The invoice from the rebuilder I might believe. Reset hour meters without the rebuild invoice I would NOT accept.
This.
It is my opinion the proper way to document these items is through actual documentation in a log book. Leave the hour meters in place. There is more to a drive system than the engines. In other words...you get the boat new and complete. Hours begin to climb. Say you get to 2000 hours and the port transmission takes a dump and you have it rebuilt. You then get all invoices and document that the port transmission was replaced at 2000 hrs Hobbs time.
Then at 5000 hours the starboard engine requires overhaul. Gather invoices and documentation for ALL items overhauled and make a log entry for each major component. For instance if the injector pump was done at this time...note it. If the complete long block was done and cylinder head overhauled as well, note it.
The maintenance should be tracked in a logbook with detailed entries and reference the Hobbs time.
If a stuffing box is rebuilt..log it with Hobbs time.
If a cutlass bearing is swapped out...log it with Hobbs time.
If injector #3 and #6 is changed...log it with Hobbs time.
If an alternator is changed...log it with Hobbs time.
If just a cylinder head is redone...log it with Hobbs time.
Just be sure to save invoices. A good invoice is the verifiable proof of the log entry.
Keep those Hobbs meters rolling.
Even for complete engine overhaul...keep the Hobbs meters rolling.
Doing it this way you will be able to track time on all major and even some minor drive line components.
IMO the only time you change a Hobbs meter is when they break...and they do break. In that instance you put a new 0 time Hobbs meter in and then you placard the new meter " Add 5045.6 hours" note the Hobbs meter change in the log book and then continue tracking.
There are a whole host of reasons to do it this way.
So as Rgano stated...the documentation is MUCH better proof than someone swapping in a new Hobbs.