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Seller's Description

Irwin 31 Centerboard Yawl, 1968 sailboat for sale LOA 31’ 1” LWL 22’ 3” Beam 9’ 7” Draft 3’ 4” board up, 7’ 10” board down Disp 9600 lbs Ballast 3800 lbs Sail Area 460 sqft

Electrical 12 Volt DC 30 amp shorepower Balmar 75 amp dual output alternator with external voltage regulator Spare 50 amp Mitsubishi alternator Battery charge combiner Guest dual bank battery charger Group 27 house battery Group 24 engine start battery

Instruments/Electronics NMEA 2000/Raymarine STNG instrument network Raymarine i70s instruments with depth, speed, sea temperature and wireless wind Raymarine S1 Tillerpilot Fluxgate compass Wireless remote instrument display DSC VHF radio Masthead Windex

Machinery 21 HP Westerbeke W21RD diesel with 607 total hours Hurth HBW 100-1.5R transmission Westerbeke Admiral control panel with analog engine gauges Columbian 3-bladed propeller Morse MJB engine/transmission controls

Sails & Rigging Tall rig – 2’ longer mast than a standard Irwin 31 Harken roller furling on headstay Sail Suite: roller furling working jib, roller furling 140% genoa, storm jib, main w/full battens & 2 reef points, mizzen with 1 reef point, mizzen stay sail, spinnaker, spinnaker staysail Spinnaker pole 2 Enkes 22 two speed primary and 2 Barient 20 single speed secondary winches on cockpit coaming, 2 Barient 10 winches on cabin top and 1 Barient 10 and 1 Lewmar 8 winch on mast Garhauer mast base organizer Rebuilt and rebedded stem head fitting

Cabin Forward v-berth with filler provides sleeping for 2 with storage under berth and on outboard bookshelves Full beam enclosed head Saloon has dinette seating to port with a folding table that drops to create a double berth. Galley is to starboard Saloon storage outboard port and starboard and under furniture 2 full length quarter berths port and starboard in saloon aft with storage under 6 New Found Metals opening ports with screens Insect screens for companionway and v-berth hatches Dedicated wet locker for foul weather gear Solar ventilators in v-berth and saloon

Galley Starboard side galley features a generous counter top with heavy duty latching cooler compartment. No need to load and unload the ice box. Pack your cold provisions once at home, strap it down in the cooler drawer and go! Deep sink with foot pump fresh water Outboard dish/cup storage and dedicated spirits locker 3 drawers for cutlery and utensils Gimbaled 2 burner Origo alcohol stove with cutting board Built-in trash receptacle

Head Manual Raritan PH-II head Hand pump sink basin to port and dresser with hanging locker to starboard.

Cockpit Removable cockpit table Sun/rain cover Custom tiller extension Large seat lockers port and starboard along with a lazarette at stern provide plentiful storage for PFDs, sails, fenders, lines, shore power cord, and chemicals.

Deck Bow and stern pulpits with double lifelines. Gates port and starboard at cockpit. Anchor rode storage in forepeak 22 lb Danforth anchor at bow with 6’ of chain and 84’ of nylon rode Folding swim ladder Full canvas winter cover

Other Equipment Radar reflector Spot light 2 electric and 1 manual bilge pump Tool rolls USCG required safety equipment Comprehensive owners manual with equipment maintenance manuals, electrical and mechanical system drawings, maintenance logs and rigging and hose schedules Sailplan drawing Sunbrella sail covers, winch covers and tiller cover Bosun’s chair Westerbeke engine spares (gaskets, filters, raw water impellers, zincs, alternator belt)

Comprehensive equipment upgrade list and dates available upon request or phone 610-751-seven-six-two-one

Specs

Designer
Ted Irwin
Builder
Irwin Yachts
Associations
?
# Built
?
Hull
Monohull
Keel
Stub + Centerboard
Rudder
?
Construction
FG w/balsa cored deck

Dimensions

Length Overall
31 0 / 9.5 m
Waterline Length
22 2 / 6.8 m
Beam
9 6 / 2.9 m
Draft
3 3 / 1 m 7 6 / 2.3 m
Displacement
9,600 lb / 4,354 kg
Ballast
3,800 lb / 1,724 kg (Lead)

Rig and Sails

Type
Sloop
Reported Sail Area
448′² / 41.6 m²
Total Sail Area
448′² / 41.6 m²
Mainsail
Sail Area
224′² / 20.8 m²
P
31 11 / 9.8 m
E
14 0 / 4.3 m
Air Draft
?
Foresail
Sail Area
224′² / 20.8 m²
I
37 0 / 11.3 m
J
12 1 / 3.7 m
Forestay Length
38 11 / 11.9 m

Auxilary Power

Make
Universal
Model
Atomic 4
HP
25
Fuel Type
Gas
Fuel Capacity
25 gal / 95 l
Engine Hours
?

Accomodations

Water Capacity
50 gal / 189 l
Holding Tank Capacity
?
Headroom
?
Cabins
?

Calculations

Hull Speed
6.1 kn
Classic: 6.32 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

6.1 knots
Classic formula: 6.32 knots
Sail Area/Displacement
15.9
<16: under powered

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.
15.87
<16: under powered
16-20: good performance
>20: high performance
Ballast/Displacement
39.6
<40: less stiff, less 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

39.6
<40: less stiff, less powerful
>40: stiffer, more powerful
Displacement/Length
389.3
>350: ultraheavy

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
389.34
<100: ultralight
100-200: light
200-300: moderate
300-400: heavy
>400: very heavy
Comfort Ratio
29.2
20-30: coastal cruiser

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
29.18
<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
1.8
<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
1.8
<2: better suited for ocean passages
>2: better suited for coastal cruising

Notes

TALL (sloop) RIG:
I: 39’
J: 12.1’
P: 34.0’
E: 14.0’
Disp.: 9600 lbs.
Bsl.: 3800 lbs.
Also offered as a yawl.
(info provided by user)

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