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RE: [PSUBS-MAILIST] How to trim and ballast bigger boats.
I am not familiar with the sub in Grand Canaria, but it looks like it is one
of the hulls built by Submarines Oy, which is a later version of the LG-50
(Looking Glass Submarine).
I am not sure if I am understanding your comment, but I get that they are
ballasting heavy and going to the bottom? If this is the case is just the
way they have decided to operate it. If the bottom is a sandy bottom it
should not be a problem as it is not damaging a thing. The problem comes
when they hit coral reef.
To avoid hitting the bottom, the sub must always be ballasted so that the
sub is approximately 50 to 100 lbs lighter than the net buoyant force
exerted in it by the sea water (many of us refer to this as being 50 to a
100 lbs buoyant). This will cause the sub to tend to rise very slowly, adn
therefore all the pilot has to do is to keep pushing the sub with the
vertical thrusters as the dive goes on. Since the thrusters are always
pushing the sub downwards, the trhust is going upwards. This keeps the pilot
from stirring up silt and causing a cloud which is not desirable while
taking passengers. It also pretects the reef from damage caused by the
vortex of the thrusters.
I hope this helps.
Hugo
-----Original Message-----
From: MerlinSub@t-online.de [mailto:MerlinSub@t-online.de]
Sent: Wednesday, May 12, 2004 3:13 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] How to trim and ballast bigger boats.
Hugo Marrero schrieb:
>
> Carsten,
>
> The ballast system in these subs is more complex than the scope of this
site
> is, but I'll try to give you a quick explanation.
>
> There are 8 separate tanks ( In reality each is a single tank divided by a
> wall and with independent valves) located on the sides of the sub. Each
tank
> has it's own valve. Each valve actuates 4 tanks in port /stbd pairs.
These
> use a combination of air pressure (calle a pre-charge pressure) and a
rotary
> vane pump. There are two pumps connected to 5 HP Brushless DC motors that
> can run the pumps in either direction to fill / drain the tanks.
Ballasting
> between dives is done while passengers are being transferred between the
> boat and the sub. There is a table that you must use to determine the
> average amount of water needed for the number of passengers and crew on
> board. This gets you within 200 to 300 lbs of your goal. Once you start
your
> dive you have to immediately determine if your ballasting condition and
> adjust it accordingly.
>
> This system is quite complex as there are pumps, 4" Stailess tubing,
Valves,
> pneumatic controls, electronics and instrumentation.
>
> But that's it in a nutshell, hope this helps...
>
> Hugo
Why the Gran Canarian pilots use the bottom - if the boat is such
perfect fit with tanks and pumps ?
Carsten
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