Flush Mount Through Hulls

Akoni is out of the water for the year and one of the projects I had lined up was to install a new ST-40 system from Raymarine for speed and depth. The old depth unit was barely working, so it's time for a new one. After looking at the bottom of a couple of the other racers in the yard, I decided that flush mounting the transducers and fairing them in would make sense. We had a warm weekend so I decided to get started and drill some holes. The job was easier than I thought, so I got pretty far.

Here is akoni after the haul out:




Here are interior and exterior shots after I removed the old transducer and cleaned out the existing 2" hole. I traced a circle around the new transducer flange so I knew what to remove in the next step:



What I did to recess the transducer was to use a router set at the thickness of the flange to remove the hull material around the hole up to the circle I traced. I also added a second hole for the other transducer:



I mounted the depth transducer ahead of the speed paddlewheel to prevent turbulance from potentially interfering with the depth sounder. I ran out of time and needed to let the 3M 4200 sealant dry before fairing everything over. I do that next week if the weather is good: