A Convention is an international agreement, typically developed and adopted at an International Conference organized by the IMO, where member states discuss and agree on regulations. The final agreement is recorded in a "Final Act of Conference."

A Protocol is used to introduce significant changes or new regulations to an existing convention. It's essentially a supplementary agreement that modifies the original text without requiring a completely new convention. A classic example is MARPOL 73/78, where the 1973 part was the initial convention and the 1978 part was the protocol that significantly amended it.

Amendment:

The regulations enforced by conventions require frequent amendments to keep pace with rapidly evolving technology in the shipping industry. Amendments to a convention can be made in either of the following ways:

• After consideration within IMO:
• Amendments proposed by a contracting government are circulated at least six months prior to consideration by the relevant IMO committee. These amendments are adopted by a two-thirds majority of the contracting governments present and voting.
• Amendment by a conference:
• A conference of contracting governments is convened when a contracting government requests it and at least one-third of the contracting governments agree. Amendments at such a conference are adopted by a two-thirds majority of the contracting governments present and voting.

Order of adoption by IMO:

Convention → Protocol → Amendment

Earlier procedures for implementing amendments under IMO conventions were very slow, often resulting in adopted amendments never coming into force.

To overcome this, the "Tacit Acceptance" procedure has now been incorporated into most of IMO’s technical conventions. This approach facilitates quicker and simpler modification of conventions, helping them keep up with rapid technological changes in the shipping industry.

As per Article III of SOLAS 1974, an amendment is generally deemed accepted two years after it has been communicated to the contracting governments—unless within this period:

• Not more than one-third of the contracting governments, or
• Contracting governments whose combined merchant fleets constitute not less than 50% of the gross tonnage of the world’s merchant fleet

object to the amendment.

If such objections are received, the amendment is deemed not accepted. However, if sufficient objections are not raised within the stipulated time, the amendment is automatically deemed accepted, even without formal acceptance by contracting governments.

This process is known as "Tacit Acceptance."