No question, the original 9913 could be a water hose. It had an air gap between the center conductor and the foam dielectric with a spiral winding of Teflon (?) to keep the spacing constant. A friend and operator of a repeater went up to determine why the performance was deteriorating. He found water running out of the feedline into the utility building. My first satellite station, circa 1986, used 9913 to the preamps at the tower, and then RG-213 (later LMR-400UF) to the antennas. I put some additional sealing at the preamps, and never had a problem with water. Perhaps I was lucky; I certainly was not good. :)
However, 9913 has evolved over the last 30 years in all versions. After my tower and antennas were destroyed, I rebuilt the system using LMR to the preamps, and hardline for the 24 cm feed. I had never been satisfied with the actual flexibility of the 400UF. 9913F7 is the loss equivalent and far more flexible. It lacks the air gap of the original, so no water. With some trepidation, I ordered some for the "rotator loop." After 5 years, based on performance and loss measurements, they are as good as new.
FWIW,
Alan WA4SCA