Emergency ballast systems

kimwhite
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My Ship Yard: HMS Heather (Flower Corvette 1942, under construction), HMS Glamorgan 1981 (under construction)

Emergency ballast systems

Postby kimwhite » 30 Jun 2011 17:30

Hi to the Sub Drivers,
I have just been reading the latest Sub-Driver newsletter and saw an article on emergency blow systems for use below signal depth where the sub has been compressed to the point where it has achieved negative buoyancy and so cannot float to the surface. There seemed to be lots of fiddling around trying to decide if a pump can scavenge enough air from the WTC to blow the tank enough to get some positive buoyancy. I got the impression it was a tricky thing to get working well.

Has anyone ever thought of the old system of using a drop keel or something similar? Seems to me a small weight held in place which could be released by a timer (electric or clockwork) would be less complicated? Set the timer for 1 hour or whatever you decide, if the sub gets lost then just wait for the weight to drop off and the sub should surface.

Another system which was used in the 1/1 scale bathyscaphe TRIESTE which could be adapted to a model submarine would be to have a small cylinder full of steel shot (which a modeler can get by buying the stuff from a gun shop which sells reloading gear) held in place by an electromagnet powered by a small battery. By trial and error you try to arrange it so the battery will hold the shot for an hour or two. When the battery powers down the magnet lets the shot go and the sub surfaces. Has the advantage that the shot will corrode over time without polluting anything, unlike a lead keel.
Just a thought..........
cheers
Kim
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Re: Emergency ballast systems

Postby SlatsSSN » 01 Jul 2011 09:51

kimwhite wrote:Hi to the Sub Drivers,
I have just been reading the latest Sub-Driver newsletter and saw an article on emergency blow systems for use below signal depth where the sub has been compressed to the point where it has achieved negative buoyancy and so cannot float to the surface. There seemed to be lots of fiddling around trying to decide if a pump can scavenge enough air from the WTC to blow the tank enough to get some positive buoyancy. I got the impression it was a tricky thing to get working well.

Has anyone ever thought of the old system of using a drop keel or something similar? Seems to me a small weight held in place which could be released by a timer (electric or clockwork) would be less complicated? Set the timer for 1 hour or whatever you decide, if the sub gets lost then just wait for the weight to drop off and the sub should surface.

Another system which was used in the 1/1 scale bathyscaphe TRIESTE which could be adapted to a model submarine would be to have a small cylinder full of steel shot (which a modeler can get by buying the stuff from a gun shop which sells reloading gear) held in place by an electromagnet powered by a small battery. By trial and error you try to arrange it so the battery will hold the shot for an hour or two. When the battery powers down the magnet lets the shot go and the sub surfaces. Has the advantage that the shot will corrode over time without polluting anything, unlike a lead keel.
Just a thought..........
cheers
Kim



Hi Kim,
yes the Subdrivers Gazette is an excellent on-line publication. Unlike the Subcommittee Report its free and chock full of relevance too.

That article in particular shows a new evolution in emergency blows - or if you like surfacing beyond snorkel reach depth. From what I understand its slated to go into smallish sized water tight cylinder units (1.5" diameter jobs) where gas (airbrush propellant) back ups become problematic. This is not to say therefore there is anything wrong with those gas backup systems. I use them and they are very very efficient with only around 30mls of airbrush propellant consumed over the course of 2 days sailing.

The system your describing dropping weights has been tried and tested, but its really a different kind of "Emergency" surfacing device to the "Emergency blow" that most people associate with a Missing pulse (a loss of radio signal),

In a lot of cases a sub experiencing a Missing Pulse (a loss of radio signal), is not in significant harms way. In fact most places I sail have signal drop outs that activate the Missing Pulse Detector, and if this is a prolonged state for more than 4 seconds, my fail safe commands an Emergency blow. In some cases this can be a nuisance as its just a patch of water the boat is sailing through causing the problem rather than dire flooding etc. That said in other cases it can save your boat.

The problem with dropping weights is that in the case of a signal drop out that is purely a temporary reception drop out you have then dropped (usually lead), into a waterway that may not be recoverable. - This is in its basic form is littering as weights are often difficult to find in a lake. It also means that you now need to re ballast the boat - replacing what you dropped to use the sub again. - Not practical nor good for the environment.

With my boats should I experience the Missing pulse detector commanding a blow for a temporary reception drop out, I typically have regained signal before the boat surfaces (like in a second or so), and I keep note of the incident as the gas backup is good for at least 8 of these events, and keep sailing. If I'd dropped weights for this the boat would have to come out of the water to get re-ballasted, and for the sake of the environment I'd be benching the boat whilst I retrieved the weights.

Dropping weights I have seen employed as a critical backup. That is it is not linked to a Missing Pulse / radio drop out, but its triggered during a far dire situation such as flooding of the dry spaces of the sub. Water sensors have been used to actively drop ballast in these situations. The problem being is that if the sensors fail your stuffed. A better critical boat saving device in a catastrophic situation is a marker float that releases after a prolonged period of time. Jim Russell used an ingenious release mechanism involving a tictac, where the tictac fully saturated after dire flooding dissolved and this dissolved tictac then mechanically allowed a float to rocket to the surface.

So dropping weights Kim aren't really a practical tool for a missing pulse / loss of signal.

I also have to say Kim, that the modern WTCs we now use, particularly the Merriman brand of Subdriver are quite advanced at keeping all leaks out that catastrophic failures and flooding are far far less of an issue.

Best

John
He who dies with the most toys, just dies...you can't take it with you.

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