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Regulator Mouthpieces

Do you feel jaw strain after diving? Does your second stage regulator mouthpiece bother you? If so, changing your regulator mouthpiece style may make diving more comfortable. Before swapping out your mouthpiece, keep a few things in mind:

  • Be sure that the new mouthpiece will fit on your regulator's second stage, as not every mouthpiece will fit every regulator.
  • Many of the regulator mouthpiece styles are available in a variety of materials. The differences in material can effect your comfort.
  • Once you find a regulator mouthpiece style that suites you, buy several mouthpieces and keep the spares in your save-a-dive kit.

Regulator Mouthpiece Orifice Sizes

Generally there are four common 2nd stage regulator mouthpiece sizes:

Standard size orifice regulator mouthpiece
- size 1-1/8 inch x 1/2 inch (28.6 mm x 12.7 mm)
Fits: Apollo; Aqua Lung older metal regulators, Conshelf 7 through 21 – snug; Atomic manufactured pre 2005 only and newer T3; Beuchat Evolution, Iceberg and Nitrox, VXT8, VXT Octo, VX4, VX8; Cressi-Sub Ellipse is a 2, XS Compact is snug; Dacor after 1992; IST except Proline is an intermediate; Ocean Master; Pro Sub Avalon; Scubapro S600, S360, S560, R095 and all models before the A700; SEAC; Sherwood most early models – Brut, Shadow, MagnumII, pre 1992 Blizzard + Oasis; Spare Air; Subgear R series and Cayman; Tabata/Tusa not TUSA Imprix.

Intermediate size orifice regulator mouthpiece
- size 1-3/16 inch x 5/8 inch (30.2 mm x 15.9 mm)
Fits: Aeris; Aqua Lung newer, including Titan, Legend, Kronos and Mikron; Atomic pre 2005 use a Standard, newer, larger orifice an Intermediate, if not sure, measure or try on; Beuchat VS3, VS4, VS8, VX10; Dacor Viper + Eagle; Dive Rite including O2ptima rebreather, but not the Jet Stream 4500; Edge HOG + EPIC; Forte; Genesis; Halcyon Rebreather + Regulators; Hollis except 500SE is a Large; Mares (not MARES MR-12-II, III, IV or V); Ocean Edge; Ocean Reef; Oceanic cannot fit Alpha 9 or Omega 3; Odyssey; Scuba Max; Scubapro models after 2010, including A700, C series, G260, R195 and S620TI; Sea Elite; Sherwood Maximus, 1992 and newer Blizzard + Oasis, SR1; SPORASUB; SUBGEAR SG50, SG30, SG10, Aruba and Bonaire, Tigullio, Tilos; XS SCUBA (previously IDI, Osprey is a standard).

Large size orifice regulator mouthpiece
- size 1-5/16 inch x 11/16 inch (33.3 mm x 17.5 mm)
Fits: Apeks; Dive Perfect; Hollis 500SE; and Zeagle 2nd stage regulators. Plus many rebreathers, including Golem Shrimp BOV; Hollis Prism+Explorer; ISC Megladon; Kiss Gem; Poseidon (snug fit); and Titan.

Extra Large size orifice regulator mouthpiece
- size 1-7/16 inch x 13/16 inch (36.5 mm x 20.6 mm)
Fits: Poseidon regulators.

Tech Tip: Inspect Your Regulator Mouthpiece

When is the last time you gave any thought to your regulator mouthpiece? Our service technicians tell us one of the most commonly damaged parts they discover during routine maintenance on a regulator second stage is the mouthpiece itself.

Many divers bite down much too hard on the mouthpiece, particularly if it is a poor fit. Besides the fact that biting too hard may cause the diver to climb out the water with an annoying headache, we even find bite tabs completely missing from the mouthpiece where they have been literally 'chewed off'. If that's happening to you, consider trying a different style of mouthpiece.

A more subtle damage often responsible for second stages 'breathing wet' is an almost invisible tear in the mouthpiece, just past the mounting lip on the second stage body near or under the cable tie. These often can't be seen unless you stretch the mouthpiece by hand and inspect in bright light.


Rotomahana

Wreck Dive Wreck Dive | Boat access Boat access

Deep Rated Outside Port Phillip Ships Graveyard Wreck Dive Site

Passenger and Cargo Steamer | Max Depth: 39 m (128 ft) — Graveyard

Rotomahana
Rotomahana
Source: State Library Victoria

Level: Advanced Open Water and beyond.

The Rotomahana (aka SS Rotomahana) was used in the trans-Tasman service and later as a Bass Strait ferry. Said to be the first steel-hulled steamer in the world, she had a clipper bow and graceful hull. She served for many years on the Melbourne to New Zealand routes and was known as the "Greyhound of the Pacific" due to her great speed.

The Rotomahana shipwreck lies on a sandy bottom, 39 metres deep, in the Victorian Ships' Graveyard, outside Port Phillip in Bass Strait. This is a dive for experienced deep/technical divers.

Diving the Rotomahana Shipwreck

The Rotomahana shipwreck site lies in 39 metres of water with the bow pointing roughly to the east. There are four large condensers and/or two boilers amidships sitting side by side. The large clipper bow, which is separated from the rest of the hull, lies intact over on its port side, slightly to the port of the centreline.

An area of broken hull structure reaches to boilers amidships, behind which is the remains of a formerly intact deckhouse, which used to be penetrable before it collapsed. The hull and remaining structure from here on is flattened and gradually disappears into the sand.

The hull is badly broken up although there are plenty of steel girders and other debris including the old bowsprit. Several anchors and winches can also be seen. Some penetration is possible between and underneath the boilers of the shipwreck. Large schools of fish patrol the wreck.


SS Rotomahana | © Debra Laurie

r Rotomahana Dive Site Plan
Rotomahana Dive Site Plan | Source: Jim Anderson

Bass Strait Warning: Always keep an eye on sea conditions throughout any shore or boat dive in Bass Strait on Victoria's coastline. Please read the warnings on the web page diving-in-bass-strait before diving or snorkelling this site.

Rotomahana Shipwreck History — Built in 1879

SS Rotomahana
SS Rotomahana
Source: State Library Victoria

The Rotomahana was a 1,777 ton steel steamer, built in 1879, by William Denny and Brothers in Dumbarton, Scotland. Built for the Union Steamship Co. of New Zealand, it had 4 cemented bulkheads, two decks and a single screw.

The overall length of the vessel was approximately 90.89 m (298 ft), beam 10.73 m (35 ft) and draught 7.22 m (24 ft) giving a displacement weight of 1,777 t (1,959 s-ton).

Rotomahana Last Voyage and Sinking — Scuttled 29 May 1928

Rotomahana Hulk
Rotomahana Hulk
Source: State Library Victoria

The Rotomahana was laid up in 1921, purchased by a Melbourne ship breaker in 1925 and slowly stripped of valuables.

Once the pride of the Australian coast, the fastest ship in these waters, with a mysterious turn of speed, the holder for many years of the proud title "Ocean Greyhound," and designed as a private yacht for a prince, the old ship Rotomahana made her last passage on Tuesday 29 May 1928. She went to join her sisters, the Buninyong, the Coogee and the Courier at the bottom of the Bass Strait, after half a century's faithful service in Australian waters.

Her fanciful title of "Greyhound" was earned by her then, prodigious speed of 15 knots, but on her final voyage she lumbered down Port Phillip in tow of the tug Minah, under the command of Captain McBain, at five knots.

Formerly she was equipped with luxurious fittings, but then she was a decrepit and empty shell. A figurehead no longer distinguished her: the panels in the saloon, carved by hand from bird's-eye maple, had been taken from her; the old time notices in the steerage requesting passengers to remove their boots before getting into bed had been removed. Her lead piping, her superstructure, her 14,000 super feet of pine decking, her teak-railings, her funnel, her boilers — all had been taken out of her and only the shell of the old ship set forth in the ghostly light of the morning in tow of the Minah. It was her last voyage in the waters which her keel had ploughed for many a year.

SS Rotomahana Stem Frame
Rotomahana Stem Frame under repair
in the Port Chalmers dry dock, Otago,
after she bumped the Waipapa Point
reef, Southland, in August 1883.
Source: Ian Farquhar collection

Few people were on the Railway Pier to see the cortege set out from Port Melbourne at 2 a.m. on 29 May 1928. A line splashed into the water, the Minah's propeller churned the surface and soon the old Rotomahana moved gently off down Port Phillip. She was said to be the first steel steamer ever built. On her trials, she made over 15 knots, but at sea attained 17 knots on occasion.

The Minah and the Rotomahana passed through Port Phillip Heads at 11 a.m. J Larkin, a marine surveyor, then boarded the Minah and piloted the tug to the sinking place three and a half miles south-west of Port Phillip Heads. The pilot steamer Victoria, with the chief sea pilot Captain Palmer in command, accompanied the Rotomahana from Queenscliff and was present at the sinking ceremony.

The gelignite charge, placed amidships in the engine room, was fired. A signal honour was paid to the old vessel when the international pilot flag (a St. George's cross on a white background) was dipped while she was sinking. Three active members of the pilot service were former captains of the Rotomahana.

Just 25 minutes later nothing was to be seen of the once popular steamer but a few floating spars. She sank on an even keel into 20 fathoms of water in Victorian Ships' Graveyard.

See also, Heritage Council Victoria: Rotomahana, and
Australian National Shipwreck Database: Rotomahana.

Heritage Warning: Any shipwreck or shipwreck relic that is 75 years or older is protected by legislation. Other items of maritime heritage 75 years or older are also protected by legislation. Activities such as digging for bottles, coins or other artefacts that involve the disturbance of archaeological sites may be in breach of the legislation, and penalties may apply. The legislation requires the mandatory reporting to Heritage Victoria as soon as practicable of any archaeological site that is identified. See Maritime heritage. Anyone with information about looting or stolen artefacts should call Heritage Victoria on (03) 7022 6390, or send an email to heritage.victoria@delwp.vic.gov.au.

Finding the Rotomahana Shipwreck

Over the years we've been provided with different GPS marks for the Rotomahana. The GPS marks we know of in circulation for the Rotomahana are:

  • Book - Victoria's Ships' Graveyard GPS (verified)
    Latitude: 38° 19.191′ S   (38.319857° S / 38° 19′ 11.49″ S)
    Longitude: 144° 32.167′ E   (144.536123° E / 144° 32′ 10.04″ E)
  • Dive Victoria:
    Latitude: 38° 19.197′ S   (38.31995° S / 38° 19′ 11.82″ S)
    Longitude: 144° 32.175′ E   (144.53625° E / 144° 32′ 10.5″ E)

    15 m, bearing 133°, SE
  • Geoff Rodda:
    Latitude: 38° 19.204′ S   (38.320066666667° S / 38° 19′ 12.24″ S)
    Longitude: 144° 32.164′ E   (144.53606666667° E / 144° 32′ 9.84″ E)

    24 m, bearing 191°, S
Wathaurong (Wadda-Warrung) country
Wathaurong (Wadda-Warrung) country

Traditional Owners — This dive site is in the traditional Country of the Wathaurong (Wadda-Warrung) people of the Kulin Nation. This truly ancient Country includes the coastline of Port Phillip, from the Werribee River in the north-east, the Bellarine Peninsula, and down to Cape Otway in the south-west. We wish to acknowledge the Wathaurong as Traditional Owners. We pay respect to their Ancestors and their Elders, past, present and emerging. We acknowledge Bunjil the Creator Spirit of this beautiful land, who travels as an eagle, and Waarn, who protects the waterways and travels as a crow, and thank them for continuing to watch over this Country today and beyond.

 

Rotomahana Location Map

Latitude: 38° 19.191′ S   (38.319857° S / 38° 19′ 11.49″ S)
Longitude: 144° 32.167′ E   (144.536123° E / 144° 32′ 10.04″ E)

Datum: WGS84 | Google Map
Added: 2012-07-22 09:00:00 GMT, Last updated: 2022-05-07 00:41:54 GMT
Source: Book - Victoria's Ships' Graveyard GPS (verified)
Nearest Neighbour: J1 Deep Submarine, 1,588 m, bearing 74°, ENE
Passenger and Cargo Steamer, 1777 ton.
Built: Dumbarton, Scotland, 1879.
Scuttled: 29 May 1928.
Victorian Ships' Graveyard, Bass Strait.
Depth: 35 to 39 m.



DISCLAIMER: No claim is made by The Scuba Doctor as to the accuracy of the dive site coordinates listed here. Should anyone decide to use these GPS marks to locate and dive on a site, they do so entirely at their own risk. Always verify against other sources.

The marks come from numerous sources including commercial operators, independent dive clubs, reference works, and active divers. Some are known to be accurate, while others may not be. Some GPS marks may even have come from maps using the AGD66 datum, and thus may need be converted to the WGS84 datum. To distinguish between the possible accuracy of the dive site marks, we've tried to give each mark a source of GPS, Google Earth, or unknown.

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