How accurate are Rolex chronometer movements at end of power reserve?

[Stratton]

Assuming a movement has say a 50 hour power reserve, how accurate should it be at 40 hours and then 50 hours of power depletion? Is it normal that they get less accurate at the end of the power reserve? The reason I ask is that a friend has a new Omega Seamaster Planet Ocean 45.5mm with in house Omega 8500 movement which has a 60 hour power reserve. Whilst it is accurate to within chronometer standards when he wears it regularly, if he has cause not to wear it for 48 hours it has gained around 6 seconds and by 60 hours it has gained around 8 seconds. Is that normal for a mechanical chronometer, including those made by Rolex, to become less accurate towards the end of the power reserve? Thanks in advance for any replies?

[iAmVice]

Here are the results from some tests (new models)

all avg.

Sub:
fully-wound: +3 sec
after 24h: -0.3 sec

SD 4000:
fully-wound: +3.3 sec
after 24h: +2,5 sec

Deepsea:
fully-wound: +1.8 sec
after 24h: +0.9 sec

Hope that helps.

[Stratton]

Originally Posted by iAmVice

Here are the results from some tests (new models)

all avg.

Sub:
fully-wound: +3 sec
after 24h: -0.3 sec

SD 4000:
fully-wound: +3.3 sec
after 24h: +2,5 sec

Deepsea:
fully-wound: +1.8 sec
after 24h: +0.9 sec

Hope that helps.

Thank you for your reply which is useful. I was looking for the accuracy at about 40 and 48 hours.