Thoughts on the Battery Rule

I have broached the subject of the 4 AA battery rule with quite a few people and I realize that it is hard to challenge the orthodoxy on this subject. I hope that the reader will approach the considered arguments put forward here with an open mind and accept that my concerns have some merit.

The idea behind the 4 AA battery rule was to have this one rule control two aspects of Footy design. One was to limit the amount of electrical power available to the electronics, and the other to put a physical limit on minimum weight on the theory that such a limit would level the playing field for builders of different skill levels. AA batteries are currently widely available and accessible which meant that they passed the kid friendly litmus test. The 4 AA battery rule predates the current Footy rules as part of the draft set of rules that were posted on the Highlander Yachts website along with plans for the BobAbout.

I believe that both tiers of this rule don’t really accomplish their stated goals. I have always had a problem with rules that contain levels of subterfuge, intended or not, inherent in their writing.

First, other than classes of model yachts that come from a single manufacturer, the Footy is the only class that specifies electronic equipment that the builder must use. In the long term this is not very foresighted as the purchasers of 8 track tape decks, Betamax, and vinyl LPs can attest. Technology moves ahead at ever increasing rates, records that were the norm for most of my life time have given way to CDs and MP3 format. Newer electronic equipment use proprietary rechargeable battery packs. Most of the kids in the current crop of potential Footy skippers most likely use cell phones, MP3 players, and laptop computers that do not use individual non-rechargeable battery cells. The next generation following them may not only be unfamiliar with AA batteries, there may not be AA batteries at all. Positioning the Footy Class for longevity means reconsidering the battery rule.

When the draft rule containing the first mention of the AA battery rule was posted, the assumption was that sailors would use throw away alkaline cells, or rechargeable NiCad or NiMh. These would provide 4.8 volts of power to the r/c gear. In turn this would limit the amount of torque that the sail winch servo could output. Sail area isn’t measured in the rules, but sail winch power can have the same effect as putting a upper limit on sail area.

Along with the power limitations the AA cells mentioned above are heavy, a NiMh pack I have measures a whopping 120 grams (4.23 ounces). The weight of AA batteries was thought to be an equalizer. After all, if the pro-level builder produces a boat weighing 350 grams (12.35 ounces) there will still be that 100+ gram dead weight in the hull. That would effectively ruin their overall weight to ballast ratio, a sort of penalty for building too light. Interesting idea, only it doesn’t work.

Lithium Energizer cells have upended the apple cart. Four AA Lithium Energizer cells weigh in at 70 grams or there about. They deliver 6 volts of power rather than the 4.8 volts of the other battery types mentioned above. They make a 350 gram boat feasible. But, they also come at a hefty price. Four Lithium Energizers sell for about $20. They last for three or four regattas depending on their current draw. That translates into a $5 a sailing day cost. Central Park MYC sails 35 Saturdays in a season. That would make sailing there add up to $175 a season, making the Footy the least expensive boat to build but the most expensive one to sail competitively.

The Achilles Heel of the Footy is the overall weight (displacement) to ballast (counterweight at the base of the keel fin) ratio. The Footy is a tender craft. The most popular means of addressing this weakness is the McCormack rig. This uni-rig features spring loading that spills wind when the wind becomes too strong. While a nifty “after market” solution to the tenderness issue a more concrete and comprehensive way to address the problem and a more cost effective one battery-wise would be to remove the battery specification from the rules.

A 6 volt AAA pack that I have weighs in at 67 grams, less than the Lithium Energizer cells. On a Footy of 500 grams displacement the 50 gram weight savings of either the 6 volt AAA pack or the Lithiums would transfer 10% of the all up weight to the bulb, and that would go a long way to increasing the resistance to heeling and the upwind performance of the average Footy. Alternatively, it would allow the less experienced builder to sail his craft at a lighter displacement offsetting to some degree an overly robust construction.

If the concern is that lifting the battery specification will benefit those semipro builders and launch a race for the lightest boat or “battery wars” (as if we aren’t in one already), well maybe. There is a certain point where building light produces a fragile boat that won’t survive the rigors of a season of fleet racing. But if we don’t want to see where this tipping point is a much more straightforward means of controlling how light our best builders can go is to set a minimum overall weight limit for the Footy Class.

It is time to reconsider the AA rule. We should be forward looking and shape our class to be flexible and responsive to new technologies. Tying the Footy’s viability to the continued availability of an energy cell that is an old designation and whose fate is in the control of manufacturers, not ours, means we will have to address this situation in the future anyway. It would be better to do it now, in the early stages of class development, than to confront it later when it may become a crisis.

Well thought out, and very well presented.

Good luck from a true development class supporter.

Just to note a couple of points Niel before the discussion develops, this is not an anti change posting :).

Voltage available.
As the original rules did allow Alkaline cells then 6v has always been available, ‘dry’ cells producing 1.5v each long before the Lithium AA came along. Only the rechargable NiCads and NiMh cells were limited by their chemistry to 4.8v.

As dicussed in the Transat 6.5 thread recently here

Lithium AAA cells are also available at typically the same cost as AA Lithium cells but with less than half the capacity… ie. double the real cost.

If we were to ban specifically Lithium AAA cells and possibly Lithium AA cells then the weight arguement/cost would be more likely to work. But that can be seen as a step backwards. If AA were to dissappear (I suspect they will see me out… after all, every battery type I can remember buying as a kid still seems to be available today) then presumably AAA would also dissappear as they are less commonly used if the battery sales racks are anything to go by.

The solution which may work for the future inspired by talk of cell phones, MP3 players etc. is to go to LiPoly cells… expensive and very light requiring appropriate chargers and care. But then we may well find ourselves in the position of having less places to sail. Yes it’s an insurance issue and they are well worth avoiding… for an explanation of that look at NAVIGA and the European Power Boat Associations… some decisions of which may well filter down into club pond insurance… I don’t know, just thinking out loud.

So I am not sure where that leaves us, I certainly don’t suggest we wait to become extinct but the way forward is rather muddy and not so simple as it sounds. The AA extinction/LiPoly issue will apply to all model yacht classes if the cells dissappear, are any of those ‘knowingly’ allowing LiPoly cells yet I wonder.

I’m not really sure where I stand on the battery issue but I really would like to see a minium weight rule to help level the playing field between those that pay $400 dollars for a footy hull and the rest of us.

I think the lightest known competiive Footy is probably my Moonshadow. The hull cost about US$ 8, I think. Last weekend she was in a shootout with Roger Stollery’s steam-roller Ant design - hull about $10.

Of course the prices are made unnaturaly high by the depressed value of the dollar.

I don’t know where the $400 comes rom, but definitely not from The weight. From going out and buying a specialist produc instead of making it yourself, perhaps?:devil3:

I’d like to point out that I used AAA NiMh packs as a reference. I do not advocate changing battery specifications or outlawing any particular type. I don’t think that there should be a rule that binds us to technologies that can shift beneath us, out of our control. That you can still find C and D cells is really not the point. After all some bands still release music on LPs. At the time of introduction all new things look like they’re here to stay. I have to get my cable box swapped out because of the transition to digital signal. My Sony TV is the next thing that will go the way of the dinosaurs because of compatibility. I could still use rabbit ears I suppose but that would just be grasping at the past and not evolving with the times.

Batteries that are familiar to us may disappear because more and more tech companies see a market in proprietary battery packs and chargers. My cell phone charger won’t charge my digital camera. Each company sells their non-compatable charger and I am running out of outlets.

Lithium Energizers are marketed primarily for low end or older cameras. Eventually there won’t be gizmos that accept individual cells. That time may be upon us sooner that we think.

The way forward may not be clear, but one other issue that should be considered is the use of throwaway batteries like Lithium cells or other formulations. Cost is the factor I brought up before but equally important is the environmental impact of our hobby. Rechargeable cells or battery packs can last for several seasons with proper care before they have to be recycled. Using the CPMYC sailing season I sited before, three years of Lithium Energizer racing would translate into over 26 sets of four, or about 104 batteries rather than one rechargable pack of 4 or 5 cells. By the way, thats $520 worth of batteries rather than a NiMh pack costing $15 and charger for under $100 (the charger will last many more seasons than the battery pack as well). The class should do all it can to encourage its members to use rechargeable batteries instead of throwaways.

Well said Neil! As Dick noted, that seemed to be a very well thought out and well presented argument. I happen to agree with you, although the issue Graham brings up is a valid one… i have had a Lipo burn on me… its not fun.

[QUOTE=Angus;44104]I think the lightest known competiive Footy is probably my Moonshadow. The hull cost about US$ 8, I think. Last weekend she was in a shootout with Roger Stollery’s steam-roller Ant design - hull about $10.

I’m a little suspicious of Angus’s assessment of costs for the construction of Moonshadow… I suspect that his 250gms of Darjeeling tea used in the ruminating stages of construction cost at least $6.00, not to mention the 50P for the gas to heat the water. That would mean a 35P hull, a likely story.

I’d much rather see an all up weigh limit sans rig and total freedom where power comes from.

I have yet to finish my first boat, but I have been flying RC for over forty years and I’ve learned to adopt new technology as soon as it becomes economically feasible. The only thing I don’t like about footys is the AA cells requirement.

I can live with it, but to me it’s what I was doing forty-five years in the days of rubber band escapements.

Not only don’t I like AA’s but I have lots of lipos in all sizes available.

Oh well, I have to admit, it’s the boat I like and not the racing aspect so it doesn’t matter that much, but given the choice I would change that rule in a heartbeat, and put the weight where it belongs.


I certainly agree with you Niel on the environmental issue. I also used rechargable NiCads (not so good for the environment either) all of last season until I went to Llandudno. Having had one made-up AA Nicad pack internally short I did not think it worth risking a fire in the hold so I switched to a battery box and Lithium cells on the trip. I will most probably switch back to NiCads this summer.

I think the hard question is what would we change to?
If AA were to fade away then AAA would do the same so that is pointless.

To allow LiPoly we need to know more about the NAVIGA and associated MPBA position. Last I read was in summer this year which was that they were not allowing the use of LiPoly cells at events. As many UK clubs are MPBA affiliated this may mean that their club insurance would be impacted. The net result being that the growing number of UK Footy regattas may have no club to run them and nowhere to sail.
I have no idea if there is any similar situation at USA clubs.

Not scare mongering just need more research.

Imagine if the M class had imposed an all up weight limit in say 1960 when typical boats displaced 20pounds,what effect to you all think that would have had on the class,considering todays boats of 9 - 10 pounds??
A weight limit would be counterproductive to the long term future of the class also.

Do the sums on CG heights(complete boats) for various battery weights and you will see that lowering battery weights will lower the CG of the lightest best built boats more than it does for boats of stouter construction,This is a mathematically provable fact.Removing battery rules will favour better builders and boats of lighter displacement(If light boats are fast that is??)

Footys are extreme boats…in the case of all restrictions being removed I would move to using a single 3.7v Li po cell of about 250mah,these weigh about 5 grams and would sail most footys for about 1/2 hr…thats long enough to race,guess thats what car racers and model aircraft pilots do…
The extra weight would go to the keel improving ballast ratio to near 80% or enable a lighter all up displacement than currently possible with similar ratios to what we have now(approx 60% in well built boats)

The insurance issues are complicated and LiPoly batteries are fraught with fire risk. Certainly the future of power for all model yacht classes is impacted by battery choice. But that is what I am advocating, choice. Let the venue and the skipper decide what type of battery to use just as other r/c hobbies do. Govern the overall weight with a minimum limit if the class feels it is necessary, but don’t use batteries to do it.

Not having much experience with Lithium Energizer cells, what happens when they short? Do they behave as LiPoly of LiIon and burn, even under water?

In response to Brett’s comment:
How many competitive home built M Class boats are there anymore?
Are there any hard chine balsa hulls?
How many nonprofessionals design M Class boats besides me and a few other diehards?
Where is the excitement level in the M Class, and where are the internet posts debating rules issues like the one we are currently using?
Do we want to see the class move away from homebuilding into the realm of professionally built boats and the explosive increase in the price that has occurred in the M Class and IOMs?
I am all for lifting restrictions on rules to allow designers free reign to come up with the most advanced concepts. I don’t like the box rule. Thats no secret. But the majority has come to accept it. In this class I believe that the majority of homebuilders will benefit from shifting 10% or so of their displacement from the hull to the bulb.
One other comment about the M Class. When the technology exists to make an M boat of 7 lbs all up why aren’t the designers producing boats this light?
Boats have to be rugged enough to not only start a fleet race but to finish it as well. A very light Footy may be super fast and maneuverable out on the course, but it still has to dance with boats twice its weight during the pre-start. Collisions do happen out there. Can a 16 ounce hull take a beating? There is not enough experience with these boats to answer that question with authority.
The battery issue has muddied the waters. Brett seems to reject a minimum weight limitation for Footies while endorsing a weight limitation for Footies in the form of battery specification. That just doesn’t make sense to me.

One other thing. Thank goodness the Footy wasn’t conceived of when r/c displaced vane sailing in my area. We would all be sailing with “C” cells. Try stuffing 4 of those suckers into a Moonshadow.

Perhaps the model we should reference here is the IOM Class. This is hands down the most popular International r/c sailboat class. This class restricts both overall weight and hull weight. This approach keeps the homebuilder in play with the professionals at least as far as construction counts.

I’ve rethought my earlier comment on all up weight.

One of the things to think about is that this is a very open development class. That’s what makes the footy attractive.

I think we should leave the rules as they are, very open and just get rid of the one restrictive element which is the AA cells.

One of the dumb things about rules is that everything that can make a boat faster gets penalized, so eventually, instead of making fast boats, you wind up making the fastest boat within a bunch of cumbersom rules.


Before this thread I don’t think I’d have known a LiPoly cell if I saw one - but a quick Google came up with this. If this is what the safety fuss is about :-

. . . . then perhaps there is an arguement for not allowing them until the technology is made a bit more foolproof. The last thing we need is to have to complete a Risk Assessment every time we sail.

An advert for Thunder Power LiPoly cells quotes a 2 cell 910 mAh pack at 1.6oz and $33.99 - about £15 in the U.K… O.K. they are small in physical size but there is enough room to get 4 x NiMh at a 2400 mA rate in my hulls and they are only 4 oz. Its not as if Footys need the sort of power that LiPoy’s are capable of delivering.

If the battery rule were to be relaxed at all I would probably go for 5 x AAA at 700 mA and just over 2 oz for £5.0 U.K. and change them during a day long event.

Just a thought . . . .



Lipoly is not the only avenue here. They pack the most energy into the least amount of weight, but still can only go through a couple of hundred cycles before they need replacing. The newest technology, the “nano phosphate” cell, has similar voltages to lipo’s, but many times more cycles in their lifetime. Check the forums on A123 cells (a brand) and the VPX cells that Black and Decker uses. The VPX cells would be closest to the size you would use in the Footy. They are 1100mah, and you would only use 2 cells to get 6.5v.

They are safer than Lipos as they do not burn up when damaged. ANY battery will get hot if it is shorted, and WILL melt insulation and burn wires.

I don’t have a dog in this hunt as I don’t fool with the Footy anymore, but I do agree that class rules should not dictate the radio technology used to control them.

I have 3s Lipos in my electric heli, 6v Nimh packs in my Victoria, and now, 2s A123 cells in my IOM. Check the battery forum on for threads with more info on these.

Good luck!

The Footy was created as a class suitable for school projects and I assume the AA rule was to help keep the boat cheep and simple. In the last few years the class has evolved, as we try to squeeze more speed out of them.

Being able to use AAA cells would mean we can make lighter boats or the heavy boats can increase their ballast ratio, which seems to be desirable for every one.
The AAA cell is as cheep and accessible as AAs and uses the same charger, the joy is that the weight is cut by half.

I am against an open battery rule as the introduction of LiPos would push the cost and complexity up. One day we will be able to buy them off the shelf in Woolworth’s- that’s the time to introduce them to the class.

If you introduce a minimum weight limit, the class will try for the maximum ballast ratio, by still making the lightest hulls possible. If you then bring in a rule limiting ballast ratio the money will go in to rigs or where ever a little more speed can be found . The IOM has this sort of weight rules, does it make it a cheep class? I think not.
Complex rules mean you have to work much harder to make a faster boat than the rest of the fleet and being a competitive sport, sailors will spend the time and money.
Brett’s glass cloth-UK championship winning hulls are £40 including airmail, that’s cheaper than many IOM rudders.

You can have cheep and light boats, I am carving my new boat from polystyrene foam and sheathing it in glass cloth and PVA glue for maybe £2 giving a 20 to 25 gm hull. When I get this on the water it should be around 300 gms. This is a simple design aimed at school classes and the like.
AAA cells could make this cheaper, as I should lose enough weight to reduce the sail area enough to use a 1.5kgcm (8gm) servo at £5 instead of the £18 servo I think I need at present.

I don’t keep up with the IOM racing but as a guess I would expect to find the same amount of cheep homebuilt boats at the top of IOM fleets as i would in RM fleets?

I’m for an open battery rule, much like the open nature of the class.

If one wants to run a heavy battery, let’em. If one wants to run a light battery, let’em.

Minimum weight is a good idea. Coupled with an open battery rule, would give some more freedom to one’s build. If the boat is heavy, lighten it up with a lighter battery. If it light, use a heavier battery.

Open class means choice!