Ray Dalio, founder of the world's largest hedge fund Bridgewater Associates, says the next big monetary and fiscal move should include an airdrop of money from helicopters to stimulate the U.S. economy.

He may not be entirely serious about "helicopter money." But in a client note sent out this week, Dalio said the U.S. Federal Reserve's ability to boost growth through lowering interest rates and quantitative easing is "weaker than it has ever been."

"Monetary Policy 3" or MP3 will have to be directed at spenders more than at investors and savers, he said.

Dalio, who characterized lower interest rates as MP1 and quantitative easing as MP2, proposed some scenarios in which MP3 could be implemented.

"We can say that the range will extend from classic fiscal/monetary policy coordination - in which debt to finance government spending will be monetized - to sending people cash directly - i.e., helicopter money - and will likely fall somewhere between these two -i.e., sending people money tied to spending incentives," Dalio wrote.

Helicopter money is a reference to an idea made popular by the American economist Milton Friedman in 1969 that dropping money out of helicopters for citizens to pick up was a sure way to restart the economy and effectively fight deflation.

Dalio, who helps manage $155 billion at Bridgewater, said investors should expect currency volatility to be greater than normal when countries are fighting for growth.

When interest rates cannot be lowered and relative interest rates cannot be changed, currency movements must be larger, Dalio said. Indeed, the Bank of Japan's shocking move to take one of its main interest rates into negative territory last month led to weakness in the yen.

"To avoid economic volatility, currency movements must be larger," Dalio wrote. "That reality creates 'currency wars,' pegged exchange rate break-ups, and increased currency risk for investors."

Since currency movements benefit one country at the expense of another, he added that exchange rate shifts will not create a needed global easing. "That's just how the economic machine works."