Posted by Mike Field on October 17, 2004 at 06:28:09 from 203.166.84.206 user mikefield.
In Reply to: Re: FRAM in the ice.....Winter Holiday posted by Prue Eckett on October 16, 2004 at 22:02:01:
Water contracts as it cools until a little above freezing point (4ºC,) and then it expands with further cooling and contiues to do so after becoming ice.
Although a boat's hull embedded in water that's commencing to freeze can no longer move horizontally -- in other words, the boat is trapped -- it can move vertically.
Some (wooden) hulls are designed to do just that if frozen in -- ie they're designed to pop right up out of the ice a la orange pip, and lie on top of it until it thaws again. Hulls that aren't so designed are either built to withstand the compressive forces to be anticipated from ice formation (like the original Fram,) or they're compressed to destruction by it (like Endurance,) or the problem is obviated altogether for them -- either by their being removed from the water before it freezes (like the Dixon's dinghy on its trestles,) or with arrangements made to keep the water round them continually unfrozen (for example, by local heating or aeration.)
In the absence of other arrangements or eventualities, the houseboat's hull must simply have been sufficiently strong to withstand the compressive loads applied to it (by what was essentially only a relatively shallow layer of ice.)