In 1934, under the guidance of Qatsin Hashilton Halpern, Betar established a marine school in Civitavechia, Italy to train young Jews how to man sea-going vessels. Unlike the British and French, the Italian government then allowed foreign students to enter its naval schools. The Betar marine section was an autonomous detachment, with Hebrew as a subsidiary language, self-government in its own barracks, kosher foods, and shabbat services. Instruction was given to about one hundred Jewish cadets by Italian officers, under the supervision of Betar Mifakdim.

The Betar marine section purchased its first ship and named her Sara I. She was a beautiful four-master, originally the yacht of an American Admiral, and the largest sailing vessel in the Mediterranean. The hull was painted blue and white, and the hold rebuilt to accommodate sixty cadets and the crew. She made training cruises lasting from six months to a year, touching in at ports of the Mediterranean, the Atlantic, and the Pacific. During the winter of 1938, which was the stormiest the Mediterranean had seen for over half a century, the Sara I, during a regular training voyage, rode out thirty storms, four hundred squalls, eleven waterspouts, four hurricanes, and two typhoons. The behavior of the cadets during this period when scores of ships went down and hundreds of men drowned was characterized in the marine press as "constituting a chapter in the history of Jewish navigation that future generations will be proud of."

At Riga, Latvia, Betar opened another marine school. In 1936 Betar chartered a sailing vessel, which was renamed Theodore Herzel, for the training of able bodied seamen. The Theodore Herzel made voyages all along the Scandinavian coast. In 1938 two more vessels were added in Civitavechia, the Nekha, and Lea. The cadets from the Betar marine section proved to be valuable assets in another area of Betar activity - Aliyah Bet.