GL: Mud berth

[David H Sorenson]

Larry wrote:
"Frost heaving is less of a problem above Albany than it would be 
further south in the Hudson Valley. The average midwinter  temperature
stays  below freezing most of the time. Further south, say around 
Poughkeepsie, the  average temperature is about 32 degrees F. This means
that snow and  the first  couple of inches of mud thaw during the day,
then freeze up at  night. Concrete  sidewalks buckle under these
conditions. I'm not sure what it would do to the stability of a mud
berth. But farther north it should be OK."

REPLY:
We live in Duluth, MN, which if you will check a map is farther north
than anywhere in NY state. I will assure you that we have significant
frost heave here. What is critical in frost heaving is the degree of
moisture in the ground. Mud? Well, duh. American Tugs have flat chines
rising out and above the keel and skeg below. I foresee bad things
happening. First, the skeg will become embedded in the mud. There WILL be
frost heave! It probably will rip the skeg loose from the hull for
starters. The prop may be in the mud to a degree also. Who knows what
kind of damage may occurr to the prop itself and shaft when the hull
lifts with frost heave and the prop is frozen in the mud???

Cribbing of timbers below can alleviate this sort of thing, but then we
have the issue of stability of the boat. Unless, it is properly braced,
like it would on the hard, it will tip over on its side -- with the skeg
probably frozen to the timber or mud. But I sure would hate to do that
sort of thing on the fly without some thorough forethought. Furthermore,
the boat will then be laying on its side in mud that will at times be
thawed and other times frozen. There will be frost heave on the side of
the hull, but unevenly as is usually the case. Moreover, building
inspectors up here make a big, big deal about any protrusions on a
foundation wall or drop footing below the frost line (even a little crust
of mortar stuck out of the wall). The frost will catch whatever is
sticking out and can lift the building at the point, causing cracking of
the foundation and structure above. Imagine the frost catching the knob
of a through-hull protruding from the hull, lying on its side unevenly in
the mud. Cracking of the hull there? Bad news!!

Best bet: haul the boat and deal with it on the hard -- wherever. Next
year, maybe make thorough preparations to brace it where it is.

David Sorenson
Duluth, MN
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