On a member's photo a discussion has arisen about LR/IMO numbers for vessels whose existence ended 1963-1998, and therefore had a unique LR number, but with only 6 digits. It is more appropriate to discuss this here where it can attract wider viewing and contributions, so I am moving it from http://www.shipspotting.com/gallery/photo.php?lid=2890363
Bjørn Knudsen on Aug 01, 2018 15:46 added ship info, including "LR/IMO No: 5373335"
Phil English on Aug 01, 2018 15:56
5373335 is not a valid IMO number. It might be a Miramar ID number, or something else. The vessel was scrapped at around the time the 7-digit LR number was introduced, so probably never had an IMO number. I'm sorry, but can we please stop putting IMO numbers in comments unless they are properly checked?
davidships on Aug 01, 2018 19:22
5373335 is a compliant 7-digit LR number (as correctly noted by Miramar). Added
simonwp on Aug 02, 2018 08:46
The IMO# is correct. When the IMO#'s were introduced, vessels already in service adopted their LR# as their IMO#. Which is what happened with this vessel. Maybe it's comments that need to be checked before they are posted!!!!!!!!!!!
Bob Scott on Aug 02, 2018 09:27
This ship of course never had an IMO number but it did carry the six-digit Lloyd's Register number 537333. If it had survived long enough to have a seventh digit added, it would have been a 5. That would have eventually become IMO number 5373335
Phil English on Aug 02, 2018 09:40
I knew I was right, Bob. I don't wish to prevent people being helpful, but ships either have a 7-digit IMO number or they do not. If Shipspotting.com wishes to issue guidance (maybe it has?) on how to treat vessels which never had an IMO number, but had a 6-digit LR number, then I will gladly shut up!
and my conclusion:
Well, let's all draw breath. This one is a little odd.
There is no doubt that the 6-digit unique LR number was 537333.
Also it is apparently also true that the ship does not appear in the 1969-70 LR, because LR knew she had been scrapped (of course there were many ships that no longer existed in 1969 that got 7-digit LR numbers because LR did not know they had gone - but this is not one of those).
Miramar's practice is to adopt 7-digit LR/IMO numbers as their internal ID where they exist, and create their own internal 7-digit numbers where they don't. In practice, for vessels with only unique 6-digit LR numbers (issued 1963-1998) Miramar created their own 7-digit numbers by simply adding "5" at the beginning. These numbers are not consistent with IMO numbers (though approximately one in 10 will produce an apparently correct check digit).
Left to their own devices, Miramar would have given this ship the ID 5537333, but they do think that 5373335 is actually a LR number (and specifically say so on their site). Their source, perhaps indirectly, is likely to be from the preparatory work under way by LR during 1968. So we are in a grey area here.
That's the immediate background to this discussion and now preserved here rather than on one photo contribution (and the "IMO number" left there for the time being).