Wonk report ?

Use this forum to discuss the latest changes in the class
Ben Fuller
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Joined: Tue Jul 22, 2003 10:31 pm
Location: USA

Post by Ben Fuller » Mon Apr 03, 2006 12:51 am

Ok folks, Steve, Arne, Oliver, Alan and maybe a couple of others had a go on Wonk. Not the best conditions for test rides with breezes seldom under 15. Noted that the boat was somewhat dicy downwind, needing to be able to slide the seat back further. And noted that some repairs were needed, the usual teething of new boat. Also that this is the first IC that I have seen that is a single person load on trailer or rack

But lets get some narrative sailing impressions? What is it like to be light and narrow?
Ben Fuller
Macavity
USA 172

Steve Clark
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Joined: Fri Aug 01, 2003 2:26 pm

Post by Steve Clark » Tue Apr 04, 2006 10:52 pm

I am sorry that I didn't make the seat tracks longer. That is being corrected even as we speak. Many of the hassles I experienced were due to some stupid stuff like the jib sheets getting eaten by the sliding seat carriage and the tiller extension getting stuck under the boat in front of the rudder. Stuff that ruins your day on any IC.
I am also pretty heavy and out of shape, so it's entirely possible that Greymatter would have kicked my ass as well.
Other than that , I like the way the boat goes though the water. Tuning wasn't right, but she seems to really want to fly.
Currently the tracks are being extended aft and I hope to sail again within the next week. The distance from the back edge of seat to stern will be 1400mm, which is more like the current Nethercott max aft position. I am going to see how this works before playing with T foils. Mostly because it is the quickest and simplest modification.
I am not too worried about the going down the mine stuff. All told all fast boats will have this problem to some extent, it is just a matter of backing off enough to manage it. I know that making the bear away in a pre T foil 14 or 49er on Saturday would have been at best a 50/50 proposition given the amount of time I had in the boat....So while I am not happy I am not that concerned. It will get right pretty fast.
Things that broke in Florida were:
The jib traveler: I think that in a stuff, the jib essentially backed as it hit the water and the fastener pulled out of the windward foundation. Really odd.
The jib sheet cleat ripped off the bulkhead twice. The bond of the carbon and epoxy bracket to the plywood was stronger than the inter laminar bonds of the plywood. This is solved by laminating some carbon cloth patches under where the bracket is going to be bonded to further distribute the load.
The Vang strut broke when Oliver landed on it. It was sleeved with the appropriate piece of alloy tubing and he went back out.
My stupidly light boom broke twice, probably because of design flaws.
Things I an going to change right away:
I am going to run the jib sheets through a little tube to get them below deck. This will stop them from hanging up on the jib traveler.
The seat tracks are being extended aft 460mm.
The seat fore and aft controls are being reworked.
I am going to try a parrot perch from the mast to the head of the jib to stiffen the rig and take more sag out of the fore stay.
I want to link the lowers to the upper shrouds so they ease when I blow off the lee shroud. This will get the boom the rest of the way out.
I need to build a stronger boom, but Blue Meanie's boom will serve in the (ha ha) meantime.
SHC
Beatings will continue until morale improves

Phil Stevenson
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Location: Australia

Post by Phil Stevenson » Wed Apr 05, 2006 12:29 am

Steve,
It seems like all the problems were mere typical teathing problems with the new boat rather than faults with the design or the concept.
Some opinion has been expressed that 50kg is too light, but I note that nothinig of the Wonk hull structure failed. Do you think you could have somewhere saved the 5kg which you ended up over the 50kg target? I was surprised you carbon skinned the outside as I prefer to add the strength to the inside only. Also do you agree Andy's proposed unstayed mono rig would save even more weight?
Phil S
Design perfection is achieved, not when there is nothing else to add but when there is nothing else which can be taken away.
http://philscanoes.blogspot.com/

Andy P
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Joined: Thu Sep 08, 2005 9:31 pm

Post by Andy P » Wed Apr 05, 2006 5:19 pm

There would be little difference in weight for stayed rig, or unstayed.
The unstayed mast is double thickness and more in the lower part, in an attempt to make it stiff enough, whilst still keeping 50mm dia to suit windsurfer camber-inducers.
A larger dia mast ( 75mm? ) would not need to be so thick, and would be lighter, but would then require a bolt-rope sail and mast track.
For a stayed rig, the extra weight comes from the rigging, the prodder/spreaders, and the extra structure in the boat to take the shroud loads.

single sail does save weight however.... and $$$ too!
the main would be about the same cost, but no jib, no track, no car, no blocks, no cleat, less string, less attachments to the boat.
Also less weight up front which helps with the pitching/ inertia thing.

Steve Clark
Posts: 165
Joined: Fri Aug 01, 2003 2:26 pm

Post by Steve Clark » Wed Apr 05, 2006 8:44 pm

Phil,
I tried to prove too much at once. That you could build the boat in thin plywood, that it was going to be quick, that you would like to sail it, that the mast would stand up etc. Given all of that I got pretty conservative in the middle of the project.
I probably could have trimmed back the carbon on the topsides and around the bow.
I don't really know what physical difference having carbon on the outside or the inside makes. Certainly if it is on the outside it toughens up the skin of the plywood and makes it harder to gouge up. You get to sand it and fight the pin hole war, both of which are pleasures that shouldn't be passed up.
I know I could have been more efficient with my rig bearing structure, but I was damned if it was going to fall down and pooch the whole deal.
I did crack a chine forward when I flew into it at high speed. 2 weeks later I still have the bruise, so that shows that it didn't give up without a fight.
Andy, I think 10 m^2 of sailcloth is just about the same no matter if it is in two sails or one. Yeah you save the weight of the 3 corner patches, but crikey!
50 kg is light, I think it is tough to get to with a plywood boat and not have to spend a lot of time keeping it stuck together. I think that Andy's technique makes it easier to hit, but that is less accessible to people without his experience and skill. I am confident that with a female mold and some Nomex I can build 50 kg ICs all week.
The politics are difficult. A heavier minimum weight is better for those with existing boats that can lose weight (I reckon 60kg is about as light as anyone can make an existing class legal boat) , but is less exciting for new people coming into the class. 50 will obviously be faster than 60, but will be harder to get to using cheap materials, but does anyone really care about it? It seems that people want black stuff in the 14s and A Class and are willing to pay for it even if lower spec materials "do the job."
SHC
Beatings will continue until morale improves

jimc
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Post by jimc » Mon Jun 12, 2006 8:38 pm

Steve Any news on Wonk in lighter conmditions? is there enough speed availale to make sailing hot angles the right choice?

Steve Clark
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Post by Steve Clark » Tue Jun 13, 2006 3:13 pm

OK the second regatta was the Ottawa Skiff Grand Prix. Breeze was up and down in the moderate range.
Oliver still won, but I took a bunch of races off of him.
Sailing angles seems to work relative to Oliver going wing and wing with the boom way out.
It was hard to tell because the conditions were pretty gusty and the puffs filled left or right making it hard to say for certain. But I can say that I was able to hold my own even though I weigh close to 50 pounds more than he does.
Since Sarasota the seat tracks have been extended aft 400mm or so and this seems to have overcome the straight down the rabbit hole tendencies. I have sailed in some bigger breeze and haven't gone over the front again.
The biggest problem at this point is rig stiffness. We need to get a bit more juice out of the mainsail. I have moved the spreaders once and think I probably have to move them again.
SHC
Beatings will continue until morale improves

ifoxwell
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Joined: Mon Jul 31, 2006 6:35 pm

Post by ifoxwell » Fri Sep 08, 2006 1:24 pm

As Wonk was the first DC and therefore has probably had the most use/tinkering have you any further updates for us Steve.

The winter is on its way here in the UK and as a recent canoe convert who likes to have a winter project building my own DC is starting to appeal so it would be good to know whats working whats not.

Ian
GBR245

Steve Clark
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Joined: Fri Aug 01, 2003 2:26 pm

Post by Steve Clark » Sat Sep 09, 2006 1:36 pm

In general Wonk seems to be going faster and faster.
I have had a few painful moments when things like the seat carriage came unplugged and then later breaking the seat which have put a damper on the available sailing opportunities.
Getting the rig to stand properly has taken some work. The spreaders have been moved twice and I have been using a "parrot perch" ( strut from the mast to forestay just above the jib head) to contain things better. But now feel I have good control of the rig and can sail with some authority in force 5.
On the next boat, I am planning to add a little volume to the bow above the waterline, will add some deck level beam aft to accomodate what turned out to be the right amount of seat travel, and will lower the centerline of the V deck and make the sheerline aft a bit nicer looking.
I also will get down to minimum weight.
SHC
Beatings will continue until morale improves

Karl Wittnebel
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Joined: Tue Dec 09, 2003 9:30 pm
Location: USA

Post by Karl Wittnebel » Sun Sep 10, 2006 5:03 pm

Steve how do you feel about the rocker profile of Wonk? Just curious. Andy seems to favor the straighter line, while Lust Puppet has the chines sucked up aft which makes for attractive trim on reaches when the seat is aft - bow stays up in the air where it belongs. Amazing how she slows down at high speed when the knuckle hits the water - now sure how to explain that, but probably a wetted surface thing. T-foil wisdom on other hand would hold that upwind you mash the nose in. But T's seem to have proven effective only on short boats like Moths and 14s, and I wonder if the longer stern on an IC is really doing some of the same dynamic lift stuff at speed.

Karl
Karl Wittnebel
NC USA 193 (Lust Puppet)

Paul Scott
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Post by Paul Scott » Sat Sep 16, 2006 6:52 pm

Hey Karl-

Any lines of Lust Puppet around, so I can see how much stern tuck there is? Is there a stern rocker tuck/how much you have to move the seat at speed back relationship that you've noticed??

Paul
"Exuberance is better than good taste" -Flaubert

Phil Stevenson
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Location: Australia

Post by Phil Stevenson » Sat Sep 16, 2006 9:43 pm

This is an interesting sub topic, and look forward to other opinions.

From my point of view I keep the back third of the boat as straight as posible. I have found that any boats with any spring aft are only good in light winds and do not plane fast when there is any reasonable wind. I have made moths and 12s with spring aft and they were aways slow relative to other boats a top speed.

I made my canoe as straight as I could, even developing the S shaped chine profile so that the bottom sections were as close to prismatic as I could get them. I think hvaing the canoe stern overcomes all of the presumed problems with wide straight lined boats. There is no wide chines to drag and the lack of volume reponds well to crew weight movements.
Design perfection is achieved, not when there is nothing else to add but when there is nothing else which can be taken away.
http://philscanoes.blogspot.com/

jimc
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Post by jimc » Sat Sep 16, 2006 9:50 pm

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">From my point of view I keep the back third of the boat as straight as posible. I have found that any boats with any spring aft are only good in light winds and do not plane fast when there is any reasonable wind. I have made moths and 12s with spring aft and they were aways slow relative to other boats a top speed. <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

This was my perception in UK Cherubs too. The boats with rocker aft and even just rise in the buttock lines aft with rise of floor at the transom handle nicely, roll tack nicely, go in light airs nicely, but pay an awful penalty in a breeze. The Slurp I've seen in the UK seems to have equal oreven slightly more rise at the transom, whereas my bias would be towards rise reducing - as it does in the Nethercott.

Paul Scott
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Location: USA

Post by Paul Scott » Sat Sep 16, 2006 10:54 pm

Just looking at the piece in the Sept. Seahorse about Neal Pawson's OUT95, which is described by Seahorse as a winged canoe. It's 30 feet long. From the photoes it has some similarities with Steve's latest. Anyway, what's interesting is that Neal says that 'to achieve all round performance a planing hull form must be avoided, as this requires a minimm speed to be efficient', which would seem to have some interest for this discussion. Looking at the photo of the thing, the aft rocker does seem to tuck up some..... Not enough info to figure D/L.

He says later in the piece that 'the stern has a clean run aft, and the section flattens to avoid squatting and add stability when planing'. When Planing! (see above) The OUT95 has a 10:1 fineness ratio. Which used to be a magic number for multi's.

Windsurfers have gone from V-Flat-V rise constant rocker/variable rocker on PanAm boards (double ended) to constant sections aft/ hardly or no rocker aft (Div II's- not double ended & light air craft to boot!) to slight negative rocker hooks at the end (double ended Alpha Race, and some of the Mistrals)- is this what you mean Phil? The explanation was that the negative rocker, or the chines coming in essentially to do the same thing forced the nose down. I'm trying to use examples here of hulls that have similar L/B ratios to the DC. Windsurfer designers usually talk about rocker in terms of 1) Bow Rocker, 2) Mid Section Rocker, and 3)Aft Rocker. On the longer narrower race boards, with Pin Tails, Gun Tails, or Squash Tails the aft rocker was always more (or wierder, see above) than I thought it would be. The explanation was usually that the planing was happening up forward, and the tail was more for attitude and drag control. Which would go along with Karl's observation that the Narrowtailed Whitman (I think it was) would happily plane along, keeping up with her wider tailed sisters. (Are canoes refered to in the feminine?) I'll have to take a look at the aft rocker again.

I'm trying to find my Norwood book on high speed sailing because I think he had some stuff on hull fineness modifiying the wave resistance of the hulls, and with that leading to different rockers. He also has some stuff on double ended hulls, rocker and fineness.

Does anyone think that a fineness bright line has been crossed between the older wider hulls and the DC's? The DC's at Max L & Min. B have a L/B ratio of about 6.8. (Isn't L/B 6 a wave resistance magic number too?) Which is pretty close to the main hulls of some fairly high performance tri hulls, and a lot of the recent ones have pretty curvy rockers aft- Nigel Irens comes to mind...

Paul
"Exuberance is better than good taste" -Flaubert

Phil Stevenson
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Post by Phil Stevenson » Sun Sep 17, 2006 10:49 am

Paul,
My reference to S chine shape is nothing to do with hollows. It is just what happens to the chine when you straighten out the buttock lines.

To put it another way:
If you take a normal boat with a transom the same width and shape as the max width station, like a speed boat, but with a more rounded shape, Say like my DC: 750 wide, 100 high chines and rounded. Then cut the plan shape to that of a canoe. To keep the bottom the same shape the chine line starts out amid ship 100 above the keel and slopes down to nothing as it gets close to the centre line/transom and in the process makes an S curve when viewed from the side.

The Nethercott does it too, but there are no hollows in the buttock lines or cross sections.

I do not like hollows anywhere under water, although above water they are sometimes useful to minimise wave resistance and other structural reasons.

Phil S
Design perfection is achieved, not when there is nothing else to add but when there is nothing else which can be taken away.
http://philscanoes.blogspot.com/

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