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Rescue operations involve 28 specialist divers

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Marine experts baffled by yacht's sinking

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Boatbuilder CEO blames crew errors

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Salvage operation estimated to cost up to 15 mln euros

(Adds details on rescue operations in paragraphs 3-4, on

investigation in paragraphs 7-8)

By Guglielmo Mangiapane

PORTICELLO, Italy Aug 23 (Reuters) -

Italian search crews on Friday resumed efforts to find the

body of Mike Lynch's 18-year-old daughter, the last person

missing after the yacht belonging to the British tech magnate

sank off Sicily this week, killing seven people.

The British-flagged Bayesian, a 56-metre-long (184-foot)

superyacht carrying 22 people - 12 passengers and 10 crew - was

anchored off the port of Porticello, near Palermo, when it

capsized and rapidly sank on Monday after being hit by a

pre-dawn storm.

Rescue operations, entering their fifth day, are "long and

delicate" and involve 28 specialist divers, the fire brigade

said in a statement.

The wreck is lying at a depth of 50 metres and once

inside the passageways are narrow.

On Thursday, an interior ministry official told Reuters

that the last missing body might not be inside the yacht and

could have been swept out to sea.

The bodies of the other five dead passengers were recovered

on Wednesday and Thursday from inside the yacht. The body of the

only crew member who died, onboard chef Recaldo Thomas, was

recovered near the wreck on Monday.

A judicial investigation has been opened into the sinking,

which has baffled naval marine experts who say a boat like the

Bayesian, built by Italian high-end yacht manufacturer Perini,

should have withstood the storm.

The yacht's captain James Cutfield and his eight surviving

crew members have been questioned by police, but made no public

comment on the disaster. Investigating prosecutors are due to

hold a press conference on Saturday.

The police have also spoken to passengers and witnesses.

COMPLEX SALVAGE OPERATION

Giovanni Costantino, CEO of The Italian Sea Group

, which owns Perini, told Reuters the shipwreck was

the result of a string of "indescribable, unreasonable errors"

made by the crew, and ruled out any design or construction

failings.

Pulling the wreck out of the sea, where it is now lying on

its right side, apparently intact, may help investigators

determine what happened, but the operation is likely to be

complex and costly.

Nick Sloane, a South African engineer who led the operation to

salvage the Costa Concordia cruise liner that sank in 2012, said

in Italian media interviews on Friday that the operation would

cost up to 15 million euros ($16.7 million).

He told daily La Repubblica that salvaging the yacht would take

six to eight weeks, including preparation work, and would have

to be completed by mid-October, without specifying the reasons

for the timing.

Bringing the yacht to the surface will have to be done

"very, very slowly", and might take a couple of days, he said.

($1 = 0.8993 euros)

(Additional reporting Giselda Vagnoni, writing by Alvise

Armellini and Giulia Segreti; Editing by Sharon Singleton)