Project Blue Sky

Now that the project has started to take form, I thought I’d move this discussion over from the the “Footy in 6 Inches of Water” thread.

For those who don’t know what’s going on, I’ve chosen to take on the task of building a boat that fits the Footy class rules, is capable of sailing in shallow ponds, and as it happens, pushes the edges of existing design parameters. To date, I’ve received equal parts encouragement and skepticism.

I’m hoping this thread will be limited to design contributions and that discussion about the rules, opinions about the boat’s viability, and implications for the class will be taken elsewhere. That said, here’s what’s on the table …

Project Blue Sky
A hull and rig taking full advantage of the box rule. Once assymetry is introduced as a design option, the parameters of what is possible expand significantly … lwl expands to a theoritical 18 inches (see attached diagram) and a displacement as light 200 grams becomes practical.

Initial thoughts point towards a rig that cants towards windward, while at the same time pivoting or sliding towards leeward. (see attached diagrams)The work of Jon Howes and Gabriel Elkaim ("wing%20mast%20bearing" is instructive, pointing towards potential solutions as well as giving fair warning.

Foils are an area which will require a great deal more research. To date, Doug Lord has contributed his working knowledge and others have begun to offer suggestions and sources. It may or may not be possible to build a boat of this size which foils … to the best of my knowledge, it has yet to be done.

Platform will be developed last. At this point, I have no preconceived notions as to how it will look. That said, a rudimentary sketch of a canoe bodied mono is attached. Should leeward bouancy be required it may make more sense to build a catamaran.

For now, no testing has been done and no decisions have been made.; these are early days in the design loop. Any thoughts or advice is and will be received with gratitude. Take a look at the pics and please throw whatever advice you’ve got my way … we’ve got all winter to talk.

In the meantime, I will use this thread to provide updates of the project’s progression.

Much regard, Trevor Paetkau

I like the sketches. My contribution to the design is recommending lithium AA batteries. Four will weigh 58g and are the lightest form of AA. You’ll have to find appropriate places to mount them I think but movable ain’t allowed.

Are you planning a more traditional wing sail than the monofoil? I really like the monofoil’s airplane on a stick idea. I may try it on a standard hull and see what it does.

Keep plugging.


Moveable ballast isn’t allowed. C.25 of the SAF Equipment Rules of Sailing 2005-2008 defines ballast as

Weight installed to influence the stability, flotation or total weight of the boat. It can be of any material and positioned anywhere in the boat

Since batteries are installed for purposes quite distinct from influencing stability, floatation or weight, would they ever be considered to be ballast?

If it were to be considered ballast, wouldn’t Footy rule C.3, limit you to one set of batteries per event?

Provided the platform is not a reversing proa as originally proposed by Angus, three potential solutions to the sliding rig come to mind …

Travelling Rig Pod
Simple. May be heavier than other two. Base of mast cannot be extended past pod tracks.

Swivelling Arm
Also simple … poses a problem if counter-balance is ruled as ballast … sails centre of effort can not be controlled across entire arc. If counter-balance is ruled legal, issue of leeward bouancy is mitigated somewhat.

Tracking Arm
Doesn’t require counter-balance. Mast footing can extend as far as required. Bearing track can be designed so as to control path of rig’s CE.

Like always, comments much appreciated …

Jon Howes took years to perfect that sail … I’m not sure I have the patience, much less back-ground to go down that road … when I do start playing with the sail I’ll start by exploring the properties of both wing-masts and camber-inducers … there may also be something to be learned by taking a look at the profiles used by 3D flyers, rc-gliders and ultra-lights …

Should leeward bouancy prove to be a problem, a multihull platform will need to be adopted … this gives rise to the potential of another rig mechanism … also asymmetric but this time with a fixed mast and a sliding tack car … it seems simpler, but what is gained in simplicity is lost in lwl and potential beam …

As the program progresses I will also ask for a formal ruling on the sketch in the previous post showing the counter-balancing weight on the opposing end of the rig arm … the arguement I will make is that it’s purpose is to balance the weight of the rig and not to counter-act heel (though I fully expect that that may be the counter-arguement … and to lose … it would solve some problems though :rolleyes: )

tetrax … you seem to know the rules … any thoughts …

regards to all … T

Ooo, I like this latest idea. Does a servo drive the tack car or is it wind driven? I may try this on a monohull if I can figure out how build it and how to get the rudder assembly out of the way.

A tip for the Howes sail: don’t perfect your sail, steal his design.:devil3:

Your ballast protest will most likely be denied. Reasons for my pessimism: 1) I asked about a sliding battery tray and was told it’s illegal (unofficial ruling, I guess). 2) “C.2 Batteries are restricted to 4 no. AA size batteries placed within the hull.” Hanging off the rig isn’t within the hull. 3) The ballast definition doesn’t say influencing stability, floatation or weight has to be the primary purpose, just a purpose. Remember, these sailing guys weigh the crews’ wet clothes in some classes to get all the boats equal. I think the sea lawyers have played this game already and the definition held up.

My own idea for pushing the ballast rule is to place the batteries in the keel bulb. If I have a space running down the keel to the bulb, it’s inside the hull. Or if that fails, I’ll make a full keel footy - a microEC12. :smiley:

My own idea for pushing the ballast rule is to place the batteries in the keel bulb.

Can’t!!! Rule C.2 Batteries are restricted to 4 no.AA size batteries placed within the hull

Where’s the delineation between hull and keel for full keel boats? What makes it hull vs appendage?

According to the ISAF ERS, a hull is the shell of the boat and a keel is a hull appendage. A hull appendage is attached to the hull or another hull appendage. A keel is a hull appendage.

If the shell of your boat extends, of a piece, to duplicating the role of the (fin) keel and bulb, it is presumably hull and not hull appendage (keel).

I promised a skiff awhile back (one of my early posts on this forum I think); here is the proto hull with appendages and rig tacked on. She still needs a final fairing after which I’ll either build a mold or bag her … (Nigel, any thoughts for a simple 2-3 hull output?)

Her displacement is 400 grams. Electronics and batteries will comprise 90g (using 4 lithium AA’s) Hull and rig calcs are at 50gs combined, leaving 260 g for ballast.

Astute observers will note immediately that given her shape she is longer than 12 inches (355mm to be exact). She fits easily however, in the box with her nose up. The somewhat high cut main sail allows 360 degree rotation of the entire rig without sails, or rig contacting the box. Yup … I know … fire away … and nope, I not going to say how … a bit of fiddling will reveal the trick to anyone who wishes to try …

Wide body is designed for a touch of extra stability but may engender a nose down position … she is fairly full upfront … we’ll see. Given the time before spring I’d like to build a narrow bodied platform to test her against.

As for the Blue Sky Flyer (foiler ) … I have to admit I haven’t the stomach for it at the moment. Building it within this envelope is an entirely pointless excercise until the rule interpretations are sorted (why engineer an assymtetric swivelling rig for instance if the class is going to take a look at it and say “nope” as has been intimated in a number of threads (“twist of thumb, problem taken care of” … old fashioned take … blah blah blah).

Regards, Trevor

That looks a pretty formidable weapon!

Well done Trevor, lots of nice buoyancy up front, planing sections down aft, looks promising.
Any chance of some detail photos or drawings of your wishbone boom/mast fitting?
That style of rig is of interest to me.
Good luck.


Like the new boat.

Back to the LWL of 18" AB Axes.

Not sure that the theory of using the Diagonals will be as fruitful as would be first thought.

The boat when measured must be in Racing Trim… Hmmmm. OK the placement of the Rig & Size will be critical as if you use the Diagonal in such a manner or any diagonal other than the top surface of the box there are varying reductions which will need to be met, unless of course the rig will be placed well above deck level. Not sure if it will have the desired effect having to be up to 10" above the deck at the base of the sail. Counter weight that far above the water in my opinion might see the boat tip at the sight of a gust. COG will be high.

From what I could see the designs while quite innovative and I for one would love to see it modelled, aren’t possible as per the example diagram, given the Rigs would need to be measured outside box and not attached to the boat… ie not in racing trim.

From wat I can see It would have to be quite a stumpy rig to maximise the LWL as only the rig can extend above the Box. Or at very least it would have to be quite a ways off the deck to fit the current box configuration.

It must be in FULL Racing trim and not with collapsed sails. The example is fine but when you apply the Diagonal the Rig doesn’t fit as best I can measure. The Rig impacts the side of the Box and therefore cannot be used in the manner intended. On Downwind settings the Rig couldn’t extend very much without impacting the sides of the box and I think might defeat the purpose of the overall counter balance arrangement.

as best I can see anyway…

Building it with the Box in place will always tell whether the Boat will fit the measurement rstrictions.

Keeping it on the Surface of the box for measuring LWL and I think you’ll have a exceptional boat and very advanced model.

Ballast is another matter. But then again chucking Crewmen over to the windward side isn’t considered shifting and moving ballast. Hmmmmm that’s a good one but it has the same effect. Only reason big buggers like me get to go sailing…

Not sure if my comments are worthy, just some gentle observations.

Absolutely … give me a couple of days to get back to a camera and they’ll be up … Trevor

18 inches IS unreasonable to build to … using the AB diagonal is possible but not if utilized to its full length and then it requires all sorts of contortions to get the rig and sails out of the box … it requires, if you can visualize a single outboard stump mast (port or starboard) inclined towards centre. From the tip of this mast a freely rotating wing with canard is attached … the wing provides lift and negates heel, and does clear the box on all points of sail … it is controlled by its own micro servo driving the canard … bloody difficult

Rather, as planned the platform would have sat as you suggested on the face of the box on the 16 inch diagonal. It would have required a rule interpretation that allowed the boat to be repositioned within the box at a separate angle for starboard and port tacks independently.

All in all its been good fun trying to engineer …


That’s the idea.

Have fun doing it. Don’t want those Grey Matter Cells to die and contribute to Old Timers Disease…


that thing looks likea beast! nice!

i must say, that is what i think a footy should look like.

the rig…awesome,

the hull…ya man.

All in all its been good fun trying to engineer …

Engineer: sometimes good to remember that word before rushing off in another round of sexy draughstsmanship!:devil3: