He joined the navy in 1741 as a very junior cadet, and in 1746 saw service in
Sydermanland which was with the squadron off Algiers. Promoted to junior Lieutenant in 1749, he was granted, in 1750, leave of six months to stay at Bornholm. In September of that year he started as an apprentice at the Construction Commission and embarked two years later together with
Lieutenant F. C. Kaas on a study tour to Britain, France and Holland to learn their methods of shipbuilding. This tour took four years and included England, Brest, Rochefort, Toulon, Italy, Pisa, Venice, Naples, Marseilles and Amsterdam. He returned in November 1756 and was appointed a full member of the Construction Commission. to an Italian design, and the joint design of the frigate
Christianborg. When Kaas was posted to the ship-of-the-line , Krabbe alone supervised the building of this frigate. Late in 1757, using the best of French frigates as his inspiration, Krabbe produced designs for a new frigate which resulted in two new ships being built -
Søe Ridderen (1758) and
Langeland (1758). In September 1758 Krabbe was officially appointed as Fabrikmester, master shipbuilder to the Royal Danish Navy and his first ship-of-the-line was designed. In 1761 he was appointed as an advisor to the committee for the construction of Helsingør harbor. In 1768 he reported on the condition of the harbour at
Christiansø, with recommendations for improvements. In July 1772 he retired as fabrikmester. ==Krabbe's ships==