Toho Maru

The following information on Northern Borneo wrecks was taken with kind permission from the Panaga Divers of Brunei,

web site http://www.panagadivers.com

Many thanks to Mark Tuttle, John Elder and also Maurice Davidsons book Brunei Laut.

Approximate position: 4 Deg. 53.078’ N  114 Deg. 08.705’ E
Date of sinking: 26th November 1944

The strange story of how our home wreck the Toho Maru turned out to be the Yuho Maru. Wreckage lying about 17 miles north of Kuala Belait has been well known to local fisherman for decades. The wreck was precisely located by Shell's Topographic department  in 1970, however, the first divers to locate the wreck and dive her were Ed Ehlman and some friends in 1979. The discovery was reported in the Borneo Bulletin with the wreckage identified as the stern of the Toho Maru largely based on a report in Lloyd's list.

It was the first of eight big wrecks offshore Brunei to be discovered and dived over the next 24 years, however, its location was forgotten as the first divers were transferred. Wreck locations in pre-GPS days were often casualties of vague transits and inconsistent local knowledge.

I 1989, a snippet from the 10 years ago column of the Borneo Bulletin, prompted Bob Lowe and Pius Cagienard of Panaga Divers to search for the wreck. With more than a little help from the Topographical department the wreck was located and dived once again in the early 1990’s. It has been dived regularly by the club ever since. Borneo Bulletin describes Ed Ehlman's discovery of 1979.

It's precise location is  4 Deg. 53.078’ N  114 Deg. 08.705’ E. (Please note that, like all Brunei Shell’s coordinates, the datum used here is Timbalai, not WGS84, and that we have quoted the coordinates in degrees : decimal minutes not degrees : minutes : seconds. Many fruitless searches for wrecks all over the sport diving world have been frustrated by the lack of these basic considerations).

In the Lloyd’s list of 2nd January 1982, there is a report of a wreck identified as the Toho Maru, sunk offshore Brunei at approximate location 4 Deg. 55’ 00” N;  144 Deg. 05’ 00” E. The wreck was sunk on 26th November 1944, two days before the Atago Maru of Piasau that was sunk in a bombing campaign conducted by the Australian Air Force. The wreck was described as a Japanese tanker of some 5,000 tons.

An early side-scan sonar survey conducted by the Topographical department of Brunei Shell identified the wreckage as a vessel lying on her port side with damage to the superstructure; bows bearing 302 Deg. The vessel appeared incomplete and scattered. The length and width appeared to be about 70 * 16 metres and the wreckage rose 14 metres from the sea-bed at 54 metres below chart datum. ROV pictures taken subsequently identified solid structure at 41 metres depth.

The last three paragraphs provide strong corroborative evidence that the wreck is indeed the Toho Maru, however, there seem to be some odd inconsistencies. The wreckage sits upright and comprises the poop deck and after well deck of a small tanker. The wreck does indeed lie on a bearing of 300 Deg., however, there is no point higher than 45 metres (the barrel of the stern gun). However, with some consideration of chart datum (usually about 1.5 metres less than the measured depths on the wreck), the gun barrel lies at 43.5 metres, the sea-bed at 52 metres but there is a deep scour around the vessel to 55.5 metres. Indeed, the wreck does stand 12 metres proud of the sea-bed; just!

For many years, the club searched for the bow section believing that the ROV reports referred to a much higher standing piece of undiscovered wreckage. No other wreckage was found, nor is reported by Brunei Shell. The solution was given by Ed Ehlman over a conversation with myself and Pius Cagienard in 1997. Typically of compartmentalized tankers, the bows never sank and were towed to Singapore in 1944

What remains is the heavily bombed stern of an approximately 5,000 ton tanker. It lies upright, and only the poop and after well deck are present. There is a distinct line across the ship forward of the gun where there is intense destruction and a huge hole on the starboard side. The line is probably a stern bulkhead. The ship is fairly well collapsed inwards forward of this line and there is another hole through the hull at what was the forward end of the engine room. There is no remaining superstructure; it was either blown off in the bombing or reduced by subsequent fire. The wreck has been colonised by all sorts of fish from small fry to massive groupers.

The modern sidescan sonar image (BSP below) agrees remarkably well with a drawing compiled from composite photographs taken from 33 metres looking downwards (Elder 1994 - The drawing was made before the side-scan sonar image was available).

Click on a yellow dot to see a photograph of the wreckage. All the shots were taken in natural light between 47 - 50 metres.

The diagram above was composed from a mosaic of photographs looking down from 33 metres. (John Elder and Mark Card - 20th August 1994).

The cat-walk lies, not on the vessel's centre-line, but over to port. This is typical of Japanese tankers of this period. Based on similar Japanese tankers (Shinkoko Maru and Fujisan Maru, Truk Lagoon), a rule-of-thumb can be proposed:-

gross tonnage = (length *width * draft in metres) * 0.37

Comparing the wreck of the Toho Maru's width with these other vessels (150 * 20 *9 metres for a 10,000 ton tanker), a tonnage of 3,400 to 5,000 tons depending on a width of 14 to 16 metres, can be pro-rated. This is in line with Lloyd's estimate. In conclusion, the Toho Maru was a Japanese tanker of about 120 * 15 *7 metres of which only about a 50 metre length remains. The gross tonnage was about 4,000 - 5,000 tons and the bulk of the wreck lies some four metres above the surrounding sea-bed excluding the scour.

Diving the wreck

This is a deep dive that will take the diver below 50 metres. The club used to have a rule that the ascent was begun after 15 minutes from leaving the surface or 100 bar showing on either divers' gauge, whichever came first. These days, the Panaga rule is that each diver must carry an independent air source, the most common configuration being 2 * 11 litres. This has extended the bottom times to 25 minutes for the few divers who use a high Nitrox mix for decompression. Total dive run times are about 70 minutes. The club feels that this is a dive for PADI Dive Masters / BSAC Dive Leaders and above, who carry an extended range qualification and are dive fit. This applies to all our deep wrecks.

11th October 2003
After three low vis. dives on the Toho this year, at last we were rewarded with decent visibility. There was a strong surface current flowing to the north-east, a consequence of the heavy recent rains from the Baram. Turbid river water with just a few metres vis. was present here 17 miles offshore and 25 miles from the Baram river mouth. Below 10 metres, the vis. increased dramatically and the current vanished. The presence of a large, and rather close, school of barracuda indicated that the wreck was nearby. Indeed, the powerful shallow current on the shot line suggested that the shot had hit the wreck and held. Below 27 metres, the entire wreck was visible. This is rare and a moment to be truly savoured. Arriving on the wreck at 49 metres we tied on a jump-line.

We spent the bulk of our 18 minute bottom time investigating the centre of the vessel for'ard of the gun. This area was once the top of the engine and boiler rooms, however, the collapse of the superstructure and the incredible bomb damage make it extremely difficult to sort out the mess. Certainly there are many pipes, the remains of a boiler and close to the starboard end of the boiler room bulkhead, there is a gaping hole leading to the open sea. More than anything, this is probably the damage that sank the Toho Maru 59 years ago.

After 18 minutes, the ascent began with the computers indicating about 22 minutes of stops. I was carrying two computers and it was instructive to observe the differences between them. On my left wrist I carried a second generation Aladin Pro (mid 1990's); on my right, a Buddy Nexus. The latter was set to its 'conservative setting' and indeed, on arriving at the Buddy's first stop at 12 metres, 25 minutes of decompression was indicated against the Aladin's 23 minutes. However, the Buddy will handle two gas mixes and I had pre-programmed it to go onto Nitrox 80 at 7 metres. At this point with the Aladin still requiring 18 minutes, the Buddy dropped back to 11 minutes showing the effect of accelerated decompression. I actually did decompress on Nitrox 80, however, I did the full air stop, partly to stay with my dive buddy who was decompressing on air, and partly because of the extra margin of safety. 

The idea of diving the wreck of the Toho Maru on trimix has been around for several years, however, having suitably qualified divers in the right place at the right time has not proved easy. Last August the dive was planned, however, boat problems, weather, leave and the fact that club diving must proceed as normal, thwarted our attempts. In 2004, the trimix scene changed with two new divers arriving in Brunei suitably qualified. Down in Miri, the Piasau Boat Club held a comprehensive suite of IANTD courses and even more divers became available, all eager to test their new skills on a proper wreck.

It was decided to nominate a date and then go for it, to avoid the insidious slippage that plagued us last year. The 31st July 2004 was chosen for the dive and, courtesy of the Piasau Boat Club's recent course, trimix was made available for us.

The uncertain weather of August, and a typhoon north of the Philippines spinning off squalls across the South China Sea, made forecasting something of a lottery and the dive was not even called until 7am on the day of the dive!. Even on the day, the dive was nearly cancelled before it even started. Squalls were forecast, and the example on right was one of half a dozen that rapidly moved through the area.

Nevertheless, we managed to avoid the squalls, put a shot in the Toho first time, and on 31st July 2004, John Elder (trimix 21/35), Dave Outhwaite and Peter Henneberg descended through the surface layer of turbid water to begin one of the classic Toho dives. Visibility of 25 metres allowed us to see the entire wreck in one go!

A striking feature of the wreck, particularly to John and Peter, were the obvious signs of collapse, not present when they use to dive it in the early 1990's (below right - click on the picture to see the wreck in 1993). The visibility retained its clarity down to about 55 metres where a cold layer a few metres above the bottom rendered a visit to the ship's propeller a waste of time on the limited 18 minute bottom time.

All too soon, the 45 minute ascent had to begin, as the trimix cocktail of 21% oxygen and 35% helium slowly had to be leached from the divers' bodies. The second wave of divers, Spencer Coca and Ronald van As, diving a 20/25 trimix began a longer dive, the smaller percentage of helium requiring less of a decompression penalty. This wave of divers was followed 15 minutes later by Steve Holyoak and Mark Tuttle (both on a trimix 21/35).

All agreed that the views of the wreck were stunning. A school of barracuda greeted the divers on the descent. Millions of small fry swarmed around the stern gun (above), and a quartet of large lion fish patrolled the aft deck. Jacks swirled above the wreck in true Sipadan style.

Our recently constructed decompression trapeze (right - B$ 35 in total) was a great success, even if launching the contraption was a acquired skill. It was a stunning dive that deserves repeating. We look forward to diving this enigmatic wreck again and again. Another generation of divers now understands what it means to say:-

"I feel a Toho coming on"

In August 2004, we discovered that our home wreck, the Toho Maru, was in all probability the Yuho Maru!

September 4th 2004:  Toho Maru ??

We enjoyed excellent visibility down to the Toho, whilst large schools of pelagics swarmed above us. The width of the vessel was measured by Terry Dukes and Dave Outhwaite to be 16.5 metres. This suggests that the vessel was a 5,000 ton tanker (Yuho Maru Class) rather than the 10,000 tons of the Toho Maru Class. This was the third trimix dive made by Panaga Divers. Typically, divers are carrying a mix of 2,800 - 4,800 litres of 21% Oxygen, 25% Helium for the dive gas, with 1,400 litres of nitrox 70% for the decompression gas. A 23 minute bottom time on the wreck at 50 - 54 metres allows the divers to return to the surface 45 minutes after they begin their ascent.

24th April 2005

John has tied on the 'jump-line' (white) to the wreck. The shot-line (top right) has just passed over the side of the ship. In 1993, this deck was horizontal !! A coral grouper grazes the stern (left).

Congratulations to Dale on his 300th dive which he kept secret until after the dive (as you should*). Large dolphins swimming in close groups of half a dozen enlivened the trip back to the KBBC. Thanks to an early arrival by our guests from further afield, we were out and back by 12.30. 

* I've a bee in my bonnet about 'special dives' as Dale and many others know. I'll mention it briefly here and perhaps, some day, expand about it in the Members' Pages. The very act of mentioning that this will be my X hundredth dive, immediately puts all the other divers under a perceived obligation to make it a real good one. Most laudable, however, when the weather picks up the day before and people say "We ought to cancel but it's old Fred's X hundredth dive, so we'll go for it", a willing entry of the incident pit is accepted, and I've seen it go wrong too often. Dale was quite right. Announce the achievement after the event, and let the marshal make his decisions unencumbered.

August 2004

Terry Dukes looked at a plate recovered from the wreck by John Elder. A little research lead him to challenge the name of the Toho Maru! As time passes and more history is published of World War II (and as de-classified information becomes available) more and more evidence points to the wreck being that of the Yuho Maru, torpedoed on 26th November 1944.

On 28th October 1944, USS Pargo (SS-264) sailed from western Australian waters in company with sister ship USS Haddo (SS-255) for her sixth patrol From Exmouth Gulf she continued alone into the South China Sea where she found that increased allied air activity had further diminished use of the shipping lanes. She sank the tanker, Yuho Maru, off Brunei Bay on 26th November. Following this action she received from escorts the worst depth charging of her career but escaped without serious damage, and returned to Australia on 21st December. US History of the War in the Pacific.

Ever since Panaga Divers started diving the wreck of a tanker between Ampa and Fairley fields in 1979, it has been known as the Toho Maru. The name was reported by Lloyds of London, as the loss of a vessel by bombing on 26th November 1944. 

Recently, a dinner plate was observed amongst the wreckage. The company logo on the plate (depicted right), is that of Iinop Kaiun, a Japanese tanker company. Terry searched the archives of this company to discover that they never operated a Toho Maru, but they did have a Yuho Maru that was torpedoed off a town called Mili in Borneo. This evidence, along with the independent reports of the actions of USS Pargo suggest that the wreck of the Toho Maru is, in fact, the Yuho Maru, and that the town Mili, is, of course, Miri! How the confusion of names occurred is not known. Certainly the Japanese characters for To- and Yu- are quite different in all their alphabets.

Terry found some pictures of a model of the tanker class, the 5,200 ton, IJN AuxiliaryTransport (oil), Wartime Standard Type 1TM. It is definitely what we dive, albeit only the remaining stern third of the ship. Click on the picture (below) to see what remains today. There were at least three 'Toho Marus' sunk during WWII in the Pacific theatre, however, none match the dates or the location of Brunei. The Shinkoku Class of tanker, to which one of the Toho's belonged, is 10,000 tons, far larger than our wreck.

One can surmise that the ship took a torpedo into the stern, just under the starboard lifeboat. This opened a 10 m2 hole in the ship's side and almost instantly, the engine room was full of a fatal extra 1,000 tons of seawater. This huge weight would have broken the ship's back and the stern sunk, leaving the forward section to be towed to Singapore.

True or false? Who knows? This is simply conjecture, and adds another element of mystery to a wreck that has fascinated so many divers over the years.

So near and yet so far ...

9th June 2006:  Email from John Elder to Pius Cagienard

The story of the Toho, or is it, Yuho Maru continues. As more and more records of WWII are published, it seems that the wreck lying off Brunei is the stern of the Yuho Maru, torpedoed on 26th November 1944 by the submarine USS Pargo. If you remember our chat with Ed Ehlmann in the Hague, he claimed that the bows did not sink at that time and were towed to Singapore. There's just nothing around Brunei that matches the bows, but a few days ago, the skipper of the MV Empress (Vidar) contacted me and said that he had dived the bows of a Japanese tanker 150 miles east of Singapore (on a direct line to Brunei). He calls them the 'bows of the Yuho' for no better reason than they seem to match the stern that he has also dived. He'll measure the width of the bows and pass the information to us. I hope to join Vidar next year to dive the bows on a trip from Singapore to Labuan.

7th July 2006:  Email from Vidar to his clients

Sorry to inform you all as I write this last email from Empress before we abandon. Now sitting washed ashore in huge swell in front of our land at Lombok. Alice, Mike Worthington (Darwin Mike) and myself only, safe so far but now having to swim/wade ashore in the morning, King willing. No Joke!!! no more for charters. Please do not inundate with emails. Will get back to you in due course. I always wondered how it would all end for EMPRESS, after having sailed some quarter million miles together. Vidar. (Deposits will be refunded.) Fortunately, Vidar's boat survived and continues to ply the seas of SE Asia.

24th September 2006:  Email from Vidar

Bought myself a new long tape measure last week before we left Singapore. Measured the bow section to be exactly 16.50 m. Dived the stern an hour ago to find the width to be 16.5 metres. A couple of other features. There is box section mast laying across the bows, exactly 60 cm wide. I noticed at the stern there is a similar mast lying from the deck to the sand, also 60 cm wide. I have not seen any mast of this type of construction anywhere else (maybe other vessels also, but none that I have seen). Also the shape of the hull, where it sweeps up from the main deck to the forecastle, center castle and stern are the same shape; almost straight, rather than curved. The break seems to co-incide geometrically with both sections. Being an engine room aft model, there is no evidence of machinery at the bow section. All points to be fairly conclusive that we have both ends of the same ship.

November 2006

Terry Dukes, turned up some new and exciting information about the 'Yuho Maru' from a Japanese modeller. At last, we have a real photograph of the ship!

(Translated from the original Japanese by Kosuke Nishi.) 'Yuho Maru' - Iino Kaiun

(The name of the ship-owner, Iino is the name, Kaiun means Sea Shipment)  5,226 tons

The ship was hit by torpedo at 04deg 54min north, 114deg 07min east, approximately 35 kilometres NNE of Cape Baram, north west offshore Borneo, at 16:11 on 26th November 1944.  She was towed to Miri port and arrived there, but sank at 04:00 on 2nd December 1944. All the 26 personnel on board were killed by the torpedo hit.

Very interesting! The location is definitely that of our wreck, however, only the stern (aft of the stern mast on the picture) lies there. The ship must have broken in two as did her sister ship, the 'Nichinan Maru No.2' that was torpedoed north of the Spratleys 18 days earlier. The remainder of the ship may have been towed to Miri, however, the tanker's draft of seven metres or so would not allow it within three km of the beach. I suspect the wreck was grounded whilst the Japanese decided its fate. On 28th November, the American air force bombed the Miri Roads (offshore anchorage) and sank the Atago Maru. Perhaps realising that the bows contained precious fuel, the Japanese decided to tow it out of harm's way to Singapore. Along the way, the bows sank, for today they lie nearly 200 km east of Singapore. Amazingly, the two parts of the wreck lie just over 1,000 km apart!

The Japanese modeller sent some more information about the Wartime Standard Type 1TM tankers. Twenty-six of these tankers were built by various yards including Hitachi, and Mitsubishi at Nagasaki. The dimensions of the vessel are 120 m long, 16.3  m wide and 9 m moulded depth, very close to our estimates from the past. The tonnage was 5,228 tons. The stern section is just over 50 metres long (58 metres on the port side). The distinctive features of these utility standard ships were the square section masts and the elliptical oil tank hatch covers (see sketch earlier in article).

Our photographic survey above (1994) and the 1TM class plans are very close. The three elliptical tank hatches are very pronounced. The photo montage has simply got a few relative proportions wrong.

The engine room lies forward of the boiler room. A mangled boiler is visible in the after of the two torpedo holes. Unusually for a merchantman, the 4,000 hp steam turbine that powered the Yuho Maru, lies in front of the boilers; the prop-shaft passing beneath the boilers to the stern. Perhaps this was to insert a buffer between the fires of the boiler room and the volatile cargo. Note how far aft the funnel (directly above the boilers) is placed compared to a conventional aft-engined cargo vessel. The top of the engine, that we have never seen, must lie deeper than 55 metres, and the Yuho Maru is a pile of collapsed metal at this depth. Sadly, the Japanese characters on the diagram are illegible

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