1917/1920 Converted Navy with Unusual Markings

[Ron Smith]

I believe the translation on the SD mark is correct. However, the X'd out mark could be a Prussian Military unit.

B = "Brigade, Bezirk (District), Br�¼cken (bridging-train), Batterie, Betriebs(operations-Amt)" as per G�¶rtz

3 = #3 of one of the above.

IV = 4th Armeekorps.

4 = Weapon #4

This would better explain the odd position of the 3. The question being, if it is a Navy, why would it have Army markings? None of the markings seem to corrilate with it being a Navy. I would think that both would have to be police units.
Malcom, Are the markings exactly as indicated?
There are'nt any /'s or scriptic letters?
Ron