The leaching of plasticizers is of little real effect especially if one runs the hose for a short time before consuming the water.
Of greater concern is the fact that the so-called "safe" white hose is translucent. Some people can have adverse reactions to the various forms of algae growth which occurs because light can enter the hose. Additionally, the growth, if severe, can clog filters making them less effective, especially the ubiquitous carbon filters often seen around docks.
Given all the other things boats require on a periodic basis, a new garden hose every year seems not worth the consternation.