When the Navy was searching for the lost airplanes when they disappeared, they put a few guys in the same type of life raft to see where they would drift to. It was so variable that they could not make any conclusions out of their test. They pulled the sailors out of the raft and gave up.
In general the ocean currents are moving around 2.5 knots, the trade winds at 10.5 knots but these are just averages. The real world is much more dynamic and rapidly changing. Check out an example animation here that gives the forecast out to 180 hrs.
It seems to be that the surface winds would have the greatest impact as to where survivors might have drifted off to. It would probably be impossible to predict what the winds in the Pacific were back in 1927. Perhaps you could dig up an old shop log but that seems doubtful. I am not sure if the Navy was keeping logs back then or whether or not they even bothered to generate a report of their search attempts.
1. You latest animation also shows how constant the trade winds are in the area of interest. The animation shows variations in the far north Pacific but not in the area of interest. Start the animation and place your mouse pointer at 150 west and 10 north so that you don't get distracted by the changes going on further north, and you will see that the trade winds are very constant, east or northeast 100% of the time.
2. You again make the claim for extremly high current speeds yet all the sources you have given so far do not support that statement. The previous one you gave only shows 0.2 meters per second, 0.4 mph. The government issued Pilot Charts show 0.7 knots for the are in question.
3. We can be fairly certain that the information in the pilot charts accurately represent the conditions existing in the area in question over the many day period due to the principle of "reduction to the mean." The pilot charts incorporate more than a hundred years of data and are designed to be valid for a particular month of any year, including 1927.
4. Contrary to your claim that the Navy give up in predicting the drift of a life raft there are many tables in the National SAR Manual to accomplish making that prediction. The tables state, "With sustained winds of 6 hours or more, wind current speed will be 5% of wind speed with direction downwind." The winds in the area where you presume Doran splashed down are out of the east to northeast 90% of the time at force 4 which is 11 to 16 knots, 13.5 average. 5% of 13.5 is 0.675 knots, a whole lot less that the 2.5 knots that you claim and this current speed is the same as the 0.7 knots as shown in the Pilot chart for the area.
5. Since I had my National SAR Manual (1986) opened I scanned the table of water needs. Look at the graph for 80° F, about the air temperature for Doran, and you will see that it takes only one quart per day to sustain life indefinitely
IN THE DESERT and less water is needed in other climates, such as on the sea.
gl