[PSUBS-MAILIST] Dive report - Pickles Reef

Sun Oct 6 17:05:23 EDT 2013

Alec,

Your experience renders what I had in mind for the K-350 untenable. That post was very helpful as I am quite familiar with the conditions.

On the first problem, I'm inclined now to widen the hull and dispense with the conning tower completely in favor of a low profile hatch. This would be surrounded by a free flooding FRP tower ala Alvin. The question now is what diameter to accommodate two with comfortably and practically with all of the electronic goodies I have in mind.

On environmental, this is a conundrum caused by a subtropical environment and lack of appropriate surface support. There's no getting around the fact that if you don't own an RV Atlantis with a dedicated sub hangar and A-Frame, then a radical but practical home grown solution must be found if you want to dive in Florida.

One could conceivably plumb the exhaust water circulation of a 3500 BTU marine air unit to an external heat exchanger and scavenge the condensation to an internal water tank trim system. This unit could be powered by a removable portable Honda gas generator riding aft of the tower while on the surface. The idea is to scavenge all of that water and cool the interior prior to diving. The unit could be shut down or run off batteries after removal of the portable gen set depending on conditions. 

I don't like an internal diesel for such a small enclosed space, what to do with the generated heat is a vicious cycle, and a separate machinery hull is asking for trouble ala Pisces III. In any case some measure of surface support for battery charging and HP exchanges is a must.

Joe

________________________________
From: "Smyth, Alec" <Alec.Smyth at covisint.com>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Sunday, October 6, 2013 3:34 PM
Subject: Re: [PSUBS-MAILIST] Dive report - Pickles Reef

We'll I'm not back yet, but I'm ensconced in the Auto-train, so nothing to do now for the next 17 hours.

I'm concentrating on the next sub, but if I wanted to make further changes to Snoopy, my next thing would be to replace the dome hatch with a cylindrical tube of acrylic about a foot tall, that would sit on the existing hatch land. I would replace the dome hatch with a standard steel hatch. The K250 conning tower is low because it is designed to be looked OVER, whereas a K350 tower has viewports so you look through it. With an extra foot of freeboard, waves would pose a considerably reduced threat.

Having said that, I have no idea what the optical qualities of a cylinder might be. 

Unfortunately I don't think a K-250 sized boat has either the space for A/C equipment nor the batteries to run it. But if it had more freeboard, you might need to close the hatch less and that alone would go a long way toward improving things.

Cheers,

Alec

On Oct 6, 2013, at 9:48 AM, "Joe Perkel" <josephperkel at yahoo.com> wrote:

Alec,
> 
>I second Hugh's remarks, well written!
> 
>These are my conditions, that I will need to contend with,  in reading this I come to two absolute conclusions with regard to redesign.
> 
>1) Mitigating the swamp risk.
> 
>2) Aggressive enviromental control, (This means AC and condensation control, which means in turn an upward design spiral)
> 
>When you get back, a wish list would be most helpful
> 
> 
>Joe
>
>
>
>________________________________
>From: Alec Smyth <alecsmyth at gmail.com>
>To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
>Sent: Sunday, October 6, 2013 1:17 AM
>Subject: [PSUBS-MAILIST] Dive report - Pickles Reef
>
>
>
>In Islamorada for the 2013 PSUBS convention, we tried a few days ago to dive the reefs off the Atlantic side of the island. After towing Snoopy out to the dive site, I had to call off the dive because a three foot chop made it unsafe to board. I made it aboard myself, but water was splashing over the hatch land, and with the weight of a second person it would have been touch and go. When their hatches are open, these little boats are like holes in the water just waiting to be filled up by the next wave. Three foot waves are not large, and they are entirely normal a few miles from shore, but they are just beyond practical conditions for Snoopy.
>For our second attempt on the reefs we changed tactics, deciding to board at the boat ramp and make the tow under a closed hatch. This would guarantee a dive regardless of wave conditions, but also introduce a new challenge. With a temperature of 89 degrees above the surface and 86 degrees below it, the problem was now how to avoid getting cooked during the tow. There was hardly a cloud in the sky, and Snoopy’s big acrylic dome hatch transforms her cabin into a greenhouse. The pilot, with his head in the middle of the dome, feels that he is under a giant magnifying glass. Hot air rises.
>Steve McQueen and I boarded at Harry Harris state park at 12:30, after having spent the morning at the local school giving four hundred local children a tour of the sub. Snoopy’s payload can be maximized by adding buoyancy spheres. We installed every available one, and used their buoyancy to load twenty pounds of ice inside the cabin. Our support diver, Scott Waters, attached a white hotel towel over the dome with bungee cord, and then tied off the tow line. We set out, towed by Doug Suhr in his whaler, an ideal surface support vessel. He had fashioned a custom wooden frame that allowed towing from a point just aft of midships. That is where tugs and trawlers attach their tow lines, and it allowed the whaler to retain good control, whereas in the past I had found Snoopy often turned around the towboat when towed from the transom.
>The tow was unexpectedly interesting, because of the bottom rushing by and constantly changing scenery. Most of the time it would be sand and sea grass, but there were always changes and it would at times become more rocky, or turn to pure sand, and drop away or rise up to just a couple of feet from us. We rushed past or right through clouds of jellies. As Steve put it, it felt like an arcade game.
>I have no idea how hot it was inside the sub, but it was surely an outrageous number. Prior to departure we had applied detergent to the viewports to prevent them from fogging. That succeeded on the forward viewport, but with that single exception every other surface in the boat streamed water profusely. Every ten minutes or so I would pick up a rapidly dwindling bag of ice and give it a hug, rest it on the back of my neck, or wear it as a hat. I went through five bottles of drinking water.
>Between the rolling of the boat, and the heat and humidity, I found myself getting a bit woozy. It was not sea sickness so much as a feeling of light-headedness, so we tried increasing the oxygen concentration in the cabin to counteract it. Between us we had been consuming ¾ liters of oxygen per minute, with the analyzer readings hovering around 19 percent and a fraction. We bumped up the flow to 4 liters per minute until the oxygen concentration reached 23 percent, a limit above which the cabin atmosphere would have become a fire hazard. That is only two percent above normal, but it made us both feel perceptibly better.
>We arrived at the dive site two hours after closing the hatch, and rather incredibly only four minutes after our target time of low tide. The twenty pounds of ice had all melted. Our normal tow speed is three knots, and the distance was only four miles, but some “hatch closed” time was spent getting underway, some was spent on a stop to re-position the towel when it was displaced by waves washing over the dome, and some was spent on the final locating of the site. 
>Doug anchored the whaler and Scott swam over to remove our towel sunshade, and to attach a video camera to the sub. In the previous few days the heat and humidity had already led to the failure of a depth sounder and a compass, so I had decided not to risk the good camera inside the sub. In tropical climates at least, the cabin is a very dangerous place for electronics.
>We initiated our dive and tested communications as soon as the transducer went under water. The gear worked, yet the communications were very faint. Snoopy’s transducers are mounted above the hull and immediately behind the conning tower. Being just beneath the surface and pointed in the direction of the whaler, the transducer’s line of sight to the boat was blocked by the conning tower. Once at depth the communications were loud and clear.
>The reef was unfortunately not healthy, as all reefs in this part of the world, yet it was absolutely fantastic compared to the lakes Snoopy normally dives in. There were large sponges, fish, and interesting terrain. In particular, we found “streets” of sand running between raised mounds of coral on either side, reminiscent of scenes in the movie 20,000 Leagues Under the Sea. Visibility was about fifty feet.
>In Snoopy, almost all the viewing underwater is done through the bow viewport. Through the dome it is very hard to see the bottom unless diving alongside a wall or quite high terrain, and even in that scenario optical distortion causes features to appear very small and far off. Nonetheless, while I could hardly see the bottom through the dome, I did see a column of bubbles rising in the distance and steered Snoopy in their direction. It was Scott, who had found a lost anchor. He tied it to Snoopy’s pickup arm, and we blew some air into the ballast tanks and delivered it to the boat.
>We continued wandering the bottom, sometimes letting the current waft us along sideways and other times using the stern thruster to follow the “sand roads”. These gradually led into deeper water, and we followed them hoping for the continental shelf drop-off that is only a short distance from Pickles reef. We started at thirty feet, and followed these paths down to a little over fifty feet, but unfortunately did not make it as far as the drop-off.
>Snoopy was ballasted ever so slightly buoyant, perhaps just a pound or two. One side thruster was locked in a straight down position, the other slightly inclined to counter the rotation induced by the props. Indeed the props only needed to turn very slowly to maintain depth, as if turned by hand instead of by a motor. To slowly rise I would shut them off, or I would speed them up to descend. The side thruster throttle acted as a “depth knob”, allowing depth to be controlled with an accuracy of a couple of inches.
>Laying prone and looking out of the forward viewport, Steve had a good view of upcoming terrain. He acted as observer, calling out details about what lay ahead and asking for port or starboard headings and altitude adjustments. One tries to stay close to the bottom in order to see it better, but not touch anything in order to avoid damaging the reef. He took a turn at the controls as well, which in Snoopy does not mean that we changed places, but rather that we passed the remote controller between us. 
>At one point we lost communications with the surface. We were to learn later that the whaler had re-positioned to follow us, and in doing so ran over its transducer cable, severing it and losing the transducer. The whaler could have tracked us by our acoustic pinger, but instead simply followed the bubbles of our support divers, who were following us by sight in the clear water.
>After an hour and a half of contented wandering, we suddenly sensed that the stern thruster had lost power. A moment later we both noticed a smell of burning. I turned off power to the stern thruster speed control, looked up to ensure we were not under the whaler, and immediately initiated a ballast blow, which gives a much faster rate of ascent than the thrusters. We could have continued maneuvering on side thrusters only, but it seemed prudent to call the dive. Afterwards I would discover that a little piece of fan coral had been sucked in by the stern thruster, and wedged between the propeller and its shroud. It was very tough material, and it locked up the thruster causing its speed controller to burn out. Although the speed controllers are supposed to have over-current protection, I will be adding breakers in the near future.
>One more surprise awaited us during the tow back to shore. After about an hour of towing, we had reached a spot at which the waves were lower, and we were on the radio to the whaler planning to pause the tow and transfer to her. But just then there was suddenly a very loud pop in the cabin, and my immediate thought was of a ruptured high pressure line. It was followed a second later by another equally loud pop. I was puzzled by the fact my ears were not registering any increase in cabin pressure, when I saw Steve’s life preserver inflating. These life preservers are of the type that resembles suspenders, inflated by a CO2 cartridge which Steve’s movement had accidentally triggered. For a moment it looked like his PFD might strangle him in the tight space, but he managed to wriggle out of it. I’ll be looking at some way to secure the rip cord on these PFDs, to make accidental deployment a little less likely. There is precious little space in Snoopy
 under normal conditions, but with an inflated PFD the lack of space becomes almost comical.
>Finally we came aboard the whaler. Being in the tower, I stowed my seat, climbed out, and closed the hatch quickly behind me. This allowed Steve to reposition himself into the tower without fear of being swamped while doing so. The hatch opened again, Steve jumped out, and we were both on deck. It had been five hours since we closed the hatch.
>It was only once back on the whaler I saw Steve was quite hungry. It was six in the evening, and he had avoided eating anything all day, anticipating that it would be a long dive and knowing that Snoopy has no head. Now that is dedication!
>
>
>
>
>Cheers,
>
>Alec
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