Like the Colossus of Rhodes in ancient Greece, two new 40-ton cranes dominate the skyline of the Brooklyn waterfront, beckoning ships from around the world. Yet the $20 million Red Hook Container Terminal - one of nearly 1,460 various marine terminals in 189 US seaports - is at once symbolic of problems facing America's ports and typical of their tremendous progress and promise.
No ships stand here to lessen the wind that whips past the Statue of Liberty over the harbor's brackish gray-brown water and on to the terminal's half mile of berth space. The inactivity is due in part to the newness of the terminal, officially dedicated only last month. But another cause is that the channel is only 40 feet deep and thus too shallow for more and more of today's deep draft vessels.
Even though the US port system is well developed, ''It is an antiquated system with channel depths that cannot compare to the major ports of the world and a method of improving channels that takes nearly a generation to accomplish, which is commonly done in Europe in a matter of years,'' states Peter C. Goldmark Jr., executive director of the New York Port Authority.
Armed with enough evidence from port experts like Mr. Goldmark to sink the proverbial battleship, and with the backing of the Reagan administration, Congress will likely pass a law next year to slash the time it takes to get permits and authorization to deepen US channels.
Who will do the expensive dredging? President Reagan has upset longstanding seaport precedent by insisting that the ports, not the federal government, pay not part but all of the dredging costs. Despite the Republican budget-slashing mood, observers say, there is plenty of room for compromise on the dredging-cost issue.
Even if the administration's position holds firm, which appears highly unlikely, it still cannot cast much of a shadow over the burst of economic activity that is sweeping the ports:
* Modernization. From New York to New Orleans, from Los Angeles to Baltimore, they are undergoing a dramatic metamorphosis, spurred in large measure by the ever-increasing switch from so-called ''break bulk'' cargo handling to containerization, which is staggering. According to the US Department of Commerce, nearly $400 million was spent between 1973 and 1978 by the US deepwater port industry for modernization of marine terminals. The agency projects that the equivalent of 247 new units of various kinds will be needed by the end of the decade - including 27 additional break-bulk terminals, 10 more grain berths, and 15 new coal berths.
* Tonnage. Despite setbacks in petroleum shipping because of energy savings by Americans, total tons shipped in and out of US ports is booming-with many Southeastern and Southwestern harbors showing the greatest increase. For example , spurred in part by an aggressive expansion policy, tonnage in Long Beach, Calif., has soared from 5.9 million short tons in 1945 to about 34 million last year, according to the Army Corps of Engineers. New Orleans, the nation's second-largest port, has seen its tonnage climb from 25.2 million tons in 1945 to more than 160 million last year, thanks mainly to increased grain, petroleum, and chemical exports.
* Coal. The National Coal Association, for example, estimates that US coal exports will reach 100 million tons by 1985 and 134 million tons by the end of the decade. Yet if construction on all the new coal terminal facilities under consideration goes ahead, some industry experts say American port capacity for coal could well exceed 500 million tons. In the relatively small port of Savannah, Ga. - at least in comparison with New York, New Orleans, and other major ports - three new coal terminals are planned, with one already under constuction. Obviously, however, market forces in Savannah and elsewhere will tend to help construction conform to demand.
* Foreign trade zones (FTZs). These partly tax-free havens for shippers are a popular development. According to John J. DaPonte Jr., executive secretary of the Foreign Trade Zones Board of the US Commerce Department, both the number of zones and the number of companies using them continue to increase steadily, directly enhancing the ''infrastructure of services'' the ports can provide. Sixty-seven zones have been approved, with 40 in active operation; the value of goods received in the FTZs has gone from $800 million in 1978 to $2.6 billion last year. In a nutshell, FTZs are tax-free areas within seaports, but not necessarily limited to ports, which are exempted and shielded from normal customs duties so as to encourage foreign shipping and investment in the United States.
One optimistic Commerce Department report forecasts that US import-export tonnage will more than double by the year 2,000. But the actual shape and rate of the continued economic growth of individual seaports may well depend on how Congress deals with the variety of issues now under consideration.
Coal exports, for example, will not only depend on the world's demand for coal but on the ports' ability to relieve bottlenecks and deepen channels. Even now, coal transporters are slowly moving to ''supercolliers'' - the supertankers of coal. The Virginia port of Hampton Roads is just one, but nevertheless the biggest example of the shipping backlog caused by a lack of adequate channel depth.
It is no coincidence, therefore, that one of the biggest backers of efforts to get the federal government to continue to pay for portions of channel maintenance and improvement is US Sen. John Warner (R) of Virginia. His legislation would require the Treasury to pay for 75 percent of routine maintenance dredging and 60 percent of improvements dredging, with local authorities, through user fees, picking up the tab for the remaining work. The administration, on the other hand, wants ports to pick up 100 percent of both the maintenance and improvements.
Sources on the Senate Energy Committee as well as some industry experts are confident that a compromise can be found. They suggest that the Reagan administration may agree to pay as much as 50 percent of the dredging costs.
Peter Gatti, however, a spokesman for the American Association of Port Authorities, says he sees no movement toward compromise by the administration.
If ports have to pay for all or most of the dredging, it will hurt smaller ports such as Portsmouth, N.H.; Tacoma, Wash.; Albany, N.Y.; and Wilmington, Del. Even in booming Long Beach, a spokesman said, continued expansion could be slowed.
The midsize port of Baltimore, on the other hand, has a unique problem: After more than a dozen years of waiting for approval of its dredging plan, the federal government has refused to grant it, at least until the legislation is hammered out, to pay the $7.5 million necessary to do the job.