A hand drawn schematic of a blind spot on a (large) motorboat. The schematic was based on an image in the book "Leidraad voor het Stuurbrevet" by Richard Vooren, Paul Van den Keybus
<a href="//commons.wikimedia.org/wiki/User:KVDP" class="mw-redirect" title="User:KVDP">KVDP</a>
<span class="int-own-work" lang="en">Own work</span>