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Seamaster 47
 ·  Builder: Seamaster  ·  First built: 1977
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About the Seamaster 47

Bearing the trusted Seamaster name, the Seamaster 47 is a substantial bluewater cruising sailboat designed with serious passage-making in mind. Built for sailors who want to venture well beyond coastal waters, this vessel carries the kind of size and presence that inspires confidence on extended offshore voyages, whether crossing an ocean or island-hopping through remote cruising grounds. While detailed specifications for this model are limited, the Seamaster line has historically been associated with sturdy, capable construction intended to handle demanding conditions at sea. A boat of this size typically offers generous interior volume, making it well-suited for liveaboard cruising or lengthy passages where comfort and self-sufficiency matter as much as performance. Buyers drawn to this model are likely prioritizing seakeeping ability and range over racing credentials. For anyone researching the Seamaster 47 as a potential purchase, connecting with current owners and seeking out a thorough survey is particularly worthwhile given the limited publicly available data. Hands-on evaluation will reveal the most about her construction quality, layout, and overall condition — all essential considerations for a boat intended to take you far from shore.

Core Dimensions
LOA (Length Overall) 47.16 ft / 14.37 m
LWL (Waterline Length) 34.00 ft / 10.36 m
Beam 13.25 ft / 4.04 m
Max Draft 5.08 ft / 1.55 m
Displacement 27,308.00 lb / 12,387 kg
Ballast 8,808.00 lb / 3,995 kg
Sail Area (Reported) 680.00 ft² / 63.17 m²
Design & Construction
Hull Type Fin Keel
Rigging Type Staysail Ketch
Construction FG w/balsa cored deck
Builder Seamaster
First Built 1977
Owner Reviews

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Known Issues & What to Watch For

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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
12.05
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
35.62
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
1.76
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. 7.81
S# (Speed Number) The Speed Number (S#) is a quick performance index. Higher values indicate a faster, more powerful design relative to its size.
Under 3.0 — Slow cruiser3.0–5.0 — Average cruiser5.0–7.0 — Performance cruiserOver 7.0 — Racer
1.14
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. 1.0
Rig Dimensions
I (Foretriangle Height) 45.0
J (Foretriangle Base) 14.5
P (Mainsail Luff) 42.0
E (Mainsail Foot) 13.75
SA Fore 326.25
SA Main 288.75
How It Compares

vs. Gulfstar 47 Sailmaster, Hylas 47, Tayana 47 Cc

This boat Similar boats
Dimensions
LOA
Seamaster 47 ★
47.2 ft
Gulfstar 47 Sailmaster
47.4 ft
Hylas 47
46.8 ft
Tayana 47 Cc
47.0 ft
LWL
Seamaster 47 ★
34.0 ft
Gulfstar 47 Sailmaster
40.5 ft
Hylas 47
37.8 ft
Tayana 47 Cc
40.3 ft
Beam
Seamaster 47 ★
13.3 ft
Gulfstar 47 Sailmaster
13.8 ft
Hylas 47
14.3 ft
Tayana 47 Cc
14.5 ft
Displacement
Seamaster 47 ★
27 lbs
Gulfstar 47 Sailmaster
38 lbs
Hylas 47
35 lbs
Tayana 47 Cc
35 lbs
Ballast
Seamaster 47 ★
8 lbs
Gulfstar 47 Sailmaster
10 lbs
Hylas 47
14 lbs
Tayana 47 Cc
11 lbs
Sail Area
Seamaster 47 ★
680 sq ft
Gulfstar 47 Sailmaster
Hylas 47
1 sq ft
Tayana 47 Cc
1 sq ft
Performance
SA / Displacement (higher = more powerful)
Seamaster 47 ★
12.1
Gulfstar 47 Sailmaster
Hylas 47
15.8
Tayana 47 Cc
20.7
Ballast / Disp (higher = stiffer)
Seamaster 47 ★
Gulfstar 47 Sailmaster
27.6 %
Hylas 47
Tayana 47 Cc
33.4 %
Comfort Ratio (higher = more comfortable offshore)
Seamaster 47 ★
35.6
Gulfstar 47 Sailmaster
Hylas 47
38.9
Tayana 47 Cc
36.4
Capsize Screening (lower = safer)
Seamaster 47 ★
1.76
Gulfstar 47 Sailmaster
Hylas 47
1.75
Tayana 47 Cc
1.78
Displacement / Length (lower = lighter)
Seamaster 47 ★
Gulfstar 47 Sailmaster
255
Hylas 47
Tayana 47 Cc
239
Hull Speed
Seamaster 47 ★
7.8 kts
Gulfstar 47 Sailmaster
Hylas 47
8.2 kts
Tayana 47 Cc
8.5 kts
Speed Number (higher = faster)
Seamaster 47 ★
1.1
Gulfstar 47 Sailmaster
Hylas 47
1.7
Tayana 47 Cc
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