The Special Boat Service is the maritime special forces unit of the United Kingdom Special Forces and is described as the sister unit of the British Army 22 Special Air Service Regiment (22 SAS) with both under the operational control of the Director Special Forces. In October 2001, full command of the SBS was transferred from the Royal Marines to the Royal Navy whilst retaining the Green beret. On 18 November 2003, the SBS was given their own cap badge with the motto "By Strength and Guile". This follows opening recruitment from only the Royal Marines to all three services of the British Armed Forces. The SBS has traditionally been manned mostly by Royal Marines Commandos.
As always, the artworks feturing the insignia are available via my “Military Insignia” galleries from FineArt America and RedBubble. You can just follow the links in the article to get to the corresponding galleries.
To active duty or reserve military personnel, veterans and their family members: I grant an explicit permission to download the above images to be used for non-profit/non-commercial and charitable causes, benefiting troops and their families, as well as for non-commercial internal duty-specific purposes, such as unit website design, training materials and presentations. Please, contact for any other intended use.
The above information provided in part by Wikipedia, The Institute of Heraldry, Global Security, and the official websites of the corresponding units and formations.