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1971 Irwin Yachts 43 Classic

Listed
Expired
$34,000 USD

Seller's Description

Here is a tough old battleship Irwin, the original 43 aft cockpit sloop, handily and incrementally renovated by the current owner over the past decade.

A heavy build vessel with a very roomy cockpit and interior, the tall bow is flared to shed seas, and freeboard is ample, the ride will be comfortable in 6-7 foot seas, making this a capable blue water and long excursion cruiser.

Down below is a large main cabin with plenty of seating, galley with stove and a large, refrigerated ice box, head with shower, forward berth, and two aft quarter berths… room for plenty, a luxury for two.

The original Westerbeke 30 hp engine was replaced with a 60 hp Perkins, with the entire driveline upgraded to handle the increased power, and virtually all plumbing and wiring for both the machinery and domestic systems replaced as well.

The mast was refurbished and all the standing and running rigging replaced, and the entire cabin sole has been professionally replaced with beautiful, tough bamboo.

One owner preference alteration was to pin the centerboard at five feet of draft, a reversible modification, because the owner did not like the design of the lift mechanism, felt the boat performed fine without the deployed centerboard, and, as a long-distance cruiser, did not wish to risk being stuck with it down.

Fully equipped with ample and serviceable sail inventory, safety gear, and spares, this boat is ready to take you anywhere you wish to go.

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Specs

Designer
Ted Irwin
Builder
Irwin Yachts
Association
Irwin Yacht Owners
# Built
?
Hull
Monohull
Keel
Stub + Centerboard
Rudder
?
Construction
FG

Dimensions

Length Overall
43 6 / 13.3 m
Waterline Length
31 11 / 9.8 m
Beam
11 6 / 3.5 m
Draft
4 3 / 1.3 m 8 0 / 2.4 m
Displacement
23,000 lb / 10,433 kg
Ballast
10,500 lb / 4,763 kg

Rig and Sails

Type
Sloop
Reported Sail Area
872′² / 81 m²
Total Sail Area
872′² / 81 m²
Mainsail
Sail Area
426′² / 39.5 m²
P
44 9 / 13.7 m
E
18 11 / 5.8 m
Air Draft
?
Foresail
Sail Area
446′² / 41.5 m²
I
50 11 / 15.5 m
J
17 5 / 5.3 m
Forestay Length
53 10 / 16.4 m

Auxilary Power

Make
Unimite
Model
?
HP
?
Fuel Type
Gas
Fuel Capacity
?
Engine Hours
?

Accomodations

Water Capacity
?
Holding Tank Capacity
?
Headroom
?
Cabins
?

Calculations

Hull Speed
7.8 kn
Classic: 7.58 kn

Hull Speed

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Formula

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

A more accurate formula devised by Dave Gerr in The Propeller Handbook replaces the Speed/Length ratio constant of 1.34 with a calculation based on the Displacement/Length ratio.

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio.311
Hull Speed = Max Speed/Length ratio x √LWL

7.82 knots
Classic formula: 7.58 knots
Sail Area/Displacement
17.3
16-20: good performance

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

Formula

SA/D = SA ÷ (D ÷ 64)2/3

  • SA: Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
  • D: Displacement in pounds.
17.25
<16: under powered
16-20: good performance
>20: high performance
Ballast/Displacement
45.7
>40: stiffer, more powerful

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Formula

Ballast / Displacement * 100

45.65
<40: less stiff, less powerful
>40: stiffer, more powerful
Displacement/Length
313.7
275-350: heavy

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

Formula

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

  • D: Displacement of the boat in pounds.
  • LWL: Waterline length in feet
313.71
<100: ultralight
100-200: light
200-300: moderate
300-400: heavy
>400: very heavy
Comfort Ratio
38.4
30-40: moderate bluewater cruising boat

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Formula

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam1.33)

  • D: Displacement of the boat in pounds
  • LWL: Waterline length in feet
  • LOA: Length overall in feet
  • Beam: Width of boat at the widest point in feet
38.42
<20: lightweight racing boat
20-30: coastal cruiser
30-40: moderate bluewater cruising boat
40-50: heavy bluewater boat
>50: extremely heavy bluewater boat
Capsize Screening
1.6
<2.0: better suited for ocean passages

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

Formula

CSV = Beam ÷ ³√(D / 64)

  • Beam: Width of boat at the widest point in feet
  • D: Displacement of the boat in pounds
1.62
<2: better suited for ocean passages
>2: better suited for coastal cruising

Notes

A fixed keel version was also available, as was a yawl rig. Diesel available as an option.

This listing is presented by PopYachts.com. Visit their website for more information or to contact the seller.

View on PopYachts.com

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