Bill,
Your response may have been tongue in cheek so this may not be relevant but I think Nigel was suggesting using the shape he developed as one half of a catamaran as a skinny Footy hull.
Nigel, what is the beam of a single hull? Also what is the height at the bow and stern?
Take care,
Brent
Hi Brent,
Actually I was thinking more along the lines of a Proa than a Catamaran, but since a single sponson probably would be most effective on one tack, perhaps a Trimaran would be better. But then that six inch maximum width rule gets in the way. Then there’s also those outrigger boats the power guys love so much. Something like that adapted to a sailboat might help the Footy’s nosediving problem…
Regards,
Bill Nielsen
Oakland Park, FL USA
The cat sponson, that will be used for a mono hull (I had to LOL), is 2" wide, 2,3/8" bow height, 1,1/4" transom height.
I beleive that the Footy-multis will have a cubed box to cage’em in. Big enough for a tri for sure. A proa… Their always cool. Saw a guy who has a liv-aboard one. They tack strange.
Hi Nigel,
I saw your pictures of the FootyCat on the FootyUSA group, and I must say it’s very intriguing to say the least. What are your thoughts on a keel for this little gem, one suspended in the center between the hulls, one in each hull, or ? ? How about asymmetric hulls like the Hobie 14 & 16, which didn’t use centerboards or daggerboards? As for just using one of the cat’s hulls to make a narrow monohull, that’s an interesting idea too. Please keep us up to date on your progress and discoveries.
Regards,
Bill Nielsen
Oakland park, FL USA
If cats are to be really exciting to sail, I thibk a discussion on movable ballast w/a third channel may want to be discussed.
Cats certainly have movable ballast if you think about the dual trapize and then there are monos like Crossbow & the 18 Footer’s. So maybe have a “Unlimited Class Footy” which simply has a 1 foot length & depth limit. Why limit the width and leave the number of hulls open? The width is needed to keep weight down and still have a lot of righting moment.
Please excuse the early morning crazy thoughts.
I’m thinking dagger boards in each sponson. the hulls a symerical (as best by eye anyways). It has some sideways anti-slippage due to the two hulls, but I still am going to use some daggers.
Not so much an unlimited class, just a multi-hull class with a cubed box, to take advantage of form stability. And yes, no limits on servos. If one can make little men hike over the tramp by R/C, then more power to them. 
I’ll continue any progress in the multi thread here.
Thought I would build an r/c thin Footy just for kicks,building and sailing is what these boats are about.I have alreadya 250g 40mm beam free sailing one which sails well so I thought this thin might be worth a go…
This hull is 370mm long,40mm beam and displacment about 330g.
I should be able to get about 250g into the bulb if I use light batteries.
The long length comes from using both diagonals together.
I may use this boat to test double rudders without a keel also.May not work…in fact probably won’t,but what the heck.
Brett,
Please keep me updated on your progress with this hull. I’m curious to see how you like it as an RC Footy. My current thinnest boat has a 50mm beam and 340mm waterline. Bulb weight is around 275gr total ready to sail displacement is about 465g I could easily go down to 435g just by switching to Lithium AAAs but 330g ready to sail with 270g in the bulb is getting right down there.
I’m particularly interested in your impressions of the boat under different sailing conditions as the displacement difference is quite significant. The reason for my curiosity is that I really like the current boats ability to carry through a tack or even pinch a little to make a mark when you need to. My lighter designs always drove me crazy, one small mistake and I’d be in irons.
The hull looks great, I’m anxious to see it under sail.
Take care,
Brent
Foooty friends - Happy Christmas/Compliments of the Season/Happy holidays/Happy New year/Guid Hogmanay/Hyvaa youlua
Please accept all or any of the above good wishes:D
Sloice has taken to the water. Having designed her to precisely fit an AA battery in the hull I find it slightly ironic that AA cells have been/will be/might be de-mandated for footys
Anyway I have made a pair of Bustles in Blue foam and temporarily added them to the sides of the hull. They will eventually be attached with woodscrews or possible threaded rod (bicycle spokes) but at present they are bonded on with carpet glue
These bustles are what I had in the garage, so they are 25mm blue foam (floormate 200 to be precise). I hot wire-cut the plan shape - which is faintly tadpole-like (pollywogiform) since I believe in bluff bows and fine sterns
Servos will be multiplex 10gm mini-servos salvaged out of a Twinstar and will fit in the hull. Battery (probably a gallium-americium cell) will be low in the hull with receiver ahead of the fin box.
Once I have located the ideal positions for the fin I will probably dispense with the fore-and-aft adjustable “sanderson slot” and just have a fixed keel position and some alternative mast holes.
The rudder blade will be remade, since the hinging system - cut down aircraft nylon hinges with a removable pin - have failed. So its time for a simple system of bits of nylon and ply - still with removable hinge pin.
Deck will an extremely hi-tech polymorphic, polymeric membrane (or lamina) which I find on rolls saying “PVC insulating tape”
rigging and sailing trials next
andrew
Hi Brent,
I have covered the foam hull in a thin slurry of epoxy and microballons,installed a western red cedar fin and plastic rudder tube…so splashing should not be to far away.
My fiberglass hulls with a small sub deck to take the deck patches come in at around 10grams. The hull I built for Angus(Moonshadow) was in this weight range and has not fallen apart yet I belive.
This weight was acheived with minimal use of carbon or aything exotic and with practice could be acheived by anyone on the kitchen table.
The foam method is great for experimenting with new designs,they can be quickly built ,need no internals and you can shift things around to try stuff out(read- change something that didn’t work!!)
Once you have everything fiqured out with the foam boat,build a mould and go for the all out glass lightweight!!
Brett,
Prototyping with foam as you mention is absolutely the way to go. The minimal time and money invested means you don’t have as much tendency to stick with a design that didn’t perform well. If you do your testing with bare foam hulls you can reshape to your heart’s content by carving down or gluing on extra pieces then recarving. Moving the keel, rudder or mast is relatively simple. Save the glass work for the design that has proven success…though foam hulls do seem to stand up well to the rigors of racing.
Regarding your 10g hulls, does this weight include the structure to support the keel, mast, rudder and servos? I ask because eventually one of my designs may be done in glass and I want to see what weight is possible.
Take care,
Brent
10grams the lot,Hull shell weight is around 6.5grams.I need to get better scales.
final weights of boats with everything except ballast can be 60grams or less now with the removal of battery restrictions.It is possible to have M class type ballast ratios even at very low overall displacments.
On my gram scale (Ohaus Dial-A-Gram) 4 AA Lithium Energizer batteries weigh in at 62 grams. My rudder servo is 8 grams and winch (Bluebird 380MG) is 15 grams. Brett, these are pretty light weights for the r/c guts alone. You might be able to trim some weight from the winch servo but not elsewhere. I would agree that you need better scales.
Race results-wise Moonshadow has not lived up to all the hype. I’d be interested in some race result reporting about your ultra-light boats. Have they faired well in competition? Can they tack in a breeze and the chopped up water of fleet racing? Can whatever super-light winch servo that you use handle pulling in your sails when the wind freshens? If you are using an actuator instead of a rudder servo how do you make fine adjustments of rudder trim? This is the kind of info that you should provide to put some meat on the bones of your building prowess. Otherwise, your light weight figures, while impressive, don’t mean much to everyone else and may discouraging to new homebuilders, setting the construction bar way too high.
In the rigors of competition will the an eggshell hull stand up? I suspect that if your 6.5 gram hull were T-Boned by one of your Bob-Abouts with momentum on at the starting line that there would be some light components at the bottom of the pond. Call it model yacht building for the real world if you like.
Well as you know Angus designed Moonshadows hull not me.
From memory Moonshadow was slightly over 100g before ballast with 4 AA’s and all r/c.
As far as I have heard the boat has been raced for some time now and has not fallen apart.
As to the boats race results I have no comment…I only built the thing as instructed to the lightest I could at the time.Her results are not my concern,I havn’t rushed out to build a fleet of moonshadows even though I have the mould and lisence to build them.
My quotes above refer to boats that will not have to carry AA cells so 60grams is easily acheivable now.
I don’t have any superpowers … "setting the construction bar way to high"If others want to build 10g boats I am sure they can learn just like I have,its not rocket science.
If these hulls don’t fall apart and can handle the racing(seems they can) then it is an obvious benifit to build the hull as light as possible.
remember the pictures of Moonshadow racing against the heavy bugs etc in 30knot winds??seemed to make it through that day ok and many days since…how much longer does the boat have to last before you give up on the idea of it being t -boned and sinking??
Displacment aside there is no reason for 450 -550 gram boats not to have similar scantlings. to Moonshadow, In fact now that the battery rule is changed there is an even higher premium on light weight construction.
If 500g boats are the answer then they will have 400g ballast in the future,you can bet on that.
Niel you will only be to to well aware that as displacment falls then you need less power to drive it…so the r/c components can also be smaller.
Rudder servos and winches can all be lighter,Spektrum rx is about 2 grams and batteries big enough to sail all day less than 20gram.
It is possible to have a complete radio system for less than 40grams.
Even your servos 8 + 15 + rx 2+ battery 20(not hitech either) comes in at 45grams
There was little point in going to great lengths previously to save every gram,but now there will be. A 500g boat with 400g ballast all things being equal will be better than a 500g boat with 200grams ballast.
Don’t confuse lightweight construction with light displacment.
Moonshadow’s construction is brilliant - the only problem is a tendency forthe paint to come off the bow where people ‘pop’ it occasionally - much to my annoyance. OK - she gets handled carefully, but she has had her share of rammings without any apparent damage.
As to race resukts, when competently handled she has done very well, particularly in medium to strong winds. Unlike her successor Voortrekker, she is not overly difficult to sail - needs concentration yet, but impossible no. She has never quite got the measure of Roger Stollery - but a difference between 45 years experience and nine months might make a difference, talented though Michael van den Peet undoubtedly is. Unfortunately the South Afican Mafia who have control of her have tended to field Voortrekker rather than Moonshadow - I suspect because of the name, colour scheme an Afrikaaner cross on the stern!
I agree that the name of the game is lightweight construction. A higher proprtion of the parasitic weight is now under the control of the builder/desiner. I suspect that this will have two effects
First, those like me and Brett who are alreay paying very close attention to weight will continue to do so. I estimate that my latest design Newfoundland (75 mm beam, 520g disp) can now have a ballast ratio of about 82%. Since I think that Brett is probably better at lightweight structures than me, he should be able to get, say, 85%. Pure theory (expressed simply as ‘small things are relatively stronger than big ones’ suggests that it should be possible to get incredibly high ballast ratios/very light weights indeed -but they will not be attained by unscientfic use of baulks of dead tree.
At the same time it should concentrate the minds of what I (very unkindly) think of as the ‘balsa and woggle’ brigade. :devil3::devil3::devil3::zbeer:. It will rapidly become apparent hat once you realise that you do not need ‘bracing’, bilge stringers, carlins and whatever, you van make most balsa models much lighter. What about getting rid of the deck? The Vikings did - and they got to Vinland!
Happy Xmas everyone!
A.
How’s this for thin? Latitude 24’s “Icarus.”
The beam of Icarus is only 43.6mm. She was designed and tested in a hydrodynamic flow tank.
From the head-on picture it looks like only a 30mm beam.
That thing floats??