Tech Tip:
Will back inflation float an unconscious diver face up?

We usually hear this from divers who have always worn a jacket style BC, and we'd like to point out that it's irrelevant. It's true, that boating regulations require an approved wearable Personal Floatation Device (PFD) to float the unconscious victim face up in the water. But a Buoyancy Control Device (BCD) for scuba divers is not designed to be a PFD for an unconscious boating accident victim, regardless if the BC is jacket or back inflation.

We offer back inflation style options because experienced divers have learned the back inflation BCD is better than a jacket BCD, offering very precise control of buoyancy and trim as well as offering a more streamlined profile. An improperly fitted back inflation BCD might cause you to tip forward, but a properly fitted back inflation BCD, worn with a crotch strap, will allow you to assume and hold any position under the water, or on the surface.

When on the surface, divers new to back inflation will need to break the habit of holding down the power inflator until they feel squeeze (there won't be any), or hear the OPV release. With an over inflated air cell they will have a huge amount of buoyancy on their back, causing them to float too high in the water and tip forward. Instead, they should add only enough gas until their head is just above the water.

Finally, a very common error when selecting a back inflation BCD is to choose an buoyancy aircell (called a 'wing') that is much too big, causing a 'taco effect' that makes managing buoyancy considerably more difficult. The cylinder size, type and configuration, not lift capacity, is the best guide to selecting the correct wing. While many doubles wing designs can be adjusted for occasional use with singles, keep in mind they are not designed to be used primarily as singles wings and they are not optimal with singles. Unless you are diving one of the very large steel cylinders, a 30 lb (14 kg) is about the maximum lift you need for single tank sport diving.

Isa

Wreck Dive | Boat access

Two-Masted Wooden Schooner, Coal Hulk | Max Depth: 8 m (26 ft)

Level: Open Water and beyond.

The Isa (aka Iza), which lies in Swan Bay, on the Bellarine Peninsula, at the south-western end of Port Phillip, is significant as one of a few Asian built wrecks in Victorian waters.

Isa Shipwreck History — Built in 1847

The Isa (aka Iza) was a wooden two-masted schooner of 50 tons, built in 1847, at Howrah, Calcutta, India, on the dimensions of length [[Units?v=58&u=ft&long=1], beam 14.5 ft (4.42 m)], and a draught of 7.8 ft (2.38 m).

The Isa traded between Melbourne and Geelong from the 1850s. The last located record of this trade is in 1877. The schooner Isa foundered in Corio Bay on 4 June 1871, but was later refloated. The Marine Board Inquiry found charge of wilful damage against the master William Veale, not sustained. William Cowper, a well known lighter agent, and James Balfour were the owners at the time.

Isa Sinking — 1928

The Iza (sic) was listed as powder hulk in 1938 Survey of West Channel (Larkin 1938). In spite of an exhaustive search, no record of the Iza has been located. A wreck of that name appeared on J.P. Larkin's Survey of the West Channel, 1938 and it seems almost certain that he mis-spelt the name.

The evidence suggests that the powder hulk was the Isa, which was broken up in 1928 when the register closed and part of the remains used for a powder hulk.

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.

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.

Isa Location Map

Latitude: 38° 14.270′ S (38.237833° S / 38° 14′ 16.2″ S)
Longitude: 144° 41.286′ E (144.6881° E / 144° 41′ 17.16″ E)
Datum: WGS84 | Google Map
Added: 2012-07-22 09:00:00 GMT, Last updated: 2022-05-14 15:32:18 GMT
Source: GPS
Nearest Neighbour: Will O the Wisp, 1,211 m, bearing 109°, ESE
Two-Masted Wooden Schooner, Coal Hulk, 50 ton.
Built: Calcutta, India, 1847.
Sunk: 1928.
Swan Bay, Bellarine Peninsula.
Depth: 8 m.

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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.