I’m assuming you mean not being able to wash at all, including shaving—legs if you do that, and face if you’re a man. You stink, but you don’t usually smell it. You adapt. You will start to itch here and there, especially in the dark, moist places like the crotch and underarms. The first few days of an unshaven face can be very itchy, I’m assuming legs get itchy, too. Your facial pores fill up, you look like shit. If you have a proclivity to acne, it will get worse. Your hair gets greasy, scalp might start to itch. If you incur any wounds, even small ones, you risk minor, local infection. That’s a week. Not so bad, if you’re alone.
During stormy seas (not a metaphor) lasting more than a week, I have experienced this. It’s not very nice, and climbing into your berth night after night after being drenched on deck by salty seas can be quite uncomfortable, especially to the novice. But you’d be amazed what you can get used to, knowing it’s only temporary, if you are preoccupied by more important things. Also, almost everything out here is temporary: the weather, living conditions, even the boat and you. Realizing this helps one get through it. I’m surrounded by water most of the time. I find that Ultra Concentrated Dawn liquid soap is best for bathing in salt water. You come out feeling as if you’ve had a freshwater bath. But in calmer weather, which is most of the time, I have a fine fresh-water shower on board. It is rare that I go a week without a shower. Just thought I’d mention that in case you all got the idea my familiarity with poor hygiene was reflective of my usual routine. Honestly, I bathe daily, sometimes more so and often involuntarily.