Summary of Articles

Articles by Derek Kelsall

C L I C K   I N T O  A R T I C L E

KSS in depth

New Booklet Explaining KSS. Find out how KSS remains the leading edge of custom boat building. This booklet explains all you need to know to make an informed decision towards making the change to build your next boat using KSS. It describes the materials, build method, resin infusion, hull production, hull shaping, modular assembly, and overall savings.

KSS Kits: A No Contest Comparison. The popularity of kits has increased dramatically during the last six years. This article compares the two Kit systems available worldwide; the KSS Kit, and the Duflex Kit. Find out what advantages KSS Kits have compared to Duflex.

Kelsall Swiftsure Sandwich & Vacuum Resin Infusion Process. Resin Infusion (RI) is the perfect partner to KSS build. This article explains what resin infusion is, what KSS building system is, and why KSS and RI together provides the leading edge for custom boat builders.

The Resin Infusion Story. The story of the beginning of Resin Infusion and the magic that partners so well with the Kelsall Swiftsure Sandwich (KSS) build method.

Upgrade for KSS - Half Hull Shaping. Shaping of hulls is discussed in this article, along with the KSS set up. The set up has always started on the mould table. Read about refinements made to the shaping of hulls and about KSS Boat Building Workshops where ideas are trialled and solutions found.

The Simple Logic. Kelsall designs and KSS is the only build method to be the subject of such intensity of development, both in time and investment. Kelsall has achieved a standard of efficiency and of build which owes everything to the best application of simple, logical technology. Read how Kelsall and KSS and RI will boost your project, whatever the type, style or size of catamaran.

The Core of the Sandwich. Derek Kelsall shares his knowledge and research about Sandwich Composite Structures and the core materials. It is a topic that Derek has more direct invovement and experience in than anyone. Find out why promotion of alternatives to foam core (like Balsa, Nidacore and Polycore) is concerning.

KSS Advantages and The Strange Truth about Custom Boat Building. The advantages of KSS are set out here. Find out why KSS is the answer to inefficient, time consuming, labour intensive boat building methods. KSS Boat Building Workshops are held around the world, several times a year. See KSS and never look back.

Cat Rigs

The new - "Kelsall Cat Rig". The twin wing rig with a difference, a rig for catamarans, which just makes sense. Safer, excellent all round performance, lowest loading on all parts of the rig and structure, easy to handle, takes the hard work out of down wind steering, reef down wind, dump at least half the sail area on any tack and you can either build it or buy it. No need for lots of carbon either.

The Catamaran Rig. This article considers the options for the typical catamaran sail plan. It examines the need for runners on the standard cat rig. Rotating masts and wings. Find out about the free-standing twin wings rig on KSS 54 Cool Change.

C L I C K   I N T O  A R T I C L E

Kelsall Catamarans Stories

A Designer's Diary for 2002. Derek and Paula travel several times a year to conduct workshops around the world, catch up with friends and meet with the KSS builders and clients. This is Derek's travel diary of a busy 2002.

Report on the Pacific 2008 International Maritime Conference. Read Derek's summary of this Conference in Sydney, Australia. Derek's 40+ years of building with composites confirms that composites are proven to stand up to any typical commercial use, composites are superior to metal in fatigue, and are excellent in impact resistance. KSS allows large catamarans to be built with low tooling costs and repairs to be carried out simply.

A Short History of Kelsall Designs. This article details a selection of a few of the memorable craft and people throughout the history of Kelsall Catamarans. Including; Toria, a 42ft Trimaran which was the first foam sandwich and first to win a major open offshore race in 1966; VSD, William Saurin; Great Britain II,III and IV; and Legs of Mann I,II,III and IV, to name but a few.

Kelsall Formulas. Kelsall Catamarans has devised 3 very useful formulae. They are simple to apply and will give an accurate comparison between different craft and will evaluate changes you may wish to make.

Sail Cats

Design and Build Philosophy: My Way. Derek's career began as the pioneer of foam as a construction method/ material. Four decades on and Derek's "My Way" approach of ever seeking to find the better way, as well as his close working relationship with the owners, has kept him at the van guard of design and effective boat building innovation.


KSS 82 Bonefisth Goes Afloat in Tauranga, NZ. Read about KSS 82 Bonefish, an Expedition Catamaran. Another example of the versatility of the Kelsall design office and of the KSS (Kelsall Swiftsure Sandwich) build method. A fine example of what can be achieved on twin hulls, with KSS and the skill of NZ boat builders.

Kelsall on Offshore Power Cats. The lessons learnt over the last 40 years working with twin hulls are outlined here. Further points are considered for offshore power cats. Defining the intent of the design is important.

Sea worthiness

Offshore Sailing Performance: The Cat v Tri Debate. The cat v tri debate has fascinated most involved with multihulls since the 1960's. Derek catches us up on the roll of the tri and cat, the difference in configuration, suitability as offshore racers, what we see now and his proposition for the future. A mention is made of kite sailing as introducing more speed. Factors like seaworthiness, motion at sea, handling and weight and cost are also mentioned.

Catamaran Seaworthiness and Safety. Can a Catamaran sink? Do Catamarans have more stability than Trimarans? Do fixed keels improve seaworthiness? For serious offshore, there are a number of safety topics which can be done at the design stage, with stability and hull shape.