The submarine Otaria was originally built by the C.R.D.A. shipyard of Monfalcone on behalf of the Portuguese Navy and assigned the name “Espadante” as part of a process of deep reorganization and modernization of the Iberian country’s Navy. The Otaria belonged to a class of only two units, the other submarine being the Glauco, and designed by Curio Bernardis on the basis of the experience acquired with the Squalo class.
Eventually, upon the cancellation of the contract by the Portuguese, the Italian Navy took over ownership, receiving the unit on October 20th, 1935. Upon completing the initial shake down and testing, the Otaria was assigned, along with the sister unit Glauco, to the IV Submarine Group based in Taranto. In late summer 1936, both units were then transferred to Naples. Between 1936 and August 1937, the unit completed three missing as part of Italy’s backing of Franco’s forces in the Spanish Civil War. Despite having completed one attack against a light unit, there were no registered successes. A year later, in 1938, both units were transferred to the Red Sea to join the Massaua submarine flotilla.
Having returned to Italy, at the beginning of the conflict the Otaria was assigned to patrol areas in the western Mediterranean. Soon after, the unit was selected as one of the boats to be relocated to the newly established Atlantic submarine base of Bordeaux. Departure took place on September 23rd under the command of Lieutenant Commander Giuseppe Vocaturno. Five days later, on the 28th, the Otaria began the crossing of the Strait of Gibraltar in adverse sea conditions and with great phosphorescence (luminosity of the sea water). Due to a failure with the hydraulic system, maneuvers took place utilizing the manual override for both the rudder and planes. This would be the first of many breakdowns this submarine and its crew would have to endure. Soon after, the crew began noticing waterways around the periscope gaskets and one of the propeller shafts. Despite the sudden and continue loss of depth, and mostly thanks to the complete absence of British patrols, the Otaria was able to cross the strait. Having consumed much more fuel than expected and with a diving depth limited to 30 meters due to the aforementioned infiltrations, the captain opted to abort his patrol mission and on September 30th headed directly for Bordeaux where the boat arrived on October 6th.
After a few days for refitting and to perform temporary repairs (the base was not yet fully equipped), the Otaria was once again sent on patrol leaving base on October 14th as part of the “Malaspina” group along with the Malaspina itself, Dandolo and Barbarigo. Three days later, while en route off the coast of Ireland, there was an encounter with a British Sunderland described in the mission report:
We sighted a plane coming out of a cloud at close distance (2 to 3,000 meters) moving in the opposite direction. Judging a dive too dangerous due to the [short] distance, we increased speed and since the plane did not respond to our signals, we opened fire. As soon as I saw the plane fixed on our direction and getting closer, I turned full rudder thus getting away from the launching path and, as soon as they were closer, we opened fire with two machine guns observing the plane being hit several times. The airplane, a Short Sunderland, repeated the same attack maneuver which we avoided with continuous turns and precise use of machine gun [fire]. I noticed that by turning at the last minute, in addition to giving the gunners a better target, the airplane could not follow our change of direction. During the exchange of fire, a bullet hit and destroyed the protection shield of the radio-finding antenna. The attack continued for 22 minutes and when the plane was hit at very close range (200 to 300 meters) by our machine guns, it suddenly lost altitude and veered away from us. Since we were heading the opposite direction, I ordered a crash dive limiting our depth to 40 meters until a safety plug could be installed to stop water infiltrations from the broken direction finding antenna. While submerged, we heard three loud explosions coming from the direction of the airplane which made us believe that they were getting rid of their load of bombs.
From the 23rd of October onward, the Otaria continued patrolling off the western coast of Ireland while the weather was particularly foul, causing the malfunction of the two upper torpedo tube launchers both forward and aft. Furthermore, both the hydraulic system used to elevate the periscope and the one controlling the rudder kept failing. From the end of October until the first few days of November, the boat sighted 4 ships and a tanker, but due to the impossible weather conditions an attack could not be even contemplated. On the 5th, at night, Captain Vocaturno launched two torpedoes against a large passenger ship which was proceeding with all lights obscured; there were no hits. On the 9th, while already on its return voyage to Bordeaux, the crew sighted an aircraft carrier escorted by three destroyers of which they lost sight very quickly, but for which they were able to send a discovery signal which was picked up by the Marconi.
After the miserable patrol, the boat reached port on November 15th. The missing highlighted the inadequacy of the Glauco class design for patrol in the northern hemisphere: the cunning tower was too visible, the exposed part of the hull too vulnerable to damage, and most of all, speed never exceeded 10 knots.
After a period of refitting, the Otaria was once again sent on patrol leaving Bordeaux on January 24th, 1941 as part of the “Baracca” group along with the Baracca itself, Morosini, and Dandolo. Soon after departure, the boat began experiencing serious mechanical failures, including one with the hydraulic system used to control planes and rudder, the valves controlling the ballast tanks and dive tanks. Unable to fix these problems at sea, the boat returned to base arriving on February 1st.
After repairs, the Otaria was assigned to a mission off the coast of Ireland to be conducted in concert with the German ally and under the directives of B.d.U. (Befehlshaber der U-Boote). The boat was part of a deployment group which included U-boats and aerial reconnaissance by the Luftwaffe. The Otaria left port on February 2nd reaching its patrol area on the 13th and remaining there through the 24th. The events that took place during these few days are very confusing and still the object of much historical review.
On February 19th, the Luftwaffe signaled the presence of a convoy of about 30 ships, probably OB.288. During the events that followed, Italian and German submarines alike attacked the convoy, thus creating great confusion in regard to credits for the sinking. Confirmation of the fact that this area was full of submarines is given by the sighting of a periscope made on the 22nd of February by the Bianchi (57° 55’N, 17° 40’W). It is assumed that this could have been the periscope of the Marcello which, faced with intense antisubmarine activity, was lost in circumstances to this day unclear. The Otaria returned to Bordeaux on March 1st without having achieved any notable result.
On May 6th, another patrol began, this time as part of the “Morosini” group which included the Morosini itself along with the Bianchi and Barbarigo and again for a patrol in the North Atlantic. The boat reached the patrol area on the 10th, remaining there for 10 days. Differently from the previous missions, this time the Otaria was able to actively participate in the fight. Even during the transfer voyage the crew had sighted a motor ship, but the great difference in speed made any attack improbable.
On the 10th, after having launched a torpedo against a destroyer, the Otaria was subsequently attacked by two aircrafts which swept the cunning tower with machine gun fire killing three crewmembers. On the 11th, there was another torpedo launch against a ship which, possibly damaged, disappeared in a squall.
While in the patrol area, the Otaria was directed by Betasom to attack a convoy previously sighted by the Bianchi. Having failed to do so, on the 15th the unit was relocated, along with the Morosini, Bianchi and Malaspina to a different area. Soon after, the Morosini and Malaspina, having spent their fuel, began the return voyage to base while the Bianchi, Barbarigo (which had just arrived) and Otaria were relocated further north. During this phase, one of the propeller shafts failed, leaving the submarine to operate with only one engine. On the 19th, while the crew was still attempting a summary repair, the lookouts sighted the smoke of a convoy of about 23 ships escorted by 6 light units. This was SL.73, a slow convoy from Sierra Leone to Great Britain. Despite the handicap, the captain moved on conducting a courageous attack described in the mission report.
May 19th, 1941
08:30 While we were lifting the ball bearing of the right propeller shaft, we sighted smoke on the horizon far enough to leave us in doubt whether it may be clouds. We stopped the repairs and turned toward the smoke.
10:00 Smoke and masts are quite clearly defined indicating a convoy escorted by several destroyers bearing 60°. We proceed to bring ourselves to a better viewpoint. At about 18,000 k. bearing 35° true north we conformed a convoy of 24 ships on about three columns escorted from behind and from the sides by 3 destroyers and 3 corvettes for anti-submarine protection.
The convoy is at 350° off our bow. I cannot consider getting ahead of the convoy in daylight since my engines smoke copiously and, having interrupted the repairs on the left propeller shaft, I don’t know how much speed I may safely rely on.
I then head for the rear of the convoy with the intention of getting ahead of it at night.
22:00 We remain all day in sight of the convoy up to seeing the masts, but pulling back each time we started seeing funnels. From this viewpoint, we see that the convoy is made up of a ship of small displacement (2-3,000 t.) and only two larger cargo ships in the middle column toward the head of the convoy where the escort performs particular surveillance. About every 4 hours, from the main body of the convoy, a destroyer takes off to patrol the rear up to 5 miles away from the last unit. It is necessary to prevent the maneuver by rapidly reverting course. The convoy does not zigzag. The various observations confirm that the bearing varies at the most 10° off the main course.
22:10 I begin moving starboard of the convoy to get ahead of it. We sight a reconnaissance biplane on anti-submarine patrol. We dive and very far away and not directed at us, we hear the sound of explosions. We stay submerged for 1 hour and 25 minutes. While submerged, we pick up, still onto our bow, the convoy’s smoke. At sunset, the situation is as follows:
The convoy continues on course 65°. The submarine (with the starboard ball bearing overheating, and the portside propeller shaft leaking) is about 20 miles starboard of the convoy.
May 20th, 1941
Since we are much to the left of the convoy, I turn 90° to reach the convoy whether its course might be between 0° to 90°.
00:13 Full force ahead. After 5 minutes at this speed the main valve of the exhaust manifold and the exhaust pipes spew many sparks, which make the stern very visible.
We must slow down. Visibility is mediocre with scattered clouds which make the horizon visibility variably good.
3:30 We sight the bows’ shadows of the convoy and we head toward it.
0:40 We start distinguishing the shapes of the ships. The convoy continues proceeding with bearing 60° on three columns. I discard the idea of attacking the smaller ships to the side and I move toward the center of the convoy where the two larger ships are located. To their sterns, I sight smaller silhouettes, lower and faster which I assume to be destroyers and corvettes for anti-submarine patrol. To their sides, on both sides, another three silhouettes which go back and forth from the stern of the last larger ship to 45° ahead of the convoy. The formation is kept quite badly. The ships are not perfectly aligned one to the other and the patrol boats on the right were cutting over between the second and third column.
Once again, I discard the idea of attacking the smaller ship I have to my bow (2-3,000 t.) and I pass by its stern to attack the two larger ships. Crossing between the first and second column, I slowly catch up with the ships since being on parallel course our gain is minimal.
0:15 We are to the bow of the second ship and about 600 meters. We start turning starboard but we are fading too much by the stern, thus we slow down the turn to bring ourselves more toward the bow up to finding the boat 45° to the bow with bearing 150 at 450 meters.
4:20 Two torpedoes are released. I start turning starboard, but aware that to our stern some smaller silhouettes are moving toward us, I turn full rudder portside. First we hear a thump and we see, by the bow of the ship, a large column of water. A few seconds later, we hear a second hit and we see a large flare. The ship stops, whistles, bends toward the center and launches a flare sending out twice the signal “SSS n. 14 torpedoed”.
We move on to attack the second ship but noticed the three destroyers by the bow which had reverted course and are coming toward us. I turn more portside because I am sure not to have been sighted but I am thus unable to conduct the second attack. When I believe to be safe from the three destroyers, which have lit a blue projector, three subsequent illuminating rockets are sent in our direction, lighting us in full. The engines, which I have ordered full speed ahead, smoke and spark making a perfect reference point. The destroyers point toward us. We crash dive going down to 80 meters. As soon as we are submerged, I sense that the left propeller shaft lost the seal which we had to be tide down up to touch [ the ball bearing] and that the right ball bearing is overheating. We are forced to turn on the pumps to lighten the boat.
The hydrophones, in addition to the sounds from the convoy, distinctively pick up various sounds of turbines [destroyers] and motors [corvettes] which go away, come back and at times stop. After about 15 minutes of total silence, I decide to resurface to attack the convoy. While we are at 50 meters, the hydrophone picks up a turbine approaching. We move again back to 80 meters. At this depth, the sound of propellers passing above us is clearly heard, and a few seconds later, 4 extremely loud explosions, one by the bow, two toward the center, and one by the stern shake the boat.
The lights go off, all light bulbs break, the hydraulic pump stops, the levels shatter in a thousand pieces, the gauges’ hands go off scale. We move to manual controls. All the remaining equipment stopped: compass, power converter, etc. Nothing is working. From the rear compartment, I am informed that the seal of the left axel came off due to the explosion. In such conditions, I decide to return to base and move south using the life boat emergency compass.
I ordered the portside axel stopped and the pudding retainer pushed to the maximum. I kept the boat down by the stern so that the water in the rear bilges would not spill into the electric motors.
I took the boat down between 80 and 110 meters. The hydrophones once again indicated that the destroyers had stopped, up to the point when one of the moved full force ahead toward us. The rudder was already turned, so we pushed the portside propeller full force ahead.
Four new explosions shook the submarine causing a large water way from the compass repeaters and some minor leaks around the battery hold hatch. The explosions followed regularly, but the forth time around moved away quite rapidly. The situation was grave.
The boat was in the following conditions:
The portside axel is stopped to reduce water infiltrations which was nevertheless considerable (700 liters per hour). The starboard axel was overheating and could only be used seldom while cooling it down. High air pressure inside the hull due to a leak from one of the valves. Gyro stopped and magnetic compass unreadable. Bilges full of water and spilling over. Unable to use the asset pump due to the explosions.
For an hour, we remain around 100 and 112 meters quietly moving water and personnel from aft forward, alternating the use of the motor, and with a partial release from one of the tanks.
07:45 The main tank were empty, the bilges were spilling over the right axel ball bearing reached an unsustainable temperature. Fortunately, the hydrophones indicated that the destroyers were moving away.
08:30 I order the thermal engine readied, called the gunners to station, and while I kept the battle flag ready, I blew the tanks. As soon as the hatch was opened, I noticed that the horizon is quite narrow due to the presence of strong and low clods and fog. I ordered the diesel engine started and I moved away full force ahead. During the day, we made some emergency repairs to the damaged equipment. The bombs caused the breakage of the safety and protection glass of both periscopes. In such conditions, I decided to return to base and I turn south using the portable compass.
May 23rd, 1941
Still on my way back to base, we sighted a dingy with two men aboard. After a difficult maneuver, due to the condition of the sea, I took aboard two shipwrecked sailors, survivors of the 39 crewmembers of a French ship sunk with the gun by a british submarine, eather K26 or K36.
Signed C.C. Giuseppe VOCATURO
The ship in question was the “Starcross” the only vessel of the Exmouth Steamship Co. Ltd, a 4,662 t. steamship built in 1936 by the J L Thompson & Son shipyard of North Sand, Sunderland. The vessel, damaged beyond repair by the two torpedoes, but still afloat, was later sunk by the escort after the 40 crewmembers were rescued. According to the British report, this attack took place in position 51° 45’ N, 20° 45’ W. Due to the very precarious conditions, the submarine began the return voyage to base arriving in Bordeaux around the 24th of May, but not without first having saved, just off the Gironde, two French fishermen, only survivors of the fishing boat “Notre Dame de Chatelet” sunk by a British submarine.
During this period, the Italian government wanted to return all submarines located in Bordeaux back to Italy. The issue was discussed at the highest levels, especially because Germany had only 30 submarines operational and needed the presence of the Italian boats. The German submarines were smaller and better suited for the Mediterranean, the Italian boats larger and more useful in the Atlantic. Still, Mussolini received permission from Hitler to withdraw the Italian submarines and on June 8th an order was issued in accordance. Soon after, on the 14th, Admiral Doenitz went to Berlin to request the reversal of this order. Admirals Reader, Weicholz, Riccardi and Parona were called to resolve a very difficult diplomatic and military situation. Finally, a compromise was reached; of the 27 Italian submarines still operating in the Atlantic, only 14 would be sent back. Eventually, due to war losses, only 10 submarines made the journey back, among them the Otaria (the other boats were the Argo, Dandolo, Veniero, Brin, Mocenigo, Velella, Emo, Otaria, Perla, and the Guglielmotti).
The Otaria left La Pallice on September 7th and, while approaching the Strait of Gibraltar, was sighted by light enemy units and attacked with depth charges which did not cause any damage. The crossing began at 1:30 AM on the 14th, navigating on the surface in excellent weather conditions and a waning moon. Around Cape Malabata, 6 miles east of Tangier, Morocco the submarine dove reemerging away from the highly patrolled area and well into the Mediterranean. Uneventfully, the Otaria arrived in Naples on September 19th to begin the grueling routing of transport missions and small patrol in the dangerous home waters.
December 14th, 1941, laden with 11 tons of foodstuff, the boat left Naples arriving in Bardia on the 19th from which it left the same day. Upon arriving in Taranto, on the 24th of the same month, Captain Vocaturno passed command to Lieutenant Alberto Gorini, while his second in command, Lieutenant Amendolia became the commanding officer of the submarine Finzi.
From January 1st to mid April, the Otaria was assigned to the submarine school in Pula where it completed 16 training patrols to prepare new crews. In May 1942, it was sent back to Taranto. The same month, from the 4th to the 20th, it was on patrol north of Cape Caxine. In June, from the 13th to the 18th, the boat was sent on patrol off the Algerian coast where, on the 13th, it was attacked by a British Sunderland which was repelled by the intense fire of the submarine’s 13.2 mm Bredas. Two days later, having sighted an enemy formation, it failed to get close enough for a launch; eventually it returned to Cagliari.
The grueling routine continued with another patrol from June 29th through July 19th south of the Balearic Islands. In August the boat was once again off the Algerian coast until Midsummer Day. Thereafter, it returned to Cagliari and from there it was sent to Taranto for repair work requiring a better equipped base.
After a long period of refitting, several transport missions followed for a total of 119.6 tons of war materiel ferried to North Africa, including 63 tons of gasoline, 45 tons of ammunitions and 11 tons of foodstuff. In February, having assessed that the efficiency of the boat had greatly diminished, the submarine command sent the Otaria back to Pula where it completed another 79 training patrols.
On the day of the Italian unconditional surrender (September 8th, 1943), the Otaria was in Fiume (Istria). Following orders, it moved to Taranto to surrender. Instead, it was rerouted to Augusta from where the British authorities ordered the boat to Malta. On October 6th, the Otaria returned to Italy and was assigned to Taranto (under British occupation) where it was used as a training target until the end of the conflict. Soon after, it was removed from service and later sent to the junkyard. It was the end of a long operational life for which the Otaria had only a single sinking to its credit.
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