Approaches
The Isles of Shoals rise abruptly from water that's 50 to over 100 feet deep. The main islands that form Gosport Harbor -- Star, Cedar and Smuttynose -- are all rocky and sheer, with navigable water close to shore. If you're coming from the north, west or south there is very little to worry about that isn't normally visible. In the unlikely case that you're approaching from the east, find the Cedar Island and Anderson Ledges (both marked) south and east of Star Island.
There is an unlit Red & White bell off the entrance to help line up an approach. Halfway Rocks (mid-way between Lunging and Star Islands, marked by a nun) show more prominently on the chart than they do on the water. The rocks uncover 2 feet at mean lower low, but on a light-air day with a modest swell they may not break obviously, even at half tide.
Gosport Harbor is well-enough protected from north around to southwest. But in a stiff northwest wind, especially an extended one following an early- or late-season cold front, it can feel uncomfortably exposed.
Anchorages
Anchoring in Gosport Harbor is widely discouraged. The Coast Pilot states that "the bottom is reported to be rocky and foul. . ." Hank and Jan Taft, in their delightful and authoritative A Cruising Guide to the Coast of Maine go further: "Holding ground is very poor, in kelp and rock beds. In most harbors, you can trust your anchor more than unknown moorings, but in Gosport Harbor it is better to pick up a mooring."
It's further complicated by the shape of the harbor. Most of the water inside the 30-foot contour is taken up with moorings, so to find swinging room you'll likely be trying to anchor in depths over 40 feet at low.
Moorings
The Portsmouth Yacht Club has about eight moorings in Gosport Harbor. Some are labelled for member use only; others are used informally by visitors when not occupied by members. There is no mechanism for reservations.
Kittery Point Yacht Club maintains a few moorings here as well. They are not actively managed by the club, and are available first-come first-served to visiting boats when not being used by KPYC members.
Given the Isles' popularity with local boats out of Portsmouth from June through September, and the lack of reservable moorings, it's best to plan your stopover for weeknights or the off-season. Visiting boats should not pick up the private moorings belonging to the Star Island Corporation or to the local fishing families.
There are no slips at the Isles of Shoals.
Breakwaters
Three different breakwaters contribute to the protection of Gosport Harbor. Without them, the anchorage would be closer to an open roadstead than to anything resembling a secure harbor. It's daunting to think that all three were built after the heyday of Gosport as an active fishing community.
The smallest and oldest of the breakwaters connects Smuttynose with Malaga just to its west. The story goes that Captain Samuel Haley "in turning over a flat stone to repair a wall. . . found under it several solid bars of silver from which he realized three thousand dollars. With this money. . . he built the seawall and stone wharf that make the safe little harbor at Smuttynose." {Laighton, p. 20} Various sources date the Haley's Harbor breakwater anywhere from the 1780s to the 1820s.
Next was the breakwater connecting Smuttynose to Cedar, built with rock from Smuttynose in 1821 and substantially rebuilt after 1902. The final section connecting Cedar to Star was constructed by the US government with granite from Rockport, Massachusetts a few years later.
It's irresistible to contrast the initial promise and ultimate result of the breakwaters here and in Sandy Bay.
Fitting Out
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