Resources Rescue Boat Guidelines RBG - Part 3 - The Digital Tool RBG - Part 3 - The Digital Tool International Guidelines for the Design and Operation of Maritime SRUs less than 24 metres in length. The purpose of this tool is to document and implement an internationally recognised, simple, justifiable and scalable framework for safe and effective maritime SAR operations. Please go to www.imrfrbg.org (new window) to log-in and use the RBG Digital Tool. No log-in details yet? Request access here (new window). How to Use the RBG Digital Tool Watch the IMRF RBG Tutorial below.