BoatsHalcyon 27

Halcyon 27

Masthead Sloop · Long Keel w/trans. Hung Rudder · 1968–1975

An Alan Buchanan-designed masthead sloop with a long keel and heavy ballast, evolved from the earlier Diamond 27

Designed by Alan H. Buchanan, built by Offshore Yachts Ltd.

LOA
Beam
Draft (max)
Displacement
Ballast
Hull type
Long Keel w/trans. Hung Rudder

Is it for you?

Character

Where this design lands on the numbers a shopper trusts — read straight from her own ratios.

LivelySea-kindly

Her heavy displacement on a narrow beam gives 31 — a sea-kindly motion in a seaway.

Comfort ratio 31
CoastalBluewater

At 1.63 she sits well under the 2.0 line — a solidly ocean-capable hull for her size.

Capsize screening 1.63
LightHeavy

361 — very heavy for her waterline, a serious load-carrying cruiser.

Displacement / length 361
EasygoingPowered-up

13.1 — modest power for her weight; easygoing rather than lively, and happier with a breeze.

Sail area / displacement 13.1
TenderStiff

45% of her weight is ballast — stiff, standing up well to her sails.

Ballast 45%

Built heavy and sea-kindly — a boat made to cross oceans and forgive a rough night.

  • Narrower than ~80% of boats her size on file

Compared with 304 boats of the same type within a quarter of her length.

The record

Full specifications

The complete reference set — tap any figure to switch between metric and imperial.

Dimensions
Weights
Ballast / displacement
44.6%
Rig & sail area
Rig
Masthead Sloop
Ratios
SA / displacement
13.1
Displacement / length
361.3
Comfort ratio
30.9
Capsize screening
1.63
Hull speed
6.0 kn
Pounds / inch immersion
555
Hull
Hull type
Long keel w/trans. hung rudder
Construction
Fiberglass
Production
Years built
1968–1975
Designer
Alan H. Buchanan
Builder
Offshore Yachts Ltd

Boats like this, on the water

Nobody has filmed this one — but these are close.

Comparable boats the fleet has on camera: same type, within a quarter of her length. Open the boat, or watch the video — a timestamp means she only appears in passing.

Pacific Seacraft Dana 248.31 mSame hull familyNear-identical lengthA heavy-displacement W.I.B. Crealock cutter designed for offshore stability and serious coastal cruising
Pearson Yachts-USA Triton8.63 mSame hull family0.4 m longerA Carl Alberg-designed long-keel fractional sloop that pioneered fibreglass cruising and saw international production.
Cape Dory 278.25 mSame hull familyNear-identical lengthA 1977-1985 production masthead sloop featuring a 40% ballast ratio for stability in a traditional full-keel hull
Cape Dory 288.56 mSame hull family0.3 m longerA classic Carl Alberg full-keel masthead sloop designed for steady, comfortable cruising
Flicka 207.32 mSame hull family0.9 m shorterA Bruce Bingham-designed cutter with a long keel, originally offered as amateur plans before becoming a production classic
Bristol Yachts 247.49 mSame hull family0.7 m shorterA Paul Coble-designed masthead sloop with a long keel and over 50% ballast ratio for stable coastal cruising

The family

Boats like this

Nearby designs by size, type, and era — worth a look alongside her.

Keep looking

Nothing filmed of this one yet

Two ways to keep looking — both search what the fleet has actually recorded.

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