Why I'm Following Sven Yrvind

Do you believe Sven's latest Ex Lex will make it to New Zeeland.

  • Total voters
    27
S

sharpii2

Senior Member
Joined
May 31, 2004
Posts
2,282
Reaction score
348
Location
Michigan, USA
Some people find the new foiling AC boats fascinating. I find them somewhat interesting, as they show what can be accomplished with high technology and gobs of money. They go quite fast, maybe in the high 30s to low 40s in knots. Quite incredible for a mono-hull sailboat.

But Mr. Yrvind's projects fascinate me much more. He seems to be trying to find out how little is needed to make an ocean going sailboat. His boats tend to have little ballast and very short rigs in both aspect ratio and actual sail area.

This probably has as much to do with practicality as foiling monohulls, which can do nothing but go fast, and only in a narrow range of conditions. But it really gets me.

He once crossed the Atlantic with a 15 footer which had only 75 sf of sail. And he did it with two people on board.

Granted, a boat with a ballasted fin keel and a high aspect-ratio rig with generous sail area is certainly faster and arguably more seaworthy. Weatherliness not only wins races, but save one from the clutches of a Lee shore.

But as limited as his boats are in performance, they do have their vertues. I imagine they are easier to maintain, they can sail in shallower water, and probably have much lower hull and rig stresses. Also, on his latest Ex Lex creation, he can easily step its three masts himself, even when it's in the water.

Now, the price he ends up paying for these virtues is the interesting part of the story. Will he make it to New Zeeland? Or will he have to give up, like he had to with the first Ex Lex.

My personal belief is that the original Ex Lex could have been successfully modified, by replacing the two end house structures with a central one, adding another mast and sail, then pushing her harder, which would have meant putting up with a much greater angle of heel.

But the new Ex Lex is certainly a better boat. It's extra Beam, although not that much extra, seems to have greatly improved its stiffness. It can now carry 6 sm of sail or more. But this still gives it a puny S/D of around 6.0, about what one could expect on a more conventional sailboat which is on its 2nd or 3rd reef. Will this be enough?

If it is, I find the practical implications interesting. Perhaps motor sailors can be designed with rigs of this class, and sill go vast distances powered by mostly sail, and be a lot easier to keep and look after.
 
I looked up Sven after seeing your poll and thoroughly enjoyed reading about his approach to sailing and life. think he has far less chance of being pole axed by a ship at the moment , ..unless it's Saudi oil , he may pass away from old age , but he seems rudely healthy in mind and spirit.
 
I was following Sven for a time when I first found out about the AiT challenge. It's part of what prompted me to join this forum. That whole concept has captivated me because it speaks to independence and doing things with little or no resources.

I love what he's doing and his reasoning around the virtues of smaller craft taking less stresses than larger craft make perfect sense. I haven't tuned into his website for a while, but I will vote for his making his destination, but not on his expected timeline.

I'm also not a fan of his design choices, but they work for him.

-Will (Dragonfly)
 
I wonder if he is really sailing or more drifting with the prevailing winds and currents. After all coconuts from the Caribbean wash up on the shores in Ireland. Big logs from Oregon end up on the beaches in Hawaii. Thor Heyerdahl managed to crash land his raft near Tahiti. The Pacific voyagers set off from Taiwan found and inhabited every known island in the south Pacific they even stoped in South America and brought back people with them to Easter Island. They traveled in long lean double canoes and proas though
 
I wonder how long he has been moored in Funchal, Madeira?
I admire his patience, sailing at an average speed of 2 knots, or less.
I can think of better things to do in life.
'It is still a LONG way down to Argentina, and he has to get through the doldrums as well.
 
I have been watching his progress tracker.

It seems he is having a hard time getting to windward. His plan was to go around the north of the UK to avoid the hectic sea lanes. But now it seems the weather conditions just won't let him.

Having seen his sea trials, the boat seemed to perform well enough. It seemed to be sailing well over 2 kts, maybe 3 or even 3.5. I have been trying to figure out why the boat seems to be performing so poorly now.

The best explanation I have been able to come up with is that his S/D was much higher when he did his sea trials than what it is now.

Let me explain.

He said that the boat itself came out to be about 600 kilos. I'll assume this included the rig.
He and a friend sailed it, so I'll add 150 kilos to account for that. This gives us a total of 750 kilos. Since we are measuring the Sail Area in square meters, we must measure the displacement in cubic meters. So we end up with a displacement of 0.750 cubic meters (750 kilos/1,000 kilos per cubic meter). 0.750 to the 0.667 power = O. 825. The Sail Area of 4.0 sm/0.825 = an S/D of 4.85.

Now let's see what happens when he loads it up with gear.

He said his departure displacement was going to around 1,200 kilos. This makes good sense. He probably added about 500 kilos, which is about 1,100 lbs. 1,200 kilos = 1.20 cubic meters. 1.20 to the 0.667 power is about 1.13. 4.0 sm/1.13 = an S/D of just 3.54. Maybe this explains why he seems to be making such miserable progress compared to how well the boat seemed to do in sea trials.

He does have a third sail of what I think he said was about 1.80 sm. If he were to add this (maybe he has) he would then have 5.80 sm. This would get him back yo were he was during sea trials (5.80/1.13 = an S/D of 5.13).

But this does not tell the whole story. The boat he sailed during sea trials was a two masted schooner. The one he'd be sailing with the third sail added would be a three masted one.

Schooners already pay a price in windward performance with just two masts. Adding a third one increases this penalty. This is because each sail must be put at a greater angle to the wind than the one before it, if it is to contribute any significant amount of drive.

This means the boat has to point further off the wind until the last sail has sufficient angle to produce drive. This may mean 120 degree tacks or more (and probably more). This means probably less than 1.0 m of windward progress for about every 2.0 m sailed. IFIRC, the world's record for number of masts on a schooner was seven. And that did not work out well.

I will stay tuned to see what happens.
 
Sharpi2,

Nice analysis.
I can't understand why this boat empty weighs 600KG.
This whole thing is going to have so much wind drag in the hull compared to what the sails develop as drive, that I think your analysis is going to be optimistic. Especially in going to windward.
So much is known about boat design that could have made a better boat.
 
upchurchmr said:
Sharpi2,

Nice analysis.
I can't understand why this boat empty weighs 600KG.

This whole thing is going to have so much wind drag in the hull compared to what the sails develop as drive, that I think your analysis is going to be optimistic. Especially in going to windward.
So much is known about boat design that could have made a better boat.
Click to expand...

I don't find the 600 kg boat weight all that startling. This weight includes ballast, which he has installed externally in the form of a huge slab of bronze (I wish I had his kind of money), some hefty batteries, and I believe his ground tackle. Also, although he used foam/GRP construction, his hull is about two inches thick. His choice of this type of construction is more about insulation properties than weight saving ones.

A design of mine, which is in the same class, (though not made of expensive composite materials) will likely tip the scales at about 750 kg (with ballast) upon launching, and about 1300, upon departure. But it will have about 14 sm of sail for an S/D more than three times as great as Sven is using.

Limited draft and limited ballast along with the requirement of a good range of stability, has kept the rig relatively small.
 
It looks like he is doing somewhat better now. He is now west of the UK and heading in a South, south westerly course. He has reached speeds of almost 6 kts, but is only averaging just over 2 kts.

He says he is having trouble getting to windward. He says poor fore and aft trim might be part of the problem.

He doesn't say if he is using all three sails, or if he has a Lee helm or a weather one. Too much of either can kill windward progress. But too much lee helm is worse than too much weather helm.

The last time I checked, the winds were coming from the South, blocking his progress. I'm wondering if this is going to be a prevalent thing.
 
There's a parallel thread on the ‘‘All Things Boats & Boating’’ forum, no problem I'll think, I'm just leaving a note here about its existence: Yrvind
 
Last edited:
As for the headline, my reason for following Yrvind is, or rather are, that I humbly and sincerely admire his spirit, resilience and persistence.

His persistence however is not simply a virtue. It seems to make him hit his head on the same tree repeatedly. For this reason he will not reach New Zealand.

In an earlier message there was some pondering whether the S/D ration of 6 will be sufficient. Well, there's just no fooling physics, even if you are mighty Yrvind, so no, it is not.

Even if he had kept his cool, and not overloaded the ExLex, it still would not have been enough to give him the approx. avg speed of 3.5 kts he projected in one of his posts. He's doing about 2kts avg now, and on a very meandering track, so speed made good is, frankly, quite horrible.

Regarding the overload, the trouble with his choise of hull shape is poor immersion rate, and the fact that the boat is very (too?) small for it's mission. As the boat hardly gets any wider above normally loaded waterline, when the weight goes up, the hull goes down relatively much. And again, as the provisions needed for Yrvinds journeys are heavy compared to the hull displacement, well you see where this is going: even further down.

Yrvind has come up with some quite clever solutions on his ExLexes, I think this is where he excels. As a concept designer, not so much, there is still a lot to improve with this series of boats. If you have read his blog, you must have noticed that even before he set sails, he had already designed a new model. I'm guessing he had a hunch what this ExLex was good for...

With his latest design he seems to stubbornly hang on to the idea of long, narrow, flatsided and -bottomed hull. This time he has added a lifting keel and a trim rudder, both of which contradict his dogma of simplicity, adding possible points of failure, leakage etc.

As a (rhetoric) question, I wonder whether he would already be in Azores, should he have built something like this: :TLC 19 & Windy 580 Trailer-sailer and round the world voyager http://www.dixdesign.com/tlc19.htm

Tlc 19 is somewhat comparable to ExLex Minor, and, quite intrestingly, a custom open version of it has been sailed solo around the world. Now there's a true mountain bike of the seas, a term Yrvind uses for his ExLex Minor, but is yet to prove it.

Despite my lack of faith in his design, I wish him godspeed with all my heart.
 
Last edited:
sharpii2 said:
He seems to be trying to find out how little is needed to make an ocean going sailboat
Click to expand...
Good question. At first we should agree on a definition, what is the minimum requirement to call it an "ocean going sailboat" ?
In my opinion, it is to put a frontier between poor sailing/drifting versus real sailing with upwind capability.

For me, an ocean sailboat should be able of 4 knots minimum when upwind in force 3 to 5 wind, meaning a good enough hull design with a Lwl of ~ 5m at minimum (at Froude ~ 0,3). That could be done with a relatively short mast, here we can make a little sacrifice on performance by wind force 1-2 , very little sacrifice if you can put also a light gennaker from true wind angle 60 deg. So just 4 sails : main, jib, gennaker, stormy jib.

The second point is the stability, in particular the ability to recover from an upside down roll, meaning a high AVS and a high ratio positive area/negative area under the Gz curve (i.e. poor stability upside down) . Anf of course, the boat should be seriously watertight when necessary.

The minimum comfort you are ready to accept for a several months crossing, could be resumed by the cross section : minimum headroom x minimum beam. Something like 1,4 m (to sit with comfort) x 2,2 m (two berths 0,7 m + corridor 0,6 m+ margin)

The maximum leg envisaged and the related payload : an ocean crossing could be 3000 to 6000 NM, let'us consider 6000. A circum navigation is 4th time this length. The boat length (from the minimum 5 m Lwl) derives from this choice : here, one can consider Froude ~ 0,2 as the average speed made good :
5 m >> average ~ 2,7 Knots made good >>> duration ~ 92 days
6 m >> average ~ 3,0 Knots made good >>> duration ~ 83 days
7 m >> average ~ 3,2 Knots made good >>> duration ~ 78 days

Again, the length is an important figure, contributing to reduce the payload for a given crossing, not to mention the fun to sail a real sailboat. The "small is beautiful" appeal can be misleading if small applies to the boat length only, better for a cost or weight approach.

I remind you the Blondie Hassler approach with his Sumner (Loa 46 ft x B 6,75 ft, photo thanks to Alamy) , underrated in my opinion, a modern low cost version would worth to be designed.
Sumner.jpg
 
You must log in or register to reply here.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making any potentially dangerous or financial decision, always employ and consult appropriate professionals. Your circumstances or experience may be different.

    • Back
    Top