Hi everyone, this is my first post! I’m in Berkshire, UK and have put a short post on the Introduction section to say hello.
So, I have some bent sheets of 3 mm depron in my (aircraft) modelling stock. Hence the title of this post. They are gently curved, but otherwise in good condition. I’ve been wondering for ages whether I’d ever use them for anything! They’re not easy to use for wings or planes, but last week, it dawned on me that they should work beautifully for a simple boat hull because the curve will help to make a simple flat bottomed “hard chine” (if that’s the right word) hull. I know very little about sailing, but quite a lot about gliding (both full size and models).
I’ve been musing over Papaya III plans. First, please let me say a huge congratulations and thank you to Mario Stiller for producing such lovely work and letting us all see and use it! They are wonderful plans - so clear. Also, massive thanks to all the other people who have so generously published their plans and designs (like: Bob About, Awk, Ant, Bug3, Cobra, Razors, Harpy, Wee Nip (not a footy) and many more!).
I haven’t decided what to build yet, but it will be from scratch (not a kit). So, here are my questions and if anyone could help, I’d be really grateful :
Is a Footy a good boat to start with, or would you advise me to opt for something bigger? With gliding, it’s easier to learn on a larger plane, and I’m guessing that there would be similarities with sailing. The two 3mm sheets of depron that I have are ~49x25cm. Like, I was wondering about trying to scale a Footy up a bit, or taking the Wee Nip plan (70cm long hull I think) and scale that down? Would that work or should I stay with a Footy? I guess I’d be out of any class if I tried that! “Class Limbo”
On the Papaya III plan, there’s a rudder box on the back of the hull. I don’t understand it, and wonder what purpose it serves. Please does anyone know?
What is the best way to sheet (I think that’s the right word!) a McCormack rig? I spent some time reading about sails and was really confused by all the terminology. At some point, I realised that “sheet” doesn’t mean sheet, but line! I’d really like to use a McCormack rig - it is a very attractive design. Major kudos to Mr Brett McCormack. I don’t know what an UNA rig is, but it seems to be similar. I’ve also seen single triangular sails like on the Wee Nip, Lasers and windsurf boards. The Wee Nip plan has a sheeting diagram, that I don’t quite understand. But none of the Footy plans that I’ve seen have sails like the Wee Nip, rather they have either a jib and mainsail, or a McCormack rig. So, as you can see, it’s all confusion and no light. :scared:
Related to 3 above, how do I decide where to fix the tube for the McCormack rig? At least, what is a good starting point and how do I know which way to move it, forward or backwards? It must be a bit like a tow hook on a glider!
What servos would you recommend forthe sail sheet on a Footy? I have some Hitec HS-55 for the rudder, but don’t know what to buy for a sail servo.
Many, millions of thanks for any guidance on the above :graduate:
Jibe in peace…
If you want to build from scratch, I suggest the Razor 3. I have built several from wood and Depron of various thicknesses. The boat I currently race is a Razor 3 made of thin Depron and it was easy to build, sails well in a wide variety of conditions, and is as fast as any.
#1. build a Razor 3 to the plans. Things don’t always scale the way you think! If you want to build a bigger boat, ask Bill Hagerup for his RG 65 design.
#2 see #1- I don’t know either
#3 Use the McRig shown in the plans as a start. Check" Huntington Footys" in the photo section of the Yahoo Site for sheeting.
#4 see #1 . It is just like the tow hook on a glider - just backwards since you are pushing, not pulling.
#5 The 55 is good for the rudder. I like the HS-225 (converted to 180 degree rotation if you can get one) for the sails.
I’ve just applied to join the Yahoo Footy group, so am looking forward to seeing those photos. Thanks for all the suggestions. The Papaya III hull being three panels instead of 5 looks a lot simpler to build than the Razor3. Knowing me, I’ll end up trying to build both! :lol:
Am I about right in thinking that for a given hull, a good starting point would be to put the pivot tube for a McCormack rig ~ 1" in front of the mast position for a sloop type rig on the same hull?
Jibe in peace…
Yes, you are right, a bigger boat is easier to sail than a smaller one. One thing to do is to find out what clubs and boat classes are operating in your area. It is always better to build something of the same class that others are sailing., for help and for fun.
There are hard chine boats in the RG65 and 36/600 classes that you could try.
Whatever you choose. . .enjoy!
If you use a low aspect ratio McRig like mine (see the Razor 3 plans), the mast tube goes about 8.0 cm ahead of the centerline of the keel. If you use a conventional rig, a lot depends on the proportion of the main to jib as well as amount of roach, etc. - maybe just in front of the keel.
The Razor 3 is Bill Hagerup design, whilst the sail he outlines on his plan is, I believe, by ScottS - a very well matched pair.
Don’t dismiss the relatively crude looking Bug3, Ant or AWK by Roger Stollery. It’s not essential to use his fancy carbon fibre moulding as long as their shape and positions are replicated.
If this is to be your very first yacht then build any of the above with both hull and sail EXACTLY as shown on the plans. This will give you a very real chance of the thing working correctly. Once you have got the hang of radio sailing then by all means start making changes to suit your whims.
As to the Mc Cormack swivel position, the thing that really matters is the position of the sail centre of area relative to the centre of area of the underwater bits. If the boat turns noticably away from the direction the wind is coming from then the sail needs to be moved rearwards. If it turns into the wind then the sail needs to move forward. With this in mind it is not a bad idea to fit your hull with,say, 3 mast positions which will give you some options.
Here in the U.K the Hitec HS55 will cope well with the rudder, while the HS82MG will control the sails.
Finally, where abouts in the U.K. are you based. Send me a PM with your mail address and I let you know where your nearest Footy hotspots are.
Firstfooty is correct. I have built a Papaya III (2 infact). From a beginners point of view (me) the Papaya has 2 issues. As it is not a full depth keel its very tender on the sail shown. Certainly is a successsfull sail but soon gets overpowered. I’m Building (almosy finished) the Bug 3. With a deeper keel and alternative sails its likely to be more flexible as when you can sail it, not wating for the right wind to sail it. I did put the 507 balanced rig on one of the Papay’s but to get the CE in the right place it was pivoted where the fin fixed. I know it about right as it sauils pretty strait hands off.
Thanks for all the great advice. I must confess to being a bit of a tinkerer… :witch:
I liked the simplicity of the Papaya hull and before I read your posts I started to build it, using balsa for transom, bulkhead and stem, depron for the hull sides and underside. I never liked the rear box structure around the Papaya rudder tiller. It seemed to me that it’s there just to allow clearance for the rudder tiller. So, I’ve not included it. Also, I’m not going to follow the sail plan, I really like the look of a McRig instead.
ScottS, UshCha and Firstfooty: It’s invaluable to hear your comments about the keel, number of mast positions, and trimming.
So far, here are my:
NOTES TO SELF
- figure out my own (waterproof!) rudder servo arrangement (I think I’ve done that on paper at least)
- fit a bigger keel (will look at other plans then decide on the appropriate size)
- build in a number of mast positions (fairly easy to do I think, once I’ve got a rough idea of position)
- work out my preferred sheeting configuration (this one’s going to require some hands on experimentation, I reckon)
- find out about weight and CoG and build accordingly
WEIGHT & CENTRE OF GRAVITY
Firstfooty, it was extremely helpful to hear your super clear description of centres of area. It seems like a moment balance of sorts.
But what about weight? When I build planes, I try to build light. Should I adopt the same approach here?
Also, what about centre of gravity? What is the accepted wisdom on where it should be? On the keel centreline, to make the boat sit right, or where?
If it all goes horribly wrong, I’ll build a different model, following the plan slavishly :devil3:
p.s. I’m in Maidenhead, Berkshire.
let me say, i have built a depron razor 3 (from 3mm depron) and it sails well.
Depron works well, as its light, and relativly stiff, it also doesn’t absorb water.
Good luck, and most of all, have fun
Yes, its a good idea to have weight in mind when building a Footy. perhaps its not quite as important as with aircraft, but still worth thinking about. If you can build a boat with a ready to sail weight of about 450 grams of which 200 grams is ballast, then that would be a reasonable first attempt. There are those who claim 335 grams, but then again Roger Stollery’s insect derivitives started out at about 700 grams and are now still around 500 grams. The power to weight ratio means that a heavier boat just needs more sail area to acheive the same speed, and sails are a whole lot cheaper than brushless motors and Li-Po batteries for your aircraft. However, a lighter boat will alway accelerate quicker. In the final analysis, there are far more things that will stop you winning races than weight. Too little weight in the ballast leads to a tendancy for the boat to blow over easily in the gusts. Don’t let the doubters put you off, Footys can sail in high winds as good as well as any larger class, you just have to chose the most appropriate sail for the conditions.
Its always a good idea to put the CofG at the LCB ( Longitudinal Centre of Balance ) if only to get the hull to sit on its design waterline. If you then position the fin at the same point then it becomes an ideal place from which to hang the ballast weight. You can easily find the CLR by just putting the bare hull in a bowl of water and pressing down with a pencil or similar positioned such that both bow and stern rise and fall by the same amount. While you are about it you might as well load up the hull with suitable weights and find out what weight you are going to have to build the rest of the boat to in order for it to sit correctly on its lines.
For a first attempt at Footy building I would alway advocate slavishly following a proven design, and Bill Hagerup’s Razor and Roger Stollery’s insects are as good a place to start as any. Once you’ve got the nack of getting the balances right then by all means start doing your own thing. But don’t forget, a Footy is a small boat with the associated small tolerances that rig trimming requires.
Your being in Maidenhead puts you within stricking distance of the possible epicentre of Footy sailing in the U.K. - namely the Guildford club. Their website is http://www.guildfordmyc.co.uk/ and they sail their Footys most Sunday afternoons at the Abbey Mead lake just north of Chertsey. Not much further away is the Frensham Pond club at http://www.sailfrensham.org.uk/classes/modelyachts.php They tend to sail on Tuesday afternoons.
If you need any more info. then just drop me a PM with your mail address.
Firstfooty, thanks so much!
Really good to hear about activities at Chertsey and Frensham. I’ll get in touch with them, as soon as I’ve got my boat going.
So far, I’ve only made the hull. It looks reasonably straight and it floats evenly. I’ve played about in the bath(!) trying to find the Centre of balance. What amazed me immediately is how much pressure is needed to make it move downwards. I’ve also figured out that the Papaya III keel is about 4cm shorter than most other footy keels. Some 200g fishing weights arrived in the post yesterday so now, apart from a receiver, I have all the parts needed to finish the build.
Will try to post some photos later.
Keep in mind that a legal footy must fit inside the measurement box, in some way, otherwise your boat will not qualify to race with the footies from clubs near you. A measurement box diagram comes with the footy class rules download. It is pretty simple to build and will help with the construction of your boat because you can keep checking your work as you progress.
If the keel on your Papaya plans “is about 4cm shorter than most other footy keels” is the case then the proper length is not in comparison to most other footies but wether the boat with its keel, bulb, and rudder fits in the measurement box. As has been mentioned in earlier posts, footies are tender craft so a longer keel gives you a greater lever arm to resist heeling, so base your final keel depth not on what others do but what fits in the box.
You may notice that Bill Hagerup’s latest designs sport pretty low freeboard (the distance between the waterline and the sheerline of the hull) in comparison to the Papaya and many other footies. As his designs have become lighter weight the lever arm of a longer keel will help his boats to carry larger sail area into stronger winds so that the boats don’t need to suit down before heavier footies do. By lowering the freeboard and bow height you gain some precious mm of length for the keel fin.
As a plane builder you are familiar with building light. Most new footy builders tend to overbuild, this should not be your problem, but approach this as if were a glider on your bench. There is not much you can do to trim weight from the r/c gear once you’ve chosen appropriate components, and the rigging for a McRig is what it is as the lightest weight power plant for driving your hull. The place to trim weight from is therefore in the building and structure of the hull and appendages. What is left over is the weight that you can concentrate down low in the bulb.
I should contact either club before your boat is completed. Search out either Roger Stollery at Guildford or Charles Smith at Frensham Pond and they may even be prepared to lend you a boat just to see how yours should behave.
I haven’t had much time to build lately, but here are a few photos of where I am so far. She still needs a noseblock - er, no, that would be a plane, I mean a bow-piece :lol:
I’ve also made a footy measurement box out of card (not pictured). Does the V at the back of the box mean that the rudder pushrod and horn needs to be fairly close to the centreline of the transom (i.e. within the V) in order to fit? Or have I misunderstood that?
I’ll post more photos on my blog site here:
You would be better off with a balanced rudder, that is with 25 to 40% of the area of the rudder forward of the rudder shaft. Balanced rudders are universally used in radio control sailboats.
Thanks Niel. I’m trying to learn, so please forgive my dumb questions. Balanced rudders don’t seem universal in footydom (eg. Bug3, papaya iii) - why would they be better?
First, there are no “dumb questions”. We all had the basic ones at one time and you’ll find that there is no end to the learning curve. That is why this sport of ours continues to engross folks for years. So welcome to the “Hooked”.
Balanced rudders are preferable because they deflect more water for given area than unbalanced ones. This allows you to maintain control over your boat with a smaller rudder. A smaller rudder is less drag when not being used to adjust the boat’s direction.
In really strong winds the balanced rudder will still have bite when the unbalanced one will have been overpowered and stall. There are some more technical reasons but these are the most important aspects.
I would imagine that balanced rudders are not included in these simple beginners plans because they are not familiar to newbies looking at boat plans for the first time. Go to a regatta, just about any racing class will do, and unless forbidden by the class measuring rules, you will only see balanced rudders.
Should you decide to make a new balanced rudder or modify the one you’ve made already I would go with about 25 to 30% of the area profile ahead of the shaft to start with. Most balanced rudders are mounted under the stern. On my first 12" footies I extended the rudder tube aft of the stern just as you have. The forward part of the rudder just grazed the underside of the boat and worked fine.
Perhaps some of the more technical reasons for a balanced rudder wouldn’t go amiss. I would have thought that a rudder of a given profile would have deflected the same amount of water for a given angle whether it was pivotted at its leading edge or at some point 25 to 30% from its leading edge. The balanced configuration would certainly require less torque but that is hardly a problem with Footy loads.
A balanced rudder would be used with a diagonal boat because of its requirement to rotate within the box combined with the obvious desireability to position the rudder as far rearward as possible. An in-line boat’s rudder does not have this limitation.
Whatever you do, do not class a Stollery BUG, Ant or AWK as just simple beginners boats. They may look that way because of the method of construction, but in reality are anything but.