of course they had. Brueckner-Kanis/Dresden was probably the most innovative, but MAN and Blom&Voss were also players in this field. I do not have my source with me at the moment, but will post in a few days.
Data taken from Antony Kay`s "German Jet Engine and Gas Turbine Development 1930-1945", Airlife. All this desighs were intended for E-boats of the S-100 class.
Brueckner-Kanis developed several rotating boiler ( Drehkessel ) designs, one with projected output of 5000 shp ( very advanced, with a steam turbine combined ) and one at an early development stage for 7500 shp. Another marine gas turbine design would sport 10000shp.
Blohm&Voss developed a 7500shp ( Auftrag 353 ) pretended for continous operations MAN designed another 7500shp.
Also the Waffen-SS worked in cooperation with the Kriegsmarine. An SS establishment, the "Kraftfahr Technische Versuchsanstalt der SS", in Austria also carried research on gas turbines applied to boats.
Hellmuth Walter of Walter fame was also responsable for a gas turbine undertaken by the Germaniawerft in Kiel, combining a free-piston compressor.