Irwin 33 Mkii Known Issues

Common problems, survey red flags, and what to inspect before buying a Irwin 33 Mkii.

These are the most commonly reported problems on the Irwin 33 Mkii, compiled from surveys, owner reports, and marine forums. Use this list as a pre-purchase inspection checklist — especially the high-severity items.

Known Issues

4 High 4 Medium

Accommodations

Medium

The interior liner on Irwin boats of this period traps moisture between the liner and the hull, promoting hidden osmotic damage and mold. The liner is difficult to remove, making inspection of the hull in these areas nearly impossible without destructive investigation.

Electrical

Medium

Original wiring on surviving examples is now 40+ years old and Irwin's factory wiring used substandard connectors and routing practices common to budget builders of the era. A full rewire is typically necessary; pay particular attention to any evidence of overheated connections or amateur add-ons.

original wiring on unrestored boats

Hull/Deck

Medium

Irwin boats of this era are known for thin fiberglass layup in the hull, particularly in the topsides. Flexing and stress cracking around chainplates and the mast partner area are common findings on survey.

1976–1982 production

High

The deck-to-hull joint on Irwin 33s of this period used a toerail-clamped flange that is prone to weeping leaks. Water intrusion into the balsa-cored deck sections near this joint leads to soft deck areas, particularly along the side decks and foredeck.

High

Irwin used balsa core extensively in the deck and cockpit sole. The cockpit sole in particular is prone to saturation and delamination, often soft underfoot. Probe the entire cockpit sole and side decks carefully.

Medium

The spade rudder on this model uses a relatively small diameter rudder shaft. Bearings wear over time and play in the rudder is common; a loose or sloppy rudder should be inspected for shaft fatigue or bearing failure before offshore use.

Keel

High

The fin keel attachment on the Irwin 33 MkII uses a relatively narrow keel sump. The keel bolts are prone to corrosion and the hull-to-keel joint often shows stress cracking or weeping. Keel bolt integrity should be verified by a qualified surveyor.

Rigging

High

Chainplate backing plates on Irwin 33s of this era are often undersized aluminum or mild steel plates glassed into the hull liner. These corrode and lose structural integrity over time without visible external symptoms; the chainplate area should be opened and inspected.

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