Personally, I'll go by what the engineers do. If you only have one set of planes working, they MUST be the stern planes. Period.

A bunch of years ago, while I still owned SubTech, I used to have to constantly prove that a boat with stern planes only would work just fine with an ADC (Automatic Depth Control) and APC (Automatic Pitch Control). This meant that I would run the boat with the ADC controlling the bow planes and the APC controlling the stern planes. I would then pull the boat out of the water, remove the bow planes, and connect the ADC and APC in series controlling just the stern planes. And then proceed to show everybody that there was no difference. NOBODY could ever tell the difference!

Since a boat is controlled from the stern in either left/right or up/down motion, it only stands to reason that the bow planes DON'T have enough control for proper operations. True, you could go really oversize on the bow planes but why bother?

Look at it this way - say you're traveling at 2 feet of depth and you decide you want to come up to 1 foot (periscope depth). With bow planes only, you would have to come up quite a bit more than 1 foot then move the planes to hard dive before leveling off. And, of course, it would take much more time to achieve that depth, unless you go way out of scale as regards size of these control surfaces. With just the stern planes, when the bow has achieved the appropriate depth, you just level it out with the stern planes and bingo, you're there!

As I said, I'll go by what the experts have been doing for over 100 years. I think it's safe to say that they know what they're doing.

Skip Asay