It also came to pass that narrow skiff moths are faster than the wide scow hull forms in top flight racing.
Its been pointed out that the scow is long and thin upwind with a large flat surface for downwind…This perfect sailing machine gets beaten however by a skinny 11-1 beam ratio skiff.
planing in the traditional sense(flat bum…spray everywhere etc etc)is just plane slow compared to modern ultra narrow craft.
They dont have the traditionall sense of planing ,but just go faster and faster in “displacment” mode.
This is not experimental thinking…its a fact in the moth class at least.(foiling aside)
never downwind - always deep reaching !
Otherwise one can only go as fast as the wind. “Our” way we go faster, albeit father…
Brett - while I agree to apoint, I wonder what and how the scow would have developed if it was an open development class like the Moth. Also an 11 foot boat of at least 75 lbs. would/should be faster than a 38 foot behemoth weighing nearly 2,000 lbs. Now to really screw things up - looking at a "fast sailing device, the sailboard sort of reflects the scow more than the moth !!!
Brett, you are absolutely right about the moth class. Those narrow boats are without a doubt faster than the wide boats. even without their foils. (although, these folks don’t agree! check this out… ) however, we aren’t talking about moths. moths, as was pointed out, weigh 30 kg over an 3.35m boat. plus a crew weight of about 75 kgs, and we are talking a boat that weighs 105 kgs over 3.35m. a footy weighs (on average) 350 gms (this is the weight of your “middle” boat, correct?) and most weigh closer to 400 gms. over a hull length of 305mm. the footy is, has proven itself to be, and forever will be, a “heavy displacement boat.” you can’t get away from that. now, if one were to build a moth-like footy, and installed 4 AA batts, servos, etc, it would sink. (or it would have so much wetted surface as to be laughable) so, then, we must rule out the extreme of the moth class from our discussion… lets do some other comparisons… how does a whitbread boat stack up against a open 60? or, even, an open 40? how does an old quarter ton boat stack up next to a melges 32? we are comparing apples and oranges here, but, there has GOT to be a reason, that, when given an open class like the open 60, or the mini, or the VOR 70, or the open 40 that the boats are wide instead of narrow. none of the new 60’s use water ballast. neither do the 40’s, or the 70’s. not even the new minis. and yet, if as you gentlemen suggest, a narrow, light displacement boat is always faster, then why do these boats not resemble pencils with canting keels? you don’t need a wide boat for a canting keel. that has been proven. so, why would all these boats be following a trend that is so slow? it can’t just be because it looks sexy.
Barrett, there’s hope for you yet! The problem with tungs like mini-transats are that they are not actually terribly light - particularly on the starting line with all those cereal bars and things to hunk around. Taking a design prettymuch at random a NNicko Bandon Mini tTrasat 6.50 AUS 419 is said to be ‘one of the lightest boats in the fleet’ and to weigh approx 800 kg. - so 1760 lb. Let’s guess 210 for crew and personal equipment, 45 lb for cereal bars, 120 lb for water, and 200 lb for navigation and safety equipment and a copy of the Holy Bible (just to be sure, with a brute like this, we’ll add the Holy Quran as well - just in case of misundersrandings - so 201 lb).
This gives us a magnificent total of 2436 lb - which is hardly a featherweight (and I’ve undoubtedly missed things out - batteries? life-raft?). Displacement/length ratio is about 120 (an IOM is about 35, a full-size 12metre abut 200). In order to get this this thing to sit on its own bow-wave In other words to lift say 18" vertically, we need to produce about 2500 lb of lift. This requires X sq feet of bottom. Fine. Off we plane.
But suppose we can halve the weight. We now only need 1250lb of lift. To produce this at the same amount per unit area (i.e.start to plane at the same time as the heavier boat) we only need half the beam. Mini-transats are driven by a very restrictive rule - one that limits their length. Any sane designer faced with the problem of getting to Bahia at a cost of X euros or any other reasonably meaningful measurement would go for smething that was longer and lighter. But a fixed length sounds cute and appeals to journalists in bars.:devil3::graduate:
I’d really like a link to a page showing the ultrathin Moths. This fascinates me because I have a collection of plans for late 1800s high-speed launches, all of which were L/B 11:1 or narrower and they fell prey to the longitudinal wave phenomenon. So I’m very interested in how the narrow Moths do it.
Earl, check here: link it is the international moth site… and has build logs and links to just about everything you could want to know about moths…
Nigel, i did not realize that the boats still supplemented their canting keels with water ballast… you learn new things everyday!
Angus, your point is well taken, but, i don’t quite see how it fits into our discussion. perhaps it is my youthful density, but would you mind clarifying your position there? in every aspect of racing, weight is bad. speed is lightness, and lightness is speed so of course a heavy, tubby mini is not optimal for the rule, but, isn’t the goal to build them as light as possible? you note that a rule that limits length is rather more constrictive than meets the eye, but when you have this limit, you just have to live with it correct? so, if you have limited measure length, then the goal is always to get longer sailing water lines… correct? so then wouldn’t it be better in this case of a box rule to have a wider boat (i’m thinking of the pythagorean theorem in relation to heeled sailing waterlines here) than a narrower one, which would not garner the same waterline length while sailing. waterline length is speed. especially when you are not at planing speeds.
anyhow, i am afraid this may be rather as conveluted as anything… :scared:
It’s been a while since I’ve posted here, but I thought I might toss in my two cents.
This is sort of directed to 420sailors point about there being a reason for the beam.
One thing that may have been overlooked is that fact that most of the fat offshore boats are big time reaching machines. Wide flat bottoms work really well for reaches, especially if you have the horsepower to really get going. Also, most of the Open class boats that are optimized for upwind performance are narrower than their offwind brethren.
Also, I’m not entirely sure about this anymore, but there was a static heel requirement for Open class boats, so to get enough righting moment in the keel to handle to possible power, the boat needed to be wide.
Boats that go really well upwind are usually not too wide. For example, A-Scow is not a particularly wide boat to begin with (skinnier than 4.5:1 Length:Beam is pretty lean, assuming the 38:8 ratio is correct) and I would suspect be wicked upwind in flat water.
In terms of big boats, pretty much every Reichel Pugh maxi has been pretty skinny and quick upwind and down (MaxZ86s and Wild Oats/Alfa Romeo). They do not have any static heel requirement, nor are they specialized (as far as I know) for reaching.
That being said, I’ve got diverging ideas for a Footy. One is a relatively lightweight scow with maxed out beam (think Footy dimensioned Y-Flyer, if you know what a Y-Flyer is), and the other is a relatively slender beast with significant submerged volume. I’ll let you know how they stack up when they get out of my head and onto the water.
Hi Guys - I’ve not checked in on the forum for a while, you all have got quite a lively discussion going on.
Bill K., there seems to be some confusion about my Bantam hull, it is not a scow. It is a very broad wedge hull, closer in spirit to the IOM “TS2”. It is an old design, predating the current box restrictions, and at 21 ounces all up would be considered way over weight by today’s standards. The third of the grandfathered hulls (of Kevlar) has yet to hit the water but will come in at a more reasonable 16 ounces or less. I have been building and gutting and rebuilding her for several seasons now, and as my methods for building light and my accumulation of Footy specific component molds has expanded the revisions seemed reasonable to make this final hull in keeping with current trends and rc gear.
The attached photos show both a bird’s eye view of the deck and a bow-on shot of the hull. The Bantam hull is well rounded and even at its current weight it has a waterline beam comparable to a lot of the Footies on the water today. She has high freeboard and the freeboard overhangs the waterline. This overhanging freeboard produces more or less the same underwater cross-section at different angles of heel.
Personally I am not a big fan of the scow form. In light to ghosting conditions acceleration is the key to winning races. The scow type has too much wetted surface, a.k.a. drag, to be effective. Remember the scale effect translates to Footies sailing in honey in gale force winds.
Note, all the photos offered up in the scow’s favor are taken in a lot of wind with a crew shifting their weight to keep the boat relatively flat.
If you want inspiration for a Footy design hit up Earl B. for some vane Marblehead plans. The lines should scale (with a little massaging) into a Footy in line with Angus’s Moonshadow.
Sorry Niel, I guess I was relying on a faulty memory or assumption. I still think it would be very interesting to see how your hull form performs in competition with other shapes
Actually in practice, there is often an effort to keep it heeled to reduce wetted surface down to a canoe body. This will involve having crew hike out on the leeward side as needed. For this reason I don’t think the scow shape is appropriate for a Footy without the ability to have moveable ballast. Plus it won’t do as well in choppy conditions because of the blunt bow.
Quite all right Bill, my Bantam design has been misunderstood from its very beginnings, outlawed by the box rule because it doesn’t conform to what some folks with clout think that a Footy should look like. It has had its influence though. Dennis Desprois developed his “American Footy” with my encouragement and a handful of Bantam stats. So, in a way, the so called “American Muscle Boats” are indirect decedents of the Bantam.
The Bantam’s are wider than 6 inches at their max. beam. early in the class’s “youth” there was no box rule, and that was when niel designed and built his boats… as for being the grandfather of the “American Muscle Footy” well… winks
Having been awarded AMYA Footy registration #2 attests to the first Bantam’s emergence as a prototypical Footy. The concept of a broad boat as a platform for packing on sail area and aspect ratio to reach wind less disturbed by the boundary with the water surface exerted some influence in early designs that conformed to the box rule. That newer designs carry more modest sails (a trend mostly in the UK) is due to the stripping of weight from the hull and rig (McRig) but also sacrificing ballast in the bulb. It remains to be seen if this trend is the future of Footies or not. I still believe that sail carrying upwind is more important than pursuing extremely light displacement.
Nigel, the Bantam’s max. deck beam measures in at 7-5/8ths ". The powers that be considered this hull shape to be unattractive I guess. It was also the subject of a protracted and often heated discussion. The compromise reached was that my three hulls would be grandfathered but henceforth the box would limit the beam allowed for footy designers work with. The box effectively put an end to this particular line of development, which I considered intriguing (or I wouldn’t have built Bantam to test it in the first place). Its all water under the hull at this point.
I agree with you about the greater benefits of power over weight niel. it still seems to me, (much as angus protests) that in the end, if you carry enough power to overcome the slight increase in drag that a wider boat incurs, that the added horse power will come out on top. whenever we want things to go faster, we add more power. more-over, i recently have been wondering if we have even found how much power we could shoe-horn onto these boats before they become totally uncontrollable… i may have to cease designing new hull-shapes for a time and concentrate on rigs to test this question… who knows.
it most certainly is my friend! i am, without a doubt, a full subscriber to the muscle footy… lol. angus tries and tries to show me the light (no pun intended) of feather-weight, narrow, boats, and i may be slowly beginning to apprietiate them more (as my newest design attests to) but, i still remain fixated on wide, flat, “muscle” boats… it may be a disease…
The photos of the scow and 6.5m above, illustrate the point I was trying to make about trim.
The scow heels and trims level, so the boat is pointing at the horizon.
The 6.5m are trimming bows down, pointing at the sea bed Not only is the hull an awkward shape to drag through the water, but the foils and sails are also operating at a bad angle. You can make wide boats trim level but it’s easer to do it with a thin boat.
At up to 3m beam the 6.5s may be wide boats, but in Footy terms, The Open 60 class is narrow. The old ‘Group four/Ecover‘, now ‘Hellomoto’ (1997?) has a 5.2m beam, that makes a Footy of 86mm beam.
More recent boats seem to be around 5.6m beam, which still gives us a Footy of 93mm beam.
Today’s boats are reluctant to give dimensions but seem to be even wider at 6m or above. This still gives a moderate Footy beam of 100mm.
Footys really are an extreme class ( that’s really, really, really extreme) and there is little to compare them with.
The ’American Muscle Footy’ can use as much sail area as you want. But this is a two-rig class, so unless you can reef your working rig, you will have to jump from a big rig to a small rig with a dead zone in-between.
A light boat will start off with less sail, which makes an easier jump to the storm rig. A narrow boat will also be more tolerant of too-high heel angles.
Twenty odd years ago, Dave Hubbard designed ’Red Herring’- narrow beam, canting keel, light displacement, canoe stern, fully battened ketch rig. I can’t find the photos but trust me she’s gorgeous and did Mr Hubbard ever draw a slow boat? (even with only one hull).
