About the speed sensing, having NO experience in this field, I'd stick the pitot out the sub nose for optimum performance, maybe 1/8" out, just enough to get clean waterflow. I put the side pitot anywhere you feel like it along the side, maybe along the bottom to hide it, where the surface is perpendicular to the front tube.

Using a fake torpedo hole would not have clean waterflow, the nose would already have cut a wake and changed water pressure.

To calibrate the whole thing, I'd run the sub submerged at periscope level (so the front tube gets clean pressure) at full speed between 2 buoys at a given distance. Then I'd time how long it takes to cross the 2 buoys and calculate the speed, knots would be best.

It all sounds so easy sitting here in my basement.

Ed, this is your thread; feel free to post videos/pics of your project. I've been dreaming of making a submarine since I got into PICs, with fantasies of an aircraft carrier with working air cannons and aircraft that can be launched. The landing part would be a tad harder, maybe go for a Japanese design so I don't have to worry about that part. LOL

Robert