Technical maintenance

Six commandments for choosing your catamaran

Having worked on the design of their own boat and then sailing around the world in their Lagoon 450 S, Stephen and Estelle Cockcroft set up their website: Catamaran Guru.

March 3, 2023

Having worked on the design of their own boat and then sailing around the world in their Lagoon 450 S, Stephen and Estelle Cockcroft set up their website: Catamaran Guru. Their aim is to help future buyers in their decision-making, as a function of their requirement.

Here, the couple is entrusting us with some of their precious advice.

Even though we’re now in the era of digital modelling, naval architecture remains a series of compromises, and the intended use of a catamaran (racing, cruising, live-aboard) will considerably dictate its design and performance characteristics. For us, it’s all about safety and comfort, especially in heavy weather.

The six commandments to be taken into account when choosing a catamaran, in our opinion, are:

  • Bridgedeck clearance: it is important to have sufficient height under the bridgedeck in order to have a reliable boat and to ensure the comfort of the crew. Reducing slamming in a seaway improves performance in difficult conditions. As a good rule of thumb, 5 to 6% of the overall length is are considered to be a good proportion. 4% remains an acceptable amount, albeit a little low.
  • Load capacity: unlike monohulls, which can support weight without losing too much performance, an overloaded catamaran quickly loses performance and therefore safety. Unlike monohulls, whose stability is ensured by the weight of the keel, a catamaran relies on its beam and it is the volume of the hulls that counts. A lighter construction allows catamarans to carry more weight and perform better, so this feature is very important when choosing a cruising catamaran. If you feel the need to have heavy equipment such as televisions, microwaves and diving equipment, take a catamaran designed to manage this additional weight with wide hulls such as the Lagoon.
  • Stability: the stability of a catamaran depends on its beam and its buoyancy, so a lightweight robust construction based on good buoyancy is a good thing. Typically, cruising catamarans have a beam-length ratio of about 50% of the length overall.
  • Performance: a catamaran needs a solid center of gravity given the large amount of buoyancy forward and aft, or a good overall length to avoid creating a see-saw effect. This ensures more enjoyable sailing and better performance. Performance is a safety issue and it is always better to be able to get out of bad weather conditions quickly. So reserve speed is a big plus.
  • Ease of handling: the deck layout is an important safety factor because most cruising catamarans are sailed short-handed. On catamarans with only one helm, all lines must be led back to the helm station, from where the entire boat can be controlled. Indeed, overall visibility when under way, maneuvering or docking is the key to safety on board!

Some additional tips:

  • Decide what type of boat will be suitable for you before you buy, e. g. coastal cruising, living aboard either long-term or for short cruises, racing, etc. Make a list of the boat’s equipment and options that are important to you and see where you have to compromise on your final choice.
  • Do your research and be realistic about your expectations; make sure you buy a boat that suits your skills and abilities.
  • Decide on a budget and stick to it. After a house, buying a cruising catamaran is surely one of the biggest investments a boat buyer will ever make. Buy the best boat according to your budget, not necessarily its size!
  • Make sure you know how you will pay for the boat and also have an exit strategy.
  • Buying a catamaran and owning a boat in general should remain a pleasure, not a nightmare. Your broker should assist you, advise you and teach you things, not pressure you into buying.