OIL TANKERS are still risking death and destruction to cut costs as

they criss-cross the world's oceans -- by tapping their own cargoes to

fuel their engines, it emerged yesterday.

The outlawed practice, known to seamen as ''monkey business'', is

likely to form part of the inquiry by the maritime accident

investigation branch of the Department of Transport into the Braer

disaster in Shetland.

Although there is no suggestion the Braer was party to such an

unscrupulous and dangerous scam, maritime engineers have been puzzled by

crew reports that the ship was rendered helpless by fuel contamination

from seawater with the boiler and generator failing to function.

One expert said: ''No-one as yet has addressed the possibility that

such a ship carrying light crude oil -- registered in Liberia, under

Greek command, and manned by a mixed crew -- could have used its cargo

to fuel the engines.

''Although illegal, it is still a common practice in seas around the

world because of the savings involved.''

He added that the investigators must at least consider the possibility

that the diesel-engine failure was caused by fuel contamination during a

tapping operation, which usually involves a small pump and extra

pipelines from cargo to engines.

The Department of Transport confirmed that the Braer's engine and fuel

system would almost certainly be the subject of strict scrutiny.

Mr Tony McGregor, assistant secretary of the National Union of

Railway, Maritime, and Transport, yesterday called on investigators to

look for signs of cargo oil in the engines or fuel lines as part of a

full investigation into the tragedy.

He was well aware of the term ''monkey business'' in regard to cargo

thefts, coined in reference to ships having monkey bridges (above engine

rooms), monkey ladders, monkey rails, monkey islands (on top of

pilot-houses), and monkey suits, as naval uniforms are dubbed.

The investigation branch has not yet made decisions about inquiries,

over and above seaworthiness.

Engineering and navigation experts are still waiting to board the

stricken vessel, which is now gushing its 85,000-tonne cargo into the

sea. Their studies will be expanded if and when necessary after

preliminary findings.

A salvage expert with knowledge of Greek-mastered operations alleged

yesterday: ''I am well aware of instances where officers receive

incentives to keep fuel costs down.

''The 'monkey business' is a complex, technical operation, but the

system is such that people can get away with stealing part of the cargo

to fuel their ships.''

An international convention for safety of life at sea banned the use

of such fuel in 1974 because of explosion dangers, but a spokesman for

the United Nations' International Maritime Organisation said yesterday:

''Despite the dangers, the temptations for unscrupulous operators to use

cargo oil as fuel are considerable. It is very difficult to measure

exactly the amount of cargo carried on an oil tanker.''

The difference normally allowed between ship and shore figures is

one-half per cent of the total oil loaded -- which can still be ''a

considerable amount'', he added. (In Braer's case, that would amount to

425 tonnes, about two days' running costs).

The IMO said that a small amount of cargo transferred to ship bunkers

would not be noticed, but gains would be substantial because fuel costs

can represent as much as 60% of total running costs.

A Liberian Bureau of Maritime Affairs investigation in 1983 confirmed

a number of cases of cargo oil being used as fuel -- accomplished by

means of a cross-connection between cargo and bunker piping systems.

The Liberian report noted that the practice is ''more widespread than

may be presently apparent and is a serious source of danger to ships and

personnel both at sea and in port, and also to port installations which

service tankers''.

Losses between loading and delivery can be put down to temperature

changes and evaporation during voyages.

The IOM has warned member governments of the possibility of either

deliberate or accidental contamination of bunkers by crude oil, and

issued reminders of guidelines to give ''special attention'' in surveys

to the possibility of cross-connections between cargoes and engines.

However, it acknowledged that checks for tapping -- although a

deterrent -- are difficult to implement. A marine expert explained:

''Tankers laden with oil do not use fuel gauges for cargoes. Instead,

the tanks are 'dipped', so it is relatively easy to hide subsequent

losses from huge holds.''

It could be a year before findings of the inquiry into the grounding

of the 89,730-tonne, 792ft Braer are published, according to the

Department of Trade.

A Department of Trade spokesman said: ''It is expected the Braer

investigation work will be done in situ, but it is possible some parts

will be taken away for study.''

He added that the branch will not report ''until certain of its

facts''. That process will take months rather than weeks and it could

''take up to a year'' before formal findings are published.