Lester Gilbert

Hi Richard It would be good to know the reply to Darin's question. I believe JohnO's quote from IOMICA refers to the CRO proposal to amend the class rule. As far as I know it does not refer to a physical "CRO kicking strap", whatever that might be. The IOMICA report is simply poorly worded. Perhaps a photo of your VISS kicking strap would help us compare it to the current IOM class rules.

Hi Stuart In case it is helpful, a quick distance estimator using your extended thumb... (smile) "Thumb Tip" distance estimator Arm length (A) 550 mm eye to upright thumb Boat size (B) 650 mm Width of thumb tip (W) 20 mm eg, at nail base Size in the distance (Z) 0.1 thumb tips that is, approx 2 mm Distance to boat (DtoB) 179 m = (A*B) / (1000*W*Z) = ROUND((B4*B3)/(B5*B6*1000),1) if the data is in Excel Relationship DtoB : A ≈ B : W*Z

I've run a simple 3D printed plate in my Marblehead, and currently a SAILSetc fitting in my Six Metre, both carbon hulls, without problems. They fit inside the pot.

Hi Simon I think the 12 and 14 overlap is at a dia of 12 (outer for the 12, inner for the 14), so I guess an overlap length of 48 would be considered "sufficient". (Never did establish exactly what was meant by "sufficient"....)

Diameter at the overlap, I believe.

Hi Simon My recollection of Engineering 101 was that, other things being equal, a "sufficient" overlap should be at least 4 times the diameter. No limit on mast height. Unwanted drag a good reason to keep it as low as possible.

Hi Paul Terrific summary, thanks! There are two columns that would really be very useful to add if you had the enthusiasm. One is the degree to which: (a) the winch has an actual IP rating; (b) the winch is convincingly claimed to be waterproof; (c) is said to be waterproof in a hand-waving kind of way; (d) is said to be "water resistant"; (e) no claim or statement is made about this; or (e) is explicitly said to have no water "protection". Two is if: (a) the battery connects to the winch and also to the receiver; (b) the battery connects only to the receiver and it is the receiver which powers the winch; (c) the battery connects only to the winch which then supplies the receiver with the battery voltage unchanged; (d) the battery connects only to the winch which then supplies a different voltage to the receiver (ie 6V); or (e) two batteries are required, one for the winch and one for the receiver.

Hi John > unless you are familiar with Bernoulli's equation and know what the Navier-Stokes equations are about Yup, check, and, ah, check. > all the simple "molecules speeding up" or ^bouncing off the surface" explanations are nonsense These are perfectly good explanations, though some are considered better. The lift produced by a wing is described, but not explained, by some maths which is just a computable model of the situation in the realm of engineering that gives rather useful results. An explanation is a different matter from the realm of the philosophy of science, and a useful explanation is when a human says, "Ah, got it, I think I understand." And I think it is considered offensive in polite discussion to tell anyone they are talking nonsense.

Good stuff. But the business of the wind speeding up to follow the upper wing camber so that it meets up with the wind below is no longer thought a useful explanation. Instead, "[...] we imagine we are sitting with a bundle of fluid particles as we flow over the upper surface of a cambered wing. Starting from the nose, we are forced up by the curve of the wing. As the curve of the wing eases off, we stop being pushed up, and we travel straight and level for a moment or two. And now as the wing surface begins to drop away from us, where do we go? Well, we just want to keep going straight because of momentum and inertia. On the other hand, if we all just stop following the surface, we are going to create a perfect vacuum. So some of our bundle starts to follow the surface down, some of our bundle continues more or less straight on, and the remainder of the bundle spreads itself between those two. Technically, this results in decreased fluid pressure on the upper surface. A pressure decrease is the same thing as a partial vacuum, meaning that there is a suction on the upper surface of the wing, lifting it up. The amount of sucking – lifting – force depends on the amount of camber; more camber, more suction." https://www.onemetre.net/Design/Lift/Lift.htm

I'm told that Ian Cole ran his Renaissance with an alternate fin and rig and won the A Class Nats in light airs at Woodspring some years ago, Ian sadly no longer with us. It would have had terrific acceleration and manoeuvrability. There was a very light weight A, perhaps 10 kg, that I saw at a PRACC series once or twice with similar characteristics, but it was all for nothing as and when the wind strengthened.

Rule E4.3(b), Taking a Penalty: "If a boat gained an advantage despite taking a penalty, she shall take additional turns until her advantage is lost". There are two points to make about this rule. The first is that it seems to have the right intention -- a boat should not gain an advantage by breaking a rule. The second is that the rule is not fit for radio sailing. First is the good news. A stronger version of this rule is found in 44.1(b), where a significant advantage means the boat shall retire, and E4.3(b) reduces this requirement to one or more additional penalties. This rule is in place for other sailing disciplines -- windsurfers have their own version of 44.1 at B4 which includes it, match racers have C8.3, team racers have D1.3, and kiteboarders have F4, so radio sailors are in good company. Don't be fooled, though, by the apparently lighter version of our rule, because under the original RRS 44.1(b) a boat shall retire ONLY if her advantage was "significant", while we seem to have to take penalties for ANY advantage. Now the bad news, which can be summed up in one issue -- what is an "advantage", who gets to say it is an "advantage", and how can anyone know it is an "advantage"? We need to know what we are talking about. Earlier, I wrote, "a boat should not gain an advantage by breaking a rule", and I guess you nodded your head and said to yourself, Yeah, it shouldn't. But that was just a little trick with words. What I should have written was the more ponderous, "a boat should not gain an advantage after breaking a rule and then taking the penalty for breaking the rule". Oh, hang on, that's quite different. The whole point of our game of racing toy boats is to gain advantages, hopefully enough of them to finish ahead of the others we are racing. The point of any rules is to make the game fair(*), and the point of any penalty is to wipe the slate clear so the game can continue. I did the crime, I took the time, why can I not now get on with my life, er, race? The issue isn't the rule so much as the penalty. We know from around 5,000 years of civilization that a penalty should be in proportion to the crime, known in advance (rather than made up on the spot), imposed beyond reasonable doubt, and after it has been taken the slate is wiped clear. The problem we have in radio sailing is knowing the situation beyond reasonable doubt. Let's just check back with our sailing disciplines -- the rules apply to dinghy and yacht racers, windsurfers, match racers, team racers, and kiteboarders maybe separated by 2 metres with people on board who are within 3 metres or so of the incident, and in addition for match racers and team racers, they apply to umpires on boats within 10 metres of the incident. Radio sailing? That applies to toy boats maybe 50 metres away separated by 20 centimetres with the additional burden of E5.2, that observers and umpires shall have no visual advantage over competitors, who in turn are not permitted visual aids. Let's see how this plays out in the official guidance from World Sailing for Radio Sailing, known as the Call Book 2025-2028. We'll look at Call B2, and we will do so in detail because it illustrates the issue so well. Here is the diagram. A preliminary point to note is that the beautifully reproduced positions of the boats, the mark, and the zone in the diagram could not all have been known to anyone at the time of the incident. OK, so what do we see? P is on port and enters the zone, and though she is level with A she is apparently ahead of B and C. P tacks on to starboard underneath A and lays the mark. The Call tells us that P gives room to A, B, and C and then tells us that A luffs to avoid P. Wait -- we were just told that P correctly gave room, why did A have to luff to avoid P? The Call then explains that B luffs to avoid A, and C luffs to avoid B, and as a result it was C who was forced by P to sail above close-hauled. Wait -- wasn't it B who forced C to sail above close-hauled? Now, back to the diagram and see that B and C are windward boats and are required to keep clear of A. That B and C had to luff when A luffed is explained by the fact that they were too close to A in the first place, about 0.2 of a boat length. Wait -- what has that got to do with P? Let's just check 18.3, where P is at fault if she forces A above close-hauled. Wait -- the Call tells us that A luffed, but that it was C who sailed above close-hauled, not A; how can it be that P broke 18.3 here? The Call tells us that P took a penalty turn and was still some distance ahead of B and C. Wait -- other things being equal, there is nothing in the diagram, or the description of the incident, to suggest that, if P took a turn, B and C would still be "some distance" behind. The Call tells us that P is ahead of B and C as a consequence of breaking rule 18.3. Here we are at the crux of the issue, and ... Wait -- how, exactly, is P ahead of B and C as a *consequence* of breaking rule 18.3? At the last known certain position, which is position 1 in the diagram, P was ahead of B and C, for all that she was on port and they were on starboard. Finally, the Call tells us that P should take additional turns, although it does not say what the advantage is, not does it say at what point the imagined advantage is lost. Wait -- there are at least six (6) "Waits" here, any one of which is enough to call into question the idea that P must take additional turns because she gained an advantage. Almost there. We now need to look at Call P4. The paragraph of relevance here is the final paragraph, "Any advantage gained is to be measured relative to the whole fleet. A boat may, after taking one or more one-turn penalties, be in a better position than the boat she infringed, but in a worse position than if she had not broken a rule. In this case she has completed her penalty." So, it is fine that the infringing boat can have gained an advantage over the infringed boat. Wait -- that isn't what the rule actually says. To be clear, I have no problem with Calls B2 and P4, because I think they illustrate very well my opening remark -- the rule is not fit for its purpose in radio sailing. (*) Yes, but fair for who? Turns out that rules were developed for sports and games (such as horse racing, cricket, boxing, and, yes, yacht racing) in order to make it fair for those who wished to gamble on the outcomes. The side effect of this was to make it more certain that the team or person judged to have won indeed did so according to the rules, and could then be awarded the prize (money, silverware) correctly, making it "fair" for the sponsors and event organisers, and so eventually fair for the onlookers and audience. Nothing to do with making it fair for those playing the game.

Hi Brian Camber is the sail curvature, as set by the outhaul at the clew. Sometimes called "draft". If the foot of the sail is, say, 450 mm, then set with 10% camber the depth of the sail curvature at the foot would be approximately 45 mm.

I think you are being wound up! No more tricky than any other 6M.... Like any R/C yacht, your starting point is pretty standard. Check she floats on her lines, in particular, the stern just clear of the waterplane. Check the bulb has around 1 degree of nose-up tilt, the 6 doesn't need more. Set the mast perpendicular to the deck, that is, around 1 degree aft rake with respect to the waterplane. Then make sure the mast can rake from there, around 2 degrees forward and around 6 degrees aft (ie there is enough adjustment in jib stay and backstay and no fouling of the booms with deck fittings). Set jib pivot point at around 22.5% of foot (ie between 20% and 25%). Adjust the sheeting radius for the jib so the jib and main booms are parallel when they reach 45 degrees. For beating, sheet the main boom to 3 or 4 degrees, the jib to 12 or 13 degrees. For running, check the gooseneck axis tilts the main boom down and tightens the leech. Set around 6% camber in the foot of the jib, 8% in the main. Set main twist so that the top batten is around 15 degrees off the main boom, jib twist around 10 degrees off the jib boom. I've not yet found shrouds and spreaders to be important in first setup, except to check that they can be adjusted to ensure control of mid-mast bend as the backstay is eased or tightened. Go sailing and balance the boat to taste with mast rake. Be patient before deciding on the amount of helm, the 6 takes a little while to get up to speed, and while getting there does not like to be sheeted full in. You'll then be ready to fine tune. Good luck!

Hi Sarah, terrific project! Where might you sail her?

Might be worth mentioning that RRS 43.1(c) also deals with this. 43.1 (c) A right-of-way boat, or one sailing within the room or markroom to which she is entitled, is exonerated for breaking rule 14 if the contact does not cause damage or injury. In almost all situations, Rule 43 provides exoneration to a right-of-way boat if there was what we might call incidental contact. But there is the small point that the other boat must have been capable of giving room or markroom or tacking away or whatever. If the other boat was not capable of any action, perhaps being disabled, then a protest committee may find that the right-of-way boat infringed Rule 22 as modified by E1.3(c), and there is no exoneration for that.

There is another proposal to fix something that isn't broken, which is to require a hollow in the bow profile below the waterplane to be bridged at measurement. There are two major problems with this. The first is that finding the hypothetical waterline in a bridged gap in the profile is more or less impossible with the kind of equipment most measurers have in their workshop. How would or could this be done? It is difficult enough finding the actual waterline as it is. The second, and possibly far more serious problem for current and prospective owners, is that most, if not all, current competitive designs have bow "chins", and if a new build is submitted for initial certification it could well fail to measure at its design weight and waterline. Of course, there are a number of boats already built with bow "chins", to both current and past designs. If you are lucky enough to have one, or are quick to acquire one before the word leaks out, it will ensure you will be more competitive than any new builds for quite some time to come. I don't know that such a situation would be in the best interests of the class.

Hi Philip I "calibrated" my tension meter by hanging a bunch of cans (*) on a length of shroud wire and found that around 8 cans was my maximum IOM shroud tension, and in general 6 cans did the trick. This was when a can was 450g, around 1lb. So, tension between 2.7kg and 3.6kg for my setup. (*) Started with soup, then changed to baked beans.

There are some positives about permitting a second mast. I have considerable sympathy for a competitor worried about changing a 6M mainsail, under pressure, in poor conditions, with shaky fingers.... As importantly, there is also ever-present anxiety, because of no backup, about accidental damage to the mast spar, boom, or gooseneck, not only during a sail change but generally at any event, particularly an important one that involves a 6-hour trip each way and attendant costs of a three- or four-day stay away from home. However, I think there are some negatives in the direction suggested for measurement and compliance (% tolerances for dimensions and weights) -- too many unwelcome opportunities for loop holes and exploitation, too many difficulties and unknowns in the necessary change in the measurement approach. So what about permitting an alternative mast in exactly the same way as an alternative jib boom is permitted (with two simple additional conditions)? That is, "An alternative mast and headsail boom with associated rigging and fittings may be used provided it has been checked for compliance with the relevant class rules, (a) has the same value for dimension A as shown on the certificate, and (b) the boat's rating does not change." I am content that the rules for our toy 6M might diverge from full-size. Our contexts differ, and see no problem if our boats differ similarly.

ERS -- Equipment Rules of Sailing. 6M measurers -- Log in to the MYA Members Area, click on Measurers.

An excellent article by Malcolm Appleton on 3D printing and assembling an IOM. https://www.mya-uk.org.uk/it-is-possible-to-have-a-brand-new-competitive-iom-in-6-weeks-for-less-than-1500-really/

The "basic" structure is a touch more complex. The MYA wears two hats. When it acts as a class association, it affiliates to the class ICA, if any. When it acts as the national authority for radio sailing, it affiliates both to IRSA as the DNM and to the RYA (the UK MNA) for sailing under the RRS. Interestingly, an owner has three affiliations in principle (though they might not know that explicitly) -- to their club, to the MYA, and to the class association of the boat they sail.

There are a couple of relatively minor issues that could do with being fixed before the proposed eligibility rules are finalised. (a) Section 7.2 states that, without exception, any competitor shall be a national or a permanent resident of the country of the Member NCA that is entering them. However, Section 7.3 says that competitors from other World Sailing MNAs where there is no Member NCA may be invited to enter. This is an exception to 7.2. The fix is to add to 7.2 the phrase, "Except as in 7.3, [etc]". (b) Section 7.3 mentions a "DM", "If no DM is available [...]". It is unclear what this sentence means, because there is no longer a "DM" in radio sailing. It might be that the intention is to allow an IRSA DNM to sign the form, and it would be good to make provision additionally that, in the absence of an IRSA DNM, a WS MNA can sign the form. These two provisions are needed for compliance with RRS 75(b) and (c) respectively. (c) Section 7.3 says that a guest’s entry form can be signed by Events SC Chair. However, this would not satisfy RRS 75. The provision for signature by the Events SC Chair needs to be removed. It may be worth noting that RRS 75 requires either an IRSA DNM or a WS MNA to sign a guest entry form because it puts in place the necessary mechanisms for appeals or disciplinary actions for all parties. A competitor, guest or otherwise, must be affiliated in some way to IOMICA, IRSA, or WS. If no such affiliation can be shown, the entry is invalid.

Hi Simon Did the winch go to half out uncommanded from close hauled or running? Or did it inexplicably stop at half out when commanded to sheet in from running or sheet out from close hauled? If the first, I'd guess safe mode when overheated and/or excessive voltage drop. If the second, I'd guess worn pot, rusty gears, and/or rusty bearings.

My bad, it was the "Tensor" which was their first digital winch which was problematic, the "Olympic" was their earlier, standard analogue, design, and had very good reliability apart from a tendency to overheat when pressed. "Digital" refers to the control electronics.

Hi Simon Sounds like the winch drops into "safe" mode when it can't get enough power -- amps as well as volts. The Whirlwind would be more than 20 years old, I guess, they were unreliable from the start. It was their first digital winch, if I remember correctly, and Whirlwind sadly went out of business as a result shortly thereafter. The lack of power is as likely to come from inadequate wiring as from an inadequate battery pack. If you are using a Futaba connector and servo cable, it may be that it is good for signal connections but not for power. There is also the question of why the winch may want more power than can be delivered -- sheeting line snag or hang-up, excessive friction especially around seized blocks, rusty winch gearbox bearings?