Thread: Quenet Yann's SKROWL Carl Cramer's boat of the week.

Cheers,

Quite remeniscent of Matt Leyden's Paradox.



Even the drawing. But it does show the remarkable economy of the "Paradox" where length, beam and depth are all pushed to bare minimums.

I think it is quite a breakthrough boat in many ways.

Now if starting from Matt's boat ... which is the best to increase? Length, beam, or height?

MIK

It looks very ........................... French.

Reminds me of the stud pattern on old Peugeots. There are several worldwide standard stud patterns for wheels. They all do a perfectly good job of holding the wheels on. Would Peugeot use one of them? Nope. They had to go and use their own special one.

And I suspect the wench will be rather annoyed with the skipper sitting on top of her.

It always amazes me what some think is attractive. This to me is hideous (design decisions) on several levels as well as aesthetically. I'm sure he loves it, but I just couldn't get over the "choices" made. Good luck making those bow corners.

I doubt Yann's boat would pull any chicks, as his drawings suggest.

Originally Posted by Boatmik

Cheers,

Quite remeniscent of Matt Leyden's Paradox.

Now if starting from Matt's boat ... which is the best to increase? Length, beam, or height?

MIK

To quote from Digital Underground's Freaks of the industry, "Well the answer is D: all of the above."

PS: Incidentally, the piano solo that comes in at around 4 minutes is uber slinky.

Originally Posted by Sumbloak

To quote from Digital Underground's Freaks of the industry, "Well the answer is D: all of the above."

PS: Incidentally, the piano solo that comes in at around 4 minutes is uber slinky.

Hehe.

The clever thing about Mat's boats is that if you cut down on length beam and height you can dramatically cut costs. Using the hull depth for lateral resistance like traditional cutters eliminates more bits.

So ... doubling anything gives you a more or less doubling in cost.

Looking at beam - you can move to a full double berth width for on anchor or go a little wider to get seating opposite each other. Masts have to be bigger because of the additional stability.

Looking at height - well it looks weird without increasing something else. Matts boats are already quite tall for their width which is always good protection for recovery from capsize.

That's the risk of big wide boats.

Looking at length - you can separate into wet and dry areas or have a galley or separate different functions and gain quite a bit of performance downwind and crosswind and a bit more upwind.

However all these means the boat would be significantly shallower in the hull if you don't want to double the displacement and cost so there's a push toward keels/leeboards and centreboards. Which is a complication. So it starts to be obvious why I think Matt is so darn clever - he saw the problem then stuck to his guns.

But personally I'd go for length every time. And maybe it would be enough of a chick magnet to satisfy Bruce's requirements!

MIK

Originally Posted by Boatmik

But personally I'd go for length every time. And maybe it would be enough of a chick magnet...........

MIK

Out of context quoting is a wonderful thing.

Yann claims the Krill as an inspiration, but there is obviously a strong influence of Matt Layden’s design: Yann’s previous boat Bigornick (construire un voilier) is nothing more than a modified and stretched Paradox. But Dave Zeiger is an other source of inspiration, with his Triloboats. And Yann wanted a scow.1-Krill.jpg2-Krill.jpg3-Bigornick.jpg4_LaunchingDay.jpg
Yann’s new boat could well have been a stretched Sand Flea.

But then came David Raison and his strange 747 Magnum scow, with her rounded bow. Which proved to be a very efficient sailboat. And Yann started the design of his Skrowl…6-747-magnum-davidraison.JPG5-Magnum-David Raison.jpg

Maybe that’s the reason why you find the Skrowl “French looking”, but this boat is certainly not a mainstream French boat!! (I didn’t understand the story about Peugeot - or European - car wheels vs. US 5 bolts patterns: why should - and how could?? - small European cars have the same wheels as heavy & powerful American cars??? Big trucks need 10 bolts, small cars 4 or even 3…).

About the “sit on top” girl, it’s my fault: during the whole conception process, I kept asking Yann for human scale on his computer renderings, and sending him drawings with pretty girls (mostly stolen in Milo Manara’s strips) as there was no satisfactory answer. This is just an intermediate sketch; I found a more comfortable position on later drawings. But I didn’t change the main poster, by pure laziness, as it is made with my old Paint Shop Pro, not through computer rendering (there are other errors in this drawing).7-nositontop.png

But my main question is for Michael, about the sail: the one on the sketch is a full battened sail, after a picture I found – I don’t remember where - of a Goat Island Skiff rigged this way : what are the pros & cons of a fully battened lug sail, Michael ??

Regards
Eric

The girl was a nice touch. I could see it was a cute joke immediately.

At least she is something like real size for real scale - unlike the grass skirted topless girls in a lot of James Wharram's brochures



With the 747 Magnum scow. My experience is that if you get the shape of the foils and sail/spar combination right - super accurate then the boat will perform well almost regardless. But the Magnum does have the beam, sail area, displacement and features of a Mini Transat so she will have that sort of performance. Decent foil area is important too - I've had experience with several boats with lacklustre performance suddenly becoming very good with extra foil area. This includes the original too small centreboard on my BETH sailing canoe, A sailing version of one of Iain Oughtred's sailing canoes, the Nutshell dinghies - which have a crazy small centreboard - they are very able sailers with a longer one.

The above comment are general comments not specifically about Scrowl. But it indicates where to spend time getting things right for any boat.

Scrowl (thanks for explaining the name! Cool) isn't similar in terms of the proportions that are meant to help very roughly performance
Displacement to length
Sail area to wetted surface
Sail area to Stablity
etc

So comparisons with the 747 break down. But that doesn't mean that Scrowl is not a worthy concept in it's own right. Will be interested in sailing reports.

Best wishes
MIK

Skrowl is certainly not designed as a fast boat, much more like Dave Zeiger’s or Yrvind’s boats, in term of speed (and this could be a major issue, where Yann lives : northern Brittany, an area with 13 meters tides and 6 knots currents…)

About the shape, my own idea (I don’t totally agree with Yann on this point), is to make something like a Norge or Danish pram, i.e. a boat without a sharp ‘knife” bow, but rather with a “spoon” shape.
But we don’t like these flat “bow transoms” (is there a word for this in English? Maybe apron ?), we thought the rounded Raison bow (look at the shape of his Revolution Accueil - Afep Marine ) could be better than a flat board, in a choppy sea..1-Maria of Sondervig.jpg 3-morbihan-2013-fvan-478b.JPG 2-HERRESH2.JPG 4-GROP.JPG 5-SPLATCH2.JPG

My own project Skrome, an evolution of Yann’s Skrowl and my previous Littorine project (the grey model in the background) has a more rounded bow. The main difference with Yann’s boat is the plywood boards are “rolled” to give a curvy hull. The same “Premise” was used by Chris Waite for his Polly Wee UK Home Boat Builders Rally - Forum, and Terho Halme for his Origami Boat Designing Origami Boat in Rhino - Boat Design Forums6-485-1.jpg 7-SKROM4.jpg 8-SKROM5.jpg 9-SKROM10.jpg 10-SKROM11.jpg
(I have a lot of problems right now for the model, with the very wet weather, and the deformations of my cardboard from one day to another : a cold & wet spring / …)

More later (personal messages between Yann & me ”on the air” !!)

Eric

PS : about the full battened sail on a Goat Island Skiff, I found the pics on : 29-GIS | Flickr - Photo Sharing!11-8298279183_11219fcbe5_b.jpg 12-8299327132_1d1ab14f31_b.jpg 13-8299331234_64e3bf4f1d_b.jpg

PS2 : why do I have only the name (and link) of the pics in my comment, not openend picts ??

Speed may be a very relative notion : TriloBoat Talk: The PROMISE of Speed
Bob Wise (Boatbits, Volkscruiser, both .blogspot) is another fan of Yann. Very nice : every time he is quoted on a blog, Yann is due to a pint for everybody CIDRES.jpg

Good to have you posting here Eric. People are finding this new wide bowed Scow type difficult to get used to, so more discussion of ideas can only help. Such a design winning the Transat 6.5 fleet has to make us try to understand this hull shape more. After all, the little PDR has been asking such questions for some time now.

I have sailed with fully battened windsurfing sails, racing lug sails and built a sail very like the GIS pics shown above, so here are a few thought.

A high peaked properly cut lug sail does not need battens. Sail shaping will create a stable sail which can take great adjustment depending on wind strength. Lug rigs are already bulky when lowered and full battens will just make things worse.

The key issues are matching yard bend to sail head shape, using sufficient down haul and rigging the sail on the yard correctly.

Shaped battens as used in windsurfing rigs would make the sail power all the time, no de powered flapping, always pulling. Note a good thing.

if you make your own sail, as I did, with a flat cut, I added two profiled battens as in your GIS pictures to add stability to the sail shape and they seemed to work well. The boat planed readily and generally the sail was good. Cost very little to make. The two full battens were at the reef points so this also added to their usefulness.

So, if you make your own simple flat cut sail. Two full profiled battens can work.

Your illustration is much more of a Chinese fully battened type. Much lower head angle, again more like Paradox shape. These sails seem to use cheaper cloth, light battens and control lines from the leach, not really a lug sail and other expert in their use and setting might be able to help.

Hope this helps a little bit, and good fortune with your project.

Brian

No Brian, no junk sail at all, no control lines from the leach: I just saw this sail, thought it looked really good, and proposed it to Yann (among ~200 other propositions, I think!!).
Yann’s sail is a pure Paradox sail, with a modified furling system, but it works exactly the same way: see two videos on https://plus.google.com/photos/11620...51515662039985

I just wanted to know if its any better than a normal lug sail … But as it has straight leech, I think there will be no battens at all: much simpler, less thickness when furled, I think you are right.
I intend to use diagonal rods as battens on my personal project, see the page (all in French, sorry) I made on this subject on 2/ Voiles ferlables sur mâts non haubanés : Montaubin, Hobie, Raptor etc - Nautical Trust , that’s the reason of my sudden interest for battens.


For the speed question, Yann answered he is not decided yet for the size of daggerboards and sail (seems he told Dave Zeiger the same thing).
It will soon be too late to change anything else, as he is quite a fast builder! (he didn’t post new picts this evening, but it was pouring with rain and very cold today…).

Regards
Eric

Hi Eric,

What i found with my BETH sailing canoe was the sail didn't really need battens because of the straight leach.

I put the battens on the sail because I was copying American Sailing Canoes of around 1870. They use the battens for reefing points.

Without battens - much more power. Makes no difference to reefing. Brian found that battens don't necessarily reduce power so mine might have been too stiff.

With Battens - a little less power. Also after tacking the power increases more slowly. Without battens the sail fills quickly and BANG ... full power.

Thanks for the links to the Goat Island Skiff Photos on Flickr. I haven't seen those ones.

Did you see the pages on setting up and using the lug rig on the Goat? That is the basic setup. Most important is the Downhaul. If the boat is not sailing well it is possible that the Downhaul is not powerful enough or used hard enough
Goat Island Skiff (GIS) - systems for lug sails and rigs - Michael Storer Wooden Boat Plans

On this page is a more comprehensive set of Goat information for setting up. Also a short explanation of what Brian uses in the UK. We have a compromise system with some of the advantages of Brian's setup on some of the goats now.
WIKI for setting up and tuning Lug and Sprit Rigs | Storer Boat Plans in Wood and Plywood


Michael