IRWIN 31
Specifications
Hull
| LOA | 31.08 ft |
| LWL | 22.25 ft |
| Beam | 9.58 ft |
| Draft | 7.5 ft/ 3.33 ft min |
| Displacement | 9,600 lb |
| Ballast | 3,799.7 lb |
| Hull speed1.34·√LWL | 6.3 kn |
Rig & Sails
| Iforetriangle height | 39 ft |
| Jforetriangle base | 12.1 ft |
| Pmainsail luff | 34 ft |
| Emainsail foot | 14 ft |
| FLforestay | 12.1 ft |
| Mainsail | 465.8 sq ft |
| Jib (100%) | 223.9 sq ft |
| Spinnaker | 380.5 sq ft |
Engine
| Commonly | Perkins, Yanmar, Westerbeke, Vetus, Ford |
About the IRWIN 31
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)
The Irwin 31 is a classic masthead sloop designed by Ted Irwin and built by Irwin Yachts (USA) in 1968, with an unknown total hull count. This single-year production run represents a distinct era in American boatbuilding, featuring a heavy displacement of 9600.0 lb and a full/long keel configuration that prioritizes stability and comfort over speed.
- Best for:
- This vessel is best suited for coastal cruisers and those seeking a traditional, stable platform for relaxed weekend sailing, as its high comfort ratio of 29.37 and heavy displacement provide a smooth ride in choppy conditions. It is less ideal for performance-oriented sailors or those requiring shallow draft access, given its maximum draft of 7.5 ft.
- Bluewater capability:
- With a capsize ratio of 1.81 and a displacement/length ratio of 389.07, the Irwin 31 demonstrates strong inherent stability and seaworthiness for offshore passages, supported by its full keel design which aids in tracking and safety in heavy weather.
- Comparables:
- Comparable boats from the late 1960s include the Cal 30 and the O'Day 32, which share similar displacement characteristics and full-keel designs aimed at bluewater cruising. These models offer similar interior volumes and traditional sailing manners, making them direct competitors in the vintage cruiser market.
Performance
Pricing
We don't have market pricing data for the IRWIN 31 yet. If you own one, help other buyers — what did you pay for it? Reports build a community price estimate over time.
Estimated Cost of Ownership
Based on 31.08ft LOA. Actual costs vary by condition, usage, and local rates.
Known Issues & Pre-Purchase Inspection
16 reported issues across 7 systems for the IRWIN 31, compiled from owner reports in sailing forums and owner-association material.
Unlock the full inspection report
Thinking of buying a IRWIN 31? This is an in-depth report on the faults this model is known for — so you know exactly what to check when you walk the boat. For the price of a coffee.
- ✓ All 16 specific issues — severity, symptoms & fixes
- ✓ Model-specific pre-purchase inspection checklist
- ✓ Downloadable PDF to take to your surveyor — yours to keep
One-time $2.99 · secure checkout by Stripe · instant access · 30 days online, PDF yours to keep
Similar Sailboats
Which engine powers your IRWIN 31?
We haven't confirmed the engine for this model yet. If you own or know one, tell us — as owners report in, we build an accurate picture over time.
Brands sometimes mentioned for this model: Perkins, Yanmar, Westerbeke, Vetus — is it one of these?
Already know your engine? Search all engines → to find its exact parts.
Used sails that fit the IRWIN 31
Checking eBay for sails sized to this boat's rig…