Training and Certification
Seaman's Discharge Book for US Citizens?
As Anon posted the US version is now called a Merchant Mariner Credential. They no longer have pages for recording sea time.
Therefore, if that is what you require, after you get one
Each time you are discharged from your current yacht you will need to submit one of these to the NMC to record your time with the USCG
Alternatively you can apply for a flag specific discharge book such as this one for Bermuda
or this one for the Cayman Islands
"They no longer have pages for recording sea time."
They never did. Sea time on small vessels is normally documented with a "sea service letter." A sample letter is available through the USCG website. The discharge form lnked does not contain the information needed for the USCG to evaluate sea time. If you have one from service on a containership or tanker the CG will accept it since they know the ship and its type of service. Using one for a small boat or yacht is a waste of everyone's time.
"Therefore, if that is what you require, after you get one ..."
No one is getting an MMC without applying for a TWIC first. You cannot hold an MMC without a TWIC. A TWIC is not a seaman's discharge book and is not a seaman's document of any kind any more than a physical exam or a drug test result. If the OP holds a 100 ton USCG license without TWIC then the license has been invalid for several years.
"This is the US-equivalent of a Seaman's Discharge Book."
A USCG merchant mariner's document (MMD Z_card) never was the equivalent of a discharge book. It was an indentification card that listed unlicensed ratings on the back. An MMC is not a discharge book, it is a credential that identifies the mariner and lists the certifications and level of training (if any) held.
"If your highest US license and/or certification is a Master of not more than 100 GT, then you do not yet qualify for the MMC."
Anyone can apply for a Merchant Mariner's Credential. It is not a license and sea time or training is not a "qualification" required to apply for one.
Popeye, please spend some time reading the USCG and NMC website. It is your responsibility to know how to track your sea time and know how the system works. Be very very wary of the answers you get on bulletin boards. Call MPT or any other maritime school if you can't understand what the USCG or NMC has published. It is your career and your loss if you take bad advice.
Here is an older Dockwalk discussion on the subject: