Anchoring will never be banned in Nantucket, not as long as boats like these keep calling there… Banning anchoring for boats that can otherwise lie to a mooring, maybe someday – but certainly not for the sort of yachtsmen that Nantucket values above all others…
As others have noted, Nantucket can certainly be a challenging anchorage… Every time I’ve attempted to sneak into shallower water, the thick eelgrass has made me less than confident about my set, and I’ve always opted for anchoring in a bit deeper water where the current runs, but at least the bottom is a bit more scoured, and the holding more secure… In any event, you’ll be quite a ways out from town…
If you do anchor in any current, I’d caution against leaving the boat before you’ve experienced on full tidal cycle, or at least be back to the boat before the current turns the first time… If you’re laying to a mixed rode, use a sentinel, or a keel wrap will be a strong possibility… And, Nantucket is one of those places I always take a handheld GPS with me in the dink, even on the most beautiful days, the fog can come in with surprising speed, they don’t call it the Grey Lady for nothing, after all… (grin)
If you’re spending some time there, I’d recommend trying to get up into the Head of the Harbor for a day or two, it’s a beautiful spot… Virtually guaranteed you’ll be the only cruising boat up there… Pretty skinny water getting in there, but do-able with your draft within a few hours of high water (last time I was in there was about 4 years ago, things could have changed a bit since, of course – but it appears that route has remained fairly stable over the years)
And, if you’re up for some serious gunkholing, consider heading into the pond at Tuckernuck… This one’s not for the faint of heart, you need to time it at slack high water for the arrival at the entrance to the pond, and I wouldn’t attempt it with a swell running offshore and through the gut between Madaket and Tuckernuck… The entrance is very narrow, and very close to the beach, once you’re committed there’s little option for turning back – ideally, you’d want to try it just as the ebb is beginning…
But once inside, you’ll likely have a very special place all to yourself, aside from picnic and day visitors coming over from Madaket… the beach on Tuckernuck is beautiful and remote, and the last time I was in there, I was invited for a drink and what turned into dinner by one of the few homeowners on the island, he said I was the first cruising boat he’d seen in there in years…. Tuckernuck is a very cool place, a real adventure going in there, highly recommended…