The global charity needs to attract new funding for its annual programme, which includes sailing trips for 7,000 young people and the Tall Ships Race, which is held across Europe.
As well as devising a global commercial procurement strategy, Capitalize is charged with advising the sailing firm on its rights packages, for example how often a sponsor's logo is shown and on which occasions.
Previous sponsors include whisky brand Cutty Sark, which was on board for 20 years, while existing funders include the Sultanate of Oman.
The agency counts Puma Ocean Racing, Skandia Team GBR and youth sports and disability charity The Lord’s Taverners among its clients.
Richard Moore, CEO at Capitalize, said: 'Sail Training International is a dynamic charity that creates personal connections and makes a difference to young people’s lives. We believe in its vision to expand.'