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Seair 27
Designer: Ralston  ·  Builder: Seair Yachts Ltd. (Can)  ·  First built: 1975
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About the Seair 27

Designed by Ralston and built by Canadian manufacturer Seair Yachts Ltd. beginning in 1975, this 27-footer represents a solid example of mid-1970s pocket cruiser design philosophy. With its fin keel and rudder-on-skeg configuration, the Seair 27 offers a good balance between directional stability and maneuverability that appeals to both coastal cruisers and weekend sailors. The boat's substantial displacement of 6,900 pounds, combined with 2,900 pounds of ballast, creates a stable platform that handles choppy conditions well. The comfort ratio of 27.96 indicates a motion that's neither too quick nor uncomfortably slow, making it suitable for extended coastal passages. Meanwhile, the capsize screening formula of 1.72 suggests reasonable stability for offshore work, though this design is primarily intended for coastal and protected water sailing. The masthead sloop rig provides straightforward sail handling, while the sail area-to-displacement ratio of 14.22 indicates moderate performance in light to medium winds. Fiberglass construction ensures durability with reasonable maintenance requirements. Hull speed calculations suggest comfortable passage-making speeds around 6 knots, making this an ideal choice for sailors prioritizing comfort and seaworthiness over racing performance in their coastal adventures.

Core Dimensions
LOA (Length Overall) 26.83 ft / 8.18 m
LWL (Waterline Length) 21.75 ft / 6.63 m
Beam 8.16 ft / 2.49 m
Max Draft 4.16 ft / 1.27 m
Displacement 6,900.00 lb / 3,130 kg
Ballast 2,900.00 lb / 1,315 kg
Sail Area (Reported) 321.00 ft² / 29.82 m²
Design & Construction
Hull Type Fin with rudder on skeg
Rigging Type Masthead Sloop
Construction FG
Designer Ralston
Builder Seair Yachts Ltd. (CAN)
First Built 1975
Related Sailboats Catalina 27 · Ericson 27 · Pearson 27 · Coronado 27 · Niagara 26
Owner Reviews

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Performance Ratios
SA/Displacement Sail Area to Displacement ratio measures how much sail power a boat has relative to its weight. Higher values mean more performance and speed.
Under 14 — Heavy cruiser, slow14–18 — Cruising sailboat18–22 — Cruiser/racerOver 22 — Performance racer
14.22
Ballast/Displacement Ballast to Displacement ratio shows what percentage of the boat's total weight is ballast. Higher values generally mean better initial stability and stiffer sail carrying.
30–35% — Typical cruiser35–45% — Stiff performance boatOver 45% — Racing oriented
42.03
Displacement/Length Displacement to Length ratio measures how heavy a boat is relative to its waterline length. Lower values mean a lighter, faster boat.
Under 100 — Ultralight racer100–200 — Light cruiser/racer200–300 — Moderate cruiser300–400 — Heavy cruiserOver 400 — Very heavy
299.38
Comfort Ratio Ted Brewer's Comfort Ratio predicts how comfortable a boat will feel in offshore conditions. Higher values mean a steadier, more comfortable motion in a seaway.
Under 20 — Uncomfortably rough20–30 — Acceptable coastal30–40 — Good offshore comfortOver 40 — Very comfortable offshore
27.96
Capsize Screening Formula The USHS Capsize Screening Formula estimates offshore capsize risk. Lower is safer — values under 2.0 are considered acceptable for offshore sailing.
Under 2.0 — Safe for offshore2.0–2.2 — Borderline offshoreOver 2.2 — Coastal use recommended
1.72
Hull Speed Hull Speed is the theoretical maximum speed of a displacement hull, calculated from waterline length. Most cruising sailboats reach this speed in moderate conditions. 6.25 kn
Pounds/Inch Immersion Pounds per Inch Immersion (PPI) tells you how much weight is needed to sink the boat one inch. Useful for calculating how additional gear and stores affect waterline. 634.16 pounds/inch
Rig Dimensions
Mast Height (DWL) 31.16 ft / 9.50 m
Engine & Accommodations
Engine Make Yanmar
Engine Model YSE-8
Engine Type Diesel
Fuel Capacity 35 gals / 132 L
Water Capacity 30 gals / 114 L
How It Compares

vs. Catalina 27, Coronado 27, Ericson 27, Niagara 26, Pearson 27

This boat Similar boats
Dimensions
LOA
Seair 27 ★
26.8 ft
Catalina 27
26.9 ft
Coronado 27
26.7 ft
Ericson 27
26.8 ft
Niagara 26
26.7 ft
Pearson 27
26.9 ft
LWL
Seair 27 ★
21.8 ft
Catalina 27
23.0 ft
Coronado 27
22.0 ft
Ericson 27
20.5 ft
Niagara 26
23.0 ft
Pearson 27
22.5 ft
Beam
Seair 27 ★
8.2 ft
Catalina 27
9.2 ft
Coronado 27
8.5 ft
Ericson 27
9.0 ft
Niagara 26
8.3 ft
Pearson 27
9.2 ft
Displacement
Seair 27 ★
6 lbs
Catalina 27
6 lbs
Coronado 27
6 lbs
Ericson 27
6 lbs
Niagara 26
4 lbs
Pearson 27
5 lbs
Ballast
Seair 27 ★
2 lbs
Catalina 27
2 lbs
Coronado 27
2 lbs
Ericson 27
2 lbs
Niagara 26
1 lbs
Pearson 27
2 lbs
Sail Area
Seair 27 ★
321 sq ft
Catalina 27
323 sq ft
Coronado 27
Ericson 27
323 sq ft
Niagara 26
316 sq ft
Pearson 27
332 sq ft
Performance
PHRF Rating (lower = faster)
Seair 27 ★
Catalina 27
207 s/nm
Coronado 27
231 s/nm
Ericson 27
207 s/nm
Niagara 26
188 s/nm
Pearson 27
204 s/nm
SA / Displacement (higher = more powerful)
Seair 27 ★
14.2
Catalina 27
14.3
Coronado 27
Ericson 27
14.7
Niagara 26
20.1
Pearson 27
16.5
Ballast / Disp (higher = stiffer)
Seair 27 ★
42.0 %
Catalina 27
39.4 %
Coronado 27
40.8 %
Ericson 27
43.9 %
Niagara 26
Pearson 27
Comfort Ratio (higher = more comfortable offshore)
Seair 27 ★
28.0
Catalina 27
Coronado 27
Ericson 27
24.4
Niagara 26
15.2
Pearson 27
19.7
Capsize Screening (lower = safer)
Seair 27 ★
1.72
Catalina 27
Coronado 27
Ericson 27
1.92
Niagara 26
2.10
Pearson 27
2.04
Displacement / Length (lower = lighter)
Seair 27 ★
299
Catalina 27
251
Coronado 27
262
Ericson 27
342
Niagara 26
Pearson 27
Hull Speed
Seair 27 ★
6.3 kts
Catalina 27
Coronado 27
Ericson 27
6.1 kts
Niagara 26
6.4 kts
Pearson 27
6.4 kts
Speed Number (higher = faster)
Seair 27 ★
Catalina 27
Coronado 27
Ericson 27
1.3
Niagara 26
3.9
Pearson 27
2.4
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