[PSUBS-MAILIST] R300 Dive report - Canyon Lake, Tx

Sun Sep 6 14:51:23 EDT 2015

I agree.

Cliff

On Sun, Sep 6, 2015 at 12:58 PM, hank pronk via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Cliff,
> I think your done herding the cats, I think you have it!  No VBT and powerful
> thrusters.    I think if you want to go away from the VBT, powerful
> thrusters are the answer.   For what it is worth, that is my conclusion
> after 150 plus dives with no VBT.
> Hank
>
>
>
> On Sunday, September 6, 2015 11:28 AM, Cliff Redus via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Hugh, if I lived in New Zealand, I would accept my boat as is and go
> exploring.  With the lake visibility so pour in Texas, it is kind of hard
> to see anything.
>
>  In other words the VBT should be flooded to capacity to achieve neutral
> buoyancy just under the surface and then minimum air can be added at depth
> to compensate for crush/buoyancy-change.
>
> I see the logic in this from an air consumption perspective but this would
> prevent you from going from a pilot and one passenger to pilot only without
> adding fixed ballast.  In this case, lets say that your VBT are at say 90%
> filled with water and boat is neutral and now you surface, blow MBT and 200
> lb passenger exits the boat.  You could not take on enough water in VBT to
> compensate for the lost 200 lbs so you be forced to take on fixed ballast
> even with this big VBT system.  So let say instead you design fixed ballast
> to get you neutral with say 50% water in VBT.  With a big VBT, if  you dive
> the boat, and have to open VBT at depth, you have to add a whole lot of
> fairly high pressure air to use the tank as the low pressure air in the VBT
> would collapse.  One way to address this would be to have the big VBT and
> set the neutral point at say 50% then use a PD pump on the vent leg of the
> VBT to adjust water level.  The key would be to find a PD pump that marine
> grade that does not have a lot of slip.
>
> I think designing a new psub is a lot like herding cats.
>
> Cliff
>
> On Sat, Sep 5, 2015 at 7:44 PM, Hugh Fulton via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Cliff,
> Forever the Engineer.  Why can’t you be satisfied with just accepting it
> the way it is and go and explore!
> Ok, I understand midlife crisis and all the rest. Yes, we are all the
> same.  Pot calling the Kettle black.  Thanks for the update. Some
> interesting points with the VBT.
> First I was horrified that I have fallen into all the same problems.  I
> was quite happy on having large VBT’s and now you have spoiled my day.
> Then I thought the use of the VBT is in question.  ( I know Vance is going
> to pounce on me and correct it all )
> Should the boat not be weighted so the VBT is an extension of the MBT . In
> other words the VBT should be flooded to capacity to achieve neutral
> buoyancy just under the surface and then minimum air can be added at depth
> to compensate for crush/buoyancy-change.  Then at surface that air in the
> VBT can be used to expel the water.   As you have so timely pointed out
> that if there is any air volume in the VBT there is going to be a lot of
> air used just to neutralize the air space at depth.  It is a pain that what
> I had allowed for in VBT capacity was to prevent the pre-dive weigh-in and
> adjustable ballasts.
> The other bone I have to pick with you is that I always read your blogs
> with great interest and then go out and buy bits as close to the same, only
> to find by your latest admission that you are just experimenting. It is
> like trying to herd cats.
> Regards,  Hugh
>
>
> *From:* Personal_Submersibles [mailto:
> personal_submersibles-bounces at psubs.org] *On Behalf Of *Cliff Redus via
> Personal_Submersibles
> *Sent:* Sunday, 6 September 2015 2:26 a.m.
> *To:* Personal Submersibles General Discussion
> *Subject:* Re: [PSUBS-MAILIST] R300 Dive report - Canyon Lake, Tx
>
> *Why did you decide to remove the VBT?  Was it problems with the VBT
> system, need for the space, or...?*
> *To use a VBT or not, that is question.  In my case, I had a hard VBT,
> with a volume of approximately 1.1 cu ft.  Because of the size it could
> only generate about 70 lbs of differential displacement.  As such I still
> had to add and subtract ballast to accommodate a difference in pilot
> weights. I found that that my VBT had a hysteresis while operating and it
> was sluggish in establishing neutral buoyancy.  If I got the boat neutral
> near the surface, then if I used the VBT at depth, there was a sudden
> inrush of water that would have to be blown out to get back to neutral
> buoyancy at depth. Adding air at depth uses a lot air and my air capacity
> is limited.   I used electrically activated ball valves on the vent and
> flood ports of the VBT.  It would take about two seconds for these valves
> to fully open or close.  While the VBT system worked, all of these factors
> caused the VBT to be less responsive than I would have liked.  Last weekend
> was the first time to dive my boat without the VBT and just relying on
> adjusting ballast prior to diving to get neutral and then using the
> vertical thrusters for descending, ascending and depth control.  I found
> with two MK 101s, I had much better depth control and the system was more
> responsive (until the last dive in which they failed).  Two other reasons I
> switched are that I used much less air and it gives much needed storage
> room behind the pilot.  It also simplified diving in that to ascend all I
> do now is flood the MBT, trim the boat longitudinally with a trim system
> that moves a 100 lb weight forward or aft hydraulically and then use the
> vertical thrusters.  To ascend, it is even easier, as now, all I have to do
> is use the vertical thrusters. VBTs need to be located at the CG/CB of the
> boat.  For a small boat like mine, this is an awkward location blocking
> access aft of the VBT.  Yes you can split the VBT in two but this doubles
> the values, tanks and plumbing. *
> *Having said all that, fish have swim bladders so we know nature likes
> the VBT concept.  Maybe I just need a better design for the VBT system.*
> *I have always looked at my boat as a test bed.  I change things all the
> time.  I have never taken the boat out configured the same way.  I will run
> this way for a while and see if I continue to like it as much as I do
> now.   If not, I will try something different.*
> *Long answer to a short question.*
> *Cliff*
>
> On Fri, Sep 4, 2015 at 10:00 PM, via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
> Cliff,
> Why did you decide to remove the VBT?  Was it problems with the VBT
> system, need for the space, or...?
> Thanks,
> Jim
>
> In a message dated 9/2/2015 7:22:37 A.M. Central Daylight Time,
> personal_submersibles at psubs.org writes:
>
> Alec,
> Agreed, I carry a bypass cable to power up my motor in case the controller
> quits.  Bypass switch is a must!
> Hank
>
>
> On Wednesday, September 2, 2015 6:04 AM, Cliff Redus via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Yes, same battery.
>
> On Tuesday, September 1, 2015, Alan James via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> That's real weird Cliff, especially the fact that 2 separate units
> are playing up. The only common denominator is the batteries I suppose.
> Are they both drawing from the same batteries?
> Alan
>
> ------------------------------
> *From:* Cliff Redus via Personal_Submersibles <
> personal_submersibles at psubs.org>
> *To:* Personal Submersibles General Discussion <
> personal_submersibles at psubs.org>
> *Sent:* Wednesday, September 2, 2015 2:21 PM
> *Subject:* Re: [PSUBS-MAILIST] R300 Dive report - Canyon Lake, Tx
>
> They shut down at about 3 PM on Sunday.  I disassembled them today
> expecting them to be filled with water but they were dry.  I reassembled
> today. I charged the batteries up last night so they were full charged this
> morning.   When I powered the thrusters up today, the were at ambient
> temperature and the controllers had been sitting all night so they were
> cool.  The thrusters started up misbehaving like they did when they shut
> down, i.e., would not spin up.  After playing with them for about 10
> minutes they both came back to life a few minutes apart.  They have been
> running fine ever since.
>
> Cliff
>
>
>
> On Tue, Sep 1, 2015 at 9:00 PM, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Cliff, How much time lapsed before they fixed themselves?  maybe they
> needed encouragement to restart because they were just on cusp of being
> cooled enough.
> Hank
>
>
> On Tuesday, September 1, 2015 7:39 PM, Private via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Wonderful detailed report Cliff! My theory is a thermal shutdown of the
> controllers as Hank suggested. Although I have no documentation on their
> speed controllers, the fact it fixed itself suggests that. But then on the
> other hand why did it take all that switching on and off to reset?
>
> This reinforces my intention to put a speed controller override into the
> new boat.
>
> Best,
>
> Alec
>
>
> On Sep 1, 2015, at 5:40 PM, Cliff Redus via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> I took the R300 out this weekend.  This was the first time to have it back
> in water since the 2013 Psub convention in Islamorada.  The objective of
> the dive was to evaluate some fairly significant modifications.
>
> To improve low speed maneuverability and reduce noise, I junked the jet
> pump and ailerons and went to four fixed MK 101 thrusters. I also junked
> the VBT and just add ballast to get neutral. Also I added a Garmin AIRMAR
> DST800 Smart Sensor to measure altitude, speed and water temperature.  It
> worked great.  Installed a new LED 5k light, upgraded to a new HMI, and
> changed the foot and joystick controls.  I also rewired the main battery
> bank for 36VDC rather than 120VDC and installed four MK 101 motor
> controllers.  I modified the aft horizontal MK-101s by adding Kort nozzles
> and used air to pressure compensate.  I used the same pressure reducing
> regulator Hugh Fulton posted about awhile back that he is using on the
> QSub.    The changes decreased the weight of boat by 200 lbs while the
> displacement remained the same.
>
> My son, wife, a diving friend and I took the boat to Canyon Lake in Texas
> this Sunday.  Visibility was less than 5 ft so could not see much.  My main
> interest at this point was just to get into water.  After launching the
> boat, I did some testing to get the base line ballast both mid-ship and in
> the stern correct so that I could get neutral and trim after flooding the
> MBT.  After establishing the fixed ballast, I took the boat out to test how
> the horizontal thrusters work for surface maneuvering.   I was very happy
> with way the horizontal thrusters performed. Surface maneuverability was
> excellent and these motors are supper quite.  I did find that you could
> cavitate the props on the surface if you hit it with too much power. As
> before the changes, when you get up to about 4 knots, the bow wave obscures
> the pilots vision.   Breaking is much improved and it is now possible to
> rotate on the surface or in the water column.
>
> I then took the boat out for the first submerged maneuvering.  The
> vertical thrusters were very effective for depth control, pitch and roll
> control.  I found that it was much easier to get to specific depth and hold
> this depth using the vertical thrusters than the old way I did it with the
> VBT.  They worked great.  While removing the VBT simplified dive
> operations, it did result in loss of freeboard of about 1 inch.  This is a
> downside of removing the VBT as the freeboard was already quite low.  I
> just have to be careful when opening the hatch.  I opened and closed that
> hatch throughout the day and only took splash one time when a boat came by
> I did not see.
>
> The new Garmin AIRMAR DST800 Smart Sensor worked great. With visibility
> less than 5 ft, being able to know the altitude was very helpful on dives.
> As usual, it got darker as you descend but knowing when the bottom was
> coming up was nice.
>
> On the negative side, during the last dive of the day, the vertical
> thrusters failed while my son was on bottom in about 27 ft of water.  He
> had to surface using the MBT. Why these thrusters failed is a mystery.  It
> was at the end of the day and I had pushed the batteries pretty hard all
> day along but we still had plenty of battery voltage.   My sons second
> attempt to surface was to put some air in the forward MBT to lift the nose
> and then use the aft horizontal thrusters to power to the surface.  This
> failed as aft horizontal thrusters were not responsive.  After surfacing
> with the MBT, we discovered that tree limb about 1.5” diameter had lodged
> in the starboard horizontal thruster between the prop and the Kort nozzle.
> This explains why we lost horizontal thrust but not vertical.  After
> getting the boat back on the trailer, I tested the vertical thrusters.
> They would barely turn even when giving them full power.  My first guess
> was that the air pressure compensation system failed and the thrusters were
> full of water.  When I got the boat back to my workshop, I disassembled
> both vertical thrusters and discovered they were dry. After recharging the
> boat, I tried the vertical thrusters again and got the same slow speed
> operation.  After turning them off and on for about five minutes, the
> starboard vertical thruster stared working correctly.  I kept switching the
> port vertical thruster off and on and all of a sudden, it began working
> correctly.  When I had the motors apart, I put a multimeter on the wires
> going to the brushes and found it showing 35VDC.  At this point the control
> signal to these motors was 2.5V so voltage to the motors should have been
> zero.   My guess is that the MK motor controller is acting up.  But it is
> strange that both the vertical controllers would fail.  Also, if it were
> bad motor controllers, then why did they both start working again.  This is
> still a head stumper for me.
>
> Also towards the end of the day, the OTS underwater communication stared
> acting up.  Base and standby diver using an OTS Guardian full face mask
> could hear underwater transmissions from me but I could not receive either
> from the diver or from the base.  The underwater commns had been working
> great for the previous 7 hours.   I was also having trouble about this time
> with the VHF radio that Alec gave me.  Again I could not receive.  When I
> get a chance I am going to see if the connection to the antenna got
> disconnected.
>
> One of the nice new features of the new HMI besides being larger and
> having a higher resolution, was it has built in data logging.  So after the
> dive it was very nice to be able to download into Excel about 50 variables
> logged at a one minute interval. I was able to plot these and get a
> detailed picture of how all the ship systems were working during the day.
>
> If anyone has any thoughts on why the vertical MK 101 thruster motors
> failed, or have had any negative experience with the MK101 motor
> controllers, I would love to hear them.  When they are working, they are
> great.
>
> All in all, I was very happy with the changes but have a few kinks to work
> out before I take her out again.  Now if I could just find some clear water
> to dive in, I would be a happy camper!
>
> Cliff
>
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