Proa - Cat Hybrid?
I don’t want to be negative, but looking at the model I see a LOT of vibrations and uneven bouncing of the different hulls. I think that boat would shake itself to pieces quite soon in any kind of waves. With enough carbon it could probably endure the enormous loads, but the crew will need spare spines and kidneys. If they want to build something cool and hightech they should start thinking about hydrofoils and proas. The only way to survive sustained 50 knots in any kind of waves for any duration is to lift the hulls out of the water.
Johannes
It appears to be moving and with the inclined rig stable, not sure if any hapa type foils involved. It is a windy day mind.
If I believed hydrofoils are the way forward for mass sailing I would give up on proa design. I think something less fragile, more robust and easy to launch etc will eventually prove to have more appeal than hydrofoils.
The thing I like about this is that you can have the relatively small planning hulls working efficiently some distance apart. Dave Culp explained the angles etc in another forum. The model does shake about a lot but the beams could be flexible (D class land yacht style) if you could decouple it from the rig.
I once drew a proa with two small planning hulls like this at bow and stern of a long fore and aft beam. The two hulls could independently pitch and roll and yaw 360 degrees. Each had a board / skeg at the stern so the bow always faces in the direction of travel. Still with me, needs a picture. There was then control of the yaw so that the two hulls and their boards counter rotated. This acted as steering and therefore CLR control like my TP02. Everything else was a conventional proa, I used a cat rig.
Will try and get a simple sketch because I am sure no body under stands my description
TINK
I see a LOT of vibrations and uneven bouncing of the different hulls.
That seems to have been part of the problem with Yves Parlier’s catamaran a few years ago, seen here at the start of a transatlantic race (Parlier started a bit late for some reason and is seen working his way through the Open 60 fleet and the 50 foot multihulls): http://www.youtube.com/watch?v=AY0ssDA70gY
In test tanks, the stepped hull had been faster than the trimarans with banana foils. When the designs met at full size, the cat could only keep up on some courses, and I read one specific problem was very rough motion upwind. It was not good for either boat or crew. Parlier got shaken about a lot. That precedent makes me think you’re spot on.
Unless the Wiebel gets suspension. I suppose that’s possible, at the expense of some weight. In a rough sea, it might still be worth it not just for comfort, but for speed. It takes energy to shake the whole boat about, less energy to shake only bits of the boat. Still, hydrofoils are probably a more practical solution to that problem.
A very basic sketch for post 2
If I believed hydrofoils are the way forward for mass sailing I would give up on proa design. I think something less fragile, more robust and easy to launch etc will eventually prove to have more appeal than hydrofoils.
Without wanting to be upstage or too cocky, I want to say that hydrofoils are simple and cheap. They can be very robust and easy to launch. I can not see any large problems with hydrofoils. If one can accept deep fin-keels then hydrofoils are simple and robust in comparison.
I can agreee that most examples of hydrofoils are way to complex and extreme. But they don’t have to be.
Cheers,
Johannes
Someone has to say it ...
Weibels wobble but they don’t fall down. (This is in reference to a child’s toy catchphrase sold in the 70’s here in North America for those that do not recognize the phrase)
From the model video, it looks fast, but man it would shake your brains into Jello. Hope everyone on board has a mouthguard or the dental bills could mount.
Seriously, I think the ground broken by foil borne hulls like Hydroptere and Sailrocket deal with the uneven surface conditions by sailing above it and taking it out of the equation for the most part. This design remains in partial contact with the uneven surface (if on different floats & foils) all the time. It will be interesting to see how the two seat model performs and how much the upscaling of the model changes things.
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Bill
I am perplexed by this, I couldn’t figure out how it was supposed to tack, the side view of the rig shows why. I had a dig on the website (http://www.wiebel-sailing.com/) and it only gybes! There is a big track at the bow to drag the foot from side to side. I can’t imagine going upwind and gybing all the way.
IMO they need to turn the whole rig through 90 degrees and turn it into a proa…... Is it just me?
TINK
I believe that to change tack it is jibed like a windsurfer except when reefed when it can be tacked conventionally.
I am perplexed by this, I couldn’t figure out how it was supposed to tack, the side view of the rig shows why. I had a dig on the website (http://www.wiebel-sailing.com/) and it only gybes! There is a big track at the bow to drag the foot from side to side. I can’t imagine going upwind and gybing all the way.
IMO they need to turn the whole rig through 90 degrees and turn it into a proa…... Is it just me?
TINK
It’s not just you. The rig as currently configured doesn’t seem to make much sense. I’ve done skiff sailing for years, and we can keep a skiff on the plane through a gybe when downwind tacking due to the speed of gybing a big asymmetrical spinnaker inside the bowsprit - which is moving through only about 60-70 degrees of change from tack to tack. If you aren’t as fast as possible doing so, the boat comes off the plane and the rig loads up due to the hull slowing. Once the rig loads are up and the boat is stuck back in displacement mode, you can expect to be swimming pretty soon.
With this design, manually winching the foot(tack) around a huge track, while floating the flogging wishbone 270 degrees forward of the bows, with huge sheets in front of the forestay is a recipe for a slow draggy mess.
I’m also suspicious about the four hulls - that is four sets of waves and surface interaction, no reduction in wetted surface area at higher speeds by flying hulls or lift causing planing only on the after portion of the hull.
The model behaviour seems to support their concepts, but I’ve always wondered how well tiny R/C models scale up to real world. Servos on models provide dramatically more speed and strength at tasks than actual people do grinding winches. Wavelengths and periods on model scale make everything look like flat water, because hull lengths are tiny compared to normal waves. Models are great for testing some components of designs, but not so good at everything.
About every six months or so there is a new hyperventilating bleated announcement on social media of revolutionary design concepts that will blow away all previous efforts. Canting keels, CBTF, canting keels rotating so far they are flying above the waterline, prow fronts on Mini transats, stepped hulls, wave piercing everything, Dynamic Stability System (DSS). These announcements are never ending, but most of these rule beaters never generate any real world performance that seems to last longer than the press excitement. And very few of these concepts ever achieve large scale acceptance and class racing due to very limited range functional benefits. It is possible to find a solution that works spectacularly in a very small window of wind, sea state and point of sail, but can not be applied to all points of sail, all weather conditions and all sizes of boats. Paul Larson’s Sailrocket is a great example - designed for Walvis Bay, Namibia, works only on one tack and only launches in a very specific set of conditions. Just about all the Maxi-canters and CBTF boats drop keels off the hulls at alarmingly frequent intervals.
This is a huge part of the appeal of proas to me - the long term viability and history of the design proves the performance benefits are without question. I’m amazed at the brilliance of Pacific Islanders figuring out how to use crappy materials to well exceed the state of the art in evolved designs elsewhere that persists even today.
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Bill
😉
This is a huge part of the appeal of proas to me - the long term viability and history of the design proves the performance benefits are without question. I’m amazed at the brilliance of Pacific Islanders figuring out how to use crappy materials to well exceed the state of the art in evolved designs elsewhere that persists even today.
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Bill
Well put,
110% agreement here,
TINK
“With this design, manually winching the foot(tack) around a huge track, while floating the flogging wishbone 270 degrees forward of the bows, with huge sheets in front of the forestay is a recipe for a slow draggy mess.”
I may be wrong but I don’t think there is a fore stay,.I suspect the sail is square topped and with full battens and is attached to a sail track on a yard, The traveler track for the yard foot is curved so that the end of the wishbone will pass in front of the fore and aft split mast when tacking,.as will the top batten of the square top if the sail is reefed,.I suspect that the sail would always be reefed beating and that off the wind with full sail the rig would be jibed like a windsurfer with little drama. I don’t think that it would be necessary to winch the yard foot from side to side . The wind should take care of that.
This is what their web site says
” In the second generation Wiebel rig, the way in which the boat changes tack has been improved. The boat is designed to jibe. During the jibe, the boom swings over the bow over an angle of more than 270 degrees. At the same time the mastfoot travels from left to right or vice versa along the curved rail at the forward edge of the frame. The mastfoot is operated by winch.
This makes it possible to keep the gap underneath the sail minimal during sailing. This in turn results in the socalled “endplating” effect, preventing leakage under the sail and increasing the pressure in the sail, resulting in the ultimate sail. Hence the optimal position of the sail as it is known from windsurfing, i.e. with very little or no gap underneath the sail, is always reached.”
I wonder what they did before it was improved
On their home page they compare themselves to: Sailrocket, l’Hydroptere, Macquarie Innovation and the AC72
I don’t see it close to 500m record breaker
As said by others you’d nead a new spine to go off shore
And I can imagine it round the cans
Tink
Tink
“With this design, manually winching the foot(tack) around a huge track, while floating the flogging wishbone 270 degrees forward of the bows, with huge sheets in front of the forestay is a recipe for a slow draggy mess.”
I may be wrong but I don’t think there is a fore stay,.I suspect the sail is square topped and with full battens and is attached to a sail track on a yard, The traveler track for the yard foot is curved so that the end of the wishbone will pass in front of the fore and aft split mast when tacking,.as will the top batten of the square top if the sail is reefed,.I suspect that the sail would always be reefed beating and that off the wind with full sail the rig would be jibed like a windsurfer with little drama. I don’t think that it would be necessary to winch the yard foot from side to side . The wind should take care of that.
I don’t buy it. Tacking really isn’t an option. They would have to reef/drop the square topped main around halfway to clear the head of the sail (if the drawings are to scale), leaving one hell of a lot of heavy, bulky laundry to wrap/bundle and move manually at the foot. The comment about manually winching is from their site (See Boat Design/ Technical Aspects/ The Rail). They clearly specify gybing as their tack changing method. Besides, you would have to re-route the sheets behind the luff and disconnect the ones running around the front. They wouldn’t want four sets of sheets (port & starboard x one set inside the luff [tacking], one set outside the luff [gybing]). Another problem is that this boat will be just as bad as a proa being caught aback - so blown tacks aren’t an option. Chicken gybes on this design would actually require gybing!
There is no forestay, but the luff of the sail acts like one - it is fixed from the a-frame to the moving base attached to the “Rail” at the bow(s). Then there is the sail track which would be on the wrong side 50% of the time. Round the front windsurfer gybing works because the rig weighs 10% of the operator, and stability is dynamically maintained by the operator - I’m not so sure 15-30 square meters of cloth flogging forward of the bows would be drama-free.
I always hate dissecting these rule beating / speed freak schemes for functional problems, but I know a few really smart people like Steve Clark and Magnus Clarke and Fred Eaton (C-Class wing sail designers) that have spent countless hours and dollars hunting for speed. Ideas like this have to be somewhat practical on the water to be workable.
I wish them all the best, and I’ve been wrong more times than right. Just pointing out the obvious.
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Bill
I wish them all the best, and I’ve been wrong more times than right.
I’m with you Bill….I wouldn’t want to “tack” that thing offshore in big wind and waves. Even if it did work and I am still not convinced that it does or is practical in any way…...
Ditto foils, as you mentioned in an earlier reply….I appreciate that inshore in flat water at certain wind speeds foils clearly work, and on a proa with 2 working rudder foils on the vaka and a central foil on the ama they would form a very stable arrangement. Offshore at high speed a front foil failure would be catastrophic so by the time they are built sturdily enough for high speed in big waves and hitting whales, logs or semi submerged containers, the additional weight and drag would render them counter productive in almost all conditions.
Read David Sheehan’s article in the March “YACHTING WORLD” page 24.
Rob