Most licensing organizations (MCA, RYA, Cayman, Marshall Isl.) and
professional/union organizations have either gone to or have used logbooks
for a number of years. The Master takes the book and enters time and other
pertinent data to the log of the mariner. The mariner then uses this
official document to provide proof of sea time for advancement. For those of
us with multiple licenses where the reference license is issued by the USCG
this is a real problem.

As for logging time in hours, I think that's because of the nature of
aviation vs marine. Air travel is measured in hours where marine travel is
typically in days. The USCG, in its infinite wisdom as decreed that the time
shall be referenced as an 8-hour day at sea counts as one day (4-hours is a
half-day, and 12-hours a day-and-a-half). Unless you are on a tanker of
tug-tow or some special consideration you will unlikely get anything over
the 1-day/8-hours rate. The USCG does mandate that sea time must be over a
designated period of time (something I don't think is an FAA regulation) to
show that the mariner is reasonably current with techniques.

In my case, as Master, I use a template recomended by the USCG to log days
at sea, hours, postions held, and other information. The document is signed
by myself as Master or the owner (as I am the Master) and a copy of the
Document of Registration sent is attached before sending it to the USCG for
inclusion in my personal folder. As others may indicate, USCG (and most
other organizations) require days at sea over a specified period of time to
show that you have the basic proficiency to warrant consideration for
licensing or upgrading. When renewal time comes, I reference the USCG
license but send certified copies of my logbook (if possible, otherwise I
have to send the actual logbook) to the other licensing organizations. Then
I wait for the players to agree that I do have the requirements for
renewal/upgrade.

The current solution as I see it (and this is subject to change at the whim
of the various organizations) is to do things depending on the mariners
nationality and desires. By that I mean I fill out the mariners logbook for
those organizations that want the data in their approved format in their
designated logblooks, provide a sea-time document and copy of vessel
registration for those with multiple licenses or those whose licenses are
based on the USCG, or do a combination of both.

This applys to mariners, licensed or not. I have gotten requests from former
crew requesting specific documentation for their purposes. So, I have to
keep detailed records of everyone that has ever passed over the gangplank to
my vessel.

In your case, I would contact every person you've sailed with and obtain a
sea-service certification and copy of the vessels documentation. I would
also ask for (and usually receive) the same information when terminating any
time at sea. You should be aware that the USCG has significantly increased
its checking of sea-time documentation and the days of receiving 100% your
own sea-time are becoming more difficult. The more sea time you can provide
from other licensed Masters/owners the better the chances of your total
sea-time being accepted. This is a direct result of the USCG and IMO trying
to counter critcism from other maritime organizations that believe the USCG
is far too lax in granting licensing approval. The main complaints (as I've
heard) are that sea-time often fails to substantiate the mariners documented
experience or license class, there is no practical test for USCG licensing
(and this is becoming a requirement as you read this, so I'd suggest you
apply and get grandfathered in), and that the guessing process for questions
doesn't test the candidates knowledge well enough.

In the near future you will have to show verifyable sea time, complete
testing that will include essays as well as multiple-guess, and pass an
on-the-water practical test in order to get licensed. You now have to decide
how much you want the license and then apply immediately. It's only going to
get harder to get licensed.

I hope that helps clarify your question.
--
If it doesn't make the boat go, it's a no.