• *Widely-flaring chines and overhanging bows.
• *A considerable “rocker” underwater profile to allow manoeuvrability and skidding to leeward under high winds.
• *Solid foredeck with no trampoline.
• *Twin inboard diesels (sited aft), or single centrally-placed steered outboard.
• *Vertical transoms.
• *Aft cockpit with protected wheel steering.
• *Conventional accommodation, with two main berths on the bridgedeck forward of the saloon.
• *Occasional single berths further aft in the hulls.
• *Galley-below layout (in the port or starboard hull).
• *Single head & shower room.
• *Roller furling on the forestay.

(Thanks to Rick at the Catamaransite for originally collating this data)

(aka 27)8M data *LOA: 27“ *LWL: 25' 4” *Beam: 13' 8“ *Draft: 2' 4” *Displacement: 6,000 lbs (dry) *Sail area: 376 sq ft (Main + number 1 Jib Lack Brochure) Often now fitted with larger furling genoas

(aka 30) 9M data *LOA: 29' 3“ *LWL: 25' 4” *Beam: 13' 9“ *Draft: 2' 6” *Displacement: 8,000 lbs (dry) *Sail area: 420 sqft (Main + number 1 Jib Lack Brochure) Often now fitted with larger furling genoas

(later update to 9) 900 data *LOA: 29' 3“ *LWL: 25' 4” *Beam: 13' 9“ *Draft: 2' 6” *Displacement: 8,000 lbs (dry) *Sail area: 420 sqft (same as 9m).

(aka 34)10M data *LOA: 33' 8“ *LWL: 27' *Beam: 15' 3” *Draft: 2' 9“ *Displacement: 11,000 lbs (dry) *Sail area: Main 283 sq ft, Genoa 333 sq ft

(aka 36)(modified 10M) 11M data *LOA: 35' 9” *LWL: 28' 3“ *Beam: 15' 5” *Draft: 2' 9“ *Displacement: 13,000 lbs (dry) *Sail area: Main 290 sq.ft; Genoa 333 sq.ft

(aka 41)12M data *LOA: 40' 10” *LWL:36' (est) *Beam: 17' 6“ *Draft: 3' 1” *Displacement: 18,500 lbs (dry) *Sail area: Main: 336 sq ft, Genoa 410 sq ft

The Catalac company's first model was the 9-metre 9M. All the other models are derived from the 9M and use a similar design concept; the 8M even used the same hulls as the 9M, so the 8M had the same LWL as the 9M, but was 2' 3“ shorter; The LOA difference being that (unlike the 8M) the 9M has a platform aft of the cockpit and transoms, plus the bow rises slightly higher - incidentally giving the front berth more foot room!.

All Catalacs were very strongly-built with thick grp hulls and glass windows, although some have been modified to Perspex or Acrylic windows.

Some of the superstructure, such as the solid foredeck, was of sandwich grp construction. Compared to modern designs, Catalacs had a narrow beam of less than half the LOA. The 9M's beam for example is 0.466 of its LOA. Most examples have vertical transoms (rather than the more modern “sugar scoop” with transom steps).

Initially they featured lifting dinghy-type rudders, but moved to fixed rudders protected by a skeg; this allowed the boats to sail a little closer to the wind. Only the 9M has a staggered sheerline (which allows easy aft access from a pontoon, but a step “up” when moving forwards on the side deck); the other models all have an unbroken sheerline.

The sailplan is usually a masthead Bermuda sloop of modest area. Although modern catamarans tend to have a fractional rig, the Catalac's mainsail has a straight leech, short battens and no roach. Twin backstays run to the transoms, enabling the forestay to be kept taut. The babystay gives a slight mast curvature to enable a fuller-shaped mainsail.

It is usually reported that “ There are no known examples of a standard Catalac ever pitchpoling or being blown over and upturned.The designer Tom Lack even offered a reward if any sailor managed to “fly” the weather hull; Lack kept his money!” Practical -Sailor reported that a Catalac survived the Queens Birthday storm when another catamaran capsized. ( https://www.practical-sailor.com/sailboat-reviews/multihull-capsize-risk-check)

It has been suggested that one pitchpoled in Biscay during a storm. (Source unknown) ”here was a young couple on board (honeymoon) and the wife was lost, presumed drowned. The husband, an officer on a cruise ship? had said he had never seen seas so big. Quite a few other boats were 'destroyed' in the same storm.”