Sea-Gull ST3600

Description

One of the most famous modern Lepine pocket watch movements is the Unitas 6497, later taken over and rebranded by ETA as ETA 6497.

Meanwhile, it is also copied in China by Sea-Gull and as is, as caliber Sea-Gull ST3600, the base caliber of a whole caliber family with (mostly aesthetical) different versions.

Since several years, this 16 1/2 ligne movement with a diameter of 36.7mm is no longer used for pocket watches, but for “mature” wrist watches, which should often remind of military ancestors.

Execution-wise, there’s nothing wrong with the Sea-Gull ST3600. We have ruby-bearings everywhere (except for the mainspring barrel, of course), all parts fit perfectly, only the decoration is limited to the visible parts only.

Aesthetically, the gear train is no highlight, but it is strictly functional constructed:
Mainspring barrel - center minute wheel - third wheel - decentral seconds wheel opposite the crown and escape wheel.

Of course, a swiss pallet lever escapement is used.

The three-leg Glucydur balance is beared in two Incabloc shock protections. Whether the balance wheel is really made of Glucydur and the two shock protections are real Incablocs, or if they are only good copies, cannot be said with certainty.

The hairspring is attached and regulated Etachron-like, but the swan neck regulation is a funny one, because at least on the specimen shown here, it is just a dummy and not effective at all, since the regulating screw is way too short.

On the dial side, there’s the yoke winding system and a full concentric perleage decoration. This looks much nicer, than the, often disparagingly referred to as “Shanghai welts”, crude stripes decoration on the gear train plate.

On the standard version, the dial side lacks decoration.

The performance on the timegrapher is pretty impressive. Although minute wheel and changer wheel have an unusual amount of play, the timegrapher shows perfect results in some positions:

For a watchmaker, this is a very easy to handle movement. Apart from the larger mainspring barrel screw, you need only one single (1.6mm) screwdriver, and everything is made to fit perfectly.

In the lab

Timegrapher result

This movement shows in both versions out of the box a very good performance on the timegrapher, even within the chronometer specs. The first numbers are from the standard version, the second one from the version with swan neck regulator.

Technical data