Monohull Speed: Speed Dream by Vlad Murnikov

Single track foils are what the Moth uses to avoid being labeled a multi-hull. Single track as in conventional bicycle. Two supporting devices in-line with the major direction of travel.

The cool thing about this development is that the dynamics of a Moth sailing upwind are very much like those of a sailboard or kiteboard. All three boats use a portion of sail force as lift. All three boats use a portion of hydro lift to oppose leeway forces. These three are very much alike. Of the three the Moth is the slowest. All three sailing craft are faster than "boats".

Ten years and you have two examples of the "revolution"? Not convincing.

R

 

Suggest you re-read Bethwaite re: reverse scale effect.

If in the next ten years we see a successful 35-40 foot mono that uses lead ballast and foils to sail faster than a mutli of equal length I'll buy you a case of Mount Gay rum. I'll take out an add here and on SA that reads, "I was wrong".

The fact that lifting foils have been abandon for military and commercial use and for serious speed attempts on water makes that bet pretty safe. All the pretty concept drawings and reams of theory do not change the fact that there are no examples of any of them working at all, much less showing potential that warrants further development.

R

 

Speed Dream

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Well, the technology of the Moth does have applications in ocean going monohulls and probably,to an extent, in multihulls as well. But at this point, it does not have direct relevance to Vlads design because what he is proposing is a foil similar to Wellbourne's DSS foil that will lift 40-60% of the boats weight coupled to a planing hull. Interestingly, that is close to the same range of foil lift common to the ORMA 60 tris.
The Whitehouse "flying canting keel" design(post 74,this thread) is also similar to Vlads canting keel-and the need for movable ballast is critical to his design.

 

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Make that diet coke and a charcoal steak.....

 

Indeed ... the topic is that the brain behind speed dream thinks there is no difference between dipping a chunk of lead into the water and dipping a buoyant hull into the water.

There are some of us that are mildly amused at the use of stored power systems to move lead being accepted while boats that do not require stored power are not.

Construction methods and materials have evolved independent of the number of hulls you build. The multi-hull has been faster since 1980 or so.

Dumb ballast is not a speed producing design feature. Smart Ballast(tm) is. As soon as the requirement for ballast cannot be met by the crew, boats that use lead will be slower than boats that do not.

It is just that simple.

R

 

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You don't consider Banque Populaire's Jules Verne attempt serious? Groupama 3's Jules Verne record was not a "serious speed attempt"? You don't consider the Hydroptere ocean going records program serious? Hydroptere.ch?(variable geometry planing and lifting foils) not a serious commercial venture?
Mirabaud became the first bi-foiler to beat a Moth and the fastest sailboat at the Weymouth speed trials-that wasn't a "serious speed attempt"?
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The fact is that lifting foils are being incorporated on more and more sailboats all the time. Many, many designers and sailors recognize the potential speed increases and better seakeeping possible with the proper implementation of lifting foils either as "foil assist" like Vlads design or full flying like the brand new Hydroptere.ch-a "test model" for the Hydroptere program's 100' maxi.
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Your attitude toward these developments is unfortunate-and off base.

 

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Modern movable ballast systems utilizing state of the art electronics and hydraulics IS Smart Ballast(tm). To ignore the potential of movable ballast in large fast sailboats is to ignore reality: it works, it's fast and its here to stay.

 

Look at a boat sailing with the AWA < 30 deg. Pick some average wind speed that uses 90% of the RM. Don't touch anything and change the wind speed up 10% and down 10%. Add a change in true wind angle of +/- 5 deg. Work out the changes in force from the sail(s) with no adjustment and with instantaneous response. You now have a matrix that represents the normal fluctuations of a "steady" breeze. We all know that breeze is seldom this steady but it is a place to start.

One of the comments that James Spithill made was that while monohull boats can react to changes in the wind with little penalty, mutli's must anticipate those changes. SpeedDream is using multi-hull dynamics so she will sail like a multi. The leeward capsize and pitchpole risk will be about the same as a multi on one hull. What SpeedDream gives up is the mutli's response to windward roll. The multi has equal resistance to windward capsize as leeward capsize, SpeedDream does not. The multi reduces the RM used passively, SpeedDream must have an active system.

Mono's work because they don't use anywhere near RM max at the design point, there is a RM reserve that handles gusts and provides positive stability in roll. Once you use most/all of RM max at the design point that safety margin goes away. SpeedDream has done just that, it is good that it might self right, it will need to.

R

 

No, serious speed on water uses planing hulls, not foils.

Look at the history of hydrofoils outside sailing. You can't look at many current commercial hydrofoils since most of them have been replaced with other technology. If Boeing could not dominate the commercial ferry market with hydrofoils what would lead anyone to think that hydrofoils are the future?

Foil assist ... what are they using the foils for? Resist the forward pitch from the drive force of conventional sail rigs. Change the rig to reduce the forward pitch and use some of the rig force to lift the boat and you eliminate the need for the foils (and the extra drag they create). This is one reason that kiteboards and sailboards are faster than foilers.

The ama foils on multis are a brute force solution that could be solved by canted rigs and a fore and aft ballast shift.

Rather than continue down a path that big budgets have abandon, why not try to mimic the dynamics of what is known to produce higher speeds? Planing hulls and lifting rigs?

R

 

Lifting rigs? No argument from me. But you still need foils ... if you want to go to windward. And a kite board at maximum speed IS a foil. If you're suggesting Yellow Pages/Macquarie Innovations-type planing hulls, there are a bunch of foils used there too. Foils are foils, angled or vertical or whatever ... they're quite essential on any type of craft, cobra.

 

When I say lifting foils I mean as a dynamic substitute for displacement. Displacing less water using lift is the basis for hydrofoils, planing shapes, and lifting rigs. You can use a lightly loaded foil for leeway control. Better is to have the same lift producing surface perform both functions. The fastest sailing craft have the smallest foils, use planing shapes, no ballast other than the crew, and lifting rigs.

Since the topic of this thread is a SpeedDream, how many of the 4 keys to speed does it use?
Planing shape = Y
Minimum foils = N
Lifting rig = ?? (N)
Dead weight ballast = Y

2 of 4

Lets consider foils used for lateral force. Un-balanced lateral force turns the vessel. Should we be looking at the dynamics of things that turn at high rates in water? Formula 1 tunnel hulls, foils or outside planing surface? Slalom water skis, foils or tilted planing surface? Kiteboards?

The fast craft don't use hydrofoils for either displacement reduction or lateral force.

It makes more sense to me to look at what works at very high speeds and loads and figure a way to use the wind to power that platform. Rigs that lift and have very low heeling forces should give greater increases in speed than foil development. We already know what works over 100 knots on the water, hyrofoils don't or they have a poor power to weight ratio so for a given power planing is faster. In the limited realm of semi-displacement sailing, foils remove the drag "hump" but once you have the power to weight to plane foils lose. Add the notation that hydrofoils do not deal with waves and debris very well and you have another reason not to consider them for ocean travel.

R

 

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1) the history of hydrofoils inside sailing has been one of slow but steady expansion since the mid 90's.

2) Foil assist is used in the I/14 class and the National 12 class to lift the boat and crew upwind as well as to reduce the incidence of pitchpole downwind. It is used in DSS systems to increase RM and lift the boat. Foil assist is used by almost EVERY new mutihull from the 16' Stealth up to the 131' Banque Populaire to reduce wetted surface and increase speed-a use by the way that is not an accident: it is based on YEARS of proven performance by foil equipped boats vs those not so blessed. Just recently, the Verdier/VPLP collaboration has used lifting foils on Open 60's with more sure to follow. And the Americas Cup was won for the first time in history by a boat using lifting foils(which the LOSER did not use in Cup racing!). And the boats in AC 34 will be using lifting foils. And more and more sailboats all the time are taking advantage of the real, proven attributes of well designed lifting foils.

3) Bull. They are an elegant solution proven to work and to increase speed inshore and offshore and around the world. And by the way many of the boats that use foils for lift also use canting rigs and movable ballast! The Moth pioneered a new kind of application of physics to sailing with "Vealheel" which is NOT the same windward heel used on any other kind of boat: not only does it generate lift from the rig and unload the vertical fin, it increases RM by up to 20% or so-a feat that can be accomplished only on a bi-foiler or a bi-foiler using power foils(100% independent of altitude as long as the boat is solely on foils) because the center of gravity of the whole boat plus crew is moved to windward.
Canting rigs, movable ballast and lifting hydrofoils go together like hot fudge and a sunday for maximum performance on a modern sailboat designed to take advantage of their unique properties.

4) Repeat: the most successful small foiler takes advantage of lift from the rig as a byproduct of veal heel. The new Hydroptere.ch takes advantage of variable geometry stepped planing hulls and hydrofoils. Mirabaud takes advantage of a planing hull to get started. My new MPX-12 design uses a planing main hull AND planing amas along with lifting foils. See below for "big budgets"......
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Randy, don't you think you're being a bit obtuse when there is abundant evidence that the most well funded projects in sailing are all using lifting hydrofoils to one extent or another? Don't you realize that your dogmatic approach here is way over the top(and at the same time very limited) when weighed against what is actually happening in the world of fast sailboat design?

 

It would interesting to speculate what kind of design might provide the next breakthrough in ocean racing, if SpeedDream does not deliver. The essential differences between ocean racing and a sprint-style speed attempt are the requirements for endurance and wave-handling, plus whatever impact safety and crew size and support might have. The first change is the need for a big boat; not merely a bigger boat but a bloody great big boat by the standards of most of us. Can the lessons being learned - rather painfully at present - in the sprint arena be applied to ocean racing?

Let’s get extreme right away; what do “panel members” think of the chances of a seriously upscaled SailRocket for example? A great deal more robust of course so it can get away from that use once and throw away tendency ...

First off it’s going to need to sail with the wind off either beam, which is a challenge with a canted rig, as I have already discovered on a smaller scale by experiment. I think I might consider shunt-tacking, which is less of a disadvantage for ocean work than for a round-the-buoys race, although it may compromize the sail design.

Reefing? Nah; no race sailer worth his salt will do that anyway.

A wave-piercing hull might prove a little more comfortable for the crew, too. Big question is whether it will be able to race effectively in all the conditions the sea will throw at it ... any other wild suggestions? BTW, no demands for container-proof designs please, there’s no such thing!

 

There seems to be two avenues of thought here in this discussion... well, in so far as the discussion has evolved to this point, to be more specific.

One side is looking at this from a global, broad brush perspective where lifting foil technology is but one point.... a stop-over, if you will, in a long line of progression as speed oriented sailing machines move towards their logical conclusion given what we already know about boats.

The other interests in this dicussion are looking at this like a plate of three peas in front of their noses. They are only concerned about the simplistic meal before them and have little incentive to look beyond because that's the way they operate.

One party looks to drive beyond the obvious, in the moment, answer, while seeking something deeper. The other interests have this singular moment to fuss over, caring little about tomorrow as they are always willing to shift their technological paradigm in a constant, trendy is best, effort to always be correct for this limited moment in which they focus their attention span.

It's illuminating, to be sure. Some of the illumination has long ago lost its luster as the tune has never changed. This group sees nothing beyond that aforementioned plate of peas and is destined to always be involved from the catch-up position, rather than one where conceptual leadership and a broader method of thinking rules the landscape of decision making.

From my perspective, none of these big questions are going to be answered until technology develops to the point where variable/adaptable hull surfaces are commonplace and can operate seemlessly in an organic fashion. Foils may be one very small, narrow-bandwidth answer within some of the design solutions, but by and large, the successful, very fast craft will not need them. Hulls will have surfaces that can be morphed underway to offer the optimal flow presentation when coupled with available power sources.

Foils, it would seem, offer certain benefits to a very select group of fast craft at this point in boat design development because they provide some possible benefits within our present understanding. Unfortunately, I'm of the opinion that, historically, they have already run their course and that there will be few, if any, gains to be made from that arm of the technological tree. Yeah, sure, there will be remnant advances in specific applications, but I'm thinking that they, too, will soon be abandoned in favor of other pursuits.

I'm also of the opinion that direct advancements in hull form efficiency and operational cleanliness of a given craft will be far more important to everyday boats, as we know them, than any addition of foil technology. The result will be boats that are easier to manufacture, less expensive to own and maintain and as a result, will be used far more often than anything that is burdened with overly complex solutions for simple sailing interests.

 

Doug, stop preaching and start thinking.

Think of what has proved to be fast on the water disregarding the power source. Familiarize your self with the failure of hydrofoils in the ocean.

Now that you know that the hydrofoil concept is a failure you have to look at why what works for fast watercraft does not work for sailboats.

Your use of the term Vealheel is amusing. It is not unique at all. It does place the cg to windward of the source of lateral resistance, sailboards have been doing this years before the foiling Moth. There is no need to unload a lateral foil if you don't need one to begin with. The proof of theory is that sailboards are faster than Moths in breeze.

You refuse to look at what forces the foils on big multi's are resisting. Remove or reduce that forced and you don't need an opposing force to balance it. This is all about the heeling arm and the drive arm of a conventional rig. As soon as the rig heels to leeward it acts to increase effective displacement not reduce it. Heel or cant the rig to windward and you reduce effective displacement. That leaves the bow down pitch force due to rig height. Reduce that and you reduce the bow down pitch that either buoyancy or lift must resist.

The simple answer is to tether a kite rig at deck level on a trolley, rather than move ballast, just trim the tether point fore and aft to pitch the platform to the low drag planing angle and you have no need for foils to do the job.

Some people are using foils to solve problems rather than reduce or eliminate the source of the problems.

What you can safely say is, "Given the nature of traditional rigs, foils seem to be a lower drag solution at moderate speeds than using displacement."

I don't think I'm being obtuse. I just refuse to limit my thinking to things that look like traditional sailboats (Moths and Hydroptre just barely qualify on that score).

There is no reason to use foils to compensate for the shortcomings of traditional rigs when there is ample proof that higher speed craft don't use them at all.

Reverse engineer the problem. Decide you want to run 100 knots, look at what watercraft can do that then find a way to do it with wind power. Don't base your design on a system that has been found to be less than seaworthy and not capable of the speed you seek.

R