Chris wrote:

I need to drill
into the coaming through heavy glass and tap into a metal backing plate
and the bottom holes clearance is less that 11/2" above the deck.

There are pneumatic angle drills used in the aviation industry that will
work in very tight spots. They take threaded drill bits, so they don't need
a bulky chuck. These drills show up on ebay pretty often. Try searching
ebay for "aviation angle drill", or for manufacturer's names such as Dotco,
UAT or Cleco.


--
--Steve