Let's say you have a boat with thru hull exhaust (thru prop disconnected), and a Alpha or Bravo drive. Has anyone tested their top speed with the disconnected thru prop exhaust inlets capped, and then tested again upcapped to the atmosphere (not connected to the exhaust).

My instinct says it should run slightly faster with the inlets open to atmosphere, because the vacuum behind the prop would be reduced by the incoming air. However, I am not sure this is enough to be measureable.

Michael

Just remove the exhaust bellows in the gimble. It is much easier, usually just one hoseclamp and the rubber hose comes out. And yes it may help speed a little filling this void behind the hub.