1970 Irwin 34 vs 1978 Cape Dory 270 — Comparison

1970 Irwin 34
VS
1978 Cape Dory 270

Specifications Side by Side

Specification1970 Irwin 341978 Cape Dory 270
General
ManufacturerIrwinCape Dory
Year1970–19781978–1985
TypeSloopSloop
CountryUSAUSA
DesignerTed IrwinCarl Alberg
Dimensions
LOA10.36 m (34.0 ft)8.23 m (27.0 ft)
LWL8.23 m (27.0 ft)6.40 m (21.0 ft)
Beam3.20 m (10.5 ft)2.59 m (8.5 ft)
Draft1.52 m (5.0 ft)1.14 m (3.7 ft)
Weight
Displacement5,443 kg (12,000 lbs)2,722 kg (6,001 lbs)
Ballast2,177 kg (4,799 lbs)1,134 kg (2,500 lbs)
Sailing
Sail Area47.9 m² (516 ft²)28.0 m² (301 ft²)
Hull MaterialFiberglassFiberglass
Keel TypeFullFull
Engine & Tanks
Engine18 HP12 HP
Fuel Capacity76 L (20.1 gal)38 L (10.0 gal)
Water Capacity114 L (30.1 gal)68 L (18.0 gal)
Accommodation
Berths64
Cabins21

Performance Comparison

SA/D Ratio (Higher = more sail power per displacement)
1970 Irwin 34
15.73
1978 Cape Dory 270
14.60
Ballast Ratio (Higher = more stability)
1970 Irwin 34
40.00
1978 Cape Dory 270
41.66
Capsize Ratio (Lower = safer offshore)
1970 Irwin 34
0.73
1978 Cape Dory 270
0.74
Comfort Ratio (Higher = gentler motion)
1970 Irwin 34
22.58
1978 Cape Dory 270
24.39

Detailed Comparison

The 1970 Irwin 34 and 1978 Cape Dory 270 represent two takes on sloop-rigged sailing. The 1970 Irwin 34 is a 1970s design by Irwin from USA, while the 1978 Cape Dory 270 is a 1970s offering from Cape Dory from USA. The 1970 Irwin 34 was penned by Ted Irwin. The 1978 Cape Dory 270 was designed by Carl Alberg.

In terms of size, the 1970 Irwin 34 measures 10.36m (34.0ft) overall with a beam of 3.20m, compared to the 1978 Cape Dory 270 at 8.23m (27.0ft) with a 2.59m beam. The 1970 Irwin 34 is 2.13m longer than the 1978 Cape Dory 270. The 1970 Irwin 34 displaces approximately 100% more than its counterpart, which significantly affects how each boat handles in different sea states.

Looking at performance, the 1970 Irwin 34 has moderate sail power suitable for relaxed cruising with an SA/D ratio of 15.73 and 47.9 m² of sail area. The 1978 Cape Dory 270, with an SA/D of 14.60 and 28.0 m² of canvas, offers modest sail power for its displacement. The 1970 Irwin 34 has the edge in terms of raw sailing performance.

For comfort and safety, the 1970 Irwin 34 offers a moderate motion comfort level (comfort ratio: 22.6) and excellent capsize resistance suitable for offshore voyaging (capsize ratio: 0.73). The 1978 Cape Dory 270 has a comfort ratio of 24.4 and a capsize screening value of 0.74. The ballast ratios are 40.0% for the 1970 Irwin 34 and 41.7% for the 1978 Cape Dory 270, reflecting their respective approaches to stability.

Below deck, the 1970 Irwin 34 provides 6 berths in 2 cabins with 114L of water capacity and 76L of fuel. The 1978 Cape Dory 270 offers 4 berths in 1 cabin with 68L water and 38L fuel capacity.

Verdict

For cruising: The 1978 Cape Dory 270 is the better choice for comfortable cruising thanks to its higher comfort ratio, offering a gentler motion at sea that crews will appreciate on longer passages.

For racing: The 1970 Irwin 34 has the performance advantage with its superior SA/D ratio, meaning more sail power relative to its displacement for competitive sailing.

For liveaboard: The 1970 Irwin 34 offers more sleeping accommodation, making it better suited for extended living aboard. Consider water and fuel capacity for extended stays away from marinas.

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