Ward Setzer, who focuses on motoryachts rather than sailing machines at Setzer Design, adds a few more ideas. The central question for his designers, he says, is “How green can we go with it?” No boat, particularly a motoryacht, will ever be considered completely green, but, says Setzer, “It’s merely designing responsibly—the correct speed, the correct hull form, and aerodynamically efficient, too.” He specifies renewable or recycled materials wherever possible, including woods certified as sustainable, but acknowledges that such an approach reduces the selection of material available to an owner or his decorator. Some choices, such as using wool in place of synthetic carpet or fabrics, or using water-based finishes instead of petroleum-based, are easy and do not add to the cost, but others are not. Controllable- pitch propellers would be suitable for many yachts, he suggests, but there is an added cost in both construction and maintenance. The use of more exotic items such as large solar panel arrays for electrical generation, and sky sails or wingand- wing sails on a foremast for long downwind passages, are concepts Setzer has explored on a speculative basis, but none of his clients have yet been willing to incorporate them.