A couple of design questions

[Manny]

Hi Glenn,

When designing a sailboat other than a racer, how much, if any, consideration is given to the aerodynamics of the structure of the boat? For instance the deck design, cabin top, arches, gunwales, etc.
My other question is regarding bow bulbs. I've never seen that feature on a sailboat. Since it effectively increases water line length isn't there the possibility that it could improve the speed of a sailboat? Are there stability or other issues due to heeling? I know a lot of the newer designs have a vertical bow but an angled bow design could effectively keep the same waterline length (or longer). Also, couldn't it be filled with flotation or used for a bow thruster?:stirthepot:

Thanks for taking the time to answer our questions!

Manny

 

[ghen]

Manny,

When designing cruisers, interior usefulness overrides aerodynamic drag. It is minimized as much as possible however. That is one advantage of a fractional rig is that per unit area compared to a masthead, a fractional rig genrally has less windage. The problem with bow bulbs on sailboats or even small boats is pitching moment. As the bow is lifted by a wave and the bulb nears the waterline, a lot of wave making drag is incurred. The bow bulb needs to be submerged enough that wave making is minimal. Bow bulbs also work at specific speed/length ratios. A tanker knows he is going to be at a certain speed all the way across an ocean. Us sailboaters accept whatever speed we are dealt. I suppose that is why a lot of people by power boats.