By Arathy Somasekhar and Georgina McCartney

HOUSTON, March 20 (Reuters) - Rising oil tanker

chartering rates due to global shipping disruption are forcing

oil shippers to take on longer-term shipping charters,

executives said this week at an energy conference in Houston.

The global oil tanker fleet must now travel further to get

crude to refineries and fuel to consumers. European sanctions

have forced Russian exporters to send oil to Asia that would

have otherwise gone to Europe. Attacks on vessels in the Red Sea

have forced some shippers to sail around Africa.

Low water levels in the Panama Canal have also led some

vessels to take alternative routes.

The detours have added up to three weeks sailing time to

some routes, adding significantly to shipping costs and reducing

vessel availability. Some ships are no longer available because

they have joined the fleet carrying Russian oil or have been

sanctioned.

All of that has added up to 26% to tanker chartering rates

in some cases. Insurance rates have skyrocketed for those

shippers that still transit the Red Sea to save time.

Chartering rates for an Aframax vessel, which can carry up

to 800,000 barrels, have surged to about $49,500 per day from

$39,000 a day five months ago, according to shipping data.

"It's just kind of been a perfect storm," said Andrew

Jamieson, co-head of Gunvor Group's chartering and shipping arm,

Clearlake Shipping.

"There are not enough vessels."

To save money on ship chartering, Gunvor has taken on more

longer-term charters on ships, he said.

"The record time-chartering rates are a pain," Jamieson

said. Time chartering contract allow companies to take a vessel

for a given period of time rather than on a specific voyage

between two location, protecting them from the cost of

disruptions.

Clearlake Shipping has entered into more long term deals as

well, partly due to 50-60% volatility in 10 month-front

contracts. Locking in time charter contract in advance are

typically cheaper than nearer-term contracts and protects the

company from volatility in price.

"We don't like doing it, but we think rates are here to

stay."

The company has over 100 time-charter contracts now compared

with a few prior to 2020, he added.

Some operators also use hedges to lock in prices. Interest

in forward freight agreements - futures contracts that allow

participants to trade on an expected future level of freight

rates - have risen in recent months, industry sources said.

The coming expansion of Canada's Trans Mountain pipeline

will add further demand to the tanker market. Vessels will be

needed to take crude from the Pacific Coast terminal of the

pipeline to refiners.

Vessels avoiding the Red Sea have increased marine fuel

consumption by 100,000 barrels per day and added 3% to the

distance traveled by the global shipping fleet, Vitol CEO

Russell Hardy said on Wednesday.

To ease the shortage in the market, companies are also

looking to build new vessels.

About 100 Aframaxes are likely to enter the market in the

next three years, while about 25 Very Large Crude Carriers will

enter the market in 2027, Clearlake's Jamieson said.

Most of the factors that have forced ships to sail longer

routes are unlikely to change any time soon, said Geoff Houlton,

a senior vice president at U.S. oil producer Occidental

Petroleum ( OXY ).

A "chunk of these suboptimal trade flows" are probably here

to stay, he said.