Design and Construction
Early boats were Carter’s work. Later Series I through III boats, and those from the Mk II onward, became a collaboration among Carter, Humphreys, and Northshore.
Northshore built the 115 with solid, hand-laid fiberglass below the waterline and balsa-cored topsides and deck. Plywood core was substituted in high-load areas. The hull-to-deck joint sits at the top of a bulwark, where it is through-bolted and chemically bonded, then capped with a teak rail. Teak-capped raised bulwarks also improve security on deck.
A fiberglass floor and furniture pan covers the swing-keel well, while a separate fiberglass headliner finishes the overhead. The Mk I carried a 4,962-pound cast-iron “pancake” internally, plus a hydraulically operated 2,016-pound iron swing keel, for total ballast of 6,978 pounds. Humphreys’ changes for the Mk II and later boats added keel weight, raising total ballast to 7,597 pounds while giving the foil greater depth and lift.
Rig, Deck, and Handling
The deck-stepped Seldén aluminum mast has double spreaders and bears on a compression post in the cabin. All chainplates are inboard, toward the wide cabin trunk, which restricts space on the sidedecks. A single chainplate on each side anchors the upper and intermediate shrouds, while the lowers attach aft. The masthead backstay splits to port and starboard chainplates and has a block-and-tackle adjuster.
The Seldén boom carries internal reefing lines and a rigid vang. A Lewmar halyard winch sits to port of the mast, with foldout steps on both sides. A short stainless sprit to port carries the tack of an asymmetric spinnaker forward of the headstay.
The cockpit and deck are plainly arranged for North Sea and Channel cruising rather than marina lounging. Period testing found cockpit entry and exit awkward, particularly beneath a dodger or bimini—a consequence of the North Sea-inspired cockpit geometry.
On the water, test sailors recorded just over 6 knots on a beam reach and 5.5 knots to windward at 35 degrees apparent. The builder claimed the boat could be sailed safely with the keel either up or down.
The Mk I’s single shallow rudder tended to ventilate as the boat heeled. Humphreys corrected this fault by fitting twin rudders, which retain directional control when heeled while preserving shallow draft.
Accommodations
Below, the 115 is richly finished, with teak ceiling and well-made joinery. Forward, a comfortable pair of over-and-under single berths replaces the usual cramped V-berth.
In the saloon, a U-shaped settee to port wraps around a table mounted on the compression post. The L-shaped galley lies to port, forward of the companionway, and includes a two-basin sink with a teak cover.
A step up aft leads to a spacious owner’s stateroom with a nearly king-size berth. One owner report notes that headroom is limited, partly because of the space needed for the swing-keel mechanism.
Keel, Steering, and Machinery
The hydraulic keel system makes changing draft quick and easy, and a helm display helps the crew assess keel depth. On late Mk IV boats, the pedestal also carried a bow-thruster joystick alongside the keel raising and lowering controls.
Steering is by a Whitlock cable-and-quadrant system. The Lewmar Torque Tube steering is regarded as nearly bulletproof and oversized for the boat’s displacement. Surveyed examples carried Yanmar diesels with shaft drive.
Known Issues
The Mk I rudder’s tendency to ventilate is a historical design fault that was corrected on later models. The cast-iron keel and plate also need periodic refinishing, as rust eventually works through primer and barrier coats.
Cosmetic upkeep varies with hull color. Light blue gelcoat options fade and craze faster than white.
Original boats lacked GFCI interior outlets. The factory shaft seal also used a light-gauge bronze hose barb that becomes fragile with age.
The Verdict
The Southerly 115 is a thoughtfully engineered variable-draft cruiser. Successive generations corrected the early steering fault and added ballast for greater offshore poise. Its interior is unusually refined for a boat offering this degree of draft flexibility, and the later twin-rudder versions are the ones to seek.
Pros
- Twin-rudder Mk II and later models retain steering control when heeled
- Solid fiberglass hull below the waterline, with balsa-cored topsides
- Refined teak interior with practical over-and-under forward berths
- Hydraulic swing keel with a helm display and easy operation
Cons
- Mk I single rudder ventilates when heeled
- Cast-iron keel and plate require periodic refinishing to control rust
- Light blue gelcoat fades and crazes faster than white
- Original shaft-seal hose barb and lack of GFCI outlets need attention
