In 1977, LEGO released several boat sets as part of the LEGOLAND theme, some of which featured specialized large hull pieces designed to actually float in water. These sets were sold in different markets under various item numbers.
Key 1977 LEGO Boat Sets
Several sets were available in 1977, covering both emergency services and commercial vessels. These sets often used large, pre-molded plastic hulls to ensure they were watertight.
LEGO 709 Police Boat: A smaller police boat set that used a white hull piece and included some basic accessories. Reviews indicate that this model did float.
LEGO 775 Fire Fighter Ship: This was a more detailed fire boat set that also featured a large hull designed to float. It included functionality such as an elevator platform at the back and a water sprayer cannon. In some markets, this set was also known as LEGO 316 Fire Fighting Launch in 1978.
LEGO 371 Seaplane and Boat: This set included both an airplane and a small companion motorboat, providing two types of water-related vehicles in one package.
LEGO 1575 Finnjet Ferry: A significant set from 1977, this was a promotional item for the real-life GTS Finnjet ferry. It was a detailed, brick-built model using standard bricks (no specialized hull pieces) and was designed at a 1:500 scale to represent the fastest conventional ferry at the time.
LEGO 1580 Silja Line Ferry: Another promotional set released the same year, based on the "Bore Star" ferry and using a similar brick-built style to the Finnjet.