SINGAPORE (Jan 7): The last time Singapore's marine-services industry was staring at what would eventually turn out to be an 18-year drought in demand for oil rigs, Ronald Reagan was starting his second term as US president.

Jackup rigs, used to drill for oil in shallow waters, saw orders evaporate between 1985 and 2003. As Macquarie notes, rampant overcapacity means such a prolonged slump could well occur again. That definitely would not be good news for the rig- building industry's two Singaporean leaders -- Keppel Corp. and Sembcorp Marine.

After a decade-long boom, there were zero new orders globally for jackup rigs last year. With oil prices swooning, and rigs' daily rental rates having crashed to US$92,000 from US$130,000 in 2014, there's a risk that 70% of Keppel and Sembcorp Marine's order book might get cancelled, especially if the Petrobras bribery scandal in Brazil deepens, Macquarie analysts Somesh Kumar Agarwal and Justin Chiam wrote this week.

If the downturn does indeed end up being a repeat of That '80s Show, rig-builders' shares may have to give back much of the China-induced exuberance of the past decade. That could be quite painful for investors, including Temasek. Singapore's state investment company owns a little less than half of Sembcorp Marine's parent, Sembcorp Industries, and 21% of Keppel, Bloomberg data show. It can't be feeling very chuffed about the 47% slump in Sembcorp Marine over the past year, or Keppel's 26% slide.      

And there might be more trouble ahead. Since early 2004, the two stocks have returned about 300%, thanks primarily to hefty dividends. Those might now start thinning out.

According to analyst estimates compiled by Bloomberg, Keppel's dividends will shrink by as much as 11% over the next three years, compared with annualized growth of 3% over the past three.

No orders coming in the door doesn't augur well for shareholders, who will be far behind debtholders in getting paid, and the latter will have substantial claims. Oil and gas- linked companies with outstanding Singapore dollar-denominated bonds have to refinance or repay some $625 million of notes this year, a further $390 million in 2017 and $700 million in 2018, Bloomberg-compiled data show:

The other big risk comes from the duo's Brazilian yards. Japanese shipbuilders like Mitsubishi Heavy are cutting their losses and exiting as the Petrobras saga drags on. Stock in Ensco, the London-based owner of shallow and deepwater rigs, fell 15% in intraday trade Wednesday after Petrobras said it was scrapping a contract in the U.S. Gulf of Mexico because, it claims, Ensco knew about improper payments between a shipbuilder and a consultant when the drillship was constructed, a charge Ensco denies.

Analysts are being predictably slow in sounding the alert. Their median price estimate predicts a 25% jump over the next year in Keppel shares, and a 15% climb in Sembcorp Marine. Were that triumph of hope over experience to prove elusive, what might Temasek do? It recently decided to sell shipping company Neptune Orient Lines to CMA CGM at $1.30 a share, after having paid as much as $2.80 in 2004 to acquire a part of its 67% stake.

If the Macquarie analysts are right about Keppel and Sembcorp Marine eventually trading below book value, like South Korean yards do, then there may not be much point in Temasek's hanging on to the rig builders either.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.