RE: [PSUBS-MAILIST] Lessons learned?

Hi friends,
Well that was an interesting development about the sub ops in Florida. I had heard about it through the grapevine, and I think it's great it's being discussed. Keeping it quiet struck me as a rather glaring error in judgment. But let's at any rate try to learn from it as we should have from the start. I would like to pose a few draft lessons learned. Please feel free to comment, add, or correct them. Especially Jim as respects to BG design lessons, and Jon as respects to event planning ones.

VESSEL DESIGN
1. Looking at the photos of BG in the projects section, I notice the VBTs appear to be in the aft half of the hull. It would seem to me that any adjustment of VBT would therefore throw the boat off trim. I understand from David's account that there were weights being moved around, but those VBTs look awfully big to compensate for in that way. The weight in these aft VBTs must have been in balance with the three crew members forward. Remove the crew, and the vessel tips down by the stern. Perhaps that's the point of the VBTs being aft, to allow the boat to be trimmed with varying crew weights. Several Paul Morehouse boats come to mind, like Alicia and S101, which have crews forward like BG. In those designs, however, Morehouse used large movable weights to adjust trim, for example putting the entire battery bank on rails. The foolproof method is to have longitudinally centered crew AND VBTs, like a K-250. I would suggest if someone is going to use VBT for adjusting buoyancy, then the tanks should have volumes that balance around the longitudinal center of flotation. And if using VBT for longitudinal trim rather than flotation, it would be better to make it a separate system from the one used for buoyancy adjustment.
2. Whatever the trim method, if your crew is not roughly amidships then crew movement has to be slow and possibly accompanied by trim adjustments.
3. It has been said "don't carry rags". Maybe we should also put strainers on the sea cocks too. I also like the idea of seacock being placed in the top rather than the bottom of the hull (although I'm not sure where BG has them).
4. Forward and aft MBTs allow you to adjust trim on the surface very easily. Saddle tanks do not allow you to do this. In boats where the crew weight is a big static stability factor, such as three people grouped at one end of the boat, fore-and-aft tanks would seem a much preferable approach. I think Eurosub's crew positions are closer to the longitudinal center of flotation. Am I correct, Emile?
5. Saddle tanks should be divided into sections. Visualize a situation with the tanks half blown. If the boat were 1% out of trim the bubble will run up toward one end of the tank, increasing the boat's pitch. In other words, continuous saddle tanks are dynamically unstable. By dividing saddle tanks into independently flooded and vented sections, you both reduce the instability and ad a degree of trim control similar to fore-and-aft tanks.
6. MBT openings (on saddle tanks or otherwise) should be low enough not to vent when the boat is significantly out of trim.

EVENT OPERATIONS
1. All boats must have communications. Sending a diver down to bang on the hull just doesn't cut it.
2. Any member attending an event should be able to black-ball a sub from diving. This is like the famous Toyota practice (at the time revolutionary but now accepted) that any worker can stop the production line when they see something wrong. In the past, we've talked about a committee approving subs to dive. This is hard, because who would want the liability of "approving" a sub? But letting anyone who sees trouble halt operations seems to me common sense and less troublesome. In this instance, I know people at Ft Pearce who saw the problems with the boat while she was still on the dock.
3. Organizers should have lift bags on hand. Dan Lance tells me that since the convention, he's acquired some huge lift bags just for this purpose.
4. Although it was not relevant in this instance, I would also suggest organizers should have on hand tools and an agreed methods for getting into the cabin of attending boats. These tools and methods should be supplied by the owners. In the case of externally operable hatches there's no issue. But with a K-250, for instance, you might need a battery operated drill or saw capable of cutting through the acrylic dome.
5. When an incident or accident does happen despite everyone's best efforts, don't stay quiet about it. It prevents us all from learning, and it puts us all at risk of regulation for not acting maturely.
Finally, please know I am not trying to embarrass anyone with the items above. I have a good idea of the untold hours and funds Jim must have in his boat, and I once co-organized a PSUBS convention where my procedures would not have prevented this incident. I'm curious Jim about BG's current status. Did you reach any additional or different conclusions that have led you to design changes? How did the sub equipment fare after the dunking? Did the batteries survive, for instance?

Thanks,

Alec

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