Thursday, June 12, 2008

Screws

A friend and sailor described a boat as an old cottage with
construction issues surrounded by water. Issues have kept Speakeasy
from sailing for 2 weeks. The current issue is the mismatched screws
holding the mainsail slider plate. This plate keeps the sail from
leaving the slot that holds the luff to the mainmast. The plate is
design to slide in one direction to allow the sail hanks to come off and in
the other direction to prevent them from coming off. Tension screws keep
the plate in one orientation or the other.

The issue is that the original screws are missing and the replacements
do not fit the threads tapped into the mast. I read a document on the
Catalina 320 site that put the screws at 4 mm. Threads on a screw
measured in millimeters are not the same as threads on an English screw
even if their diameters were the same, which they are not. Not only
are the screws incorrect they are incorrect in different ways. One is
too wide and one too thin. One is a straight slot head and the other a
Philips head.

The original screws had knurled thumb heads so that a sailor might
tighten or loosen the plate without tools. The current situation took
two screwdrivers. In fact one was so tight that pliers were necessary
to remove it--three tools.

This is Chicago not Dresden so the local hardware store does not have
stainless steel screws in 4mm size. This takes a trip to the boat
store. Even the boat store can't supply original screws. I opted for
4mm hexhead screws and hoped the threads in the mast haven't been
harmed so badly these screws won't hold.

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