USS Parche

[GabesDad]

The Submarine Reserve Buoyancy Problem

A bothersome factor when addressing the underhull configuration of Parche, and even those of Halibut, Seawolf, R.B. Russell, and, to a lesser extent, the Jimmy Carter, is the concern for maintaining sufficient reserve buoyancy during extensive hull modifications. For a submarine, reserve buoyancy is the difference in the maximum upward force provided by its empty ballast tanks and the dead weight of the ship's hull and all its contents. The reserve buoyancy must be able to provide sufficient freeboard when the ship is surfaced at its design waterline.

Naval architects build sufficient reserve buoyancy into a ship design so that it can accommodate future modifications and additional equipment—but only up to a point. I recall seeing some hull plans for a 637 identifying those vertical "stabilizers" on the stern planes as "space and weight" for a future passive, wide-aperture-like sonar that never materialized. Reserve weight is designed in by including many hundreds of tons of fixed lead ballast into the design trim and waterline. These ballast blocks are attached to the inside of the hull, usually low in the frame bays of the pressure hull or elsewhere. I've been through a new construction, a decommissioning, and too many overhauls and extensive yard periods. When a boat has had some or all of its fixed ballast removed, it floats much higher than under normal circumstances—and it's "tippy."

I"m not a naval architect and don"t have access to actual numbers, but I"d estimate that under normal circumstances, a modern SSN probably has between 15–20% reserve buoyancy, or possibly even less. If anyone knows the actual numbers, please correct me. For an Archerfish-class boat of about 4300 tons, that means the addition of about 750 to 850 tons of extra weight would sink the ship. In any case, it"s not the actual numbers that matter but the idea of the sensitivity a submarine has to adding extra dead weight to the hull.

When Parche went through her initial conversion, the key visible alteration was the addition of quite a massive object called the DSRV Simulator, well aft of her center of gravity. To compensate for this weight, a lot of fixed ballast would have had to have been removed from the engineering spaces to maintain an acceptable draft and fore-aft trim on the surface. When one considers that there may have also been the mysterious "gondola" attached to the underside of the hull, and the additional dead weight that it entailed, the reballasting of the ship must have been a big headache for the naval architects.

To illustrate my point, here is an undated photo of Parche that appears to have been taken sometime shortly after her initial conversion overhaul. Notice the amount of trim aft compared to the average 637 or 678 boat. Obviously, when submerged, shifting around variable ballast could give her a zero bubble, but the photo illustrates the issues of maintaining sufficient reserve buoyancy and satisfactory surface trim.

The "DSRV Simulator" wasn't the only thing visibly added the vessel during her career. Early on, based on available photos from the Web, other structures appeared:

• The "Bustle"

• The aft fairing

• The bow blister

And, of course, later on was the big extension. This is what was visible from topside:

So, preserving sufficient reserve buoyancy was obviously a critical task. Considering the ship's substantial freeboard in her final configuration, there must not have been too much uncompensated weight added to the ship out of sight.

[GabesDad]

Thrusters

It is clear from Blind Man’s Bluff (BMB) that most if not all of the special project submarines mentioned were fitted with maneuvering thrusters and mushroom mooring anchors (to be addressed in the next post). These would be essential for station-keeping over deep intelligence targets as well as precision maneuvering and mooring in the vicinity of the Soviet cable taps.

Halibut initially had something called a thrust/vector control, according to BMB (p. 60). This was installed during her initial conversion around 1966. However, its design was a failure and replaced by four ducted thrusters installed between the pressure hull and outer hull (Project Azorian, Appendix E; N. Polmar and M. White). Seawolf’s thrusters were visible in every photograph taken of her following her special projects conversion around 1973–74, because they were installed in her freeflood casing above the pressure hull well above the waterline. The existence of thrusters following Parche’s initial conversion was confirmed in CAPT John H. Maurer’s book Sea Stories (p. 137).

From an engineering point of view, the effectiveness of the thrusters in twisting and moving the ship sideways would be maximized by placing them as far apart as possible near the ends of the vessels. These locations provided the longest lever-arm for pivoting the hull—their primary job. This arrangement would be similarly effective for breasting the hull sideways. Such motions, in combination with the fore-and-aft motion provided by the ship’s normal propulsion, would have been needed for station-keeping when conducting deep-water tethered camera operations as described in BMB.

Redundancy and reliability would dictate that a pair of thrusters be provided at each end, as well as the ability to operate each thruster in either direction. Thus, if one thruster in a pair were disabled, then the second would provide a full backup for this mission-critical function. The paired-thruster arrangement was confirmed in the Seawolf photos as well as the Project Azorian description of Halibut.

Placement of the thrusters was limited by available space in the hull structure. Both Halibut and Seawolf were early-design nuclear submarines that still retained the extensive free-flooding casing that formed the weather deck and covered external piping common in WWII submarines. It was logical to locate the thruster motors and ducts in this area external to the pressure hull. Parche, on the other hand, was built to the modern US submarine form, where the pressure hull is a streamlined cylinder, forming the outer surface of the hull for the most part (except in the way of ballast tanks and the sonar dome). The interiors of these volumes were already completely occupied and could not accommodate thrusters. So, though BMB does not address the actual location and configuration of Parche’s thrusters, they must have been installed in structures located under and attached to the hull (since they are not visible above the waterline).

It would be reasonable to assume that the Mission Designers would utilize the same-sized thruster motors, impellers, and ducts throughout all the vessels, though this didn’t strictly have to be the case. I attempted to do some basic photogrammetry using the photos and plans available at the Covert Shores website and other images found on the Internet to determine the size of the thruster ducts in Seawolf. It turns out that the blueprint of Seawolf/Nautilus by Edward Wiswissen(?) has some serious defects in terms of scale and fidelity among the various views in the drawing. I urge anyone intending to use that plan to note the differences in dimensions between the two boats provided, then thoroughly evaluate the drawings. (For example, the plan ostensibly shows Seawolf’s configuration, with inserts showing the differences of Nautilus, but the dimensions of the end view of Seawolf are those of Nautilus.) I ended up obtaining a rough estimate of the duct diameter to be about 4 feet, which seems to agree in comparison to the size of the crew photographed standing on the deck in the vicinity of the thruster ducts.

[GabesDad]

Mooring Anchors

The location and description of the mushroom anchors employed by these ships is more problematic. Blind Man's Bluff (BMB) mentions such anchors were installed in Halibut. These were described as "huge" and were installed at the "bow and stern" (p. 171). As with the thrusters, these locations would make sense from an engineering viewpoint. By anchoring at both points, the orientation of the ship could be much better controlled when dealing with water currents. Halibut evidently conducted her early cable tap work "suspended" (e.g., neutrally or very slightly positive buoyant) only on her anchors, which got her into serious trouble during a storm. Seawolf received anchors as well. According to the storm narrative in BMB on pp. 226–229, Seawolf would bottom using her anchors but would retract them while on her skegs. Where these anchors were attached is never clearly mentioned in BMB. They, their cable drums, and winches may have been installed within ballast tanks near the ends of the ships. Or they could have been incorporated into the gondolas mentioned in the book. We can assume Parche had anchors as well due to their essential contribution to the mission. However, there would have been no room in either the forward or aft main ballast tanks for any such equipment, and certainly not within the pressure hull. So, as with the thrusters, they would likely have to have been located in a structure attached to the bottom of the hull.

The design of the anchors would have had to be somewhat different from the standard navy mushroom anchor. A standard mushroom anchor is intended to be tipped over and buried into the seabed. The inverted mushroom "cap" was hollow and cup-shaped to facilitate this. Most diagrams of a navy mushroom anchor also show a tall, relatively narrow shank. The anchors employed by these submarines for bottoming would have needed to stay vertical as the boats winched themselves down onto the mooring. In addition, the anchors would have needed to be much heavier than a normal mushroom anchor, since their weight alone—not digging into the bottom—performed their function.
Taking these factors into consideration, Mission Designers may have used a pre-existing anchor, such as that provided in the Permit-class boats, or they may have been designed for-the-purpose. It seems reasonable that they consisted of a steel mushroom-shaped form supporting either a massive concrete or lead casting molded into the "cap" to add weight. This would have served two purposes: filling in the mushroom cap so it didn't pick up sand and rocks, and supplying the added weight needed for the mooring. As with any engineering design, the anchor would have been a compromise between providing sufficient weight without overtaxing the cable and winching gear, and being physically too large to fit into the hull structure. The shank would have needed to be strong enough to support the anchor weight and tension exerted by the ship, and it would have included a locking collar to secure it in place for transit, such as that provided by the Permit-class anchor shown below.

Permit-class Anchor

Greg Sharpe's excellent plans for a Permit-class submarine indicate that the exposed part of the mushroom anchor when stowed was about 5 feet in diameter. Referring to the photo above for comparison, that would indicate a stock that was about five feet long as well. A model of the Permit anchor done in Trimble's Sketchup yields a volume of about 6.7 ft³. Assuming an average density for steel of about 493 lb/ft³, that gives the anchor a dry weight of about 3300 pounds.

Model of Permit's Achor in Sketchup

Assuming marine concrete was used to fill in the cap of the anchor as shown the following diagram, this adds a volume of about 10.55 ft³ according to Sketchup. At a density of 140 lb/ft³ for marine concrete, that adds about 1477 pounds and increases the composite anchor dry weight to 4777 lb.

Model of Composite Steel & Concrete Anchor

Since cold seawater has a density of about 63.9 lb/ft³ (depending on a lot of factors), we have to subtract the weight of displaced seawater to obtain the "wet" weight of the composite anchor (Archimedes Principle). Total anchor volume (17.25 ft³ ) times the density of seawater (63.93 lb/ft³) equals about 1100 lb. So the anchor has an effective weight of 4777 lb – 1100 lb ≈ 3680 lb. Total wet weight for the two anchors was about 7400 lb.

This seems somewhat low for anchoring a 4500 ton vessel. However, recall that the submarine hovering over a mooring site would be essentially weightless. Mooring would involve lowering the anchors to the bottom first. When they are supported by the seabed, the boat becomes 7400 lb light, which adds tension to the anchor cables. Then the ship winches itself down until it touches bottom. Variable ballast is taken in to set the ship on the sea floor. So, unless adverse currents are experienced, the combined anchor weight of nearly 4 tons should have been more than enough to secure the vessel to the bottom.

[GabesDad]

Cable Tap Pod Details

Blind Man's Bluff (BMB) provides numerous references to the equipment used for tapping the Soviet cables. However, other than some general dimensions and basic capabilities, there is little to go on for determining the space and weight requirements for the submarines that carried them. The following is a sample of what we can learn about dimensions and weights of the tap pods from BMB:

• The "second-generation" pod was nearly 20 ft long and more than 3 ft wide. They weighed about 6 tons each. (p. 175)
• The pods used a form of nuclear power to operate the recording equipment. (p. 175)
• The cable tap pickup worked on the principle of electrical induction. (p. 175)
• The pod's appearance was "a giant tube that had been squashed some from the top and welded shut at the ends." (p. 175) But see below.
• Parche had the ability to carry at least a pair of pods. (pp. 239, 253)

The publicly-available information of the actual tap pod equipment has been supplied mainly by Soviet and Russian websites devoted to the Cold War and intelligence collection matters. Most of these sites are maintained by private individuals, though several are official websites. A lot of the images of the tap pods themselves and diagrams relating to the cable taps have been reposted on English-speaking websites over the years (including elsewhere in The SubCommittee Forums). The following images are examples of the kinds of information publicly available:

Web image of a recording pod sealed and contents extended, allegedly taken from a US cable tap; Source: a Russian website


Detail photo of an alleged cable tap pod showing cable connection and skid pan. Source: Russian website.


Alleged onsite arrangement of a cable tap pod and its tap cables. Source: Russian website.

Note that none of the photos or sketches suggests the pod was "squashed some" nor were the ends "welded shut." At least one end was fastened in place with bolts to provide access to the recording equipment.

One image of the pod that I used for reference seems to be a near-photorealistic illustration of a pod. I say an "illustration" because some of the details are at variance with actual photos. However, it provides a good side view of the device, whereas the photos are mostly foreshortened end views. Another issue at variance with the BMB description of the pod is dimensional ratio. The book gives a width-to-length ratio of about 1:6.7. This is my reference image:

Soviet-sourced diagram of a US cable tap pod in operation.

And this is a reconstructed three-view diagram of the pod with the assumed dimensions:

Reconstruction of the cable tap pods showing approximate dimensions.

Using this as a reference, one can make an approximation of the volume required to carry a pod, as well as estimate the size of the underhull structure that surround it/them.

[GabesDad]

Looking at Parche's Unmodified Bottom

There are several illustrations available on the Web showing how Parche may have looked after her initial "ocean engineering" conversion for Special Projects before she received her 100-ft hull extension starting in 1987. Hal Sutton's illustration of Parche at Covert Shores is representative:

As Tom Dougherty and others have noted, placing a hypothetical gondola along a majority of the hull bottom doesn't seem practical due to interference with propulsion plant and other key hull penetrations—particularly main ballast tank flood ports—and other things attached to or projecting from the hull.

Let's look at propulsion plant seawater and other penetrations. The arrangement of these was strictly controlled by the Naval Reactors Directorate of Naval Seas Systems Command of the US Navy department. Getting permission to obstruct or move them would be technically difficult if not impossible for a number of reasons. Considering that the Special Projects Office was trying as much as possible to keep ADM Rickover out of their business, they probably made sure that none of the modifications could have impacted the propulsion plant, which would have required Naval Reactors input (Blind Man's Bluff [BMB], p 182 and other pages). So we can assume that a gondola attached to the hull under the Reactor Compartment and farther aft had to avoid interfering with any nuclear propulsion plant equipment.

The other key submarine feature that could interfere with an underhull gondola in Parche would have been the main ballast tank (MBT) flood ports, which are covered by gratings. These openings are at the lowest possible points within the MBT shell plating unless something else in the MBT requires a shift in position. Thus, most of the MBT flood ports are arranged along both sides of the bottom centerline within the MBTs. The Sturgeon Class submarines had six main ballast tanks—three at the bow just aft of the sonar dome, two between the Reactor Compartment and the Engine Room (surrounding the Auxiliary Machinery Room #2), and one all the way aft just forward of the propeller. These MBTs were divided longitudinally in half (except for #6) for reliability in case of a collision or battle damage.

The capacity and design of the MBTs in later classes of submarines were a critical factor in the Submarine Safety (SUBSAFE) Program that came about after the loss of the USS Thresher. Regardless of the intended purposes of the modifications, or even the critical nature of Parche's new mission, her SUBSAFE Certification could not have been compromised by these modifications. So it was unlikely that a gondola would have been allowed to interfere with any MBT flood ports. That being said, since the reserve buoyancy provided by the MBTs likely had a safety margin designed in, it could have been possible that NAVSEA would have approved the flood gratings being shifted somewhat away from the hull centerline if needed, as long as an adequate buoyancy margin per the SUBSAFE Program specifications remained.

Taking these factors into account, I drafted up a diagram of an Archerfish-class submarine hull as viewed from the bottom, based on Greg Sharpe's detailed plans of a Sturgeon-class submarine. I extended the hull forward the 10 feet commonly accepted as the length difference between 637 and 678 hulls. Then I moved all the hull features forward the same distance starting with the hull penetrations at Frame 47, or thereabouts. The cross-hatched areas are where it would be unlikely to attach a gondola. (Obviously, I didn't include the sonar dome in these excluded areas, since there wouldn't be any place to attach a gondola, not to mention the noise it would generate near the sonar arrays.)

Suggested areas of exclusion on the underside of an Archerfish-class submarine hull relating to attaching a putative "gondola."
Modified from an original drawing by Greg Sharpe. (Click to enlarge)

So, there seems to be justification that there could have been at least two gondolas needed to provide the minimum support for the hull when the vessel was on the bottom, without intersecting the reactor compartment and key propulsion plant hull penetrations. Another consideration would be that these gondola(s) likely weren't removed when the ship was moved into drydock, so they would have had to be of a sufficient length (and structural strength) to provide the necessary longitudinal support to the hull when out of the water. I'll discuss these and other issues in my next post on this subject.

[tom dougherty]

The nuclear power source was a plutonium thermoelectric power source. The heat from decaying plutonium is employed as one junction of a thermocouple (the other end employing the cold of the surrounding water) as a source of electrical power. Same power source for the 1976 Viking Mars missions and the current Curiosity rover on Mars. I think the box like structure is more likely the container for the large tape reels that would have to be periodically swapped out. The semi-sealed cylinder would be a pain in the ass to open up the bolts each time you needed to recover and replenish the tapes. Just because someone labels it as the nuclear power source on the internet doesn't necessarily make it one.

The pod was moved into place employing flotation balloons which compensated for the majority of the weight. One illustration I have seen had the tapped cable in a semi-circular holder along the length of the pod itself, rather than a separate set of cables from the pod to the cable, as shown above. This allowed the induction to occur along a greater length of the cable. The particular illustration was from one of the Halibut divers.

I think you have to consider the idea of a "soft" underwater gondola in the form of a fine mesh net, rather than a hard enclosed gondola with all the problems you cite above. Again, one of the saturation divers indicated that a mesh net that could be tightened up against the hull was used to carry objects to and from the "destinations" that the Halibut visited. Maybe Parche was different...or not.

[GabesDad]

Hey, Tom. Thanks for your information.

I apologize for the wordiness of my posts. I was a professional technical writer for nearly 20 years before I retired, so I have a habit of trying to explain things as thoroughly as necessary (probably more than necessary).

The nuclear power source you described sounds like a radioisotope thermoelectric generator, or RTG. A number of years ago I read about these things in a Wikipedia article (and elsewhere on the Web), which is linked here. The US developed them back as early as the 1950s and 60s. They were used, among other things, to power the Apollo lunar science instruments, which were more-or-less contemporaneous with the Special Projects cable taps. I thought then after reading the articles that their function of providing remote, unattended, low-power service over long periods of time would serve the purpose of powering the cable taps, even before I found the photos of the pods online. According to the Seebeck effect, by which these things operate, the maximum voltage generated depends on the bridging the thermocouple with the largest-possible temperature difference between the hot radioisotope and the heat sink. So I assumed that the "box" you mentioned housed the RTG and would need to be raised off the pod platform in order to provide free circulation of the cold seawater through the device to sustain the electric source, as well as to remove waste heat by convection.

You mentioned that you believed the "box" may have instead housed the tape reels that were swapped out on-site during the tap servicing. I"m not sure how that would have been accomplished. The Okhotsk taps were at 400 feet according to Blind Man's Bluff (BMB), which equates to 12 atmospheres of sea pressure. There is no indication from the available photos and diagrams of the pods that the box would have been able to withstand such sea pressure if the tapes were at atmospheric pressure. I suppose the tapes and their drives could have been housed in pressure-proof cases. One possibility for the earlier tap designs may have involved the ship recovering the tape contents housed inside the pod by copying the recordings to onboard tapes via a temporary cable connection with the pod while moored to the bottom.

However, BMB discusses in several places where the submarines recovered the pods themselves and transported them back to home port (e.g., p. 175), completely avoiding having to transfer the tape-reels on site. In particular, on page 253, the book states that Parche on one of her Barents runs recovered the existing pods and planted new ones (plural in both cases). So, at least in Parche's case, swapping out the pods could have been done on each trip, routinely. I could be mistaken. This process would also permit doing maintenance on the pods as well as equipment upgrades, which were also mentioned in BMB.

Regarding the movement of the pods at the tap site, Halibut may have used the flotation-balloon method early on because she was hovering off the bottom on her anchors. The divers would have had to lower the pods to the bottom somehow. Also, it seems that the first-generation taps weren't as large as the later versions. BMB describes on pp. 171–173 that the original Halibut recorder was about 3 feet long and connected to a separate inductive collector. Using flotation balloons for 20-foot, six-ton pods would seem to be quite difficult to manage under the conditions at the tap site. And imagine what could have happened if one of those floats got loose and floated to the surface!

Regarding the "soft" gondola, which was mentioned for Halibut (BMB, p. 173), we need to remember that her original intelligence-gathering mission was deep-sea imaging and missile fragment collection. I have a hard time imagining what a "soft" mesh gondola would have looked like. However, the facts that she traveled at only 13 knots max (BMB, p. 169) and that the gondola was originally designed to carry chunks of metal and other debris, suggest that such a gondola might have been feasible in her case. However, Parche probably could have done at least 20 knots, even with all the hardware hanging off her. That speed would have required an entirely enclosed and streamlined gondola to minimize drag and flow noise. Such noise could have compromised her intended mission, which was routinely working in the vicinity of the Soviet Northern Fleet. Recall that she was modified several years after Halibut was retired, so trying to equate the hull modifications of two ships will be problematic, at least regarding the gondolas.

It would be great if other members would join this conversation and share their ideas!

[tom dougherty]

Yes, the plutonium powered RTGs are exactly what I was talking about. Many people confuse these with small nuclear reactors (e.g., SNAP-10A), which work on a different principle.

My understanding is that the tapes were contained in a sealed cassette like device that had data and electrical connector plugs to the pod. I would imagine in that case the divers would want the installation point to be readily accessible with a minimum of effort on their part, since they were wearing saturation gear, warm suits, gloves and were constrained by umbilicals. You certainly would want the interior of the pod with all of the electronics to remain watertight, so opening that would not be an option. Once the pod was installed on the tap, you would not want to routinely haul it in and out each time just to swap tapes. As electronic equipment improved over time, I can imagine replacing newer versions for the older pods.

Also, keep in mind that BMB is over 20 years old, and some of the chapters have been superseded by additional information that has become available. The chapter on the Hughes Glomar Explorer is not particularly accurate, for example. Not a criticism of the writers' efforts, they did the best they could given the time period and constraints.

[GabesDad]

Parche's "Gondolas"—Part A

Before starting into this post, new readers of this thread should probably begin with my original post starting on 5 February, 2020. A reminder that all the information discussed here is from open, publicly-available sources and reasonable conjectures based on sound engineering principles and submarine practices. The intent here is to provide dedicated submarine modelers some ideas for creating as credible a model of USS Parche after conversion to her Special Projects configuration as possible, since her actual physical configuration will probably always be classified to some extent.

A second purpose is to respond to Hal Sutton's original post that started this thread back in November, 2016.

Tom, I’ve never seen anything in open sources about pressure-proof tape cassettes in relation to these cable taps. If you can direct me to such a source, I’d appreciate looking at that. With respect to Parche, at least, I’m going with swapping out the pod if not the entire tap assembly with every visit, as discussed in Blind Man’s Bluff (BMB).

When considering the nature of Parche’s “ocean engineering modifications,” one must keep in mind that she was originally intended to conduct Soviet undersea cable-tapping operations in the Barents Sea, according to BMB (p. 211). Unlike Halibut and Seawolf, which were originally converted for deep-sea surveillance and missile debris recovery, Parche’s mission was mainly to sit on the bottom to deliver and recover tap pods (BMB, p. 253), and monitor Soviet communications for lengthy periods of time while moored. All of this is discussed in some detail in BMB. So it is to be expected that whatever underhull modifications were made to Parche would have been at least somewhat different from those of the former two vessels.

Taking into account the many factors discussed in previous posts, I think that Parche’s underhull gondola(s) needed to meet the following requirements:

• Provide the minimum-necessary capacity for carrying the mission equipment.
• Provide the structures needed to support the mission-critical auxiliary equipment, such as thrusters and mooring anchors, toward the forward and aft ends of the hull where these devices would be most effective.
• Either avoid impacting the location and/or function of propulsion plant and ship control hull features, or making minimum alterations to these consistent with operational and ship safety needs.
• Be able to support at least part of ship’s weight when in drydock as well as at the seabottom mooring.
• Provide the minimum necessary hull standoff distance when on the bottom to avoid fouling and damaging seawater systems by ingesting marine sediments.
• While meeting all of the above criteria, minimizing the structural dead weight to conserve as much reserve buoyancy as possible.
• Finally, to minimize flow resistance and turbulence consistent with the previous requirements.

A brief digression: While I was a contract writer for the National Center for Construction Education and Research (NCCER) a few years ago, I was tasked with revising a textbook on Mobile Crane Operations. In the process of demystifying crane load charts, I realized how important understanding the mass and placement of various counterweights affected crane stability. With regards to our topic, gondola placement and design must have considered where the major masses within a submarine were located, not only to support the submerged vessel on the mooring, but, more importantly, to bear the weight of the ship in drydock. At the same time, the size and mass of the gondola(s) needed to keep to the bare minimum.

Following is an illustration showing qualitative estimated locations of the main centers of mass in an Archerfish-class submarine, again based on Greg Sharpe’s 637-class hull plans, as extended. While any object has an overall center of mass, complex objects can have their mass concentrated in multiple areas surrounding their overall center of mass. This submarine’s internal mass tended to be concentrated in several places:

• The forward portion of the Operations Compartment
• The Reactor Compartment
• The forward two-thirds of the Engineroom.

An estimate of the main centers of mass within a submarine.

Granted, there is a lot of mass in other areas of the ship. However, they can be viewed as being concentrated at these three locations. For example, with exception of the Emergency Diesel Engine, most of the volume of the 637-class Bow Compartment was mostly taken up with bunks. The Bow Compartment pressure hull was surrounded by ballast tanks. The Sonar Dome contained only relatively low-density sonar arrays. When afloat, these volumes contained seawater, and in dock, they were full of air. The dome itself was glass-reinforced plastic. So the forward part of the ship had fairly low mass compared to its volume. Its mass could easily be factored into the mass of the large Operations Compartment, which included the sail, variable ballast and sanitary tanks, the Torpedo Room, and the Sonar Equipment Space.

Assuming then that there were at least two gondolas, it would make sense that the forward one would have been placed somewhere under the Operations Compartment, and the aft gondola under the Engineroom.

The forward gondola could have been fairly long, even extending aft under the Reactor Compartment while remaining clear of most hull penetrations (with possible exception of the Trash Disposal Unit [TDU]). The forward end of the gondola could have extended underneath at least MBT 3 without interfering with significant hull penetrations. This gondola could have been as much as 90 feet long or more. The forward pair of thrusters and the forward mushroom anchor could then have been placed at the front end of the gondola to be most effective.

The aft gondola would need to be positioned fairly well aft to avoid a lot of propulsion plant hull penetrations and access points below the forward part of the Engineroom. It also would have had to be located forward of MBT 6 to avoid interference with the standard ship’s anchor and flood ports there. The aft pair of thrusters and the mushroom mooring anchor could have been placed at the aft end of this gondola.

The tentative positions of these two gondolas would provide support for the most massive regions of the ship on the moor and while in drydock. Note that areas of the hull that were not supported by gondolas in drydock could have been supported by standard keel blocks built up to support the hull, so there would be no problems with hull sagging or deformation.

After tentatively locating the gondolas, the next task for naval architects would have been to reduce as much as possible their masses to the minimum required, while providing the needed carrying capacity for mission equipment. Since Parche’s original SP mission was conducting cable tapping, the gondolas would have been designed for this purpose. The later-style tap pods were about 20 feet long (BMB, p. 175) and less than 5 feet wide; two could easily have been placed side by side within the gondola, requiring an external width of about 12–14 feet (including internal framing). If we assume that an equivalent amount of space was allocated within the forward gondola for the other tap-site equipment, such as cables, reels, inductive pickups, handling gear, etc., then the gondola might not need to be much longer than, say, 60 or 70 feet, including the rounded ends for streamlining. If some of this mission equipment were stored in the aft gondola, the forward gondola could have been as short as 40 or 50 feet. Such a reduction would have cut the overall mass of the original gondola weight estimate by as much as 50 percent.

However, this length would not be sufficient to also contain the forward thrusters and anchor. The housing for these would need to be only wide enough to hold the 5-foot-diameter mushroom anchor (see my previous post on mooring anchor considerations), and the thruster motor and impellers. The gondola would need to be only 6 or 8 feet wide, not the 12–14 feet required for the main gondola. Providing a separate gondola for these items could reduce the overall gondola dead weight even more. Since it would be located under the Bow Compartment, it likely wouldn’t need to constructed as heavily as the main gondolas, either. The main gondola could be located so it would bear the majority of the weight of the forward half the ship, thus eliminating the need for the forward gondola to even be in contact with the bottom. This is all conjecture of course, but reflects my concern that minimizing the dead weight of the gondolas was a major design issue.

To be continued...

[navy2000]

I plan on making a model of the Parche in 1/96 scale that will be RC. I will be watching this post closely to what your thoughts are on how the sub looked completely above and below the water line. Any help will be welcomed here. On the first page of this post their is the cutaway drawing of what someone thinks what the sub looked like could that drawing be very close to what the real sub looked like?


The gondola could have been just short of forward and aft ballast tank vent grates and as for the TDU opening it could have been extended through the gondola. What are your thoughts on that?

Duane

[tom dougherty]

The cutaway drawing is a speculative one from Hal Sutton, author of Covert Shores. If you stop and think about it, the Parche got a 100 foot section installed forward of the sail. I suspect there might have been no need for a gondola of any sort, as you could incorporate storage space accessible from the outside into the hull extension itself. The pressure hull would have to be "necked in" at the bottom to create a space external to the pressure hull, similar to the ballast area around the reactor. That is exactly the way the Carter (SSN-23) is layed out, with free flooding areas in the extended section. The 100 foot extension would have room for a saturation diving chamber with direct outside access to the sea, and a lock area to deploy various items such as camera bearing ROVs. It would have ample room for a storage section as well.

A gondola would add drag and flow noise. Why not build storage space into the streamlined hull? But all of this is speculative; those who really know can't say.

[GabesDad]

Still working on some diagrams showing more detailed—but still speculative—views of Parche's gondolas.

Blind Man's Bluff's (BMB) narrative regarding Parche's career basically dries up following her conversion at the end of the Cold War in the late 1980s and early 90s. With the exception of a brief statement about the hull extension length (p. 262) and some speculative statements on possible capabilities (p. 272), there is very little additional information to be gleaned from that source.

So her extended underhull configuration from that point on until her retirement in 2004 truly is conjecture.

What I have been working on here is developing a credible model of what she could have looked like after her first conversion overhaul that completed in 1978. As I mentioned in an earlier post, all subsequent changes were evolutionary, building on the previous modifications. Consequently, even the 100-foot hull extension overhaul would probably have incorporated at least some of the previous modifications, especially in the underhull area. The ship still needed thrusters and mooring anchors. She still needed something to support the hull well off the bottom, and she still needed to carry the large tap pods external to the hull. The latter may have become less of an issue as digital technology improved. Bell Labs may have been able to miniaturize them to the point they could have been carried in a much smaller space. So why would the program ditch all those earlier mods?

I'm not sure I would expect too much equipment to be stored in the freeflood space around that extension. If Parche retained her operating-depth certification typical of 637-class submarines, she would have required fairly hefty exterior frames surrounding the pressure hull of the extension. Some of the space between the pressure and outer hulls may have even been devoted to ballast tanks to provide reserve buoyancy to compensate for the extension. Some of the remaining space might have been occupied by diver-gas cylinders that some sources (e.g., Covert Shores) speculate were carried in the former DSRV Simulator or elsewhere in the hull additions. More likely, these could have been mounted under the extensive superstructure on top of the hull. The interior of the extension would have been occupied by living quarters for the divers and Special Projects Division (BMB, p. 218, notes that in the early days, most of the Torpedo Room was vacated of weapons to provide bunk and operations space for these folks), the operations control center, and the decompression chamber. Also, a passageway had to exist to the bow compartment, where the Emergency Diesel Generator was located as well as extensive crew berthing. The ship would have also needed extra dry stores space for the 25% larger crew as well. So I suspect that any mission equipment for other capabilities was housed in an exterior gondola or deployed via the torpedo tubes.

[Edited] Therefore, after the extension, the aft gondola and a possibly-separate forward gondola with the thrusters and mushroom anchors were probably retained. The main gondola may have been enlarged and/or moved forward under the extension to be located nearer to the operations center and to better support the added length.

All in all, this arrangement would make for a more interesting model, in my opinion!

[tom dougherty]

"and the main gondola as well."

For which there is absolutely no evidence that it even existed. Why would you think the crew became 25% larger? A 100 foot extension would have allowed plenty of room for storage, saturation diver accommodations, equipment and stores, and potentially a free flood space that could be reached from the outside. And, you end up with a smoother hull with less flow noise.

But, at the end of the day, this is all hypothetical. That's it for me, I'm done.

[GabesDad]

Why would you think the crew became 25% larger?

Probably would have been closer to around 20% of a standard 637-class crew of 110 +/–. When you factor in several work crews of divers, technical support staff, officers, etc. You are probably looking at 135 to 140 total crew. I'm not sure how many bunks an Archerfish-class boat had, but I estimate it was around 120 bunks; perhaps less. This leaves a deficit of about 15–20 bunks needed to be made up in Torpedo Room skid pans or in the hull extension berthing. That's a pretty good-sized berthing area!

I have no idea how much MikroMir is going to charge for their extension to a Sturgeon-class static model. I couldn't find any evidence on their website that it is available. I know from earlier posts in this forum that at least one person has built a large RC model of the extended Parche based solely on Hal Sutton's illustration and extant photos of the ship. And navy2000 has recently expressed an interest in doing the same thing.

If someone is going to the effort and expense to build such models simply on one visionary's conjecture, they are risking perpetuating some conceptual errors that could be ruled out by simply thinking about the most likely engineering solutions. Not criticizing Hal's efforts. But his illustrations are as subjective as any—unless he has input from credible sources.

And I'm certainly not stating that my suggestions are any more correct or less subjective. But I am trying to hone in on what might possibly be a more accurate estimation using available information.

In the end, I suppose the question depends on what is important to you? Do you want to make a nice waterline diorama? Then Parche's underhull question is irrelevant. Are you building an RC model where the underhull is visible only when on the maintenance stand, your main concern is that your surfacings equal your dives, and that she looks good underway? Probably not important. But if you are seeking a nice static model to display on your shelf or mantel, and you are picky about accuracy, then the underhull view is as important as the correct number of blades on the prop.

We need more participants to discuss these topics.

[navy2000]

If you think about it could Parche been an enlarged version of what NR-1 was? I was attached to NR-1 for a short period of my Naval time and when NR-1 had to go from one location to another we towed her to that location. As far has water flow noise she may have had a slower speed to operate at, after all the Parche would be at slowest speed possible to maintain ship handling while operating off of another countries coast line. This would be similar for any sub the had the DSRV or a Drydock shelter on them as well.

Over all I would also like to know one way or the other if the sub had the lower gondola or not. It will be another year before I get this project going so I have some time to maybe find out one day if it is there or not. I wonder if the side profile and top plan view can be found at the Naval Archives, after all the sub has bee gone now for 16 years. I know that some things still remain classified for a long time, but it couldn't hurt to try with the Freedom of Information Act request.

Another thought on this the reverse missile deck as I call it on the topside. Could that been basically a gondola mounted topside?

Duane