Wayne.B wrote:
On 16 May 2006 10:27:26 -0700, "
wrote:

OK, I'll bite. If my the "bridge clearance" (height) of my vessel is 30
feet and the vertical clearance of a fixed span bridge is 42 feet,
there is only one possible answer- the draft of the vessel. If it
exceeds 10 feet, it's not going to make it. :-)

The other missing dimension is horizontal clearance, not usually an
issue for recreational boats, but definitely a consideration for tug
and barge combinations.

Ah yes, right you are.

I can't think of many regional examples where a vessel that could make
the vertical clearance of a fixed span would have any difficulty with
the horizontal clearance, but now that you mention it I can think of a
handful and in certain parts of the country (with a lot more river
navigation) it is undoubtedly a much larger issue. As you say though,
not usually a problem for vessels with a beams typically less than
20-feet.