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wannabefd

What is the secret of upwind planing

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Fooling around singlehanded in a Speedball dinghy yesterday and tried to see if it would plane upwind.

Wind was moderate 6-8 knots which is about the limit that one guy could keep the boat flattish enough to surf and have minimal chop.

Started on a reach to build speed and then turned upwind and tried to keep it planing. Instinct tells me to move forward to stop the transom from dragging and then move back a bit to lift the bow, a bit of a balancing act. Top speed 7kn

Anything else I should be doing/thinking about?

Uphill planing is automatic on my FD

 

 

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Some, indeed most boats simply don't have the power/efficiency to get much beyond displacement speeds upwind. Looking at the headline specs I would think it likely this is one.

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wouldn't think 6-8kn is enough to get a 102kg/12m^2 dinghy planing upwind. As Jim says, this sounds like one of those ones that just isn't efficient enough, especially with only one body.

 

Enough wind to get two hiking hard would be the point at which planing may give you max VMG, but depends on the design. 10kn TWS?

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Definition of upwind planing is subject to debate. Usual definition is that upwind planing implies VMG > VMG in displacement mode close hauled. Many boats can plane while making upwind VMG (Viper can easily exceed 10 knots at 60 degree TWA but can't match its VMG Going hull speed at 40ish degree TWA. )

 

Only a few designs (defined by Bethwaite based on sail carrying power) can upwind plane with VMG exceeding displacement VMG. I reckon a sportboat like Viper has SCP in the 0.25 range but that's a guess.

 

Bethwaite mentions FD, 505, Tasar and of course 29er, 49er and other skiffs with sufficient SCP to upwind plane by VMG definition. That said, close reaching at 10 knots plus is too much fun to worry about definitions unless your racing on W/L course.

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Figured it might be marginal, but maybe possible with a touch more wind.

The Speedball is a pieced together project hull I keep on the beach

Presently fitted out with a 505 rudder and about 145ft of sail so a bit more power than standard.

Might not achieve VMG nirvana but will have fun trying.

 

 

 

post-101699-0-16496000-1471759132_thumb.jpgthe green one

 

 

 

 

 

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.

 

...juss smoke another big one,, you'll be planing all the time,, even in the bathtub :)

Wish I'd done that this evening for my wind assisted drifting session...

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Figured it might be marginal, but maybe possible with a touch more wind.

The Speedball is a pieced together project hull I keep on the beach

Presently fitted out with a 505 rudder and about 145ft of sail so a bit more power than standard.

Might not achieve VMG nirvana but will have fun trying.

 

 

 

attachicon.gifspeedball.jpgthe green one

 

 

 

 

 

 

It won't be sail area limiting you upwind -- it'll be RM.

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505 and FD don't "plane" upwind until you are having to barberhaul the jib /rake the mast /move the boom off centerline. This happens with wind in the teens. A boat like you show won't do this ever--unless you put a trapeze on it and get the wind in the teens.

But "planing" isn't even what is happening with FD/505. They are getting past "hull speed" but not planing. Pretty much the only true upwind planing boats are the 18s, the 49er, the 14 and 16. In terms of speed ratio to sqrt(L) you have to include a lot of catamarans in the same category, as well as of course kites, foilers, canoes etc.

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A few similar boats make claims of upwind planing ( tasar,v15) so wondered how they do it.

A quick search gives me lots of info on what is true planing and seems like you need to exceed 2.4x hull speed, guessing 10+ kn.

So never going to happen without more wind which will require more ballast/RM, and then chop etc.

Trapeze is on the list.

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^ Lol Dawg, chasing that sort of thinking is why we lost the circuit, the big names and moolah and worse have one design things, where the rigs at least look modern, as the " thanks we still got iteenz" .

 

I figured having the OD Hull was a good thing to help control costs.

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505 and FD don't "plane" upwind until you are having to barberhaul the jib /rake the mast /move the boom off centerline. This happens with wind in the teens. A boat like you show won't do this ever--unless you put a trapeze on it and get the wind in the teens.

 

But "planing" isn't even what is happening with FD/505. They are getting past "hull speed" but not planing. Pretty much the only true upwind planing boats are the 18s, the 49er, the 14 and 16. In terms of speed ratio to sqrt(L) you have to include a lot of catamarans in the same category, as well as of course kites, foilers, canoes etc.

 

Not sure where you get that. Having sailed a 505 upwind where the spray is constant,coming from approx the shroud location, the speed is around 9 knots and the wave from the hull is pretty much no where to be found, I would say it meets the definition of planing upwind.

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7776 I also race 505s. To me that is not true planing. 9 knots (which is only possible when you are in footing mode in flat water with about 18 or more knots true) is what I was referring to as "planing" with the barberhaulers on... When you turn the mark and put up that spinnaker, now *that* is planing! (But I'm being an engineer about this. There needs to be dynamic lift "chines dry" for true planing...)

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I don't think the modern skiff style hulls truly plane upwind. They achieve planing speeds, but tend to keep the bow knuckle just touching the water. I think the hull behaves more like a catamaran hull in that they don't really develop much of a wake.

post-13071-0-20170100-1471999973_thumb.jpg

post-13071-0-53440500-1472000000_thumb.jpg

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Now that is a cool photo!

Is it really 8 feet on the waterline? Fantastic! When I was a young whippersnapper, I took out the seaplane coefficients and the gimcrack coefficients and played around and convinced myself that what you describe was technically possible (planing upwind faster than the wind in a small boat), but I never went to the trouble to make it happen. Glad it worked!

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This.

 

So many boat owners think they are planing when their boat is clearly surfing, going partially through waves not really over. Having driven a 505 doing 9 upwind and then turning down, the amount of boat in the water and the way the boat tracks changes dramatically.

 

I don't think the modern skiff style hulls truly plane upwind. They achieve planing speeds, but tend to keep the bow knuckle just touching the water. I think the hull behaves more like a catamaran hull in that they don't really develop much of a wake.

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To add to that, in all the boats I've sailed, the more high performance they are, generally the more they do as you say--make the transition with less noticable change. At the extreme is the canoe--I never "feel" like I am planing. At the other end, when a GP-14 starts planing--you know it! The 505 is in between. The first time I sailed one, I was amazed at the way you could go upwind while leaving the wake flat. But out on 2-sail reaches I quickly discovered that actually planing on a 505 was a whole nother level of speed sensation.

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I don't think the modern skiff style hulls truly plane upwind. They achieve planing speeds, but tend to keep the bow knuckle just touching the water. I think the hull behaves more like a catamaran hull in that they don't really develop much of a wake.

 

Well, something has to hold the boat & all it's contents UP against the force of gravity. I am waiting for a boat that is so fast that the angular acceleration of going around the Earth(some call it "centrifugal force") flings it upward.

 

A boat that is floating still in the water is held up by displacement, that is the force of water pushing back against a weight equal to the amount of water displaced.

 

A boat that is skimming across the water with very little immersed volume, not enough to displace a volume of water equal to it's weight, is held up by the force of water rushing under the hull ie planing.

 

We can assume there is a state somewhere between the two, where the boat is partly held up by displacement and partly by planing; we can observe this directly with a speed boat accelerating as it begins making waves, then those waves lengthen into a large bow & stern wave, then the stern wave begins to shift aft of the transom and decrease in size.

 

Just this weekend I was observing my boat, a Buccaneer 18 (hardly a modern hi-perf boat but still one with some jump), we could sail quite tight to the wind and still have the stern wave cresting a couple of feet aft of the transom. Planing to windward? Not really but getting there. I think most trap boats can do at least somewhat better.

 

FB- Doug

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I always felt the 29er (and the I14 from the very brief time i have it in it) have a very distinctive transition between displacement and planing. The 29er in light air obviously sinks. As you approach "design wind" the boat is very comfortably sailing along - maybe 9kts. When it gets to 14 or so every now and then you might start dropping the bow down hoping the increase in speed will make up for the angle. Still maybe not a full on plane but certainly a substantial increase in speed is possible. You'll ease the sheets some, give one last kinetic pop, and then move back on the rail and transition to smooth sailing. If it picks up speed it is a very fast transition and abrupt speed change as the boat gets on a plane or at least greatly exceeds hull speed. If the boat squats then you go back to high mode and you wasted your time trying to go low-road. When you reach full overpowered conditions, maybe 18+, the boat is really flying along up wind with the bow clear of the water. There is no doubt that i would say the boat is planing. You are far back on the rail, sails are eased/jib is pinned-down on the track, and you just feel like you're flying. Kinetics , at this point, will generally not be beneficial aside from maybe a slight pop over a big wave.

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In those tricky transition times do you also hear when to let it break free, in flatter conditions?

I always felt it was a check-and-see sort of thing - like a puff hits and you think everything feels right to go low-road, but maybe i just suck. Certainly if you check and it gurgles, bring it back up to high mode.

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In those tricky transition times do you also hear when to let it break free, in flatter conditions?

I always felt it was a check-and-see sort of thing - like a puff hits and you think everything feels right to go low-road, but maybe i just suck. Certainly if you check and it gurgles, bring it back up to high mode.

 

From Cherubs to 18s most chine boats make a sound, rounder hull shapes mostly require a bit of slow visual or wiggle & see action.

 

when they're ready to plane, or when you try to make them when they cant. im very familiar with the latter.

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wannabe; Get your giant body out on the trap and keep it flat. You have enough righting moment to flatten the Queen Mary! Converting that to speed will get you planing.

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I sail an fd and i cannot say it planes upwind.

That's because i don't sail it very well. In addition it's an old boat and not very well setup.

And i know what planning is.

The 49er is a different story. Hard not to plane upwind.

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I sail an fd and i cannot say it planes upwind.

That's because i don't sail it very well. In addition it's an old boat and not very well setup.

And i know what planning is.

The 49er is a different story. Hard not to plane upwind.

So you beat up on your sailing ability because of something very heavy and designed only just post WW2 and is round bilge because?????

Sorry i don't understand your post.

What I'm trying to say it that boats like the FD and i assume also the 505,don't just plane upwind like that.

You need to know what you are doing and do it well.

For a weekend worrier like it's not a given.

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The following was written for Tasars, but can be adapted for most similar classes:

 

http://www.tasar.org/media/3307/manual_4.pdf

 

The section on planing to windward is on page 7 near the bottom of the first column and continues on pages 8 and 9.

 

I'm not sure I'd sail exactly the same way - the text seems a little dated, for example, I wouldn't pull the foil up halfway - but there is a lot of detail that will certainly get you thinking in the right direction.

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I'm not sure I'd sail exactly the same way - the text seems a little dated, for example, I wouldn't pull the foil up halfway - but there is a lot of detail that will certainly get you thinking in the right direction.

 

Not sure about 'half way' -- but pulling the board up to balance your available righting moment as wind and speed increase is top of the list of things you absolutely must do in a fast dinghy/skiff. Flat is fast.

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Interesting topic.

 

I love Wikipedia, so much so I donate money to them each month! Their definition!

Planing is the mode of operation for a waterborne craft in which its weight is predominantly supported by hydrodynamic lift, rather than hydrostatic lift (buoyancy).

Few entries back someone said its when the boat is supported hrdrodynamically rather than hydrostaticaly!

Regardless of how fast you go, there will always be a component of hydrostatic's, and there is no clear cut definition.

Dad used to say it was when 2 molecules of water that are split at the bow, do not re-attached at or behind the transom. And of-course there is always going to be a % of that also.

 

Re the Tasar, I can assure you it planes up-wind, I have done it many times, and my seat of the pants definition comes back to the VMG concept previously touted!

 

So if you can crack away say 5-10°, so from say low 40° to high 40° and the boat pops from say 5knts to 8-9 knts, which it dose, then VMG will higher and that to me is Planing-Upwind.

 

The reason the Tasar can do it is because it has quite a short rig (18ft) and a low and efficient sailplan so the CoE is very low.

Plus its wide and light, easy to hick.

And pulling the centerboard up 6" (150mm) also lifts the CLR so your power triangle just got a whole lot better.

 

I could rant on about the Prime Mk3, by the time it hit hull-speed, (6 knts) it was planning, bloody light (99lbs) 22ft wide wings, 2 crew, its just could not, not plane.

 

So this double HS notion, dose not work either!

 

Think hulls lines are very important, let me go hunting, did something interesting about that last week!

 

Jb

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I'm not sure I'd sail exactly the same way - the text seems a little dated, for example, I wouldn't pull the foil up halfway - but there is a lot of detail that will certainly get you thinking in the right direction.

 

Not sure about 'half way' -- but pulling the board up to balance your available righting moment as wind and speed increase is top of the list of things you absolutely must do in a fast dinghy/skiff. Flat is fast.

 

 

and to demonstrate -- this afternoon's race was in a blustery 15-20kn WNW. Flat water, slack tide on the river.

 

We had our board up a good 10" (2-man hiker) - that's probably 20% of the board length, and its got a taper, so maybe 25+% area reduction -- we're light (me 74kg, my 8yo daughter maybe 35-40, and she hasn't got the hang of hiking yet).

 

Jib sheeted out 4-6" and pointing low and fast as Julian says. Upwind planing was the faster VMG option by far.

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