New low-cost "hardware store" racing class; input on proposed rules

Going into rule "cheating" mode again.

My Zest dinghy has buoyant wings, so has three discrete buoyancy areas. so technically it counts as a trimaran. So I get more money to spend and the boat can be wider than 5ft. It all comes apart in seconds for roofrack transport. No point in making it longer as it is a singlehanded boat

Richard Woods

 

Arguably. But will it sail well with the end of one of the 'wings' immersed? That's what I'd be looking at if I were a class judge. If the answer is yes, I'd call it a trimaran.

 

The use of wingtips is extremely complicated, and still somewhat controversial, however, at the risk of annoying aerodynamicists, this is an EXTREMELY simplified version.

Turned up wingtips are not magic at all. Span is the answer to almost all commercial (and GA for that matter) airplane ills, but in the past aluminum technology limited this somewhat. With new aluminum(s) we could now exceed the old span limits, but unfortunately all airports had now standardized on gate widths, including taxi way, light standard spacing, and building clearance for each class of airplane. These are absolute limits, and are complicated by a wing full of fuel bends DOWN, mowing the top tip of a winglet OUT.

When we can, i.e. no limits, we use a RAKED wingtip, like the 787 and newer 767’s. This is the most efficient, and allows passive gust load alleviation i.e. no actuation certification issues. But, this has little or no recognition value.

What turned up wingtips do is provide an apparently longer wing without exceeding the gate or other span limit. Roughly speaking, the turned up winglet is half the efficiency of a straight wing, i.e. the 14’ high 737 winglet is roughly equivalent to a 7’ wing extension, or raked wingtip, though much heavier. Again, very roughly, the vertical winglet lifts IN, and this is converted to ‘up’ by the structure. The smaller turned DOWN segment on the new 737 MAX is largely (not completely) cosmetic, and serves as a external distinction from earlier models.

This proposed class has a mast (rig) height limit.

Richard; I thought the Laser might be one, and presumably the BIC as well. The Mirror dingy was designed for just such a task, including a Gunter rig so the spars would fit in the boat. The boats I was describing had far higher freeboard than the Laser, seats around the gunwale for passengers, and a cutout in the transom for the OB. Having now studied your catalogue of work, I am particularly impressed with Stealth and Bee as the basis for a Hardware Store boat.

Worrying about breaking ones mast when completely inverted and stuck in mud seems a bit extreme. I would have thought a broken mast was the least of ones troubles in this case. Perhaps i am concentrating on the ease of use for new sailors rather than the all out competition you are discussing. I agree, matching a sail to the mast IS necessary in serious competition, but is it necessary here. My point earlier about larger, less efficient sails, was to try to escape the tyranny of purchasing new sails each season.

Skyak; I think we are describing completely different sailing conditions. Neither I nor my crew would be out in wind conditions exceeding 20kt. I am aware of ‘feathering’ the main, and de-powering it by flattening it, Cunningham led to the skippers rail etc, and accept this is a legitimate practice for serious sailors. Indeed we often practice this on the big boat toward the end of a beat if the wind gets up. It saves reefing and unreefing at thwe mark.

I am discussing the ability to carry less sail as a result of forecast winds, or a change in wind (direction or strength) whilst picnicking on a shore. Forecast winds could be handled by a smaller rig, much as Sydney harbor 18’s, or some other form of area reduction, reefing etc.

I wonder where you get your tarps from, some have a rather higher modulus fiber in them (Mil Spec even) and i would use these. I would also add full length battens, either pultruded carbon (Kite rod), or similar plastic bar. Duct tape, or gorilla tape, works fairly well, but real aviation grade 100 mph tape will handle several hundred MPH, and sticks well. This tape can be sewn on later if necessary.

 

I got interested in aerofoils and sails when a design student. I read many papers, including one that looked at bird wings. It compared the soaring bird like the albatross or frigate bird with the eagle. The latter has a short wing (relatively) and spread out wingtip feathers which I understood act as endplates. And of course they control them all individually and can also adjust twist and camber. I have never seen a glider hover like a hawk can, but it should be possible.

I assume the fuselage is a big endplate. Many boatyards like to limit their models beam/length because of shed size restrictions (notably catamarans of course)

People tend to think of a square sail as inefficient, because they think of the single sail as the Vikings used. But the latest developments were the clipper ships and each mast had maybe 7 sails, all could be set at different angles of attack, so different twist and camber. All done without winches. Quite sophisticated especially once they had wire, not hemp rope rigging. Full circle now of course, all race boats use "soft" rigging if allowed.

Thank you for the compliments. The Bee has no rudder as it has a raked transom, might be challenging making it a real sailing dinghy. I am using my 1998 Stealth sail on my Strike 15, as you probably noticed, so full battened mainsails can last a long time (they don't flog/flap). It is the cheap dacron sails that have a limited life. Especially on a Laser, for example, when the best sailors buy a new sail for every major regatta. Even my brother bought 4 a year in his prime (but back then he was about equal to Ben Ainslie)

The best person to talk to about polytarp sails is Dave Gray http://www.polysail.com/

he said hasn't had much luck with full battened sails, preventing the inboard ends from tearing the cloth is a challenge. Obviously a sleeved luff sail helps but you cannot reef it. Two cheap rigs will probably cost more than one good one. The sensible maximum sail an average person can handle in a dinghy is about 12sqm for a mainsail and 3-4sqm for a jib. Bigger jibs need a 2:1 jibsheet. That's one reason most dinghies are under 16ft long

I was brought up dinghy sailing in Poole Harbour, which is typically 8ft deep. Even in the Solent there are huge areas where a dinghy mast can hit mud. Same of course for most of the east coast USA and many lakes. We hit mud doing a capsize drill at Lake Eufaula on a lug rigged boat a couple of years ago at SailOK.

Generally the less well tuned a sail the baggier it is. That makes the boat heel more and also makes directional stability suspect. So a well tuned sail is even more important for beginners, they will be blaming themselves, not the rig, for capsizes and control problems offwind

Rather a long list, but this from my brothers recent "how to sail a Laser" blog (note the first comment b)
===========================
1. Cunningham on really really hard - as hard as you can pull it

a. Even consider using a double becket block in a lot of breeze for more purchase

b. At the bottom mark, I sit back in middle of boat, and with 2 hands and foot wedged against cockpit, I pull as much Cunningham on as physically possible

c. Rig the Cunningham one side of the boom, so it can be pulled down beyond the gooseneck

2. Boat flat – let the sail out rather than allow the boat to heel

a. Even more important than flat – is “CONSISTENT HEEL”

b. If you can’t be flat, at least keep consistent heel to keep flow of water over the foils

c. You will see videos of Goodison for instance heeled in waves but the key is he has constant flow on the foils, particularly in QM on Sat, with gusty conditions, the guys struggling flat, then heeled, then broaching up into the win, then *** in the water, this is all inconsistent flow on the foils and really slow

d. Pre-empting the gusts helps.

e. Tight toe strap = really tight. Guide – the strap should be tight so as it cannot touch the floor. Then a strong hiking position, not a ninja hike if you’re not fit enough. Then you can confidently look out of the boat and pre-empt the gusts and react in advance to keep consistent heel

f. Using a lot of mainsheet, you could be playing it 3 foot out, to block to block

3. Weather helm is usually a sign of too little Cunningham and too much heel

a. Note – Going block to block and pulling the kicker both pull the draft of the sail backwards. Meaning the power goes back. This means the boat has more tendency to pull up into the wind. Regardless of whether you are over powered you will need Cunningham to pull the draft forward again, neutralising the helm.

4. Foot quite tight - some people suggest that you should have a bit of bag in the sail on the foot in strong winds, but at least to begin with I’d be inclined to go on the side of having the foot a little too tight rather than too lose in survival conditions. As you pull the Cunningham on the foot will naturally get tighter

a. On the lake, flat water, you can afford to have a tight foot.

5. Kicker on hard is the usual aim:

a. The reason you want the kicker on hard is that when you let the sail out in a gust, if the kicker is loose, the mast straightens, and the sail gets fuller. So letting the sail out will not reduce the power as much as you want.

b. The problem is that if the wind is really strong, this can lead to problems tacking, and getting stuck in irons. So when it is survival conditions – as it was from time to time on Saturday – it is sometimes an idea to let it off a bit, especially when tacking – easier said than done

i. Kicker can be so tight, so that when you sheet out, the boom goes straight out rather than popping up.

6. Block to block is good if you are not overpowered. Pinching a bit can help, especially if the water is flat, but if you do this too much you will stop in the waves. So the best approach is to let the main out when the gusts hit. This way you can get through the choppy conditions we had on Saturday more easily. You can do a combination of luffing a bit and letting the main out

a. Per Gareth’s note, if you keep the boat moving fast, then the loads are lower. Fast VMG and consistent heel, working 100% to keep it moving. The laser just punishes as soon as you stop working hard.

b. You can use both kinetics, body weight, and a lot of tiller action to work through gusts.

i. Stabbing the tiller in a gust causes the leach to flick, losing power, keeping the boat flat

ii. Kicking your legs, you can flick the leach in a gust also

7. I think it’s a good idea to sit at the widest part of the boat usually – but you can sit back a bit if the cockpit is filling with water.

8. REACHING – I was actually using a lot of Cunningham on the reaches.

a. Pulls the draft forward, so power pushes you forward rather than fighting you

b. Again consistent heel is key

c. A lot of people have tendency to think you should be fully powered up on the reach

Summary for me:

· Consistent heel, keep flow on foils, keep boat moving fast

· Pre-empt gusts

· Tight toe-strap, strong hiking position

· Use combination of a lot of sheeting, stabbing tiller, kicking legs to work through gusts

· Lots of kicker and loads of cunningham

· Point bow down to accelerate then come back up

o Pinching just loses boat speed and increases sheet loads

o This takes loads of upper body ability to sheet out two foot then in again, in / out/ in out
=============================
And that is a nominally simple rig!

The Laser sail is only 3.8oz, cheap dacron and cannot really take these big loads for long. But without flattening the sail like this you end up with something baggy and you start swimming fast!

a long post, but I bet you are reading it instead of watching the "game" as the Seahawks are currently losing badly (or so my wife says)

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Yes I read it, but I am back at the TV for the finale.

The fusilage is not REALY an end plate, but there is significant 'near field' effect.

 

yes I gather it is now a draw

 

Go Hawks

Sorry i had to watch the end of the game.

Just finished a celebratory Cheese Cake with kids and grand kids.

Don't get me started on bird wingtips. Much of the relevant research is not much use as the birds use continuous dynamic and interactive positioning of individual feathers. The Eagle does not really have end-plate effect, but does individually position each tip feather depending on load etc. They also use continious variable camber, something we were working on recently, though Fairey had an excelent system in 1914 (on the "Hamble Baby'), one worth copying in fact.

We spent a lot of time optimizing wing to body aerodynamics, look along the leading edge of a 777 or 787 somtime and note the dis-continious twist from root to tip, especially over the engine strut.

I know about Polysails, but i suspect we will do our own research, just as we did earlier with adhesives, fastners, and sealants.

 

Crr

Written much earlier,

As promised we had our CRR, (Critical Requirements Review) on Saturday, complete with consultants from out of state. We might have an honorary, acting, unpaid Project Manager, but whether we get an IMP (Integrated Master Plan) is another issue.

If you are lucky you might get 3 boats out of this from us, the “X” prototype, the “Y” improved prototype, and “A” initial operational test version (US Military convention for aircraft development). Alternately you might just get 3 different boats.

The review agreed that a 14’ monohull was appropriate with a 23” bowsprit (State regulations have boats less than 16’ tax and license free), foil cross section and plan forms (CB and Rudder), general structural issues and form, and discussed rig options. Actual wood area and volume against densities were discussed, as was tailoring the wood in the mast for bend etc, and tables consulted for the appropriate wood characteristics. Wood is anisotropic, and these characteristics can be exploited by careful engineering.

Sails and sail cloth options were discussed and generally agreed, as was rigging and general arrangement.

As we can make 12+ computers available between us and connecting these together as a kind of home grown ‘super computer’ running UNIX (which naturally shares processors), we could run CFD beautifully. However no decision was taken on this or the water table testing.

We are aiming for a single hull that can sail single or double handed, allowing a wide range of fixed and movable payload weights. As few of us are as agile as we once were, actual sailing and controls were discussed at great length. Polling grand children for sailing talent might become necessary.

The beach launching and human power are still exercising our design talents, how much weight do we give this in the associated 'spider' or 'pareado' charts.

 

So my wife tells me they won. Congratulations, a repeat of last year maybe....

This is going to be interesting. I think we will be stopping by Gig Harbor in early March!

I expect you have already read it, but this thread and similar ones might be of interest.

http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=11344&title=dzero

and for sure you have read this

http://www.boatdesign.net/forums/hydrodynamics-aerodynamics/physical-art-sailing-51948.html

maybe the sailors are like the bird in controlling their wings?

RW

 

As before I enjoy your enthusiasm. I would sure like to see three boats from your group demonstrating differing values and tactics -great fun.

CFD capability would be very interesting but I tend to think your group has more than enough intuition and estimating ability to project the result. I think there is enough challenge producing reliable foils for all the likely conditions that no time is left for analysis because you can't reliably make the shapes anyway. I do hope you do as much testing of materials because this class has much to learn about what is most cost effective. I get my tarps at the hardware store of course -Menards and harbor freights seem to have the same cheap source. I don't know the material, capabilities, or detailed mechanical properties. It sure would be nice if some smart engineers tested them. One thing -I am pretty sure that heat deflection temp is rather low which could be useful in thermoforming. Tensile properties, bending, fatigue, and creep...

Your question about beach launch and courses is important and I don't recall that it was detailed anywhere in this forum -or anywhere period. The idea was that the courses and locations would be chosen locally for the most desirable experience. The beach launch and human power are most important for creating 'well rounded' boats and desirable outings. If you put a race on the calendar you can be sure it will happen. The mix and locations of race outings are at the discretion of the local fleet and should get some detail before boats are built. The only race I know to include beach launch and no limits on human power is the raid.

The last thing I feel the need to say is that one design racing tends to emphasize some minutia because there is such limited variation. The boundaries are very well known and it is easy to extrapolate the benefit of small variations within the rule. This development class is intended to give you more big picture improvements than you can handle -more than enough rope, just don't hang yourself.

 

The "simple rig" makes optimum adjustment complex. In contrast look at the AC wings -I guess you would call them "complex" but adjustment is extremely simple -angle of incidence, camber, and twists. Each adjustment has an independent linear control. Even I can handle that!

With that in mind what do you think of wing masts? The sail could be an extremely simple flat cut with battens. Tom Spears did some analysis that showed a good range of camber ability from mast rotation control. This class is wide open for sail configuration. I don't see much value to 'developing' a simple rig that needs complex control. Why not go the other way? Bend shmend, just make the right shape and turn it the right angle.

 

So the answer is "no, we're still talking, the rules are not final, no boats have been built, and there has not been a race"?

 

On small unstable boats like the ones proposed power reduction in gusts has to be very quick, and preferably automatic. I doubt if that can be done with a wing mast. And a wooden wing mast will be heavy, even if made in balsa with a mylar cover it is unlikely to be as light as a used dinghy mast from say a 420, which will weigh around 10lbs. Wing masts are also tricky to handle ashore and if you use a curved leech wing mast and flat sail (as on Lady Helmsman) you may need to turn the boat on its side to hoist it

Edensaw is selling good plywood for USD40 a sheet, 5 sheets USD200, plus say USD100 for epoxy/glass total USD300 to build a best quality hull - not a "hardware cheap" disposable one.

That leaves USD300 for a used rig. Quite feasible using ebay or CL. A suitable brand new square top mainsail from Intensity Sails is USD180

http://www.intensitysails.com/pohemasafor4.html

You can buy a suitable mast/rig/boom on CL for USD120 or so. (The rig I have on my Strike 15 actually ended up costing me less than that)

So you'd have an individually designed/built boat that will last 20+ years yet wouldn't look out of place in any dinghy fleet world wide within the USD600 mark

As I said earlier, if I can reduce my existing fleet, I will build a Zest in the 2 day Edensaw Challenge, and I think at least one other builder from this forum will build something as well. So there could be 6 local to Seattle boats ready to race come September.

http://sailingcatamarans.com/index.php/designs/1-beach-cats-and-dinghies-/436-zest

Richard Woods

 

However a 'wing' mast may be 'short' in the fore/aft dimension say 70-80mm so then weighs the same as an alloy one for equivalent beam stiffness (not compression) if carefully made. This may not be counted as a true 'wing' mast but at least can have some similar effects on flow.

I do not know of any fully battened sails that fit by luff rope, that can be raised other than head to wind. The luff batten holders are the problem, however they (the sails) will drop from almost any wind angle, good for safety.

One othe thing, Mylar sails are fine especially fully battened, however do not jump into them on a capsize or you WILL go through it.....
at least if a suitable weight fabric!.

 

That makes it a rotating mast rather than a wing mast in my book. I tried a rotating mast with my 14ft Stealth, it worked well. Then I went away and came back to find someone had stolen my mast. So I got given a Hornet mast, the boat never sailed as well

I think I said I was one of the first Moth sailors to have a sleeved luff sail- early 1970's

RW