Books for a physicist to learn sailboat design (preference for mutihulls)

Another vote for this one.

 

I have both 'Sailing Theory and Practice', and 'The Aero-hydrodynamics of Sailing'. There is a bit of crossover between them. Aero-hydrodynamics goes into a bit more depth. Can't go past them really.

It's a bit of a misnomer that you can get more power out of a wing rig than a conventional sail. Aircraft wings are designed for low drag more than they are for high lift. On an aircraft you only need high lift for take off and landing, when their lift is usually augmented using flaps anyway. When cruising, aircraft wings are mostly operating at reasonably low lift coefficients, because drag is the main issue. For sailing boats, wing rigs are not practical in the sense of transport and rigging. If built light enough, they are fragile and don't handle capsizing very well. They are also generally expensive, although some proponents say the can be cheaper. They are most useful on boats with a high apparent wind speed and which have a requirement for very low drag, e.g. C-class cats. They have been tried on A-class cats and on Moths, where you would think low drag would be an advantage, but so far the improved performance, which is marginal at best, doesn't justify the cost, build time and other practical problems.

Sails need controllable twist, so that has to be designed into wing rigs if high performance is the goal. Sailing boats differ from aircaft in that they need the sail to be as efficient as possible aspect ratio wise, but at the same time have as low a centre of effort as possible. Twisted soft sails do this very well. Thin section cambered airfoils (soft sails) are very good at providing high lift coefficients, at least as good as a thick aerofoil, but they do have more drag. On an average sailing boat, the major cause of drag is the hull, and the drag of the sails is a small in comparison, so not a major issue. Wing sails are very good if you want to feather them rather than reef them, particularly if they have a tail to control the angle of incidence, which is why you see them on things like unmanned sail drones where reefing is not an option. But reefing, which is easy enough to do with a soft sail, is always more efficient due to the low center of effort requirement.

Sorry for the rant. Just had to clear that up.

 

Sorry I mispoke there. From what I can see wings get slightly more power and a much better power/drag ratio which alligns with what you're saying, they also achieve that power at a much lower AOA meaning they can sail considerably closer to the wind. While there are definitely disadvantages to wing sails and a lot of very impractical designs (e.g. inflatable wing sails) things like Omar wing sails https://www.omerwingsail.com/ which use a specially shaped, free standing mast and simple battened fabric sails are able to twist, seem practical (though I'd want to change their piston operated system out for lines and winches) and achieve superior performance to traditional sails, which could likely be improved further. Though admittedly the need to use a free standing mast will make them expensive.