"Chine-Runners" greatest invention of 20th century?

It is a terrible boat. Gonzo is being very generous. Sorry if I am not being PC here, but no-one should think this is an advance.

We really need to get a simple cheap way to create sailing polars, so the actual performance can be measured and have something to discuss in realistic terms.

 

Forget the preposterous claim; the designer might have been imbibing too much potent European beer and now regrets the statement. The boat is alright. It does the job, (like Atlantic crossing, hello) is a clean hull with an attractive profile, has a low rig that works, and off wind, I'm sure, sails quickly and efficiently with minimum crew work required to keep on course, or to trim the sails. The steering position reminds me of Newick's Cheers - and that boat got rubbished by eggspurts too.
Agreed a dagger, lee or centreboard would transform the windward ability ... but the owner obviously didn't want through hull appendages, has a compromise solution which works okay for him. Cheers.

 

Time will tell.

So far only a few boats have been designed to use them, and they seem to be catching on in relatively remote but growing part of the sailing community.

And what is there to compare them too?

Just about everything I can think of:

Outside ballast,
roller furling,
center boards, and
keel/centerboards,
was really invented during the 19th century.

I suppose we could compare them to canting ballast keels, but, for my money, chine runners are far more accessible to the general public than CBK's.

And probably of greater practical value as well. They favor low to moderate performing hull types that happen to not only be relatively easy to build, but more seaworthy than they look

I have always thought that great sailing draft has been a big detriment to the popularity of sailboats.

 

I saw both Sven and Matt at Cedar Key a couple years ago where Sven probably got the idea for the chine runners. I'm also a skeptic about the efficiency of the chine runners but we have to look at what they are intended for and that they have taken Matt on some long journeys, including, I think, to the Bahamas. I watched Matt tacking in to shore once and was surprissed at how well his boat went to windward. He also ran the EC with them and may have won, if I remember correctly. They don't fit in my theories of high lateral resistant foils but the are on his boats not mine.

 

He did win. At least in Class 4 (mono hull sailboats w/unlimited sail area).

I think it's easy to forget that, though water and air are fluids, air is compressible, water is not. This fact may increase lift on the leeward (bottom of wing) side of the keel more than standard aerodynamics would predict.

Matt's SAND FLEA did have a dagger board, so it's not like he is delusional. He designs super yachts for the super rich for a living.

Let's suppose a more conventional board would get him 45 deg. into the wind (90 deg. tacks) and his chine runners only got him 35 deg. into the wind (110 deg. tacks). The Sine of 45 deg. is 0.707. The Sine of 35 deg. is 0.573.

0.573/0.707 is 0.811, which means in more approachable terms, the chine runner equipped boat is going to have to do five tacks for every four the board equipped boat will have to do (assuming, of course, the tacks are of equal length) to make the same progress to windward.

For a boat that is going to be sailed down wind and rowed or paddled a lot, that is not too shabby.

For your average day sailor, which has to return to where it departed from on every voyage (using auxiliary power minimally), this may not be acceptable.

I won't be surprised if motor sailors suddenly start sprouting chine runners on deep box sectioned hulls.

 

Hey Sharpii, don't forget also that if the following conditions are satisfied:

- Reynolds numbers of the two fluid flows (air and water) are equal
- Mach number of the airflow is much less than 1 (approaching zero - incompressible flow)
- cavitation number of the waterflow is much higher than zero (i.e. no cavitation)​

then the two flows are hydrodynamically equivalent and will exert the same force on a submerged body.

Cheers!

 

Sharpi2,

Take a look at the video again.

You keep saying this boat makes ONLY 10 degrees less into the wind.

No hard fact and from the only evidence I seriously doubt the number.

Good luck to Sven but I doubt this is wonderful. To each his own.

 

Bilge keels cant downward or outward at an angle...Chine runners are basically an extension of the bottom panel out sideways...like you forgot to trim it up.

 

Matt seems quite rational and he is called the "Wizard" for good reason. On the other hand he does not drive a car which some of us might glance askance at.

Sven is another case altogether. There are not many like him. Sort of like Tristan with an exponent.

 

As was the case with the pictures I posted and called them looking like bilge keels...

Agree on that too . . :idea:

Cheers,
Angel

 

Are you trying to say that a boat going through water at, say, 4 kts is the same as the same shape going through the air at close to the speed of sound?

I just don't understand what you are saying here.

 

I have watched it may times. in some segments, the boat seems to be drifting upwind. Surely you don't believe that's happening. I don't. I think there is some kind of current or tide involved.

As for the bit about the cat boat sailing quite far ahead of it, it may be experiencing a different direction.

I have done much of my sailing tree choked lakes. Once I got so frustrated at the wind constantly changing direction, I just let out the sheet and pointed the boat where I wanted to go. It worked.

In this video, the conditions are nowhere as extreme, but there do seem to be plenty of trees around, as well as high bluffs.

Not only that, but the cat boat seems to be at least a quarter of a mile ahead of Sven's boat. If that is true, ten degrees can look a lot more like thirty.

 

Saying that if Reynolds numbers of the two flows are identical, if the flow around the shape going through the air is incompressible and the flow around the same shape going through the water is non-cavitating, than the two flows will exert the same force on the shape.

 

All of you miss the point of the chine runners, and I have also read the article from Small Craft Adviser, it was not described accurately. He does not use the rudder for lateral resistance, but rather the hull itself.

The idea from the inventor was to make the hull itself act more like a keel by using the runners as flow fences to keep more of the flow on the hull. He described the idea like the lifting bodies that NASA had experimented with decades ago. Us the runners to direct the flow along the hull to generate side force to eliminate the need for a keel.

He knows it is not efficient, but neither is a shoal draft keel. The designer has built a number of micro-cruisers and this was his way of eliminating the keel all together. It works reasonably well since it achieves all his goals, he knows it will never make a high performance hull, and will certainly not be useful for a racing boat. IT was intended as a compromise between a shallow keel and having an easy to trailer and beach launch hull design without a retractable keel. That it has accomplished, and better than he expected.

And that is why Yervind likes it so much, a simple non-movable surface that achieves a degree of lateral resistance without a center keel. He can beach the boat without concern for a keel, and he gets maximum use out of the tiny interior of his boat.

It is not high performance, but it works for a simple shallow draft cruising hull. I think it is great idea, and I have been contemplating how the combination of hull shape with the runners can be optimized to make it perform even better. I think for now I would stick with a simple dagger board design for the performance, unless I am convinced I can get the same performance from a "lifting body" hull design.

 

that looks dumb.