Special transport supplies to isolated japanese garrisons WW2

[VG33-Arsenal]

Hello, i'm looking to experimental projects for supplying isolated japanese garrisons in ww2.
For example: Special containers used with submarines.
Unkato, Tokugata Unkato, Unpoto.
Special waterproof landing craft on after deck of submarines.
How the supply were stoked on the deck ? With a net ?
I-36 had 12 Rubber containers with food supplying Guadalcanal
I-36 had also an Unkato Container for supplying Kiska.
I-38 was used to carrying Unpoto for Truk
Submarines typ D-1 special transport could be fitted with a landing craft on after deck but i don't find if it's a Dahaitsu or a Chuhatsu.

Source: combinedfleet

If you have drawings, pictures, some others additionnal information, i will very glad.
Happy new year.

VG33

 

[Temistocle]

I found some info in the US Pacific Fleet Weekly Intelligence, below the pages extracted (I attached also info abut a small Army supply sub, maybe it is interesting)

 

[tom!]

Hi.

Following Jentschura, Mickel, Jensch there were three types of the Unkato submersible containers plus a motorized prototype designate Special Unkato-Type. All had a tube-shape body with cones at front and fins at the rear. The access to the inside was possible through umber of short turrets with hatches on the top of the bodies. All three were towed by larger submarine types and beached to be unloaded.



The drawing attached are from that book. But the only pic of an Unkato 3 Type container I have shows a different rear shape than in the drawing. So I don´t think the drawings are 100% correct.



Regarding the landing craft, drawing from the same source (and same reliability problems): Daihatsu Chuhatsu and Shohatsu could not made water-tight. Therefore the Unpoto-Type powered by two Type 93 torpedoes without warhead was designed by the Navy to be carried on deck by submarines. It had a waterthight transport compartment with a closing ramp the bow and it was possible to transport additional load on deck. But the deck load had to be unloaded from the submarine before launch making them vulnerable.



Yours

tom!

 

[tom!]

Hi

The japanese Army used speedboats, transport submarines and semi-submersible boats as special transport vehicles.

The submarines were designated "Type 3 Transport Submarine Maru-Yu" and are also known as "Yu-Go submarines". They had a standard displacement of only 230 t and were powered by two simple 200 HP Hesselmann-type engines for 7,5 kn on the surface and two small electrical engines with limited battery load for 3,5 kn submerged. There were no watertight compartments to increase the payload capacity and to allow easier transport of larger crates. The boats had no torpedo tubes but a modified Type 1 37 mm Tank Gun as deck gun plus some MGs for (more or less symbolic) close defence if necessary. The total transport capacity was around 20 t.


The transport speedboats were introduced in 1943. As most japanese speedboats they were modified Thornycroft-Type with a length of 33 m and a width of 5,5 m. It was designated "Yi-Go Speedboat" and had a displacement of 95 t with 30 t payload capacity. Three 800 HP gasoline engines allowed a maximum speed of 25 kn. The crew was up to 28 men. Armament consisted of a mix of Type 4 20 mm twin AA-Maschine Cannons and modified 37 mm tank guns with a total maximum of three guns. Only around 30 boats were built



The semi-submersible boats were designated "Maru-Se Transport Boat" and are still some kind of mystery to me. They were related to the "Type 5 Semi-Submersible Attack Boats" but had a larger transport compartment instead of the explosives compartment in the bow. Both types were able to drive slightly below the surface similar to the modern drug cartell semi-submersibles. A small conning tower above the surface allowed orientation and navigation up to a certain roughness of the sea. Sadly I have no data on this boats.



Yours

tom!

 

[World B4]

H I Sutton - Covert Shores

 

[Justo Miranda]

Very interesting and unknown to me, I had read that the Japanese destroyers supplied the troops on Guadalcanal with half-full drums tied to each other that were then recovered by boats from land.

 

[Temistocle]

There is a paper about IJA transport submarine YU-3 on Warship International, 1998, N.1, and other comments in a letter printed on the 4 of the same year.
And a paper about the "Maruyu" Submarines on N.3 of the same magazine, 1999.

There are a couple of pages (in japanese) about the containers (and some images, as the picture of post #3) in the book "Warship of the Imperial Japanese Navy Photo File №20" (IJN Submarine Vol.2).

Some info (in english) at pages 204-206 of the 1947 book "Japanese Navy Vessels at the end of WW2". You can find it here (it is a fantastic website).

 

[tom!]

Hi.

A big THX for that link. Besides the mentioned book there are also several Navy related rare gems like a 1945 japanese overview of the late-war IJN rocket development etc.

Yours

tom!