In 1936 Polish naval authorities decided to strenghten the fleet with small torpedo/gun fast attack craft termed as chasers (sing.
ścigacz, plur.
ścigacze). They were (reasonably) perceived as very useful vessels in the confines of our-then coastline (which was much shorter than it is now - barely 150km including Hel peninsula), especially Gulf of Gdańsk.
Most interesting (and ahead of it's times) offer was presented by
Towarzystwo Techniczno-Handlowe "Polski Diesel" (
Trade-Technical Company "Polish Diesel") on behalf of
Aktiengesellschaft Gebruder Sachsenberg from Dessau, Germany. It was a design of "of original speed torpedo boat on lift wings" - or in today's words, a small torpedo hydrofoil.
It's planned length was 14,45m (without torpedo launchers), beam 5m, draught during stop 0,8m, displacement 15t, speed of 40 knots (with Mercedes BF2 engine of max. power 800hp). Armament: 2 x 450mm torpedo launchers, 1 machine guns, 2 depth charges. Hull was to be made with significant content of light alloys and with welding as primary means of joining.
Offer was met with significant interest from Polish side, despite full understanding that it would need significant R&D effort, but eventually it didn't led to a contract, although reasons aren't fully known due to incomplete sources. On a note, it should be mentioned that due to average hydrometeorological conditions on Gulf of Gdańsk usefulness of such tiny hydrofoils could be disputable for most of the year, which was probably one of main reasons for dropping of that project.
Eventually Polish Navy opted in 1938 for more conventional design from British shipyard S. White, Cowes. Two ships (with plans for 5 altogether) were ordered. Their standard displacement was to be 39,1t, total length 22,86m, beam 5,08m, speed 42 knots with 3 Isotta-Fraschini ASM183D engines (1150 hp each). Planned armament: 2 x 533mm torpedo tubes (of Polish design), 1 x 40mm Bofors gun, 1 x twin AA machine gun and up to 6 depth charges.
These ships were ultimately built, but outbreak of war in 1939 led to significant design changes.