The ferries have a maximum speed of and a cruising speed of .
The LST carried of diesel fuel for a range of at the cruising speed of .
The wings are swept at 31.5 degrees and optimized for a cruising speed of Mach 0.8 ().
The increase in normal displacement to over 1,000 tons was due to the desire to combine a heavy armament with a substantial cruising range.
"Polar Star" was an all-metal Northrop Gamma, which had a low-wing, reducing the effects of winds and wide skis that could be swapped with wheels or pontoons and a cruising range of .
"Adventure" was built to replace the converted First World War veteran "Princess Margaret", and her design was dictated by a requirement for a large mine capacity and a good cruising range.