All might have heard of different Conventions and Standards etc. stipulating different rules of how a ship has to be built and managed.
The top of the pyramid is actually United Nations (UN), and in there is an Organization called International Maritime Organization (IMO) and from there most of the regulations are churned out for our safety etc.
The 1st regulatory item came out shortly after the Titanic disaster and it was called Safety of Life at Sea (SOLAS), this book has now been edited numerous times and is a big tome today. In this book you'll find standards set for hull, machinery, electric installations, safety equipment, safety of navigation & other misc items. This is the corner stone when you start to build or alter a vessel.
After SOLAS it was followed by the launch of Maritime Pollution prevention convention (MARPOL) due to all oil pollution in the world and if I remember correctly after the foundering of Amoco Cadiz in France. Today it is an equally impressive book as SOLAS and it covers all aspects of pollution including exhaust emissions. This resulted for the 1st manual to be placed onboard, namely the Shipboard oil pollution prevention plan (SOPEP).
Then when the disasters came one after the other the eyes turned into the education of seamen onboard and the Standards of Training, Certification and Watchkeeping (STCW) was launched in 1978 and in 1995 was revided extensively. This book as it says covers what your training should be if you want to study for a STCW standard certificate.
After these books it was quiet for awhile but when the Herald of Free Enterprise capsized outside Zeebrugge and the Scandinavian Star burned down on the North Sea then in 1990's the International Safety Management (ISM) was brought forward. A seemingly draconian system to find the weak link in accidents which increased paperwork onboard ships dramatically. It is now mandatory for all ships over 300GT to have this Code implemented and when used right it becomes an effective tool for the Ships Officers.
Eventually Osama bin Laden shocked the world with his twin tower bombing and it resulted that the International Ship and Port facility Security Code (ISPS) was launched onto us. This code is similar as the ISM code but relates to the security aspect of the boat. As an interesting tidbit for everybody to know is that this Code is divided into two parts and those boats who pays visits to US ports have to implement both parts. Additionally there is no size restriction for ships entering US, all must have a Ship Security Plan onboard.
In addition to these publications there are instances like the Chamber of Shipping and MCA publishing manuals and books that refers and translates these regulations, also IMO publish numerous smaller rags that relates to Load lines, Code of safe working practices etc.
Anyways, the publications mentioned above are mandatory for SOLAS ships, i.e. >300GT and carries more than 12 passengers so you may wonder what is in this for yachts?
Well, if they are not SOLAS yachts then there not so much that applies but if you are a Commercial yacht you need to comply wiith the MCA Large Yacht code (LY2), now launched as a M-notice by MCA and can be downloaded for free on the net. As a Large Yacht you need to have most of these pulications onbaord as well as the ISM implemented etc.
Some useful links:
MCA MAIB reports