Incoming Hamilton Model 21 chronometer

The clockmaker told me he noticed that there was zero base tension on the mainspring and that’s quite strange. It means the last service skipped setting the base tension which meant the last hour or so, the movement was wildly inaccurate. This mite of caused it ? It's all fixed that's what it did before the service also old oil made some parts stick so you did not hear the clicks good to have it back all serviced. It runs perfect now the second hand don't go backwards and she don't stop when winding when the movements running since the service. I used John Crabtree in Arizona to service it. The first time I notice the movement would stop and the second hand would go backwards I stopped winding it until I got it service I hope I make better since this time. Mine was second in line when I sent it to him he was working on a model 22 before mine. I got it done fast 2 1/2 weeks.

I wasn’t certain from your post whether that problem had been fixed, or not. Had you continued wind it with the seconds hand backing up, you could have been in a world of hurt! Sounds as though the components in the maintaining power system had seized from congealed crud. I’m glad you have it fixed. Enjoy.

You refer to “base tension”. The maintaining power has nothing to do with the mainspring. When a 21 runs down, completely, the mainspring and the maintaining power spring are both totally run down. The maintaining power spring is armed after you start to wind the chronometer, and when you first release the key. That is the precise moment that the maintaining power spring is “armed”. And it remains armed until the chronometer runs down again. Winding the chronometer keeps the maintaining power spring armed.

Well this chronometer been running none stop since Aug 3 about 20 days strait. I been winding it once a day like the quartermaster would of done aboard ship. It has gained 24.5 + seconds in 20 days so gained 1 to 1.5 seconds per day I guess COSC spec. not bad for a 73 old timepiece that was used as intended and then sat for about 43 years with out a service. She works great since I had it serviced.

Because the marine chronometer runs in a face up position, constantly, one should expect consistency in rate. How they would do when carried as a watch would be carried, is a moot point. No positional error to take into account. I serviced my XXI in 1985,when I first bought it. I fussed with the regulation for the first month or so. I finally got it to where it was 15 seconds fast in 3 1/2 months. That was about 0.15 seconds per day gain. But there’s certainly nothing wrong with the performance of yours. The Navy had a requirement of no more than a 2 second variation in mean daily rate. I am certain Hamilton could have striven for greater accuracy than that. The Navy requirement was for ALL chronometers, not just the Hamilton. Mercer and Nardin chronometers had to meet this standard as well. The Whitney book on the marine chronometer is a wealth of information in this regard. Glad you took pains to have it serviced. Despite the initial expense, it will be cheaper to operate, in the long run.

I bought mine in 1985. 33 years ago. It was expensive then, too. But I have never had any regrets.

When I added my first chronometer a Hamilton model 22 I guess you can call it a chronometer watch due to the movement I was living in a 800 SQ FT condo had it stored in a book case for room so don't let a small space stop you do got a bigger space now. As Canuck said there all ways expensive. All you got to do is wait until a fair price one pops up if you live on the east coast the BIG clock auctions is were you can get a deal some times seen the hammer price when I checked there prices at the end. Could never make it to one due to I lived to far. Only saw a few at a NAWCC mart the seller was all ways firm on his price and it was as bad as Ebay. So I put it off like you dieale2 until I saw one for buy it now 1700.00 it did have problems the seller never said any thing about he said it ran perfect a little white lie but a service fixed all it's problems. Even with a service it was cheaper than what they sell for I was lucky . Just wait until one you feel comfortable with price and do it. I mite be done collecting after this one it's been on my bucket list for over 15-20 years when I got into military watch collecting. Don't let it be a 15-20 year wait for you.

Waiting for that grail piece at a bargain price is almost a sure way you’ll never have one. It’s like the proverbial carrot on a stick. Always just out f reach. I bought mine from an antique dealer in Coupeville, Wash., on Whidbey Island. I saw it on a Sunday, was entranced by it, and decided to stay an extra day, and think about it. I stayed the exta day, and decided not to buy it. On the way to catch the Olympia ferry off the island, my wife blew her stack. She convinced me to buy it. It took me 24 hours ta receive a cashier’s from my bank about 1,000 miles away, but by noon on Tuesday, I owned it! Never a regret.