Playing Hurricane Katrina remains the key investing issue right now, James Cramer said on his "RealMoney" radio show Tuesday.

The short-term trade was probably last week, said Cramer. Be careful with Shaw Group ( SGR) and Caterpillar ( CAT), he said. Even though Shaw will benefit short term from New Orleans reconstruction, the stock has already had a big move, and long term, its core business of environmental remediation is threatened by national energy priorities. Caterpillar has also had a big move, but Cramer likes the stock on a pullback. Also, be wary of cement stocks. That trade "seems over to me," said Cramer.

Nevertheless, to make money in the short term, think about what the Federal Emergency Management Agency and the Department of Homeland Security need right now. The most obvious need, said Cramer, is for emergency equipment, which is basically camping equipment: tents, cooking, water purification, flashlights, sleeping bags, etc. The brand that dominates the camping equipment market is Coleman, said Cramer. Coleman is owned by Jarden ( JAH). "That's a trade," said Cramer, who thinks Jarden has a "couple more points to go."

Also, Lowe's ( LOW) and Home Depot ( HD) are going to make money, said Cramer. Cramer, who had been bearish on Lowe's and Home Depot before the hurricane, said, "I was wrong. I did not anticipate a catastrophe on this scale. ... This wasn't a hurricane. It was gotterdammerung."

Cramer also likes Phelps Dodge ( PD) in the short term. Even though he had advised selling Phelps Dodge a few weeks ago, "Hurricane Katrina changed some things," Cramer said. New homes have 400 pounds of copper, said Cramer, and PD should benefit.

Long term, Cramer was bullish on oil, communications and insurance. We're not finding more oil, said Cramer. We don't have enough, and we'll never have enough going forward. The long-term picture is one of scarcity.

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