Isaac
27
Regarding the erratic/jumpy sweep seconds hand on the Cal. 3300 (ie Sea Hawk II)
A few posts below noted that some Sea Hawks will exhibit a sweep seconds hand that is not totally smooth. Sometimes the hand will tick 8X per second (normal for 28.8K vph) and other times it will tick on 2-3X per second and then suddenly leap forward in a jerky, erratic appearing manner. Overall timekeeping is still fine but the appearance of the hand can be somewhat disconcerting.
I wrote an email to Ed Hahn, a very well respected watchmaker and moderator of a forum elsewhere. He replied with the following informative response:
"... I would conjecture that it is simply a center seconds hand tension spring that is a bit loose.
IIRC, the GP 3000 series is an indirect seconds design - that is, the
wheel that carries the actual second hand is not in the power flow from
the barrel to the escapement. As a result, when the hand is not being
advanced by the wheel train, it sits with little to no tension on it.
To prevent the jerkiness you see, GP fits a light spring that just
touches the seconds wheel.
However, it is very common for designs of this nature to exhibit what
you are seeing, as most watchmakers would prefer to have too little
tension than too much (which would cause the movement to have poor
power reserve.)
Here is an article by RobB that explains the general problem (don't be
put off by the fact that it's looking at an Invicta; this thing occurs
with other makers up to and including Patek Phillipe.)
http://members.iinet.net.au/~fotoplot/invicta/invicta.html
From my own experience with a couple watches like this (Lemania 8815
and a Unitas modified for center seconds), the issue will tend to get
better rather than worse. I wouldn't send it in for servicing..."
Thanks again to Ed Hahn for the knowledgeable response. Hope this is helpful for those that are annoyed by this.
Isaac in Philly.
