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 [...]

100 Knots for Hydroptere?

31 August 2013
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/

And what do I think their chances are for sailing at 100 knots? Actually those of you that have been reading my blog should be able to answer that.... (This is quiz time, lol.)

Take a look at the image of the craft they are proposing. It does look a lot like Sailrocket, but if you look closely, you might notice that they omitted one of the two most key elements for this type of design. (There's your hint; so what is missing?)

Missing is the inclined windward hydrofoil that is needed to counter the force from the inclined wing. I find it hard to believe that the Hydroptere engineers missed that. The essential set-up for roll stability is to place the airfoil and the hydrofoil parallel in such a manner that the centers of effort from the foils are in the same plane.

The craft shown will be forced up in the water by the forces acting on the vertical fins (keel and rudder). Those fins have horizontal foils at the tips which I imagine are meant to raise the hull out of the water similar to other foiling sail craft. The problem with this is that the vertical portion of the fins will raise the craft; therefore the tip foils are going to have to be used for down-force to keep the fins immersed sufficiently to maintain power. This down-force will add needless drag and will limit speed (this is similar to the problem Trifoiler encountered with their set-up.)

Look at my drawing for the post "More drag for VSR2?" (2 Jan 2012) and you will see how the forces relate to the Hydroptere set-up.
http://www.sailblogs.com/member/speedtech/?xjMsgID=204631

In the configuration shown, 100 knots is not going to happen.

Bob
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