AboutKeith Patton Expertise I can answer questions regarding fresh and salt water Catamarran Sailing, techniques and equipment. I can also answer questions regarding the repair of decks and the updating and installation of running and standing rigging on mono-hulls
Experience I have sailed catammarans in fresh and salt water for over 16 years.
I currently own and sail a 30 ft monohull out of Kemah on Galveston Bay, on which I carried out a complete refit.
Expert: Keith Patton Date: 4/1/2008 Subject: 18th cen ship speed
Question Hello. Since you answered another person's 18th cen question, I thought I'd give you a swipe at mine. I'm trying to determine how long it would take a mid size shipping vessel from that time period to get from Nantes, France to Morocco (or more specifically, the Canary Islands), and then back. Any idea?
Answer Colleen:
I don't know the distance but you can calculate it using a map. Other factors include prevailing winds and currents. Then there is the boat itself. A sailboat is limited to is theoretical maximum speed by the following formula. Where LWL is length at the water line.
Hull speed = SQRT(LWL)*1.34 so for a 30 foot boat the maximum speed is around 7.3 knots. This includes being pushed by a motor. So the smallest motor you need to get it to its maximum is all you need.
This is the theoretical hull speed for a displacement hull (most sailboats). It is a function of the length of the wave created by the boat as it moves through the water. Wave speed is a function of wavelength; longer wavelengths are faster. Longer boats make longer waves. Since longer waves are faster; boats that make longer waves are faster.
A displacement boat has to push water aside to move through it. A power boat like a speed boat can climb up on the water and plane. If you have ever water skied then you know what I am talking about.
Another factor are hull condition, is is covered with algae and dragging a beard of marine growth?
So you can see that calculating a precise speed and from that, time to destination is difficult and iffy at best.
