At first I thought that the spelling of Pionier might be incorrect (Poineer) until I saw the other photographs you had posted on another sailing forum.
Looking at the name board picture, I can confirm what has been said on the other forum that the last letter is indeed a 'D' and not a zero and I wondered if the first number was a 'Nine' or a ''Three'. I searched for both. Also, there might have been a further character after the word 'Ding' (Dingi)?
I used a more technical search engine (IXQUICK) than Google and came up with the following which refer to the small Pionier boat as a 'folding' and 'amateur build' type of boat which suggest a kit build boat?
I also thought, had a feeling, that there might be a German or Dutch connection as these boats just might have been built for the German soldiers during World War II of as a company project to get the economy going in the late 1940's?
Try these web links and see if any of these might point you in the right direction. The first link certainly refers to a small kit self-build Pionier canvas and wood.