The Ship Model Forum

I’ve been working on several projects over the last two years but just haven’t had the time to post any W-I-P threads. Things have finally eased up a bit for at least the moment. So, a bit belatedly, here is a thread for the IJN fleet oiler Kazahaya, completed last fall, 2024. I will post installments as time allows. A quick preview of the end result:

First, some lengthy background on how this came to be:

The release of Aoshima’s 1/700 Hayasui fleet oil tanker kit in 2016 was an unexpected and pleasant surprise. I picked up one immediately, thinking I would build it within a reasonable amount of time, but that never happened. I find Hayasui a fascinating ship; basically, it was one of the IJN’s Kazahaya class tankers modified to carry attack aircraft as a supplement to their regular force of aircraft carriers while also providing UNREP capabilities. However, that was bit of a desperation move, coming too late for any meaningful participation. Hayasui never carried more than a few E13As seaplanes to supplement ASW and reconnaissance efforts.

As time has gone by, plenty of Hayasui builds have appeared on numerous modeling sites. While still interested, I found myself even more intrigued by the possibilities offered by the Hayasui kit hull. All the Kazahaya class ships, and the subsequent 1TL standard wartime tankers, were all based on the hull and machinery of Kuroshio Maru, which was the only Kawasaki type tanker built using a steam turbine engine instead of a diesel engine. Kuroshio’s hull and appearance was otherwise identical to that of the other Kawasaski type tankers. The Kazahayas retained the same basic hull with some simplifications, and utilized a more compact bridge structure and simplified aft deckhouse. They also were better armed.

The Kazahaya class tankers were a response to the Japanese Navy’s recognition that the twelve Kawasaki and three Harima built, Kawasaki type tankers would not be sufficient to handle the IJN’s UNREP and oil transport requirements. Nor did these ships accommodate the additional transport of aviation gasoline. As a result, four steam turbine powered fleet oilers were included in the Japanese Rapid Naval Armaments Supplement shipbuilding program of 1941. (This is the same program that authorized the construction of CA Ibuki, CV Unryu, the second batches of both the Yugumo and Akizuki class destroyers, and several kaibokan classes. ) However, the IJN found its own shipyards overwhelmed by new construction in 1941, so the design was contracted out to Harima Shipbuilding, which had already built Kuroshio Maru.

Only Kazahaya and Hayasui were ever completed of the class; the latter to a modified design. For the record, Kazahaya was laid down on September 30, 1941 (before Pearl Harbor) but not completed until March 31, 1943. She had a brief service life of six months before being torpedoed and sunk by USS Steelhead.

The other two were cancelled (probably because of the lack of available shipyard space), though another seven such ships were authorized two years later. These, too, were cancelled. In their place, another four fleet oilers of the Hario class were authorized in 1943-44, but only Hario was ever completed. The Harios were 1TL tankers to be built by Harima strictly for the navy.

Unlike the Kazahayas, the 1TL ships were built as commercial ships that could be, and were, requisitioned by the IJN for oil transport. Also, to the best of my knowledge, they did not carry avgas and carried less armament. The hulls were the same as the Kazahayas, but their forward bridge structure was that of a commercial tanker, though simplified as compared to the Kawasaki type. Nineteen such ships were completed during the war, and several more afterwards.

So, I had several choices open to me. I toyed with the idea of building one of the 1TL types as used for UNREP by the navy, but eventually decided that I wanted something that was more distinguishable from the Kawasaki type tankers that I’d already built. Hence, Kazahaya.

The build would be aided by the virtue of Kazahaya having the same bridge structure as Hayasui, along with a tripod crane/mast and other shared features. At the same time, the build would be hampered to an extent by the lack of official plans or full views of Kazehaya. There are descriptions, and countless extrapolated, but speculative drawings of her and the class, but nothing definitive. There are three photos of Kazahaya, but they are all focused on her bow at the waterline. One of these shows a portion of her bridge and its similarity to Hayasui. Still, the hull set-up was pretty basic, as were the deckhouses. It’s really a matter of the smaller details.

Here’s the available Kazahaya information, outside of written descriptions. It’s possible that there’s something in some Japanese archive somewhere, but it hasn’t surfaced as of yet that I know of.

It also helps immensely that Motoyuki Iwashige, noted Japanese author and modeler who focuses on Japanese merchant ships and merchant auxiliaries of WWII, happens to have authored two articles published in Model Graphix magazine that deal with conversions of the Hayasui hull. So, his work greatly simplifies the task of measuring out facets of a conversion. Below is the graphic from his article in Model Graphix v.408, November, 2018 that discusses the wartime 3TL type tankers. Depicted is alterations to either the Hayasui kit (top) or the Fujimi Kawasaki type tankers (bottom) as the basis for a conversion. Of course, as great as it is to have plans, execution is just as critical.

A view of the Hayasui kit and hull prior to start.

I started by just cutting some styrene sheet for the new main deck and positioning some components. (and stay tuned)

I then took the plunge and cutdown the forward bulwarks to return the hull to its original configuration, then test fit the forward part of the main deck. Once satisfied, I glued the scalloped portions of the bulwarks that I had removed into their original design position and sanded everything smooth. Drilled out some portholes as well.

Maybe now is a good time to mention that the Hayasui hull is a more accurate representation of the Kawasaki type/1TL type hull than the Fujimi Kawasaki Type kit hulls are.

Love it! Will follow with great interest!

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http://www.3xblackcats.wordpress.com

Great work on the conversion of this kit.

Greetings Christian

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At work:

1/700 IJN Yahagi

Thx, guys. I'm glad it's been found interesting.

I then prepped the forecastle and stern decks, as well as add the mounts for the main oil transfer line to the main deck, along with bollards. Initially, I thought I might be able to retain much of the molded on detail, but that proved to not be the case.

After completing some additional work on the stern deck, I masked off the main decks for painting. This occurred at an earlier stage than with my Kawasaki tanker builds, to take advantage of the mostly unobstructed decks.

Time to go down the rabbit hole once again with another epic DanK build. Dan, the final version looks great. Did you just make a lot of assumptions based off other Japanese ships or were you able to find some data to help with the construction?

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- Greg

Also, gotta ask: what are you using to make significant cuts in the hull? Hand saw? Power tool?

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- Greg

Thx, Greg. Yep, another rabbit hole. Maybe not so deep this time around.



The details are mostly extrapolated from what hard information and visuals are available for Kazahaya, Hayasui, the 1TL ships, and Harima Shipbuilding as well as assumptions about circumstances in 1943. My result doesn't seem too much different from the few builds I've seen out there, just differing in certain details. To a certain extent, there's some reverse engineering of Hayasui, as Hayasui was modified from the Kazahaya design.



Mostly my trusty handsaw and a razor blade. All hand powered.

While tempted to add railings at this point, I thought it wiser to do some basic superstructure construction to minimize messing up the railings (something I’m a little too good at). I focused on the aft superstructure.

This utilizes the central housing of the Hayasui kit (and standard 1TL versions) and adds outer compartments. These were crew accommodations. I chose to utilize styrene V groove to represent wood planked decking for the boat deck above. The wood is somewhat speculative, but this was the practice for the merchant tanker designs. It would have also cut down on heat absorption on the deck above the living quarters.

I also experimented with two in-line bandstands astern for two 12cm mounts, per some depictions and descriptions. However, I ultimately opted for a different configuration, given the 1943 time frame of her completion and the trend toward more AA. Eventually, there will be a 25mm AA mount and bandstand on a superimposed platform. Again, this is speculative but not unreasonable for such an important fleet asset.

Unusually for me, I opted to not replace the funnel’s molded on ladders with PE versions. The molded-on ladders are pretty good; I judged that replacements wouldn’t gain me much. Other opinions may differ.

Other bitts were also added to the stern deck along with solid rails for the aft refueling sponson.

Eventually, I decided to advance the completion of the aft superstructure to a standalone module for later placement.

Hi Dan!

As said before: EPIC!
As usual, I like your sharp work and methodology thru the build.
Raillings damage: you're not alone

Thank you
Rui

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Ship Modelers of the World UNITE

Thx, Rui.

This build wasn’t exactly linear, so work on the bridge superstructure was intermittent. I’ll lay out the basics now.

You’ll note that the first level (01/bridge deck) is wood planked liked the aft boat deck, as opposed to a metal deck. This is strictly my call and not because of any solid reference, because there aren't any that I’m aware of. My feeling is that it’s primarily a merchant design being constructed by a private shipbuilder whose tanker designs typically utilize wood on this deck. Opinions may differ.

The upper portion was specifically designed for naval applications and is essentially the same as the Hayasui version. I’ve tweaked it with details that apply to IJN design. The proximity of the searchlight platform to the RDF antenna are typical for the IJN and reversed from what was Hayasui’s layout. Why Hayasui had these two positions reversed is anyone’s guess. Maybe it had something to do with the closeness of her foremast.

While most of the PE is from the dedicated Hayasui PE set, the searchlight platform is scratch-built from spares, along with a 90cm FineMolds searchlight. Forward, the kit provides what appears to be 3.5m rangefinder for the main battery. I installed a low railing around it and an access ladder. The Hayasui kit bridge top just provided some generic raised columns in front of that. I cut those off and placed a 2m navigation rangefinder in front of that, then a 25mm gun director at the fore (for the triple 25mm AA mounts to either side of the bridge). My reasoning here is that a naval auxiliary gets navy grade equipment whenever possible. Later during the build, after the bridge was painted, I added a custom shaped wooden grating topped by two 12cm search binoculars in that open space in front of the 25mm director.

I also speculated about linoleum decking on the compass bridge deck and placement of additional 12cm search binoculars and the navigation lights. What I chose made sense to me.

The 25mm AA bandstands have proper 25mm ammo boxes in place as well.

Moving along............

Prior to adding railings, I used Tamiya tape to mark off some hull plating lines. Doing so would allow for the buildup of different paint layers, showing some differentiation to mimic hull plating. It worked reasonably well on the Kawasaki tankers, so I repeated it here. I also improved on (IMHO) the small, kit bow sponson used for feeding out refueling lines when the tanker trailed its client vessel. I scratch-built a larger version similar to that seen on the Kawasaki type ships.

I then added railings to all the main decks using the railings from Aoshima’s comprehensive Hayasui PE set. Reconfiguring the kit hull to replicate Kazahaya just meant using the existing railings cut to different lengths. This set’s railings are a bit thicker in depth at .006” (scale 4.2”) then optimum for proper scale, but it’s by no mean unusable. It does make for a stiffer rail which is easier to handle, yet it still allows for a decent approximation of scale for the horizontal rails.

Another point worth mentioning is that these railings are solid horizontal two-bar railings, as opposed to the three (or four) bar railings used on pre-war built merchant ships like the Kawasaki type oilers. While two bar railings were more typical of IJN warships and purpose-built auxiliaries, the few photos of Kazahaya also show solid two bar railings in use on her forecastle. However, these were all rigid bars, not the drooped chain links used by regular IJN vessels. So, my guess is that Harima Shipbuilding simplified the railing type for the war-built tankers. The one existing plan of Hayasui also shows horizontal, two-bar railings.

I also needed to scratch-build access hatches for the oil storage tanks, the oil transfer pipes, and the aft pumphouse. It’s not known if the access hatches were rectangular like the prewar tankers or oval-shaped like most of the war-built tankers. Given when Kazahaya was laid down, I opted for a rectangular look. Likewise, Kazahaya’s exact transfer piping layout is unknown. Mine is based on the that of the following 1TL class, but I included a steam line as well for the pumps and winches.

The pump house was semi-scratch built using the unfinished version from the Hayasui kit as a base. Aoshima left it unfinished probably because it was hidden under the aircraft handling platform where it was barely visible. The finished pump house approximates those found on the 1TL class ships.

Also included at this stage was the assembly and painting a resin cast anchor windlass based on a prototype created during the Kawasaki tanker builds. I have a number of spares left from the castings by Mike C. The anchor chain is a 3D printed set from Shelf Oddity. Their IJN BB set worked perfectly here. Better views of this windless will appear later in the build. Some small deck hatches were added as well.

And a couple of views of the completed, painted bridge, forward bandstand, anchor windlass, etc. Some touch-up were needed at this point, particularly for the pump house.

Lovely as always, Dan

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Battle of Savo Island Collection (all 1/700)
Recently completed: USS Wilson DD-408
At works: USS Astoria CA-34 | USS Patterson DD-392 & USS Bagley DD-386 | HMAS Australia
Prep stage: USS Vincennes CA-44 | Yubari | Kako