High-Speed Sailing

Vessel Name: Sailien
Vessel Make/Model: Experimental/custom
Recent Blog Posts
28 September 2013

The America’s Cup

I watched, with interest, the videos of the 34th America’s Cup. At last we have fast sailboats engaged in a competition that is fun to watch. The virtual images (such as course boundaries, distance grid lines, separation between boats, etc.) overlaid on the real images really helps to keep the race [...]

31 August 2013

100 Knots for Hydroptere?

The latest news from Hydroptere is that they have plans for a 100 knot sailboat. This was posted on 26 Aug 2013, so look for that date at this address. http://hydroptere.com/en/the-news/last-news/

17 November 2012

Aptly named Sailrocket, blasts off!

While yet to be ratified, Sailrocket posted an average speed over 500 meters of 59 knots. I will not be surprised if they increase their record into the 60 knot range during this record attempt.

02 January 2012

More drag for VSR2?

I want to start by pointing out that the whole VSR2 team has done a stellar job and has demonstrated conclusively that the forces that drive a sailboat can be aligned for roll stability without using ballast and without using any down-force. (Trifoiler achieved roll stability by using down-force, but [...]

18 December 2011

My analysis of Sailrocket

I copied a diagram of VSR2 (wing doesn’t show well) and added in the major force arrows that apply. Be aware that these arrows are not correct in terms of scale (length) and some of their locations are guesses, however I believe I’m correct enough for us to learn something about what VSR2 has been [...]

23 October 2011

60 is within reach, what’s next?

I have been watching Sailrocket’s progress with great interest and there’s no question they have a winner. I fully expect to see them reach 60kt in the near future. Sailrocket has now demonstrated what I first learned with my models and again with my full-sized prototypes, that if you get the forces [...]

Pitching

23 January 2010
There have been some interesting comments that I'd like to address. J. Rob talks about pitching and the problem that it causes for sailboats. Pitch (bow/stern up/down motion) is an ongoing problem for sailboats.

There are actually two different pitch problems for a sailboat. One of them is the problem of sailing over rough seas in which the surface is irregular. In its forward motion, the sailboat follows the (ever changing) irregular surface, with the craft pitching constantly. There are three ways to minimize this wave induced pitching. The most obvious is to simply build a longer hull. As the hull gets longer, the smaller waves become insignificant since the hull bridges across them. This allows us to sail in rougher seas with a larger craft, but there is a practical limit to the craft's size.

Another way to minimize wave pitching is to use hydrofoils and raise the hull of the craft above the water's surface. This is a more technically advanced way to control pitch and can be very effective, but once again, the craft will need to be quite large if it will be operated in very rough seas. Trifoiler is an excellent example of a small hydrofoil sailboat and I recommend learning about it (use the link on this page and see my earlier posts on Trifoiler).

The third solution to wave pitching is to get above the surface totally. There has been much research on surface-effect craft, which fly just above the water's surface. I have a strong interest in this technology, but it requires an engine for power and is outside the realm of sailing.

The other pitch problem that a sailboat has is the tendency for the bow to be driven down by the forces driving the sailboat. This happens because the driving force that propels the craft forward is above the water and the resisting force (drag) is mostly at the surface and below. This appears obvious enough, because the sail is in the air and the boat is in the water. I do want to mention that the driving force is not necessarily at the sail, but can be somewhere between the sail and the keel; this will depend on how the craft is configured and the direction it is being sailed relative to the wind, perhaps I'll discuss that some time.

On a bit different subject, Paul is interested in racing BOR 90 against Hydroptere. I agree that this would be fun; however BOR 90 is way too fragile to run in 25 knot winds. In lighter winds I would expect it to outrun Hydroptere. This leads us to the interesting problem of what wind (and sea state) are we going to design for. Some of the maneuvering for the America's Cup has been over the "playing field" (light or strong winds, smooth or rough seas).

Bob
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