Posted by Mike Field on September 13, 2004 at 10:08:37 from 203.166.84.240 user mikefield.
In Reply to: Swallow and Dreadnought posted by Dan Lind on September 12, 2004 at 20:14:14:
Good question, Dan.
Here's a guess. Internal ballast (whether as pigs of lead, sand-bags, or window sash-weights) are often carried for trimming purposes -- you can move them round inside the boat as necessary to counteract the effects of different burdens carried, so as to keep her level and easy to sail or row. Admittedly you seldom do it, because it means lifting up the burden-boards to get at them. I carry half-a-dozen small sand-bags up forward of the centreboard case just to keep AL's bow down when I'm single-handing, which is most of the time. But even without the sand-bags, AL's steel c/b would be enough to sink her if she filled.
Now Swallow had no c/b but she did have a deeper-than-usual keel to make up for it, and I suspect that it might have carried some iron -- either as external (fixed) ballast, or else perhaps just as keel protection. Along with a few metal fittings like rudder pintles and gudgeons, mooring eyes, rowlocks, and whatever else, this could well have provided enough negative bouyancy to keep her down once she'd gone under.
On the other hand, Dreadnought, being a punt, was essentially just a shallow, flat, wooden box -- no keel, no ballast, no fittings, nothing to weigh her down. If you were to swamp her she would float full of water with the gunwales just breaking the surface. In this condition she would be visible to an observer, which of course was what Tom didn't want. The mud-weight would make sure that didn't happen.
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Or alternatively of course, Swallow might just have been made to stay down to give us a good read.