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Posted: 29 Aug 2007, 09:48
by valpro
Quite right Roy. The whole issue of rule compliance and change is driven by the members, not the Executive and if the membershop at large was unhappy with Spektrum or Texalium or Black Magic or anything else it always lies with them to start the ball rolling, either by protest or via their National body.
I haven't seen anything in this thread that reflects that, only a lot of people getting worked up about something that had been around for some time and wasnt a problem until someone suggested it was. And does it make the boat go faster? I think not.

DX6/ 7

Posted: 29 Aug 2007, 10:37
by Ray Flanigan
Actually to cover all bases we need to approach our various NCA's in order to get emergency rule changes done, before the IOM worlds in France.

Rule C.5.3


Rule D.2.4

Quite ironic really as the frequency range is on the 2.4Ghz band......... :lol:
A quick consensus from our technical rep to all the NCA's requesting their feedback and a simple yea or nay on the 2.4ghz spectrum systems from the various manufacturers eg Futaba, Spektrum and the rest, as the principle remains the same throughout.
Look at the futaba receiver specs. ... I=FUTL8926

The Bilgerat

Posted: 29 Aug 2007, 12:03
by Chairman
Ray love your work
Roy suggest you as TSC make a proposal to the executive to approve a TSC proposed emergency rule interpretation that radio control equipment using spektrum technology is class compliant subject to a full investigation by IOMICA / RSD.
This will remove any problems for the WC and allow due process and technical understanding of this new technology.

Hope this public post which would normally be posted in the executive section will help all members follow the normal process.

But just to throw a different light on rule change discussions. Why do we need to change rules to accommodate new technology that increases the cost of IOM racing :roll:
We have spent so much time discussing the virtue of keeping the class a budget class but are happy to ok the use of very expensive multi channel multi function radio equipment. If the expensive radios are ok why not carbon ? Sorry the devil advocate has taken control. :twisted:

Posted: 31 Aug 2007, 00:43
by Richard Rowan
I have been asked by Ray as his NCA representative to request that the Executive take action on clarifying this matter.

Obviously this follows on from Greg's message and supports his suggestion to RoyL.

Personally, I would be very happy to see the issue blow up at the Worlds as we would then get some answers pdq. :D

I also think that the issue is very straightfoward - basically the Spectrum equipment permits one sailor to control one IOM with two control units (ie a rudder control unit and a sheet winch control unit). Would that be the correct approach to sorting out the class rule.

I note Greg's point about expense but the genie is already out of the bottle as far as IOM costs are concerned.

Anyway, I am in favour of rc equipment that reduces interference and decreases (eliminates) frequency clashes. And I will buy a set of Spectrum equipment when the cost comes down to a level that suits my pocket.

Posted: 31 Aug 2007, 01:43
by Hiljoball

In addition to your ‘one sailor’ argument, and building on the ideas expressed by Ray and Marko, I would argue the case this way.

The reference in the rule to ‘one receiver’ refers to a device. A device has a name, a function and an implementation.

The DX 6 and DX7 are sold as a single device. They both provide the expected functions of a single receiver. They convey no performance advantage to the boat. The DX6 and DX7 have one location to plug into the battery, and one location to plug in the servos. They receive signals sent from a transmitter and convert that into directions for the servos. While the DX6 and DX7 have two receiving circuits, they are functionally one device. The two receiving circuits are the technical details and packaging of the implementation.

The manufacturer sells the DX6 and DX7 receivers as one device. The invoice will read one device. You cannot buy the receiving circuits separately. If you separate the receiving circuits from each other, you do not get two working receivers.

The DX6 and DX7 both meet my tests for a ‘single receiver’ as intended in the rule.

So in summary, I argue that that the Spectrum equipment is legal within the current wording and that no rule change is necessary.

Posted: 31 Aug 2007, 12:32
by Andy Stevenson
Hi John
The DX6 and DX7 both meet my tests for a ‘single receiver’ as intended in the rule.
That’s a good point. They meet your tests, but not those of others.

Perhaps an alternative solution would be to specifically define a receiver, in the context of RC, within the Class Rules. Something like: “an item of RC equipment capable of receiving one or more signals with the intent of controlling the position of attached RC control units.â€

Posted: 31 Aug 2007, 18:31
by Barry Fox CAN262
I think that it actually meets the test of almost everyone based on the opinions expressed here. A small sampling to be sure but very likely representative of reality.

On the wording side though you really have it. Whatever the wording is needs to cover technology and not brand names or else it will need to be updated or interpreted everytime another manufacturer enters the fray and tries to have an ever more wowwy description of their similar technology.

Describing the function and not the physical layout will likely take care of it.

Posted: 31 Aug 2007, 18:53
by Hiljoball
Hi Andy
andy111 wrote:
Something like: “an item of RC equipment . . .
But then some wordsmith may argue the word "item" is still singular and a DX7 has 'two' boxes.

I believe a better approach (if any action is taken at all), is a technical interpretation that accepts that the DX6/7 are functionally one receiver for the purpose of the rule.

Posted: 31 Aug 2007, 23:24
by Andy Stevenson
Hi John,
But then some wordsmith may argue the word "item" is still singular and a DX7 has 'two' boxes.
Indeed, we will need to get the wording correct.
a technical interpretation that accepts that the DX6/7 are functionally one receiver for the purpose of the rule.
The problem is that we have no guarantee that a request for an interpretation will go this way. Hence the need for a class rule amendment to ensure the DuaLink receiver remains usable by the class if an interpretation goes against it.

I’m wondering if it might be a better idea, if an amendment is needed, to add a definition of a receiver rather than amend D.2.4.


Posted: 03 Sep 2007, 07:29
by Steve Landeau
Richard Rowan wrote: I note Greg's point about expense but the genie is already out of the bottle as far as IOM costs are concerned.
Slightly off topic, but since you mentioned it.....
The ONLY reason an IOM is expensive is because you are paying for someone elses time and effort to design and build your boat for you. It has been proven by many skippers time and again that an IOM can be built VERY inexpensively and still be competitive.

Posted: 03 Sep 2007, 14:15
by Henry Farley
To avoid having to find words that define a receiver surely the simple thing is to remove the restriction of having only one.

Posted: 03 Sep 2007, 21:13
by valpro
Well before you all go crazy trying to tie the definition of a receiver down with words, let me tell you that all you will do is create a lot more loopholes than you thought you shut and the problems will multiply. Henry probably has the most pragmatic idea so far.

Posted: 04 Sep 2007, 10:39
by Chairman
Yep I think your onto something. As I understand it the rules re Radio equipment are intended to allow the control of 2 functions. per C.5.3 and then to make sure there is no positioning information transmitted from the boat.
Does a 2.4 gig transmit ?
If not what does it matter if the boat has 2 or more receivers (say one for each function :) )
Simple fix change D2.4 (a) (1) to Receivers.
Can it be that simple?

Posted: 04 Sep 2007, 17:49
by Barry Fox CAN262
Yes it can and for RC cars there are telemetry modules already on the market. I thought that C.5.3 (c) was written to address the 2 way communication of 2.4 systems and if my memory is correct then we have already recognized the use of the technology.

For me, at least, that's all I need, another distraction to keep me from watching what I'm doing but it is capable. ... ID=SPM1305

Posted: 04 Sep 2007, 18:13
by Hiljoball
If we do nothing, then the DX6/7 remains accepted as legal.

If someone 'protests' or if a formal request is made, then the matter gets refered to the technical committee.

They can rule either way. If they rule against then we need a rule change.

The best rules don't say anything where they don't have to. When you add words, you risk these types of problems.

The rule does not need to be specific about receiver(s).

A phrase like 'batteries and radio equipment' covers the needs yet is quite open for technology changes.

The important restrictions, (quickly paraphrasing) '2 servo control functions for sail and rudder' and 'not using transmissions off the boat' remain valid.

The existing part about allowing replacement of 'like with like' still holds.

This section of the rule could be reduced from

(a) The following is permitted:
(1) One receiver.
(2) One rudder control unit.
(3) One sheet control unit.
(4) Battery cells assembled in one or more packs.
(5) Electric cables, connectors and switches.


(a) The following is permitted:
(1) Batteries and radio equipment.
(2) One rudder control unit.
(3) One sheet control unit.

Posted: 04 Sep 2007, 20:30
by Barry Fox CAN262
Old (2003) C.5.3 (c)

Except for control unit positioning information, no radio transmissions from the boat shall be made.

New (2007) C.5.3 (c)

Except for control unit positioning and radio link information, no radio
transmissions from the boat shall be made.

I'll dig through old email, etc. if needed but that was changed specifically because of the advent of Spektrum radios. It doesn't say so because it shouldn't but the 2.4 systems are teh ones that can communicate so it is really aimed squarely at those systems and effectively rules them legal. If we didn't have 2.4 systems in use when the 2007 rules came out there would have been no other driver to make that change.

Let's find another dead horse to whip as this one is tired.

Posted: 04 Sep 2007, 23:53
by Chairman
Barry think you have caught me out. I know I refered to an old version of the rules when I tried to resolve this issue. On reflection I am now convinced the current rules give a clear answer for C.5.3 (c). Interesting question is, what rule version where u looking at when you posted previously :)
And if need be I think we have a couple of good options for D2.4.

Posted: 05 Sep 2007, 00:51
by Barry Fox CAN262

You aren't caught out at all. That was a good add on to the question because I don't think many understand the technology in use or just how it is being used in other forms of RC vehicles.

I do remember that some time ago there was a discussion that raised the issue that there is the potential for information to be sent back from the boat and that prompted the additional word in the 2007 version of the rules.

I'll go hunting for that discussion but I am as positive as I can be that took place. What I couldn't remember is what set of rules I saw it in but a quick look back at the 2003 version clearly reminded me.

I don't think any of the "conventional" radios transmit back to the Tx so it didn't used to be an issue.

Posted: 05 Sep 2007, 06:06
by Barry Fox CAN262
I have just spent the last few hours trying to find the DSS/Spektrum reference relating to the change in C.5.3 (c) in the 2007 CR.

I finally found a copy of it and would include teh whole thing here but I can't do an attachment so here is the relavent section. To me we have clearly allowed for the use of these radios at last year's AGM. This was subsequently adopted/approved by RSD so now we can see what a complete waste of time this discussion has been.

AGM Exec Proposal 2: Spread Spectrum Technology Comment: With the advent of the spread spectrum radio systems, frequency information is being transmitted from the boat. The above change clearly permits the use of such radio systems.
Change C.5.3 From: C.5.3 REMOTE CONTROL EQUIPMENT (a) The rudder control unit shall control the rudder only. (b) The sheet control unit shall control the mainsail sheet and headsail sheet only. (c) Except for control unit positioning information, no radio transmissions from the boat shall be made. To: C.5.3 REMOTE CONTROL EQUIPMENT (a) The rudder control unit shall control the rudder only. (b) The sheet control unit shall control the mainsail sheet and headsail sheet only. (c) Except for control unit positioning and radio link information, no radio transmissions from the boat shall be made.

If you also are having trouble finding the reference document send me a note and I will forward you a copy.

Posted: 05 Sep 2007, 08:12
by Chairman
Barry, thanks for the effort. Pitty we all didn't check our facts before we started tapping away.
So as I see it we have already covered the wish to use these radios and we have provision to use them all we need to do is sort out the receiver issue with D 2.4 and go back to my initial proposal to simply insert "Receivers" in place of 1 receiver.
Am I reading this right.
I know Roy is in discussion with Robert regarding this.


Posted: 05 Sep 2007, 23:12
by Marko Majic
Hi Barry,

I wouldn't call it a waste of time - at least not the part that discussed the issue at hand (the rest - probably)... :lol:

Anyway - the fact that class introduced a rule change in which it (attempted) to overcome a potential area of conflict in the past - does (certainly) show that the class wants to allow this technology - however, it does not necessarily imply that the rules (as they are written now) do.

Personally - I certainly don't see a problem and I've stated my reasoning earlier in this thread.

The best way to illustrate my position is: Let's say that I'm taking a test and I'm allowed only one pencil. The fact that I can break that pencil in half and sharpen the broken bit and thus have 2 working pencils (which is more than you could say for a Spektrum receiver - neither part of which can function on its own AFAIK) does not (in my mind at least) override the fact that I really only have one pencil...

However - others see it differently and it is conceivable that an interpretation is necessary. This would be in order to figure out whether or not the wording of our current rule is adequate (rather than whether Spektrum technology is suitable). The fact that the class already (implicitly) endorsed the technology in the past should help if it comes to emergency rule changes or any such stuff... The fact that Roy (according to Greg) is discussing this with Robert (Grubisa, I assume :D ) is also very positive as he should have a good idea which way this might swing ahead of time...

While we're on the topic - (IMHO) even that last change (the one you're quoting - AGM Exec Proposal 2) wasn't really necessary either because to the best of my knowledge Spektrum receiver does not in and of itself transmit anything back to the transmitter. It is the transmitter in fact that has both transmit and receive capabilities (needed to figure out where the empty spots are). The receiver simply "listens" on each of the 79 channels until it finds the two where the broadcast ID matches what was stored in it's memory during the binding procedure. The whole procedure is described on their website:
Spektrum website - FAQ Section
The Module System features DSM2 technology with DuaLink. When first turned on, the transmitter scans the 2.4GHz band and finds an open channel to broadcast on. The transmitter then scans the band a second time and finds a second open channel and locks onto that channel. Once complete, the Spektrum Air Modules will be transmitting on two channels simultaneously. The receiver scans the band looking for the module´s GUID (Globally Unique Identifier) code and, when found, locks onto both channels. DuaLink provides modelers with dual-path redundancy, offering a level of safety and security unavailable with a single channel, single receiver system.
As you can see - it is the transmitter that "chooses" the frequency and all that the receiver does it "scans the band" to figure out which channels the transmitter selected - doesn't say anything about sending the stuff back...

But I guess the new wording doesn't hurt... :lol:



Posted: 06 Sep 2007, 02:03
by Barry Fox CAN262
Pretty close to right Marko. There are however telemetry modules for the RC car crowd so the capability is there and some ingenious electronic person will figure out how to adapt that to record and send sail position, heading or something that may (or may not for me at least) offer some performance advantage.

Posted: 11 Sep 2007, 14:01
by becsta
G'day guys,

I stopped my RC sailing last year for reasons outside of this discussion, and have taken up flying RC aircraft ( I now have 16 or so gliders...). Anyway, I've been looking in on this forum from time to time, and keeping abreast of what's happening in the community, and thought I could add a few points to this discussion, so please bear with me.

One of the reasons I left the sport was the bickering, arguments about the RRS and ERS, through to outright threats of harm. Reading through the first few pages of this discussion, I was taken back to that time when I didn't enjoy sailing at all. There's some pretty heated arguments (a lot of it political and off-topic) in this thread about a dinky little receiver (!), and whether it's actually two receivers or not. In my opinion, common sense says that it is functioning as one receiver. This is easily verified - look at where the servos are connected to.

One of the reasons why Spektrum moved to a "split" receiver system is the inherent problem with reception of the radio signals through carbon-fibre fuselages - the faraday cage problem. The idea with the remote Spektrum "receiver" is to be able to place it in a different spot in the plane (in the wing), to allow reception of the signal regardless of the plane's orientation. We don't have this problem in the IOM's, as they're fibreglass, so the requirement for a remote antenna module for proper signal reception in an IOM is debatable, but otherwise outside the scope of this discussion. But it begs the question - why not allow a remote module up at the mast head, so it's well above the water line?

A question I pose is, if it's considered that the remote unit is another "receiver", why restrict the number of receivers allowed in an IOM to one? Is it cost? Why would I use two receivers in an aircraft? Simple. Redundancy. Am I going to trust a $5,000 aircraft to a single receiver and battery? Probably not. The scale glider guys usually have two receivers, two battery packs, etc etc. Why couldn't I add a second receiver to my boat if I felt there was a risk of a receiver failure causing the loss of or damage to my boat?

Receiver failures do happen. Spektrum for one is renowned for it - their AR6000 receiver is especially sensitive to battery voltage fluctuations, and resets if the voltage falls below a certain level even for extremely short periods of time (usually under heavy servo loads), causing a lockout until it reboots.

Does having two receivers "performance enhancing"? No. It may reduce the number of glitches. It will certainly add weight to the boat. As a boat owner, I would therefore need to ensure that there are only two output signals being used - one for the rudder, and one for the sheet control.

Can you plug servos and batteries into the "slave" unit? No. It's an extension of the main receiver.

Would I consider the receiver in question class legal in the context of this thread? Absolutely.

Would I use a DX6/DX7? Absolutely not. The technology is still too bleeding edge for me at this stage, but that's another discussion for another day...

- bec

Posted: 11 Sep 2007, 20:24
by RoyL
becsta: good sense and a rational worldview are always welcome. Yes, there sure has been an awful lot of fuss over a two box receiver and I am afraid most of it had little to do with the product itself. I have a feeling that if there wasn't a contested IOMICA election coming up this issue would have died out a long time ago.

I also agree with you and others that have said that simple common sense shows that this is a "single device" and perfectly legal under current IOMICA rules. I always chuckle a little to myself when I think of the suggestion made by Marko a while ago that anyone who thinks these are two receivers working here should cut them apart and try to sail with them seperately.

Having said all that, there has been so much talk here that in order to put all of this behind us, expect to see in the next few days an "emergency" rule change that permits the use of multiple receivers. Hopefully, then we can all get back to the business of sailing.

Finally, I too would be hard pressed to trust my airplane or glider to 2.4 gig technology today. If you lose signal to a boat, it will float around and hopefully eventually reach shore. A plane, copter or glider will also return home, unfortunately in very tiny pieces.

Hope you decide to come back to sailing. And to the extent I contributed to all this fuss, I apologize.

Posted: 11 Sep 2007, 23:22
by valpro
Well here we are again, arguing over a non issue. The first thing that any trained measurer will tell you is that you must see what the rule says. Not what you think it says and not what anyone else thinks it says.
The rule says 'One receiver'. It does not say that it has to be in one box. It does not say what it should contain. It does not say what it should do. It says 'ONE RECEIVER'. You buy a Spektrum and you get one receiver. Now hold that thought carefully. Roy already told you that the matter had already been provided for in the rules and interpretations, yet not only are you all ignoring this while you ride your hobbyhorses into the sunset but still bickering like a bunch of schoolkids in the playground. Read what the rule says. What it actually says. One receiver. So there is no doubt as I said several posts ago. Spektrum is legal and falls within the class rules. Now can we get on with something more meaningful please?

Posted: 12 Sep 2007, 20:12
by ole_peder
I support Val by whole my hart!!!!!!

I hope this is the end of yet another discussion over something which don't have anything with sailing to do.

Us non english speaking countries do have problems when the fluently english speaking wordtwister starts fireing up their discussion over minor details, and sometimes looses the idea of what we are doing, having fun out on the sea sailing our wonderful IOM's.

I am going out sailing the norwegian Championship this weekend with my Spektrum radio same as 15 out of 29 others. Glad I dont have to worry over crystals and radio infringement.

People wondering why so few are voulonteering for positions in the exec comitee, well this is part of the reason.

Personally I was evaluating if I would seek a position, but decided not to do that, mainly because of the above mentioned reasons.

I feel it more satisfying to work with spraeding the class in Norway and see more sailors on the sea. During the last five years we have grown from app 20 to 120 boats today, We have app 60 skippers on the ranking lists.

We are lacking a bit on certifying the boats, app 25 boats are certified. But as long as they are sailing I am happy.

Posted: 23 Sep 2007, 14:16
by jeffbyerley
I don't know why I am doing this as I promised myself I would not get involved in the type of discussion we have re the Spekrum receiver.
Perhaps the best way I can define both sides of the argument is to compare them to another sporting competition taking place right now.
It is the Rugby Union World Cup. Now this sport may not be everybody's cup of tea, but there is a very close correlation between the arguments used on this forum and the style of refereeing in the World Cup.
On the one hand we have the pedantic, sometimes overbearing UK style of refereeing,where the game has a very stop start type of action, and on the other, we have the Southern hemisphere style of refereeing, where the flow of the game is given some importance.
Both games are played under the same rules, played by teams and refs that read the same rule book.The difference being that in general, the games refereed by the Southern Hemisphere group, are enjoyed by players and knowledgeable spectators more than most of the games controlled by the other refs.
The point I am making is that the influence officialdom has on a sporting activity can be at its best a very good thing, and at it's worst a very divisive and destructive element which does no one any good.
Hopefully when the votes for election of officers are cast at the WC in Marseille, that a sense of what is good for the sport is put to the fore.

Posted: 24 Sep 2007, 09:00
by Chairman
yes I agree but given the wish by one of our NCA that the issue should blow up at the WC then it is proper for us to do what we can to prevent that sort of thing and although I agree with where this is going there is some indication that it may not be consistant with other technical views so you will all see an emergency rule change before the WC.

Posted: 24 Sep 2007, 11:18
by Ray Flanigan
In Lesters words:
I think we are both agreed that the Spektrum AR7000 is a "dual receiver" comprising "a master receiver" and "a slave receiver" (I quote their own words). Great technological solution, by the way, to the problem of ensuring glitch-free reception.

We are also agreed that the IOM Class Rules, bless their cotton socks for being the product of fallible human beings, somehow say "D.2.4 REMOTE CONTROL EQUIPMENT (a) The following is permitted: (1) One receiver".

Finally, I think we are both agreed that there seems to be an unfortunate issue here. On the face of it, the Class Rule seems to be saying that the AR7000 is not a legal item of equipment in an IOM.

My approach is to seek an Interpretation. That is, to go and ask some folks whose job it is to decide such matters, what they think.

Theoretically it is a dual receiver but in practice it can only function as a receiver , hence it should be classified as a mono receiver.
Instead of all the to and fro found on this forum go and check up on all the 2,4ghz systems for radio control and read up on their specs and then decide on the legality of theses systems. ie No RF transmissions from the yacht and etc etc.
Lay all this nonsense to rest as this mudslinging will seriously harm what is essentially a good class.
Let the powers that are in charge of the class make a decision prior to the start of the WORLDS in order to "legalise" this which to my way of thinking is a triviality.


Posted: 24 Sep 2007, 11:29
by Richard Rowan

I have endeavoured to stay out of contributing to this topic but now I have to respond to your latest posting.

You refer to one our NCAs wishing that the issue should blow up at the WC. That quote was made by me on 31st August in a somewhat jokey style. I would not like it to be thought that that is the official opinion of the NCA for GBR.

However, it is interesting that IOMICA are now finally taking some action to sort out this problem or non problem (depending who you are). I think I am echoing the thoughts of a lot of ordinary IOM owners in saying that this whole matter should have been dealt with a long time ago.

Moreover, what goes round comes round. It seems to me (from my limited experience) that World Championships are often not only about the best sailor but are also about the best sea lawyer.

So I think everyone taking part in the forthcoming WC who also use these apparently excellent transmitters will be very relieved to hear that they may not now have to worry about the problem of whether the Spektrum and similar transmitters are legal.