Accuracy of Portofino Automatic

Does anyone know what average level accuracy one should expect from a Portofino Automatic.

When my Portofino was very new (3 month ago) it ran for the first 3 months about 1.6 seconds fast per day which I thought was extremeny good.

Then (when the weather in London became colder!) it is now losing 1 second per day which is also very good timekeeping but not quite so convenient, as it is of course easier to stop the second hand for a few seconds a week/month than to advance it.

Is it normal to have this type of variation and what accuracy in s/day should one expect?

Any information would be appreciated.

Many thanks

David Heard

Accuracy of Portofino Automatic

I have the same movement (Pilot's XVI) and +1 sec a day is standard. I am no expert but from what i have read here and elsewhere this is considered extremely accurate.

1 second a day is phenomenal timekeeping....

remember this is a mechanical wristwatch, not an electronic digital clock.
1 second a day means it will lose 30 seconds a month.
30 seconds a month means 6 minutes per year.
that's 1 hour in 10 years.
you would lose more than that replacing the battery in any electronic watch!
stephen

Is normal and very good performance

Think that with 9 seconds variation per day means 99,99% acurate performance.

60 seconds * 60 minutes * 24 h = 86400 seconds in a day

9 / 86400 = 0.000104

1-0.000104 = 0.9999

Cheers,
M

Is normal and very good performance

Thanks for your reply and the maths lesson!

I was not seeking to criticise but in fact praise the accuracy. I was rather looking for some technical comment on comparisons and expectations

Thanks anyway

1 second a day is phenomenal timekeeping....

Everyone seems to have misconstrued my question, I agree it is very accurate and I understand the difference betweebn an IWC and an electronic watch, thats why I bought it!

I was rather looking for a technical view if anyone has the expertise, on expectation of timekeepiing for this watch

Accuracy of Portofino Automatic

Thanks

watch timekeeping variations...

Hi walke58r,

All mechanical watches have sensitivity to positions and to temperature, as well as other factors like age (due to minute amounts of debris and the congealing of oils). While positional error can be reduced due to careful adjustment, it can't be eliminated and there would be differences of plus or minus several seconds per day except for the fact that the watch, during wear, is in several positions and the errors more or less average out. Also, there can be "isochronism error" due to the state of unwind and the relative strength of the mainspring.

Temperature is even more difficult to "average out" or mechanically adjust, but modern watches use a hairspring with a metallic composition that essentially is not very sensitive to temperature. But they still have a little sensitivity, and a change of a few seconds a day with a major change in temperature is possible.

So what you have noticed is typical, but not for this watch model. And unfortunately it is not something that can generalized (a temperature drop of X produces a rate change of Y, etc.). It is more difficult given that every owner's actual use is a little unique.

There is more about positional and temperature variances in archived posts, if you do a search, since I've written on this before.

Hopefully this helps,
Michael

watch timekeeping variations...

Thank you very much indeed, this is very hepful