Ss-type transport submarine [Japan]

[copeab]

Ss-type transport submarine
Copyright 2005 by Brandon Cope

The Japanese operated several classes of transport submarines during the war, although only the large D1’s and small Ss were built in any numbers. The Ss Type (also known as the Ha 101-class, from the first one built) was designed solely to resupply garrisons cut off during the Allied island hopping campaign, where certain Japanese-held islands were simply bypassed and blockaded, their garrisons left to starve. The submarines were assembled from prefabricated sections due to bombing raids, with some constructed in as few as five months. Only nine were built out of a planned 100 boats before the war ended.

The Ha 101 has a crew of 22. It carries no torpedoes and mounts only a single 25mm AA cannon at the rear of the conning tower. It does have provisions for 60 tons of cargo and normally can operate for 15 days. The engines burn 11.9 gallons of diesel fuel per hour of routine usage. The Ha 101 can travel 3,000 miles at 11 mph surfaced and 53 miles at 6 mph submerged. Fuel, ammo, and provisions cost $1,140.

Sen-Yu-Sho (Ss) Type Transport Submarine

Subassemblies: Very Light Corvette chassis with Sub option +8; sealed Large TD superstructure [Body:T] +3; full-rotation Medium Weapon open mount.
Powertrain: 298-kW marine diesel engines with 298-kW water screw and 2,300-gallon standard tanks; 112-kW electric motor with 8.64 million-kWs batteries†.
Occ: 20 CS Body, 3 CS Sup Cargo: 290 Body, 6 Sup, 3.5 OM

Armor
Body/Sup: 4/20
OM: 0/0

Weaponry
25mm Med. Ground AC/96 Shiki Kikanho [OM:F] (1,000).

Equipment
Body: Autopilot; 2¥backup driver controls; 600-VSP bilge; 12¥bilge pumps†; 12¥bunks; 960-VSP cargo holds; 25-man environmental control†; 5¥fire extinguishers†; 22-man-days life support†; navigation instruments; precision navigation instruments; 440-man/days of provisions; 2-mile passive sonar. Sup: Navigation instruments; 1¥20’ 15¥ periscopes; large radio direction finder; 2¥very large radio receivers and transmitters; searchlight. OM: Universal mount.
† Limited access.

Statistics
Size: 146'¥20'¥14'	Payload: 129 tons	Lwt.: 370 tons
Volume: 3,080	MH: 16 hours	Price: $163,000

HT: 12. HPs: 27,000 Body, 450 Sup, 75 OM.

wSpeed: 11	wAccel: 0.1	wDecel: 0.5(0.6)	wMR: 0.05	wSR: 4
Draft 8'. Flotation Rating 429 tons. 
uSpeed: 6	uAccel: 0.05 uDecel: 0.3(0.4)	uMR: 0.05	uSR: 4
uDraft 33'. Crush Depth 103 yards.

Design Notes
The 370-ton historical submerged weight was used for underwater performance. Lwt. has been increased by 4%.

Variants
The ten STS class (Ha 201) coastal boats were of similar displacement, but carried two 533mm torpedo tubes (with four torpedoes) and had double the submerged speed. They had no significant cargo capacity.

(((START BOX)))
UNDERWATER FREIGHTERS

Japan was the only nation to build a large number of submarines dedicated to carrying cargo and troops in WWII. Other nations generally converted existing submarines (usually minelayers) to the role; the Argonaut (p.00) is one example, as is the Typ XB U-boat (p.W:MP115), or built them in very small numbers. Although destroyers were often pressed into the transport role, they lacked the inherent ability of submarines to hide from view.

The Ss-class was the smallest of Japan's transport subs. The next size up was the D1, 248' long and displacing 2,215 tons. It could carry 85 tons of cargo and over 100 troops, plus two boats to transport them between the sub and shore. Crew was 60 men and armament was one 5.5" gun and two 25mm guns. It could reach wSpeed 15 surfaced and uSpeed 7 submerged. The first of twelve boats entered service in 1944. All were lost in combat.
Japan's largest supply submarine, the SH class, was actually a mobile seaplane base. It could carry 370 tons of fuel, 20 tons of torpedoes or bombs, and 10 tons of water. Space was also provided for up to twelve seaplane crewmen to rest. The SH was 364' long and 4,300 tons displacement. It was armed with four 533mm torpedo tubes and seven 25mm guns. It had a crew of 77, wSpeed 18 surfaced and uSpeed 7. Only one was completed, in 1945, and was sunk shortly before the war ended.

Apart from the converted Cagni class (p.00), the Italians also built the R-class transport subs, only two (Remo and Romolo) of which saw action in WWII (the other ten ships of the class were sunk, scuttled, or finished after the war). They were 232’ long and 2,606 tons. Crew was 63 and cargo capacity was 21,200 cubic feet (4,240 VSPs) in four holds. The subs were armed with only three 20mm antiaircraft guns. The R-class could reach wSpeed 15 on the surface and uSpeed 7 under water. The Remo was sunk in mid-July, 1943.
(((END BOX)))