Sea Mate II
1965–1971 · 10k Rolled Gold Plate / Stainless Steel · Manual Wind
About the Sea Mate II
Running from 1965 through 1971, the Sea Mate II pairs Hamilton's caliber 688 manual wind movement with a round 10K yellow RGP and stainless steel case that measures 9mm thick. The sweep seconds hand gives it a clean, uncluttered read, and the embossed gold numerals and markers at 3, 6, 9, and 12 hold up well against the black or white dial options. The Sea Mate II is the follow-up to the original Sea-Mate, carrying the same water-resistant intent in a slightly refined package.
Dial condition is the first thing to pin down on one of these. The white butler finished dial can develop a warm patina over time that some collectors find appealing and others do not, while the black dial tends to show its age through fading or spotting near the edges. There is also a masonic dial variant that turns up occasionally, which draws a separate collector following entirely. The embossed numerals and markers are worth examining closely for any separation or loss of finish, since that detail is hard to restore convincingly.
From the Catalog
Hamilton offered the Sea Mate II in 1965 with an alternate black dial option alongside the standard white dial, priced at $69.50 on bracelet and $59.95 on strap. By 1966 those prices had shifted slightly, with the bracelet version listed at $59.95 and strap at $49.95, reflecting Hamilton's positioning of the Sea Mate II as a practical, accessible sport watch rather than a dressy piece.
Hamilton Catalog Images
1965
1966
1968
1970
1971
What to Look For
| Dial | Check the embossed gold numerals and markers carefully. Any separation, chips, or finish loss on the raised surfaces is difficult to restore. On white butler finished dials, look for even patina rather than spotting or moisture damage near the edges. Black dials can fade subtly, especially toward the perimeter. |
| Crystal | The crystal on these is prone to scratching over six-plus decades of wear. A heavily scratched crystal clouds the dial and is worth factoring into your offer, though replacement crystals are generally available for round cases of this era. |
| Movement | Oil dries and congeals in movements of this age, and enough friction from hardened lubricants will cause a manual wind to run erratically or stop altogether even if the mainspring feels like it winds fine. Ask when the caliber 688 was last serviced. |
| Case | The 10K yellow RGP layer over stainless steel wears through at high-contact points like the lugs and caseback edges over time. Look at those spots carefully under decent light. Case backs on this model can be tricky to open without the right tools, so evidence of pry marks around the edge is worth noting. |
| Crown | The crown can detach from the stem if it has been pulled too aggressively over the years. Give it a gentle test pull and feel for any looseness or wobble. A crown that feels uncertain is a small fix but worth knowing about before purchase. Also note that despite the original waterproof rating, vintage seals this old should not be trusted around water. |
The Movement
The caliber 688 is a 17-jewel manual wind movement produced by Hamilton during the mid-1960s through early 1970s. It winds from the crown, runs a sweep seconds hand, and is a straightforward, reliable caliber that holds time well when properly serviced. Nothing exotic about its architecture, which is a good thing for long-term serviceability.