Irwin 37
Built 1971–1982 by Irwin Yachts
About the Irwin 37
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 1971–1982
- Builder
- Irwin Yachts
- Designer
- Ted Irwin
- Length
- 37 ft
- Waterline
- 30 ft
- Beam
- 11.5 ft
- Hull / keel
- fin keel
- Rig
- sloop
- Propulsion
- inboard
- Fuel
- varies by year
- Water
- varies by year
- Water heater
- 6 gal · standard
- Stern thruster
- not fitted
- Steering
- pedestal cable · Orion
Tank capacities — where the figures come from
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Fuel varies by year
“100 gallons of fuel” — review (c. mid-1970s (Perkins 4-107, $35,950 lis), sailrite-saildata.nyc3.digitaloceanspaces.comAn annual boat directory, quoting the builder, gives 100 gal fuel and 150 gal water for the sloop and ketch with the Perkins 4-107. The model went through Mk I–V changes from 1971 to 1982, and spec databases give 80 (37-1), 55 (37-4) and 85 gal (37-5), so there's no single standard figure.
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Water varies by year
“150 gallons of water” — review (c. mid-1970s), sailrite-saildata.nyc3.digitaloceanspaces.comThe builder's entry in an annual boat directory gives 150 gal; a spec database gives 50 (37-1) and 187 (37-4). Tankage changed across the Mk I–V versions.
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Water heater 6 gal · standard (Raritan)
“Hot water tank: 6 gal Raritan (37 column, Irwin standards data sheet 8-19-77)” — builder (1977), irwinyachts.comIrwin's handwritten 1977 standards data sheet for the World Cruising series lists a 6 gal Raritan hot water tank and a Par pressure water pump for the 37. It covers the 1977 boats only; the 37 was built 1971-82 with many changes, so earlier and later boats may differ. Heating method not stated.
Tanks are often replaced or added on older boats — check the tank labels or a survey for yours.
Thrusters and steering — where this comes from
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Bow thruster unknown
Irwin's 1977 standards data sheet for the World Cruising series lists no thruster, and no option list was found.
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Stern thruster not fitted
Our earlier figure of none has no source, and nothing was found either way.
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Steering pedestal cable · Orion
“STEERING TYPE (Cable Orion): Wheel Cable 4"Φ *New Std ... WHEEL SIZE 22" ... QUADRANT SIZE 12"” — builder (1977), irwinyachts.comIrwin's handwritten 1977 standards data sheet gives a 22 in. wheel (center cockpit) steering by cable over 4 in. sheaves to a 12 in. quadrant, with Orion written beside the steering type; Irwin's sheet for the 28-39 range also names Orion as the steerer.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Sources disagree on engines, displacement, ballast, draft, number built, model (standard Perkins) — left blank rather than guessed.
Center-cockpit aft-cabin cruiser built in versions 37-1 through 37-5 (Mark V was the last, 1982); roughly 600 sold. Sloop standard, cutter or ketch optional; a bowsprit was added from 1976 (37-2). Keel options: deep fixed, shoal fixed, and keel/centerboard (4.0 ft board up). Displacement, ballast, draft and tank sizes vary by version and source, so they are left null (see disputed). The original engine was the Perkins 4-107; later boats have the 4-108. LOA, LWL and beam agree across sources. Engine access through the walk-through passage is praised. Hull laminate type (solid vs cored) not stated in sources read.
Engines fitted
-
Perkins 4-108 — 40 hp, diesel, single
standard
Practical Sailor's review text: a 40 hp Perkins 4-108 turning a three-blade prop through 2:1 reduction. Its own spec table says 4-107 (see disputed). Keel Index also gives 40 hp.Sources: practical-sailor.com · keelindex.com
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Perkins 4-107 — 40 hp, diesel, single
standard
Named in Practical Sailor's specification table (40 hp); may be the earlier engine or a table error.Sources: practical-sailor.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
The 1977 standards data sheet has no generator line for the 37.
Manuals and brochures online
- Spec sheet Irwin 37, 42, 43, 44, 52 standards data sheet, World Cruising series (8-19-77) (1977) — irwinyachts.com
Hosted by the builder or an owners' association; they own the copyright.
Known problems for this model
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Gate valves on through-hulls plumbing
Practical Sailor found gate valves fitted on the through-hulls of the boats it examined, which it considers a serious shortcoming; replace with proper seacocks.practical-sailor.com
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Bottom hollows and print-through hull
Some later hulls showed deep dished areas in the bottom, blamed on hulls being cradled before fully cured; earlier hulls often show roving print-through in the topsides gelcoat.practical-sailor.com
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Gelcoat defects and crazing deck
The model had a record of warranty claims for thin, thick, discolored or crazed gelcoat, and the diamond-pattern nonskid used into the early 1980s is hard to repair invisibly. The fiberglass bowsprit could flex and craze the gelcoat when the rig was tensioned.practical-sailor.com
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Screwed hull-to-deck joint deck
The hull and deck flanges are bonded with polyester slurry and held by self-tapping stainless screws at roughly 6-inch spacing rather than through-bolts, so check the joint for leaks and movement.practical-sailor.com
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Chainplates glassed into topsides rigging
Chainplates are stainless webs laminated into the hull sides during layup, so they cannot be pulled for inspection like bolted plates; any corrosion or leakage there is hard to assess.practical-sailor.com
1 more
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Heavy helm steering
Owners report a stiff, attention-hungry helm under sail and power, which the reviewer attributes to an unbalanced rudder, a small wheel and a long steering run around the aft cabin.practical-sailor.com
Engines & parts
Perkins 4.108 parts: good
Factory standard engine — you entered “Perkins 4-108”
Out of production but very well supported. Trans Atlantic Diesels (TAD) sells complete aftermarket rebuild kits (pistons, liners, rings, bearings, gaskets, valves, guides, seals), heads, blocks, crankshafts, genuine Perkins camshafts, rebuilt injection pumps and injectors, Jabsco/Sherwood raw water pumps, heat exchangers, starters, alternators and elbows, plus rebuilt exchange engines. The Westerbeke 4-107/4-108 family and some industrial engines share the base design.
Parts sources: Trans Atlantic Diesels (TAD), Foley Engines
Common problems (1)
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Rear main (crankshaft) seal leak engine
The original rope-type rear seal is notorious for leaking and often starts leaking again a few hundred hours after replacement; Foley sells a nylon/Teflon replacement seal meant to cure it, and owners check the crankshaft sealing surface for pitting.foleyengines.com · boatdesign.net · forums.sailinganarchy.com
Maker’s service schedule (13)
| Engine oil & filter change 4.108(M) marine | 150 hrs or 3 mo | “4.107(M) and 4.108(M) Engines ... Every 150 hours or 3 months (whichever occurs first). Drain and renew lubricating oil” — manufacturer (1973), fujiyachts.net |
| Fuel filters & water separator 4.108(M) marine | 400 hrs or 1 yr | “Every 400 hours or 12 months (whichever occurs first). Renew final fuel filter element.” — manufacturer (1973), fujiyachts.net |
| Air filter / intake silencer 4.108(M) marine | 150 hrs or 3 mo | “Every 150 hours or 3 months (whichever occurs first). ... Clean air intake gauze.” — manufacturer (1973), fujiyachts.net |
| Drive belts inspect / replace 4.108(M) marine | 150 hrs or 3 mo | “Every 150 hours or 3 months (whichever occurs first). ... * Check drive belt tension.” — manufacturer (1973), fujiyachts.net |
| Valve clearance check / adjust 4.108(M) marine | 2,400 hrs | “Every 2,400 hours ... Check and adjust valve tip clearances.” — manufacturer (1973), fujiyachts.net |
| Injector test / service 4.108(M) marine | 2,400 hrs | “Every 2,400 hours ... Service atomisers.” — manufacturer (1973), fujiyachts.net |
| Transmission fluid change 4.108(M) marine | 400 hrs or 1 yr | “Every 400 hours or 12 months (whichever occurs first). ... Change gearbox oil.” — manufacturer (1973), fujiyachts.net |
| Clean water trap 4.108(M) marine | 150 hrs or 3 mo | “Every 150 hours or 3 months (whichever occurs first). ... Clean water trap.” — manufacturer (1973), fujiyachts.net |
| Check engine for oil and water leaks 4.108(M) marine | 150 hrs or 3 mo | “Every 150 hours or 3 months (whichever occurs first). ... Check engine for leakage of oil and water.” — manufacturer (1973), fujiyachts.net |
| Lubricate dynamo rear bush (where fitted) 4.108(M) marine | 150 hrs or 3 mo | “Every 150 hours or 3 months (whichever occurs first). ... Lubricate dynamo rear bush (where fitted).” — manufacturer (1973), fujiyachts.net |
| Check hoses and clips 4.108(M) marine | 400 hrs or 1 yr | “Every 400 hours or 12 months (whichever occurs first). ... Check hoses and clips.” — manufacturer (1973), fujiyachts.net |
| Drain and clean fuel tank 4.108(M) marine | 400 hrs or 1 yr | “Every 400 hours or 12 months (whichever occurs first). ... Drain and clean fuel tank” — manufacturer (1973), fujiyachts.net |
| Examine and service starter motor, generator etc. 4.108(M) marine | 2,400 hrs | “Every 2,400 hours Arrange for examination and service of proprietary equipment, i.e. starter motor, generator, etc.” — manufacturer (1973), fujiyachts.net |
Service part numbers (7)
| Oil filter later engines with spin-on filter |
Perkins 2654403 | “A genuine Perkins 4.108 oil filter - OE Part No. 2654403 ... Fits 4.108 and 4.108M.” — dealer, parts4engines.com · “Filter, Oil late type long 2654403, Length 130mm - 2654403” — dealer, lancingmarine.com |
| Oil filter early engines with element-in-canister filter |
Perkins 26540154 | “A genuine Perkins 4.108 Oil Filter - OE Part No. 26540154” — dealer, parts4engines.com · “Filter, Oil early type 26540154, Length 122mm - 26540154” — dealer, lancingmarine.com |
| Fuel filter cartridge-type filter housing (most engines) |
Perkins 4326658 Replaces 26561117 Also: Delphi (CAV) 296 |
“A genuine Perkins 4.108 fuel filter - OE Part No. 4326658 ... supersedes ... 26561117.” — dealer, parts4engines.com · “Fuel Filter (296) Was 26561117 Now 4326658” — dealer, lancingmarine.com |
| Fuel filter early engines with bowl-type filter housing |
Perkins 30242 | “A genuine Perkins 4.108 fuel filter element - OE Part Number 30242 ... fitted to early Perkins 4.108” — dealer, parts4engines.com · “Filter element, Fuel old type 30242, Length 74mm small element - 30242” — dealer, lancingmarine.com |
| Raw-water impeller Jabsco raw-water pump (3270, 3370-200 or 9970-200) |
Jabsco 1210-0001 | “4.107M / 4.108M / LL 9970-200 040 3/4" BSP Flange SK229 3298 1210-0001” — manufacturer, marineengine.com |
| Raw-water pump kit Jabsco 9970-200 pump |
Jabsco SK229 | “4.107M / 4.108M / LL 9970-200 040 3/4" BSP Flange SK229 3298 1210-0001” — manufacturer, marineengine.com |
| Raw-water pump kit Jabsco 3370-200 pump (obsolete) |
Jabsco SK33 | “4.107M / 4.108M / LL 3370-200 ... 9970-200 SK33 3298 1210-0001” — manufacturer, marineengine.com |
From the engine maker’s parts lists, or two independent parts dealers. Numbers change with serial number and get superseded — check yours before ordering.
Own a Irwin 37? Add her to your boats, then share a photo — names, numbers and faces are blurred before it appears.
Other Irwin models
- Irwin 10/4 1975–1982
- Irwin 30 Citation 1977–?
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.