Built to flood

Among oceangoing vessels R/V Flip certainly qualifies as one of the most curious. For starters, in operation she draws 300 feet of water. This draft dwarfs that of any other ship that’s ever been built. Three hundred feet equals 100 yardsthe draft of this vessel is equal to the length of a football field standing on end. As we shall see, the primary purpose of this extreme underwater length is to provide stability for the scientific equipment used in conducting the delicate observations and experiments for which Flip was built. So far no other way has been found to set this test equipment deep enough underwater in open ocean with the degree of stability and accuracy that Flip provides

"Flip" is both an acronym for FLoating Instrument Platform and also a descriptive term for the capability of this vessel to rotate (or flip) from a horizontal to a vertical orientation and back again. It is the only vessel ever built anywhere that can do this. When in the horizontal position the forward 40-foot bow section contains machinery spaces, electronics, and lab space, as well as living quarters and facilities for a crew of four or five and up to an 11-person scientific staff.

Altogether the ship is 355-feet long. The aft 150 feet of that length is a 20-foot-diameter cylinder containing the tanks that are flooded with sea water in order to swing her down from the horizontal to the vertical position. The middle 150-foot section contains the compressors and air tanks used to blow the sea water from the aft tanks back out when it is time to return to the horizontal position.

The horizontal profile reveals no propeller or rudder because there are none. Flip is not self-propelled, although it does have a small thruster attached to the exterior of the middle section. This thruster is only used when in the vertical position for the purpose of adjusting the direction toward which Flip is facing

Whenever Flip is to be moved from one location to another it must be towed. All in all, Flip does not appear in any way like any other vessel ever seen before. One of its designers, Dr. Fred Speiss, is said to have commented, when he saw it floating horizontally on the surface, that it looked rather like an oversized Louisville Slugger. One could also mistake its shape for that of an oversized toothbrush with the bow section as the brush part and the rest the handle.

Design and construction

However, although Flip looks as though Rube Goldberg had a nightmare, every detail of its design was very carefully calculated to contribute to its extremely specialized functions. It was developed at the Marine Physical Laboratory of the Scripps Institution of Oceanography in La Jolla, California. Its development was initially sponsored by the SUBROC program of the U.S. Navy for the purpose of studying ways to improve the targeting accuracy of submarine-launched rocket torpedoes.

The aiming of submarine missiles fired from underwater depends on sonar for detecting and determining the range to the desired target. However, water bends and distorts sound waves with the result that the location indicated by sonar and the actual position of a target are all too often two different places. The initial reason for the development of Flip was that, in theory, with an observation platform above the surface from which to sight the actual position of the target, and sonars placed well below the surface, scientists could then compare and calculate the difference between the actual location and the position indicated by sonar. With this information they could calculate the necessary corrections required for a submarine to locate a target accurately. Dr. Spiess and a colleague, Dr. Fred Fisher, were given the job of developing the vehicle that could do this.

They needed an instrument platform that would float in an absolutely steady position so as to provide a mounting location for sonar equipment that could be maintained at a precise depth. In addition, the unit on which the sonar is to be mounted must be silent. The normal bobbing up and down of a surface vessel would produce enough incidental noise due to the sloshing of the water around its hull that it would disrupt accurate sonar observations. A standard submarine totally submerged would eliminate that surface noise but could not maintain an exact depth for extended periods with enough accuracy. Something completely new was required.

They needed to be able to mount sonars at depths equivalent to those at which a submarine needs to detect and acquire its target when operating submerged. Furthermore, those test sonars had to be completely stable in order to conduct meaningful research. After much thought, they realized that a long, skinny vessel that could change from a horizontal to a vertical orientation might allow them to place their test sonars deep enough and at the same time keep them stable at that required depth. They tried several hull cross sections before deciding on a simple cylindrical shape for most of the hull. To keep it from rolling over in a seaway when being moved from place to place in the horizontal position, a substantial concrete ballast was needed inside of its bottom. Even with that ballast, Flip still rolls quite uncomfortably when being towed in the horizontal mode.

The final design was built in 1962 by the Gunderson Engineering Co. in Portland, Ore. Gunderson was not basically a shipbuilding yard. They normally worked on super-large outsized piping. Since 300 feet out of Flip’s 355-foot length is essentially a cylindrical pipe, perhaps that was what made them the appropriate builders.

In any event on July 23, 1962, in Dabob Bay, Wash., the completed Flip made her first Flip. Traditionally, whenever a new ship is launched those who worked on her compete with each other quite earnestly for the honor of being aboard on her first trip. In this case the people at Gunderson were apparently overwhelmingly underconfident about the safety of this extremely strange vessel they had built. Only one person from the yard was aboard the first time she flipped. Happily, that first flip went flawlessly and since then Flip has flipped many hundreds of times without incident.

The bow habitat

While Flip was in drydock in San Diego in the spring of 1998, I had the unusually good fortune to be given a tour of the ship personally guided by captains Bill Gaines and Tom Golfinos from Scripps. This gave me a closeup view of both the living quarters and research sections of the vessel. The 40-foot bow section houses the research laboratory which contains a wealth of extremely elaborate, expensive, and delicate electronic equipment as well as the diesel generators require to produce the power needed to operate that equipment. It also provides living quarters for the scientific staff who are the reason for the existence of the vessel, as well as the crew that operate the generators, compressors, thruster, watermaker, and other on-board equipment.

As mentioned earlier, Flip must be towed, often for considerable distances, in the horizontal mode in order to reach a site where a research project is to be conducted. A great deal of the work done on Flip has taken place in the waters of the eastern Pacific between her home base at the Nimitz Marine Facility of the U.S. Navy in San Diego and Hawaii. However, she has been deployed on projects as far away as the Gulf of Alaska as well as at the islands of Barbados and Puerto Rico in the Caribbean.

While under tow, the entire vessel, including, of course, the bow living quarters, is in the horizontal mode. This presents some extremely unusual requirements. In this position the forward cabin on the top deck contains electronics and controls while the aft cabin on that deck provides quarters for the officer in charge and the first mate. The middle deck forward contains living quarters with stowage below. The large middle lab space on this deck is normally unused when under tow. Aft of this comes the galley with dining area below. Farther aft of both galley and dining areas are the diesel generators.

Living quarters, including bunks, toilets, sinks, shower, and galley equipmentmeaning range, oven, refrigerator, sink, and countermust be operable in horizontal mode for extended periods while the ship is being towed. This means that all necessary plumbing fixtures must be connected to water supply and waste disposal lines. Also, the diesel generator engines must be operable to supply power for lighting, refrigeration, air conditioning when needed, the 400-gallon-per-day watermaker, and the underway electronics bank. These diesel engines require fuel supply lines and exhaust connections. Everything aboard must be properly secured when running horizontally since in this mode, with 300 feet of completely cylindrical hull, Flip will roll unmercifully even with its concrete ballast in place. Its hull shape offers absolutely no resistance to rolling. The internal concrete ballast is all that keeps it from completely turning turtle.

Flipping Flip

When the desired destination is reached, Flip is rotated 90° to its vertical operating position. This is accomplished by filling the tanks in the after 150-foot section of the ship with sea water. It takes approximately 15 minutes to take on enough water to rotate 45°. At this point the bending stress on the hull has become tremendous. The aft section is filling with water and moving down while the forward section has been lifted completely out of the water so that its weight, angled at a 45°, is now unsupported.

Fortunately, the stress is now relieved quickly since the second 45° of rotation takes only about another five minutes for a total elapsed time of about 20 minutes to swing the full 90° from the horizontal orientation around to the vertical.

In the vertical position, what is now the top deck is living quarters. Electronics are now on the second deck along with the research lab, which is now set up and connected for whatever scientific mission has been assigned. The lab instrumentation was tested, rack mounted, and installed in the lab at the dock. The third deck has a galley and dining area along with the quarters of the skipper and first mate. The generating machinery is now all at the bottom level. Exterior working platforms extend aft on all decks.

The bunks are all conveniently mounted on swivels allowing them to rotate 90°. The toilets also are rotated. The shower that was used in the horizontal mode has itself become horizontal and hence is now unusable, but it is replaced by another intended for use only in the vertical mode. In the galley the refrigerator, oven, range, sink, and storage cabinets were all mounted together in a single connected row of appliances. This entire assembly terminates at to two heavy end pivots so that all the galley appliances rotated as a unit when Flip rotated from horizontal to vertical. The complete galley unit is then locked in place. Each of the three diesel generator engines are also mounted on heavy twin pivots that allowed them to turn as Flip rotated, after which they too are locked in place. In the process of rotation, hatches have become doors and doors become hatches.

After each 20-minute flip, the crew spends the next hour resetting valves, switching water and drain lines to sinks and toilets, locking down rotated bunks and other furniture, switching fuel and exhaust lines to the diesels, and otherwise completing the reconfiguring of the living and working spaces.


Depending on the job at hand, Flip may be moored or she may be allowed to drift with wind and current. Drifting she may reach a speed through the water of up to about 0.5 knots in a 25-knot wind. Speed over the ground will naturally vary depending on relative directions of wind and current. When drifting, the exposed bow section will generally turn its "bottom" (at least the bottom when its in the horizontal mode) toward the wind, thus sheltering the exterior working deck areas.

Flip has frequently been moored in very deep water. She has actually been moored in water up to five kilometers or a little more than three statute miles deep! Setting up a mooring that deep is a rather complicated process. A full three-point mooring in deep water calls for approximately 80 tons of anchors, chain, and 1 1/2-inch nylon line. All of this material has to be carried aboard a support ship which then sets the anchors.

In fairly calm weather it takes about 12 to 16 hours to set the complete mooring system in place. Each of the three anchors with its associated chain weighs about 10 tons. These are connected to Flip on the surface with 1 1/2-inch nylon rode.

The nylon lines are connected to the anchor chains by break-away links so that when the job is completed the nylon rodes are recovered to be reused while about 30 tons of anchors and chain are left behind.

When finally moored, Flip becomes incredibly stablehorizontal movement will be no more than 250 feet to 600 feet, and vertical movement will usually be less than 10% of the average wave height. In 30-foot swells she would move less than three feet. Once settled on station, Flip can normally remain for up to 30 days.

Depending on the purpose of a specific project, various equipment arrays may be attached to the hull and tested while at the dock prior to departure. When in position at sea other equipment packages can be lowered to whatever depth may be desired by utilizing booms that are routinely attached to the forward platform for this purpose. Any of several winches may be used to drop and hold these packages depending on the loads involved.

Although Flip was initially designed and built to conduct sonar research for the Navy, many other scientific research projects have since been found that can take advantage of her unique capabilities. Many of these projects are in areas that are rather difficult for the general public to understand, but are highly meaningful in various scientific fields. Aspects of the extremely complex oceanic-atmospheric interaction is one. Since the oceans make up a majority of the surface of the Earth, they have profound effects on our weather.

In simple terms weather results from the effect of heat on the atmosphere. This heat is all derived originally from the radiant energy of the sun. The atmosphere absorbs very little of this solar energy via direct radiation. Most of it enters the atmosphere through long wave reradiation from Earth’s surface and from direct surface conduction. A great deal of the heat absorbed by the atmosphere enters from the oceans, since about 70% of the surface of the planet is water.

Immense amounts of solar heat are absorbed by ocean waters. It has long been clear that this same heat also causes huge amounts of surface evaporation of sea water. That evaporation in turn releases considerable amounts of heat energy that came from the ocean and transfers it into the atmosphere where part of that evaporated water condenses into clouds. This condensation, in turn, transfers energy that stirs up winds by producing changes in temperatures and pressures. However, it is not clear precisely how much energy enters the atmosphere from the sea, exactly where the transfer of that energy is strongest, and how rapidly it occurs. By suspending a sensor array from an instrument boom on Flip, that array can be kept in place just above the sea surface where the energy transfer has been found to occur. It is now possible to take continuous measurements of what is happening over time. An improved understanding of how energy moves between the sea and the air, and how much energy is involved, will assist meteorologists to better understand, track, and predict weather changes.

It has also long been known that surface winds cause mixing in the upper layers of the ocean. This mixing occurs in circular rotating patterns called Langmiur Cells that can be as shallow as 15 feet or as deep as 150 feet. The effect of these cells on oceanic energy distribution is also unclear. Using Flip’s sonar equipment, scientists hope to determine how the surface winds affect the circulation of these cells. Hopefully this will enable us to begin to understand how sub-surface energy is being distributed in the oceans. Understanding how energy moves in the oceans is important because, again, a majority of the surface of the Earth is ocean, and therefore the atmosphere gets, in addition to its water vapor, most of its weather-producing energy from the oceans.

Weather satellite pictures are now being interpreted to indicate sea-surface conditions such as wave heights and wave train directions. Observers on Flip can provide precise sea-surface data for comparison with the conditions deduced from the satellite pictures in order to help meteorologists better interpret their satellite data.

Although Flip by now is an old vessel, the end of her usefulness is by no means in sight. Her instrumentation has been repeatedly upgraded, and these upgrades will continue for the foreseeable future. It is unlikely that Flip will ever be able to answer all the questions that researchers would like to ask her to investigate. Until we fully understand the many interactions between the ocean and the atmosphere, Flip will be helpful, and that day of full understanding does not appear to lie anywhere in the near future.

Jeff Markell writes frequently on marine weather topics and is based in San Diego.

By Ocean Navigator