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Wharram Pahi 31

1976–present · designed by James Wharram + Hanneke Boon · built by Wharram Designs (plans) / owner-built

James Wharram + Hanneke Boon Polynesian-inspired cruising catamaran — the smallest of the Pahi cruising line. Plywood-epoxy stitch-and-glue or strip-plank construction from plans sold by Wharram Designs Ltd (Cornwall, UK); the vast majority of hulls are owner-built by amateurs over multi-year timelines. Open slatted bridge deck (no solid panel), deck-stepped masts supported by lashings rather than chainplates, hulls lashed to crossbeams with synthetic line. Wood-composite hull is repairable anywhere with hand tools, epoxy, and glass cloth — a genuine asset for remote cruising. Intended for cost-effective coastal cruising by a couple or shorthanded crew.

This is a general read on the Wharram Pahi 31 class — informed background, not a verdict on any individual boat. Condition, refit history, and how a particular hull was sailed and stored matter far more than class reputation. Use it to know what to look for; for a read on a specific listing, run a free FairKeel report on that boat.

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At a glance

Hull form: Multihull Cat
Rudder: Transom Hung
Mast step: Deck Stepped
Hull construction: Wood
Bridgedeck: Open
Production: 1976–present
Built in: UK (plans) / variable (owner-built)

What the Wharram Pahi 31 is known for

Easily repairable anywhere — wood-composite plywood-epoxy + glass cloth hull can be patched in beach or backyard with hand tools and locally-available materials. Genuine asset for remote cruising vs. production fiberglass cats requiring yard infrastructure.
Lashed-not-bolted hull-to-crossbeam connection is intentionally flexible — distributes load gradually, avoids bolt-fatigue failure common to rigid catamaran connections.
Owner community is engaged + well-documented — Wharram Designs has supported builders since the 1960s; institutional knowledge is deep and freely shared via owner networks.

Known trade-offs

Quality varies hull-by-hull — a meticulous owner-builder produces an exemplary boat; an undercapitalised first-time builder produces a structurally suspect hull. Build provenance + materials documentation are non-negotiable. Build-time hidden defects (poor stitch alignment, undersized glass laminate, missed hot-coats) can persist for decades until stressed.
Plywood-epoxy hulls have a finite lifespan dominated by moisture ingress; an old Pahi 31 with weak epoxy schedule history may be at end-of-life regardless of cosmetic appearance.
Resale market is thin and niche; expect long marketing periods and limited buyer pool when selling.

Age-related quirks to expect

Owner-built quality variance — every Pahi 31 is effectively bespoke; survey must assess THIS hull, not class priors High all (owner-built)

Plywood-epoxy hull moisture susceptibility — breached epoxy + persistent moisture = plywood rot in affected area High all (age + maintenance-driven)

Lashed crossbeam attachment — synthetic-line lashings need annual inspection and replacement every 5-10 years Medium all (architectural)

Wharram-specific rig (gaff-like or soft-wing) — riggers unfamiliar with Wharrams may quote inappropriate generic-sloop solutions Low all (architectural)

Systems to check before you buy

Hull-laminate + epoxy condition priority: coastal, liveaboard, offshore

The highest-risk system on any Wharram. Inspect epoxy hot-coat condition (UV degradation visible as chalking), plywood-stitch joint integrity at hull-bottom and bow seams, glass-sheathing delamination around through-fittings and waterline. Moisture-meter survey of every hull section is mandatory. Builder logs + materials provenance (which plywood grade, which epoxy schedule, hot-coat history) matter enormously — they may not exist for older hulls.

Lashings + crossbeam attachment priority: coastal, offshore

Hulls are joined to crossbeams with synthetic-line lashings, not bolts. The lashing design is intentional (distributes load gradually) but lashings need annual inspection and replacement every 5-10 years depending on UV exposure and line material. A failed lashing offshore is a catastrophic failure mode unique to Wharrams.

Wharram rig — mast, sails, rigging geometry priority: coastal, offshore

Wharram designs use a class-specific rig (gaff-like or soft-wing geometry) not equivalent to a generic sloop. Standing rigging geometry, mast support via lashings, and sail-handling layouts are Wharram-specific. Consult Wharram Designs or experienced Wharram riggers; generic-yard quotes are often inappropriate.

Auxiliary propulsion (typically twin outboards) priority: coastal, liveaboard

Most Pahi 31s use small outboards (5-15hp) — twin or single, mounted in outboard wells or on transom brackets. Verify configuration on a given hull. Outboard wells in plywood hulls are a moisture-ingress hotspot; inspect surrounding laminate carefully.

How it fits your plans

Coastal: Designed for it. Wide beam + shallow draft = good shoal-water cruiser; light-displacement plywood-epoxy hulls move well in light air.
Liveaboard: Workable for one or a tolerant couple. Accommodation is in the hulls only (no enclosed saloon); deck-tent or hard-top over the open bridge platform provides weather shelter.
Offshore: Possible for a well-built example with experienced crew, but the smallest Pahi is closer to a coastal cruiser than a dedicated bluewater platform. Owner-built quality variance dominates the risk calculus.

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