High-Speed Sailing

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 [...]

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/

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 [...]

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 [...]

Hard water sailing

19 December 2009

I'm happy to report that Richard is getting Greenbird ready for this winter's ice. Be sure to check out his blog (link to Greenbird off this page).

When I was a child, my family lived near Lake Michigan and I learned to ice skate on near-by smaller lakes. One year I made a sail (from plans) and went sail skating; it was fast! I also watched ice-boats zip across the lakes and I always wanted one, but we moved to Los Angeles before I was old enough to do anything about it and I took up surfing. Due to this early exposure, I've always been a fan of "hard water" sailing and I'm very interested in how well Greenbird does this year.

In his latest blog post, Richard discusses how ice boat speeds are not as high as it seems they should be. His posts from last season discuss how the vibration from rough ice got extreme at 70 mph. I am very happy to read that he plans to determine what the real cause of the slower ice boat speed is. Following are my thoughts on the subject.

Sail powered craft operate by the "squeeze" of the wind's force against the land, ice, or water via the wheels, runners or keel respectively. (See my earlier posts about squeezing the bar of soap, and going faster than the wind for more on this.) That squeeze is all that drives our craft and going fast is a "simple" problem of how do we maximize the squeeze, minimize the drag, and keep it aimed in the right direction.

The "side-bite" (resistance of the wheels or runners to sliding sideways) is what we are trying to maximize. Apparently tire technology has advanced faster than ice-runner tech. I am quite certain that the problem will trace to runner "chatter" on rough ice, but if speeds are still low on smooth ice, there is an additional problem of the runner "drifting" sideways and it may take a change in runner design to overcome this. Possibly there is a "limit" to the amount of side-bite that runners can generate on ice; if that is the case I suggest aero-dynamic down force may be needed to force the runners down harder onto the ice.

Ya know if I turned Sailien "inside-out"... But that's another problem; currently The Sailien Ship and crew is preparing for the water speed record.

Bob

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