"Following Cudell in Germany, Fritz Ziegenspeck manufactured in 1911 a single cylinder, 2-cycle gasoline engine that weighed upwards of 110 pounds and developed about 5 horsepower. ... World War I curtailed work on German outboards."

Webb - Pictorial History of Outboard Motors

After the Great War, Ziegenspeck produced outboards again, but in Germany inflation and competition from the lighter 2 cylinder motor design from the United States was too much. In 1927 he sold out to Andree Hauschild AG in Berlin. 1 That company started a construction-ready flat-twin engine in addition to production.

I believe after the war he pinned his hopes on selling the motors outside of Germany, using name FZ for the entire line of rowboat motors, both the stick motors and vertical drive shaft models.

I am including his catalog for the French market below, even though it is, I presume, the early 20s. Again, Europe was in financial disarray. It was an unfortunate time, especially to be starting a business.

Download the patent...1911.

 

This catalog is from after World War I. CLICK ON IMAGE to see page.

Effzett History
The magazine "Motoryacht" published a modest advertisement for the FZ in May 1913,
first German valveless outboard motor with magneto model for 1914 - in the
performance levels 1.5, 3 and 4 hp, with the type name F Z, for the price of 100
Reichsmark.

Fritz Ziegenspeck advertised it in Kürassierstrasse, Kreuzberg district.
The designer of this small machine had previously, since 1898, was a German
fishing tackle manufacturer, engaged in the manufacture and sale of corresponding articles.

There were inspirations for his engine tests in the form of Cudell's "engine screw" as well as in American products by Evinrude (from 1909) and in Swedish "Archimedes". In 1911, Ziegenspeck tested its single-cylinder prototype on the Rummelsburger See in Berlin.

On the bank, in Stralauer Krachtstrasse, the machine factory of Karl Hauschild (founded in 1905 - supplier of pumps, malting and bottle cleaning equipment) was a company that may have supported Ziegenspeck’s engine construction since 1914, at least as a supplier.
From 1919, Hauschild then took over the complete production of the two FZ rear engine versions (two and four PS) with the reversal by small rotation of the control tiller around its longitudinal axis.

In 1922 Hauschild merged with the Andree tool factory.

Excerpt from article by Von Wolfgang Rudolph View or download.

 
After 1927, Effsett became FZ. This poster, printed in Berlin, was an ad by the Andree Hauschild Werk AG. "With our outboard you create in 5 minutes a fast moving, dependable, unrivaled maneuverable watercraft."

1 - http://www.boote-magazin.de/test_technik/125-jahre-motorboot/a37633.html
Additionally, from PBS: Before World War I Germany was a prosperous country, with a gold-backed currency, expanding industry, and world leadership in optics, chemicals, and machinery. The German Mark, the British shilling, the French franc, and the Italian lira all had about equal value, and all were exchanged four or five to the dollar. That was in 1914. In 1923, at the most fevered moment of the German hyperinflation, the exchange rate between the dollar and the Mark was one trillion Marks to one dollar, and a wheelbarrow full of money would not even buy a newspaper. Most Germans were taken by surprise by the financial tornado.