John949

I do actually know what a sans serif font is. What I don't know is which (if any version) of the figure 4 counts as being sans serif or indeed if sans serif has any meaning when applied to numbers. If you are being really pedantic then you could perhaps argue that the figure 1 should be just a vertical line without the tick at the top but since Helvetica has it then go figure. Ironically serifs are used to improve legibility of small letters (or big ones at long range?) which is why optician's eye charts use san serif fonts i.e. it is harder to 'guess' the letter. Hopefully I have made my point about the rules perhaps not being as clear as they could be but, since the font doesn't affect boat speed, it's probably time I let it rest.

The rules say: (IRSA Supplementary Class Rules - https://radiosailing.org/download/irsa-supplementary-class-rules-2020-4/ C.11 IDENTIFICATION ON SAILS C.11.1 A boat shall display: (a) her class insignia and (b) a sail number on all sails and (c) national letters on her mainsail as required by C.12.1. C.11.2 National letters and sail numbers shall be in capital letters and Arabic numerals, clearly legible and of the same colour. The colour shall contrast with the colour of the body of sail. Commercially available typefaces giving the same or better legibility than Helvetica are acceptable. Digital fonts are not acceptable. I know it's easy to criticise and I'm more aware than most how hard it is to write good rules but the above are a beautiful example of how not to do it. Firstly Google Arabic numerals and see what you get! Secondly, "typefaces giving the same or better legibility than Helvetica ..." is entirely subjective; and thirdly what on earth is a " digital font" in this context? I recently acquired a vinyl cutter and was trying to find out which variation of the figure four I should use. The Racing Rules of Sailing (G1.2 a (4)) say " a sans serif typeface" so I'm none the wiser.

Just noticed that F.5.2 (a) says that a headsail boom swivel is mandatory. Does that mean I can't just use a cord (like a DF does) and I have to have a physical swivel? Anyone know what constitutes a swivel or what the point of this rule is?

In theory you can calculate the best position for the hounds and the spreaders if you know the loading on the mast (assuming you goal is to minimise the mast bend). In practice the loading varies with so many things (incidence, camber, mainsail twist, wind speed, etc.) that I'm not sure it's worth trying. Perhaps it is easier to consider what happens at the extremes and then decide if your rig is tending towards one of them too much. If the hounds are too low then the top of the mast will bend off too much, the leech will open and you will likely get a crease running down from the hounds towards the clew. If the hounds are too high the mast may bend excessively between the hounds and the foot. This may well induce a crease form the hounds to the clew. It will definitely stiffen up the top of the mast and lessen the tendency for the leech to open in a gust. Is this a good thing at the top end of the rig's range? I think the spreaders should be at a point where the bending moment above them is equal to the bending moment below them i.e. at the height of the aerodynamic centre. But of course the aerodynamic centre moves around with the same variables (particularly mainsail twist). Personally I would go with practical experience and perceived wisdom unless I was trying to cure a particular problem with the rig.

Many years ago I took part in something called the Classmaster Event. Three entrants from almost every singlehanded class sailed their own boats and then each of the other classes in a series of handicap races. This certainly removed the bias from sailing your own class (I'd barely seen an International Canoe before I had to sail one!). Something similar for RC Classes would require the equivalent of PY numbers for each class but any class handicap advantage evens out because you have to sail all the classes. More recently I took part in the DeQuincy Cup organised by the London Model Yacht Club. This was team racing in 10Rs. I believe they used 95s the following year.

Assuming you have the mast and the jib as far back as you can then try increasing the mast rake. It may be that the rigs are poorly designed - the jibs are too big for the size of the main and therefore there is not a lot you can do within the rules.

Not familiar with the FS-8 but I do know that FlySky have recently introduced a new protocol (ANT) which is not compatible with old Rxs (AFHDS) . Is it possible that the upgrade is using ANT by default? Maybe you can choose the protocol somewhere in the setup?

Are you making the sails yourself or buying them? Marblehead rigs sort of design themselves because of the way the rules work. First thing to decide is the balance between main and jib areas. For a conventional rig this is usually about 60 / 40 (70 /30 for a swing rig). A rig should have the longest luff allowable (depends on you kicker arrangement - read the rules) and as said you take about 200mm of the luff for the B and 400 for the C. Obviously you want to maximise the 'free' areas of the roach and foot. Once you have the luff then you can calculate the foot to give the required area and the maximum 'free' cross widths then come from the rules. If you sail predominately inland you might want to increase the 3/4 width of the main by about 15mm or so and 1/2 by about 7 and hence reduce the foot to compensate. Jib is similar but you can play around with the luff length to some extent. It's tempting to go for a long luff (higher aspect ratio) but the rules force the foot to be too short for the 1/4 width (particularly for a swing ring) and you end up with too much roach to control properly. If you look on Frank Russell's site he gives dimensions for his Gothic design and Graham Bantock (Sailsetc) has quite a lot of information on his designs. Best idea is to create a spreadsheet so you can play around with the dimensions and then draw out likely candidates (I use a roll of lining paper - cheap)

The tapping size for M4 is 3.3mm so there will be some thread left after you drill it for M4 - not ideal. You would need to use a drill press, or preferably a lathe, to stop the tap wandering and producing a 'drunken' thread. BTW I can find M3.5 socket headed stainless steel screws on eBay.

Many people (me included) use the 'exponential' function on the rudder. This makes the rudder less sensitive (i.e. more stick movement for a given rudder angle) around the centre of travel and more sensitive at the extremes of travel. Most simple radios have a function called exponential and you can set a percentage - the higher the percentage the less sensitive it is in the centre. More complex radios have a function called 'curves' which allows you define any relationship between stick and rudder you want. Pretty sure the I8 will allow you to use a three position switch to set how much exponential is in use. I have up - no exponential, mid - mild exponential, down - high exponential. I very rarely change it from the middle position. Not convinced that different throws or different sensitivities for different sailing angles is the right way to go but whatever works for you. Other people don't bother with exponentials or curves and just practice making small movements. Modern radios can do all sorts of clever things and such functions can be useful but if you are just starting out then probably best to keep it simple.

Try this: It's a bit frantic and you may not follow all of it (unless you are familiar with Bernoulli's equation and know what the Navier-Stokes equations are about) but the thing to take away is that the explanation of how a wing produces lift is complex and can only properly be explained using some fairly complex maths and therefore all the simple "molecules speeding up" or ^bouncing off the surface" explanations are nonsense.

In the interest of balance I'd like to propose an alternate theory regarding sail twist. I am not saying I'm right and you're wrong just proposing another possible explanation of why sail twist might work. The wind does indeed increase in average speed with height and it also rotates in direction with height due to the rotation of the earth. but these effects are very small over the height of a model yacht sail. More importantly the wind at ground level is far from stable in either speed or direction due to the turbulence caused by trees etc inland and waves at sea. I find it hard to believe that the flow is stable enough (lamina if you will) for you to be able to tune the sail twist to the variation in velocity. What is certain is that the more you sheet in the more force you produce (until the sail stalls), but the more you sheet in the more this force is directed sideways rather then forwards. Sail twist can be used to 'unload' the upper section of the sail thereby reducing the heeling moment and hence the hull drag In other words the lower section of the sail is producing more lift and but also more heeling moment. The upper section is producing less lift, but since it is directed further towards the intended direction of travel, the loss in 'drive' is more than compensated by the reduction the heeling moment. I actually sail my boats with very little sail twist, although you can have a reasonable amount of twist upwind it just looks wrong to have a lot of twist downwind when the sail is stalled. With a stalled sail I think you want to present the maximum projected area to the wind so this means having very little twist. On the subject of how a wing produces lift, it would be a disservice to all those people who tried to teach me aerodynamics if I didn't point out that the "air has to travel further over the top of the wing therefore it must travel faster" argument is a common mis-conception or perhaps more correctly: only part of the story. This argument struggles to explain how an aircraft with a symmetrical wing can fly at all or how an aircraft with a conventionally cambered aerofoil can fly upside down. It also struggles with a yacht sail (technically a cambered flat plate) as there is no difference in the distance the air must travel between the windward and leeward sides. This isn't the place to explain aerodynamics (and I'm not the best person to do it anyway) but perhaps if you look at the diagram you drew and replace the cambered section with a symmetrical section, think of the fluid as water rather than air and call it a rudder not a wing: then maybe it's easier to see that the change in direction of the fluid flow must cause a force on the rudder?

It does seem that the latest DF digital servos are prone to this problem and I suspect that it is a fundamental design issue. It is probably still worth trying a few things to confirm. Try the winch in a different channel on your Rx Try your winch on a different Rx Try a different Tx Try a different battery and leads I suspect that none of these will make any difference. If so then there is not a lot you can do My guess (and it is only a guess) is that the control algorithm has been too highly tuned for maximum performance (speed / position accuracy). Whilst it works well when the winch is new, if the electrical / mechanical properties change over time then control accuracy can degrade. I wonder if a new version will be released or perhaps even a software upgrade will become available.

Can't help with the ID, but pretty sure the rudder is on backwards - pivot point needs to be forward of the centreline (actually ahead of the centre of pressure). If it isn't then the hydrodynamic forces will be trying to increase the rudder angle rather than reduce it. The servo would certainly hold it but any slop in the linkage would cause the boat to be very difficult to steer in a straight line.

The idea is that by 'protecting' a boat from others tacking inside them or cutting in when clear astern, you encourage people to get on or even slightly above the lay line and give the mark a reasonably wide berth. Hopefully this lead to an orderly rounding with those that reach the zone on the lay line first rounding first, chancers and bargers have to go behind because the rule says they do. They can no longer push their luck and argue there was room.