Re: [PSUBS-MAILIST] Center of gravity Vs. Center of Bouyancy

["Greg Cotton" <gregc02@attglobal.net>]

The Navy took the problem seriously enough that, except in emergencies, we 
didn't surface or submerge during heavy weather. This resulted in lots of cold 
wet nights on watch off of the Virginia Capes, taking waves over the low 
bridge of our stepped sail. When the weather got heavy enough, we ended up 
standing watch on the periscopes, with the Conning tower upper hatch closed. 
Submerging would have been nice, but since we didn't have the power or air 
to get out from under the storm we rode the whole thing on the suface. Nukes, 
of course, don't have that problem and mostly stay submerged. On the Polaris 
boats we only surfaced and submerged once per 60 day patrol.

Greg
STS3 (SS) N0WEK
www.usstorsk.org



Date sent:      	Sun, 12 Aug 2001 09:58:26 -0700
From:           	Ed Greany <crest25@attglobal.net>
Organization:   	Dopplers by Greany,KB6DOL
To:             	personal_submersibles@psubs.org
Subject:        	Re: [PSUBS-MAILIST] Center of gravity Vs. Center of Bouyancy
Send reply to:  	personal_submersibles@psubs.org

> Hi Doug,
> 
> Honestly, I don't even remember Sub School particulars. I didn't get
> serious until I got OUT of Sub School and on a boat when I really began
> to understand and WANT to understand what boats were all about. Sub
> School to me was just another Boot Camp with it rigidity and rules and
> etc. We also could not take notes and keep them since everything was
> classified. So,
> 
> my experience on the boat was limited to a "boomer". Of course, our
> ballast tanks were 12 in number (3 port fwd, 3 port aft, 3 stbd fwd, 3
> stbd aft) but were not isolated from their port/stbd partners. In other
> words, ballast tank 1A on the stbd side forward had a hole at the top
> and one at the bottom with ballast tank 1B. So you could actually say,
> there were 6 ballast tanks and each was split port and starboard but
> they went all the way around from keel to keel instead of saddle tanks
> which infer only partially around the bull.
> 
> Subbing on a SSBN boat that weighs over 7,000 tons submerged is going to
> be considerably more different than say the Tang with only 2400 tons
> submerged and your premise of a hazard of a broadside wave is pretty
> much not even a consideration. I liken it to a sailboat where a strong
> wind can blow the sail over and actualy capsize the boat. The sail on
> the sub is much smaller in comparison to the hull and weight
> differential is no where near the same proportion.
> 
> Ah, yes, the Trigger trainer. I remember it well. Let's see, "Harder,
> Darter, Trigger 'n Trout; always in and never out!" used to be the
> saying. The actual Trigger was the first boat I took a dive on.
> 
> As for the theory of blowing entirely, that was routine anyway but I
> can't disagree with the physics you present concerning the CG and CB
> cross. I'll leave that up to the engineers. That is beyond the scope of
> my "need to know."  ;) I'm not sure it necessary has to do with ballast
> tank design however. As long as the ballast tank blows inside to the top
> of the tank forcing water out the bottom, I don't think there is any
> problem with a wave. You might incur a roll but not a threatening
> situation unless you are in the surf.
> 
> By the way, out guys raising havoc with the Diving Officer didn't have
> to go thru Control since Control was on the upper deck and we were in
> the Middle Deck so no one was the wiser. Lots different on a boat 425'
> vs 300' long.
> 
> "Straight board; even bubble".
> 
> Ed
> 
> Doug Niessen wrote:
> > 
> > Ed,
> > 
> > If I remember correctly from sub school (1964), doesn't the center of
> > buoyancy move up and down the vertical axis of the boat as the ballast
> > tanks are blown or flooded? Seems that in the Trigger trainer they
> > stressed the point of quickly and completely blowing the ballast tanks
> > during surfacing. There is a point when the center of buoyancy and CG
> > cross during diving and surfacing and at that point a big wave broadside
> > to the sail could capsize the boat.
> > 
> > This may not be a problem for small subs if the ballast tanks don't
> > encompass the hull.
> > 
> > Or..... I may be making all this up and am completely wrong.
> > 
> > We have done the same thing, moving ten or fifteen guys for to aft to
> > play with a fresh diving officer. The giveaway is these guys streaming
> > through control like a line of ants.
> > 
> > Cheers,
> > Doug,   K6STS
> > ex-STS2 (SS)
>