Wow! I take a couple of days away from the board and miss out on my whole Hydrodynamics course. I'll flunk the final for sure!
Pat, I've carefully designed the interior to allow as much trapped air out as fast as possible. The skiff is actually a solid piece, with the hard angle of the deck aft of the skiff slot filled in. All of the deck grating is practical, composed of 1/16" stainless steel mesh. The only place that air seems to get trapped slightly is in the wheelhouse, and even then it's only because my vents there are only (2) 1/16" diameter holes disguised just above the 'alligator eyes' and below their shrouds and they vent a little slower than everything else. On a side note, it makes for a really cool double stream of bubbles for a few seconds when she gets just under the surface. I don't think that trapped air is my problem.
And I use the term problem loosely here. I want to clarify that I find my model infinitely easy to drive, very responsive, and almost self-navigating. The only reason for this, however, is the addition of my third set of planes aft of my propeller.
Before this modification, I could still experience the pleasure of diving my model, but only at lower speeds. I didn't use the dive planes at all in those early days. A little forward throttle, and she'd slowly drift under the surface in a beautifully controlled dive. Kicking the rudder in helped pull the aft end down to keep her upward oriented if I needed to.
Now that I've finished the mod, I can use full throttle and the APC will keep her dead-level, with only a minute porpoising effect that occurs at full speed only.
My intent in posting this effect in this string was simply to let other Goff Nautilus builders know what I've experienced. Apparently this is a common problem, as at least three other people have experienced the same phenomenon with their models. Coincidence? I think not.
I'd consider closing in my ballast grates, except that I like having eight monstrous vents to let my trapped water out of my hull when I pull her from the water. You can imagine that a (nearly) six foot long model with two inches of free space around the entire length of the WTC will hold a lot of water. She weighs a ton when she's first pulled out!
I guess my motto is "if it ain't broke, don't fix it!" I can't imagine how my model could work better (other than a bit more speed... you can never really have enough, right?), so I'm very happy leaving it as it is.
She's currently drydocked while I do some tweaking to my WTC mounts, my battery holder, and I install a new high-output LED lighting system. After I get her underway again, I'll taker her out to Langford Lake and shoot some more video so everyone can see what I'm talking about.
This has been a great thread, (most of the technical jargon partially over my head, but educational nonetheless).