Motor Door
The NIS26 has a motor in a well. This is a great improvement over the motor-on-transom-bracket arrangement of our previous boat. Perhaps the biggest benefit is that the propeller never comes out of the water when motoring in a chop. We have a Honda 8hp short-shaft in the well. The motor is on a lifting mechanism so it can be raised out of the water when sailing.
It is not strictly necessary to fit a door in the bottom but I don't like the drag and noise that an open hole creates. I went to some effort to figure out a robust door in the bottom that opens and closes reliably. There are several ways to do this. The motor door I came up with works well enough. The main design problem was to move the door from the closed position in the bottom of the boat to the open position up and aft inside the well. As an engineering problem, the door has 6 degrees of freedom (3 translations and 3 rotations). All 6 degrees of freedom have to be controlled as the door opens and closes. If the door were simply hinged, 5 degrees of freedom (3 translations and 2 rotations) would be fixed by the hinges. Unfortunately, there is not space in the well for a simply hinged door.
To open the door, you lift the motor a little to take the weight off the door. Then pull a line that moves the door back and up. The back end is attached to a lightweight plywood frame that keeps the door straight and square while pivoting back. The front end of the door has a plastic pin on each side that slides along the bottom edge of a plastic plate installed the side of the motor well. The motor door is made up out of the piece cutout of the bottom with a slightly larger plywood plate glued to the top. The door is held up out of the opening by bungee loops on all four corners. To close the door, release the line so the door slides back over the opening. Then let the motor down onto the door to push it down into the opening and hold it shut.
Looking at the two pictures, the red bungee loops
hold the front end of the door up against the plastic plates on the
sides of the motor well. The white bungee loops hold the pivot
pins in the back end of the door up in slots in the pivot frame.
The blue bungee cord attached to the PVC pipe on the pivot frame
pulls the door shut and the white line in the top of the picture
pulls the door open. The white line leads to a cam-cleat in the
cockpit and that's how it is held open when using the motor (the
outboard runs on a track and is raised and lowered using a small
winch. On the highway, we tow with the motor down).
The whole thing works amazingly well. I have not had to do any maintenance or repairs on it in 5 years.