Sometimes it’s hard to see from the outside what performance you might expect from one sailing boat vs another and so, like in cars, one measure often used is the Power to Weight ratio, in boats this is called the Sail Area to Displacement ratio or SAD. This is a universal measure that allows us to compare widely different models and come to a reasonably accurate view on their likely relative performance under similar sailing conditions.
Multihull World use a variation of the SAD calculations used by the major sail racing organisations and the figures we publish broadly look like this:
The calculation takes the upwind sail area and divides it by the actual weight of the boat. The calculation is a little more complicated than that but that’s the essence. It takes no account of hull shape, skipper quality or any other differences.
Unfortunately, not every vendor knows the sail area of their sails and not everyone knows the weight of their boat – for this reason we sometimes don’t have the SAD available to publish. Also, some manufacturers publish a weight that is well below the real weight of their boats and in that way appear to have much more performance than they actually do.
However, leaving those anomalies aside, we think this measure is an interesting one for those who are comparing multihulls or are coming to multihulls for the first time.
As a general rule – one generally trades performance for accommodation. If your boat is under 50ft and has walkways either side of beds low in the hull then she isn’t going to sail very well!
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