Niel has summarized pretty well the thought process behind these types of designs.
I think the concept was first mentioned with my “BigFoot” design which was a standard “BobAbout” extended at the bow and transom some years ago,it caused a bit of an uproar if I recall…this evolved into the Richardson
“Moonshadow” and more recently “Comet” and now “BobAbout2”.
Stick time with 4 long boats has lead us to where we are now.
Bruju looks the buisness and I would love to race sometime Niel!!
Excellent internet course times for "BobAbout2"s close relation “Comet” over the weekend
What does this mean??? good design? or am I just sailing better?.
A little of both maybe,who knows.
“Comet” as very much the looks of bigger classes,(IOM or M) and performance that is truly impressive for such short boats,if this is what the future holds for this class then I like it!!
Niel/Brett: I assume that corner to corner placement in the box eliminates the use of bow sprits, bumpkins, and rudders that extend behind the transom, while diagonal only placement will still allow the use of a bow sprit OR a bumpkin. Correct? --Jim L
Hi Jim,
Bowsprits, bumpkins,rudders can only extend beyond the box through the slots at either end.
Hence corner to corner boats cannot not have any of these things,this is one of the trade offs of this design approach.
A boat on the centre line of the box but angled down or up in the box however could have bowsprits,bumpkins etc.
This is my opinion only…usual disclaimer attached!!
Jim - I agree with Brett’s interpretation. Thats how I see the rule.
Of course the gentleman who got me thinking outside of the box, well, actually inside the box in alternative ways is TMark. Trevor designed a very beautiful boat and an insightful discussion on alternative placement, and its pluses and minuses, is outlined in the Blue Sky Project posts. I have borrowed a photo that Trevor posted in that thread as a teaser to encourage everyone to revisit his concept.
I think its worth emphasising here that with the hull inclination that Niel has shown what is gained in extra W/L length has to be traded off against sail area and heeling moment in order to get the booms swinging outside the box to comply with Rule B1 and its explanations in http://footy.rcsailing.net/intentions.php
Cheers,
firstfooty
As a recent recruit to Footydom and r/c sailing I have been absorbed by recent discussions around the interpretation of the ‘B Rig’ requirements and the means being adopted to squeeze a lengthy Footy,with aesthetic looks,into ‘The Box’.The final picture of a sail/rig no more than 305mm above the box whilst free to rotate between its fully extended Port and Starboard positions seems to be sufficiently simple and practical for me to now embark on some paper designs of my own.
Question: What is the situation regarding an ‘A Rig’? Is that also required to rotate freely whilst the boat rests within ‘The Box’.
That’s a fact, Jack!
Firstfooty and all - It should be noted that Brujo and boats like her that are placed on an angle can carry taller Storm Rigs because their masts are angled forming a longer hypotenuse to the 12 inch limit-above-the-box-rim leg. Thus a Footy doesn’t have to be 12 inches long nor does a 12 inch tall storm rig have to be 12 inches tall to be legal.
In addition, I am an advocate of square top mainsails. Since squared off tops are found on top flight racing sailboats from Americas Cup Class to Aussie skiffs, catamarans, and windsurfers there must be something to them. The triangular tips of most of our sails don’t contribute to lift but do add drag and raise the Center of effort of the sail plan. This effects both upwind performance by increasing heeling without adding drive and downwind acts to press the bow down.
Chopping the head of the mainsail off so that the chord is about 2 inches across seems about right visually. My Bantams measure 2 1/2" across. To control the shape of the sail with a chopped top I’ve made paneled sails. Without panels the tension on the sails will form a straight line following the leach from the outhaul to the head and the roach will be unsupported and flop about. Battens alone will not solve the problem because they will force the camber (if there is any up there on a flat cut sail) too far forward to contribute to lift. To have a consistent camber along the sail there must be a panel near the top third or quarter to force camber into the top part of the sail. An additional panel would be helpful in the middle of the sail as well.
Chopped top sails would give boats like Brujo that have short keels highly efficient sails that use their area for lift while minimizing the drag that contributes to heeling and nose-down running before the wind. I think that the designer has to consider all the component ideas that go into designing these new kinds of boats. Its not enough to just build something that fits in the box, because there are so many things happening to these tiny boats when sailing that tying to anticipate different solutions to all the boat’s vulnerabilities requires fresh and comprehensive thinking.
Then again Brujo may suck and I will have to re-imagine what to do next.
It should be noted too, that many rigs already raise a sailplan’s centre of effort well above what’s necessary. Jibs with 3 inches between foredeck and foot seem common enough and would would fit Brujo or BlueSky with little or no alteration.
There are all sorst of resources suggesting greater efficiencies in a tight jib/deck gap. Lester Gilbert’s study is perhaps the most applicable in this case – http://www.onemetre.net/Design/WindHanJibDeck/WindHanDeck.htm
A more rigourous attention to sailshape (as Neil suggests) mitigates the heeling moment.
As for keel length, my BlueSky have a draught of 9 inches whcih again, doesn’t seem that far off existing competitive designs. In fact it can be plausibly argued that longer keels contribute to hobby horsing (the pendulum effect) and in turn affect performance.
I don’t want to threadjack (of course as I speak I do) and I don’t want to make you reveal any of your close guarded secrets niel, (well, actually…) but I would love to hear more about your multi-panel sailmaking technique. I have recently been trying to muddle out a way to do that myself, and can’t seem to come up with a way to effectively do it, what do you use to design the panels? Then what do you use as material?
There is some basic sailmaking and other usefull model yacht info here…http://www.myrc.org/Library/Library.htm
I think tmark may be onto something here,A while back in the RG65 thread there was some interesting research into keel length/drag /righting moment posted.
A lot of it makes sense…Our first boats years ago had 6inch keel blades,some of my friends in the UK still swear by this as the best keel length for a footy.
I have been meaning to research this some more but have not found the time.
The increase in stability by increasing draft to the limit of the “Box” is very tempting of course but does this extra stability come at too greater cost??
Pic of “Comet” in the Box and the Bob2 built today from 1/32 balsa.
Hi,
Does anyone know where to look on the net to find free plans for footy’s, or is there any one willing to make their plans available?
daftasabrush.
http://footy.rcsailing.net/plans.php
BTW, I’m getting ready to head up to Sheboygan, Wi for the 2nd annual Footy regatta.
Thanks to Graham, Jan & everyone else helping to make this a successful event. We’ll have 14 competitors coming from as far away as the East Coast.
I am happy to send panel shapes for Bob2 out to anyone who wants them.
These are panel shapes only at this stage as I have not completed the rest of the drawings.
Flick me an email,cover my postage and I will send via air mail.
Something I have noticed. The multi chine plans seem more popular than the single chine boats.
Bob2 is single chine and will hence be “unpopular” .There is much to commend the single chine in boats this small.A single chine allows the boat to be narrower or have less canoe body draft than a round bilge or multi chine boat for the same displacment and lastly the heeled shape of a single chine boat can be very effective upwind when carefully designed.
Hi Brett,
I would love the panel shapes but I will hold off for the full plans.
I am still working on my first boat, which is an uphill battle against my total lack of knowledge about how things are fitted on an RC boat.
I look forward to yours since it is very different from mine, and also quite different than a round bilge hull I’ve been visualizing. With footys you can easily have one of each. (well almost)
I am most curious about the rig on this one since you mentioned that you made some improvements. My rig is basically built but the lengths of mast and boom not finalized nor is the sail made. I bought some foam board and drafting tape as well as some craft type 1/8th double stick tape for sail making and have printed a full sized profile of the hull to stick on the foam board. The closer I get to finished the more ideas I get. I am hampered by an overactive imagination.
In other words, I really have to wait for the full plans, otherwise I might overwork my poor brain by giving myself too many choices.
Looking forward to your finished plans though!
Pete
Interesting comment, Brett, about single chine. Graham and I were having exactly the same conversation last night. I think it’s especially true with a skinny hull like your new B2…The straighter chine seems to track well upwind.
Bill H
It was interesting to read this, along with Bill H’s reply, because I too had similar thoughts when I was trying to meet the designed displacement goal of 450 grams on Bill’s “Cobra” design that I am still building. I looked at that beveled chine and wondered how much displacement it was giving up compared to a boat of the same plan with a single chine. I even thought about sticking some foam on the beveled chine, and reshaping it into a single chined hull to find out! Still, I do find the beveled chine much more aesthetically pleasing, even if it does carry with it a displacement penalty!
I’m curious as to what the displacement of the new “Bob-About II” will be. One of the big attractions of any small R/C sailboat to me, is to be able to use the most basic of 2 channel radios (since I already have several) with standard receiver, servos and batteries, yet still have enough “displacement room” left to allow for durable hull construction, and still be reasonably competitive. Somehow, having to buy a new featherweight receiver plus ultra-micro servos seems to get right back to a problem seen in the Marbleheads, and that is the need to throw money at it in order to be competitive.
Regards,
Bill Nielsen
Oakland Park, FL