[PSUBS-MAILIST] R300 Dive report - Canyon Lake, Tx
via Personal_Submersibles
personal_submersibles at psubs.org
Sat Sep 5 13:21:54 EDT 2015
Thanks, Cliff,
I like long answers to short questions... give me more than I bargained
for. We've all learned a lot from the R-300 test bed. I had originally
planned to have VBTs fore and aft, but decided to only provide for future
installation if I later feel it would be worth it.
Jim
In a message dated 9/5/2015 9:26:29 A.M. Central Daylight Time,
personal_submersibles at psubs.org writes:
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_ (mailto: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_ (mailto: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_
(mailto:personal_submersibles at psubs.org) > wrote:
Yes, same battery.
On Tuesday, September 1, 2015, Alan James via Personal_Submersibles
<_personal_submersibles at psubs.org_ (mailto: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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