The R/V Mediterranean Explorer squats at its moorings in a remote corner of the Herzliya Marina like an ugly duckling among the sleek ocean-going yachts anchored in this millionaires' water park north of Tel Aviv.

But for marine scientists in Israel and abroad, the MedEx, as it is affectionately known, is a thing of beauty. The ship and its crew carry scientists, their experiments, and students for $400 per day, a fraction of the cost of similar research vessels. The Shikmona, an Israeli-government research vessel, costs $6,000 a day to hire. American ships handling research financed by the National Science Foundation cost even more.

The availability of this bargain-priced platform at a time when budgets are being squeezed and scientists need to stretch their available dollars has created excitement among marine researchers in the Mediterranean and pushed forward several important projects, such as investigations of the effects of pollution and climate change.

Beverly Goodman, a marine geologist at the University of Haifa, used the ship to help discover the first evidence of ancient tsunamis in offshore deposits along the Israeli coast. "My research would have been impossible without the MedEx," she said.

The ship was custom-built in France in 2004 for EcoOcean, an Israel-based nonprofit organization dedicated to marine environmental research. Its use is subsidized by the group (which itself is financed largely by a Swedish family foundation). Just 69 feet long and 21 feet wide, the ship includes a wet lab, with drains and sluices, and a dry lab, with microscopes and a freezer. A diving platform and aft-deck working area contain a hydraulic crane and a 12-bottle water sampler that can be lowered into the sea.

The ship also has diving equipment and a Seabotix Mini-ROV (for remotely operated vehicle), an unmanned submarine controlled from on board the MedEx. Eight researchers and three crew members can live aboard the ship comfortably for several weeks and can travel 1,700 nautical miles before refueling.

Sea Change in Noah's Flood

In 2005, William B. Ryan, a senior scholar in marine geology and geophysics at the Lamont-Doherty Earth Observatory at Columbia University, set out on the MedEx for an expedition to the Black Sea that would change the understanding of how that vast body of water was formed. He was looking for data to support a hypothesis that the sea had been transformed from a freshwater lake to a saltwater sea connected to the Mediterranean during a sudden, calamitous event, not as a result of a gradual change. Many scholars think such a disaster could be the basis of the biblical story of Noah's flood.

Mr. Ryan was unable to secure funds for the expedition from the National Science Foundation. But with just $50,000 raised in the United States and Israel, he was able to hire the MedEx and its crew for a whole month.

"It made a large difference to us because it let us obtain some very useful, important observations that we would not have done or been able to do because the cost of using other platforms was too high," Mr. Ryan said. "To take a U.S. ship across the Atlantic would require one of the larger-class vessels, and they would run in the range of $20,000 to $30,000 a day, and it would be overcapacity for what we needed to do. The MedEx fit the bill just perfectly."

Sailing around the clock, Mr. Ryan and his crew took core samples of sediment on a tight grid from three regions of the submerged shelf, near Istanbul, that would have been an ancient beach of the Black Sea before it was flooded.

"We not only were able to study across the transition from lake sediment to saltwater sediment, but we found gravels and pebbles that we think were washed in from the straits," he said, referring to the present-day Bosporus and Dardanelles, in Turkey. "Water of high velocity would have been required to carry these pebbles in from the sea because of their size. It's not the only interpretation, but the flood hypothesis would predict these materials would be there, and they were." Studies based on findings from the expedition, published in the journals Marine Geology and Sedimentary Geology, support the idea of a flood.

Sediment cores taken from the sea floor are often stored for months before they can be studied, said Mr. Ryan. "Traditionally large ships do not do this. They are used for collecting cores to be brought back to a depository and then distributed to researchers."

But on the MedEx, he said, "we could open the cores within minutes of them arriving on the deck, carry out our examination, carry out a very important preliminary analysis, which would let us choose the very next location to optimize what we were doing. So it turned out to be much more efficient and effective than had we been on a large ship."

Yossi Mart, a professor of marine studies at the Recanati Institute for Maritime Studies, at Haifa, was Mr. Ryan's partner on the 2005 expedition. (He is also a trustee of EcoOcean.) The low cost of using the MedEx, said Mr. Mart, enables him to take undergraduates and even high-school students on research trips at sea. "It costs more to hire a bus for the day than to use the ship," he said.

Focus on Phytoplankton

The MedEx has also been to the Red Sea, where it explored the coral reefs off Eritrea, but most of its work has been in the eastern Mediterranean, an area that, because of its shallow tides, scientists believe can be an early indicator of changes in the marine environment across the globe.

"The changes that occur in the eastern Mediterranean, if the natural processes continue, will affect [every] ocean eventually," Mr. Mart explained. "Therefore the Mediterranean can serve as proxy to oceanographic changes that might take place because climate is changing."

The MedEx has been the platform for a series of expeditions on phytoplankton, the microscopic marine organisms that account for some 40 percent of the world's photosynthesis and are the basis of the marine food web. What happens to them when the climate or other aspects of the environment change is a matter of intense scientific interest.

Sven Beer, a professor in the department of plant sciences at Tel Aviv University, is the scientific director of EcoOcean. He uses the MedEx to classify thousands of species of phytoplankton by their DNA to see if they can be used to measure marine pollution.

Water samples are trapped using the 12 open-ended bottles, which can be winched down to depths of several hundred meters. Monitors in the onboard lab display the depth, salinity, light intensity, and concentration of phytoplankton inside the bottles, which can be individually sealed by remote control and brought onto the deck for analysis.

"We look at the DNA pattern, and we compare it in a gene bank to DNA patterns that have been made already for known species in laboratories all over the world," said Mr. Beer. "This is a biological indicator of pollution. Because the phytoplankton are the basis of the food web, the changes in the environment that change the phytoplankton composition are the ones that are important."

Mr. Beer is also tracking dinoflagellates, sometimes toxic organisms that, when they multiply or "bloom" in huge numbers, can poison sea creatures and, through them, human beings, in tropical and northern seas. His research aims to see whether those sea blooms are increased to dangerous levels by pollution.

The MedEx cannot do everything. Larger ships can pull up much longer cores from the ocean bottom and thus get information that goes further back in time. And the ship's seismic equipment is more limited than that on a larger vessel. "It can do small things, but what it does, it does well," Mr. Mart said.

One of those things, said Mr. Beer, is to change the face of marine research in the eastern Mediterranean.

"It's going to give us the opportunity to do important science that we couldn't do without this platform," he said. "We could not do this monitoring without having a ship where we can bring up water samples. It's an absolute must."