared to the volume of the top third of a mast, can you realistically add?



I can't imagine doubleing or anywhere's near doubling the volume. I guess, right at the beginning of a turtle event, when only the top foot is under the briny, you could double the volume *of that top foot* but, if this is a real turtle coming on, the forces at play must be sufficient to submerge the entire mast, and so, a mere doubling of the relatively small volume of the top foot won't trouble that kind of turtling force.



Maybe some of the milder turtling events can be resisted, right at the outset, due to the leverage of having some extra flotation out there, but a real gust blowind down on the tramp... Jake make's sense to me when he says, "I don't think that there is much that will prevent every turtle."