[PSUBS-MAILIST] (no subject)

Thu Aug 27 19:15:52 EDT 2015

Just two cents on this. I've actually changed my MO over time. Initially I
liked diving heavy. It was an effortless way to descend, and I would get
neutral with the VBT once at depth. If slightly heavy then you can use the
thrusters to hover, but they will be pointing down and that ruins the
visibility. I used to surface on air.

These days, I just weigh myself and passenger and I have a little table on
my clipboard telling me how many buoys to load. Once you've figured the
payload of the sub once, the method nails the buoyancy every time, and I
mean to within 5 lbs or so. I both dive and surface on thrusters, although
it is true I have to blow a little bubble in the MBTs on deep dives due to
hull compression. I find thruster dives make for better control and use way
less air. Thruster movement has less "momentum" than buoyancy driven
motion, meaning that you can shut off the propulsive power instantly
whereas, if your propulsion is coming from a tankload of air, it takes
longer to vent or flood the tanks. Its also handy that the sub just hovers
if you stop paying attention for any reason.

Best,

Alec

On Thu, Aug 27, 2015 at 4:13 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Alan,
> I agree, I need to dive slower, I have a video from yesterday with a very
> nice touch down.  As a rule I have been going down fast and using the
> vertical thrusters as breaks.  When I dive fast, there is  a bit to much
> momentum built up, thats all.  The video I posted shows what not to do :-)
> I did not put the brakes on.
> I will get my lead weight situation sorted out.
> Hank
>
>
>
> On Thursday, August 27, 2015 1:14 PM, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Hank,
> you said you know the bottom is soft & sink fast.
> I am a bit concerned as I have read of subs getting temporarily  stuck in
> the mud
> on the bottom. Haven't heard of any getting permanently stuck but there is
> always
> a first time. Have also heard of them picking up a lot of weight in the
> form of mud.
>    Would be good if there was a quick easy lead transference system.
> Maybe Alec's buoy system is the simplest & easiest to use!
> Just clip on a number of buoys that account for the weight of the
> passenger.
> With lead it has to be placed low, so when doing dive ops it would need to
> go
> in through the hatch to the hull bottom.
> Alec's system has the buoys in a tube, but I am thinking that they could
> all have
> short cords on them, with clips to attach to various points on the top of
> the sub.
> Alan
>
> Sent from my iPad
>
> On 28/08/2015, at 2:27 am, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Sean,
> This is the big debate, VBT or no VBT.  I used to like the idea of no VBT
> and that is the way the Nekton subs operate, just not sure eanymore.  I
> have to admit, my regulator idea is riddled with potential problems.  I am
> just being lazy, if I keep the sub with in 15 lbs (as per the operating
> manual)  or less of buoyant with tanks flooded, and I pay attention, it is
> easy to operate.   I can sink as slow as I want and hover at any depth if I
> take my time.   I need to correct a bad habit  that I have.  I know the
> bottom is soft, so I sink fast.  I need to practice what I preach and
> always sink as if there is a hard hazard below.
> Hank
>
>
>
> On Thursday, August 27, 2015 7:26 AM, Sean T. Stevenson via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hank, your best bet is to arrange your MBTs such thatrou they flood
> completely every time with no residual bubble(s), at which point you should
> have very slight positive buoyancy when correctly ballasted. Add a small
> VBT, either internally or externally in a hard tank (you could blow this
> with HP air instead of pumping, but would need to valve it to isolate it
> from ambient pressure changes), to compensate for minor crew weight
> differences, and compensate for the major ones by adding or removing lead.
> You want to avoid a situation where a depth change creates a buoyancy
> change, except in the sole case where you have blown your tanks to ascend.
> Sean
>
>
> On August 27, 2015 7:13:27 AM MDT, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Alan,
> It won't work unless there is a check valve between the second stage
> regulator and the ballast tank. Okay to complicated, bad idea.
> Hank
>
>
>
>
> ------------------------------
>
>
>
> * From: *
> hank pronk via Personal_Submersibles ;
>
>
>
> * To: *
> Personal Submersibles General Discussion ;
>
>
>
> * Subject: *
> Re: [PSUBS-MAILIST] new video
>
>
>
> * Sent: *
> Thu, Aug 27, 2015 11:36:09 AM
>
>
>
>
> Alan,
> I am not sure if my idea will work .  When I sink Gamma, there is an air
> bubble remaining in the ballast tank, the size  is determined by the weight
> of the sub.  If I have a first and second stage regulator feeding air to
> the ballast tank, the regulator will feed air into the ballast tank as I
> sink keeping the bubble the same size while I sink.  Right now it is
> completely manual and takes practise but it works.  I can use both systems
> ( manual or regulated) by simply turning the air supply on or off to the
> external regulators.   With the regula! tor system, I would not have to
> worry about keeping the sub at an ideal weight.
> Hank
>
>
>
> On Thursday, August 27, 2015 12:03 AM, Alan via Personal_Submersibles
> wrote:
>
>
> Thanks Hank,
> must be this one, the umbrella dive.
> https://m.youtube.com/watch?v=sflIEnkTth4
> Sent a reply to your post about using a second stage attached to your
> ballast tank, but it didn't come back to me.
> not sure how it would work!
> Alan
>
> Sent from my iPad
>
> On 27/08/2015, at 1:30 pm, hank pronk via Personal_Submersibles
> personal_submersibles at psubs.org> wrote:
>
> made some dive
> video's today, posted one on youtube under Hank Pronk
>
> _______________________________________________
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>
>
>
>
>
>
> ------------------------------
> * From: * hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org>;
> * To: * Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>;
> * Subject: * Re: [PSUBS-MAILIST] new video
> * Sent: * Thu, Aug 27, 2015 11:36:09 AM
>
> Alan,
> I am not sure if my idea will work .  When I sink Gamma, there is an air
> bubble remaining in the ballast tank, the size  is determined by the weight
> of the sub.  If I have a first and second stage regulator feeding air to
> the ballast tank, the regulator will feed air into the ballast tank as I
> sink keeping the bubble the same size while I sink.  Right now it is
> completely manual and takes practise but it works.  I can use both systems
> ( manual or regulated) by simply turning the air supply on or off to the
> external regulators.   With the regulator system, I would not have to worry
> about keeping the sub at an ideal weight.
> Hank
>
>
>
> On Thursday, August 27, 2015 12:03 AM, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Thanks Hank,
> must be this one, the umbrella dive.
> https://m.youtube.com/watch?v=sflIEnkTth4
> Sent a reply to your post about using a second stage attached to your
> ballast tank, but it didn't come back to me.
> not sure how it would work!
> Alan
>
> Sent from my iPad
>
> On 27/08/2015, at 1:30 pm, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> made some dive video's today, posted one on youtube under Hank Pronk
>
> _______________________________________________
> Personal_Submersibles mailing list
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>
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>
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