Hi, measure the distance beween the tip of the blade and the centre which is the radius then double it to get the diameter, Go for a right hand prop of the same diameter as the white metal one.

Looking from the rear of the boat a RH prop spins clockwise to give forward motion of the boat. If this is not right then reverse the connections to the motor.

The prop shaft will have a thread which is either M4 or 4BA there should be a nut of this same thread and a small washer. You will need a thin spanner of this size.

Fit the washer on first then the nut and screw the prop on afterwards. Then with a spanner gently tighten the nut against the prop and that should lock it in position.

Good luck

Roy

Hi just a small point Dacron and Terrylene are the same material in case of confusion, depends which side of the pond you live.

Roy

Hi I have cut out sails using a sharpened soldering iron bit at a minimum heat level You do need a firm durface to cut the sail on but I made the mistake of using hardboard and there is a faint brown mark which is not a burn mark from the hardboard surface.

The last lot of sails I 'made' I produced templates supplied the material and left an example of what was wanted and the lady who does clothing alterations in the local market did the sewing. Did not charge much either.

Remember to have the longest sail edge as the weft edge i.e. non stretching.

regards

Roy

Hi if the sail material is a flat surface like mylar film double sided tape is great. If it is a woven surface then there is a product called Wunda Web which is a loose filament tape which is glue and it can be laid inside a seam.

This is then ironed with the heat on medium to activate the glue to the two surfaces. Not sure if this would suit nylon or rip stock but would be good for a light cotton material.

I have sails made in this way over 10 years ago with no sign of deterioration.

If you have a material which when cut has threads ready to fall away then using a cotton bud stick apply a light varnish edge on to the cut adge and this will seal it form fraying.

Good luck

Roy

Hi at the low power end I use these esc's. The ones I have were rated at 10 amps these look very similar but I would suggest to be wary of the 30 amps quoted.

www.ebay.co.uk/itm/RC-ESC-30A-4-8V-Brush-Motor-Speed-Controller.

I have 3 in use and bought spares, I run them at about 2 - 3 amps using Marx Super monoperms. I have been very pleased with them especially at low speed.

There is a tiny switch mounted on the board which is to allow for instant reverse as you will need, or for the pause going into reverse that cars have. The switch on the long lead is for the bec for the rx.
You will hear a whine from them in use this is how they achieve the precise speed control. Many esc's use the transmitted 50 cycles for the mark / space speed control but these use about 2Khtz, which you can hear.

You will note the plugs and sockets on them. These are the same ones you find on battery boxes just 2 pin but polarised. So 5 amps max I suggest. You will also need the appropriate ready made leads both male and female. These are available probably same stockist and very cheap.

I use standard Tamiya connection batteries and just have a conversion link wire with Tamiya at one end and 2 pin at the other.

They seem very efficient as they do not even get warm in use and are incredibly small and light in weight. They will run a 385 motor no problem but note voltage limits on esc as 4 - 8 volts.
I was buying them originally for £2.50 each free delivery. It does look like 3 - 4 week delivery time now and I do not know what customs and VAT might do on arrival here.

regards

Roy

Thanks for the 'spoiler' I have to wait 12 hours to watch the race and like to see it unfold as it goes;
R

Hi all again latest update.

AC75 Sunday was postponed for races 7 & 8 and I did not envy the commentators! They kept everything going though very well and discussed the previous starts and showed edited video to look at the finer points. Each team is allowed 6 jibs, you might surmise that in a high wind you use a smaller jib, Hmmm, not so sure now. The jib selection is the last chosen item per race, the crew sit there until 10 minutes before and then the jib is chosen to suit wind conditions.

The balance point of the yacht when foiling is at the centre of area of the leeward foil. So the pressure of wind on the sails has to balance this out as the effect of the smaller jib moves the centre of power of the sails further aft. But this movement also affects the speed that the yacht can turn on the balance point of the foils, the further back it is, the quicker the boat turns when tacking or gybeing. It is a formidable calculation!

This combined with a view of the discussion points on Mozzy Sails web site elicited just how critical the operation of these yachts is. As I said before each entry is allowed 6 foils (i.e. 3 sets) and the design of them is starting to become known. Viewed end on there are 3 types all within the 2 metre width allowance. They are an inverted T then there is the anhedral shape (an upside down shallow Y) and the W shape.

Early on in testing the NZ boat was seen to launch with one T and one inverted Y to check out the attributes of each type. The W shape seems to be the one in use. As most things are now set so to speak the flaps on the foils are becoming more obvious to see.

Some are a straight forward full length hinged flap but others show an extended right angle fin pointing downwards showing that the centre of radius of the foil movement is outside the foil and this leads to the possibility of the foil extending out and down and as it changes angle so increasing the surface area. (as per aircraft flaps on the wings to give a lower stall speed)

It may seem that the yachts all look the same but the parts that count are all under water and the NZ boat and the Itallian boat are very different.

Have a look next time you see a race and see how soon the boats can get up on the foils. A larger foil area should make this sooner for a given wind speed but does it? I find it difficult to reason out why the first boat across the start line wins even against a faster boat!

Maths has always been involved in creating the fastest boat within the given Americas Cup formula restrictions but never more so than now.

Without the 'game boy' screens on-board they could not operate the yacht or even stay within the course and also somewhere along the line the overall goal of match racing has been lost, but why? Probably need a computer and a new App to find out!

regards

Roy

Well Zooma I have a model Swordsman and I like yachts, they are not mutually exclusive!

Roy

Hi all well we have got through day 1 of the races. The first race was a walk over by New Zealand leading all the way. Their boat was 2 knots faster over the entire race.
The course is 6 legs of a 3.6 Km course, total race time is 23 -24 minutes.

The start can be a bit cut throat and on the second race it would seem that the Kiwis decided who needs to worry, when we are faster so they did not engage. The Italian boat was on time with the Kiwis 5 seconds behind and from then on for the Kiwis it got worse and worse!

The second race was won by the Italian yacht by 7 seconds for a slightly longer race of 24 minutes. Analysis shows that the Italians travelled 200 metres further overall and there was nothing in it with boat speed.

Greater minds than mine are working out what this all means at this moment. The Kiwi boat was getting round the corners in an upright position and doing a 180 degree turn at 50 mph better than we do in our cars!

No one came off the foils and there was only an umpire boat following the race. The chase boats with on-board rescue were not there. There were some small errors but not enough to change the result.

Looks like we may have a race right down to the line!!!!!

Next 2 races are Friday 12th. March.

Regards

Roy

Hi nice video. Did anyone notice the two large model sailing yachts in the fore cabin?

Roy

Hi Nerys thanks for your kind remarks. Though I have to differ about atitudes of the parties concerned at the time.

Although we look back on 1851 with a soft eye, it was the time of the Great Exposition, GB was showing the world how modern they were and the products being sold would bring other countries into this new world.

You can see from the quote that the round the Isle of Wight 'race' was already part of the 1851 festivities. There were many GB entries but the America won with a big margin of victory that belied any agreement on the size of yacht taking part.

To quote-:

The history of the yacht America began with five members of the New York Yacht Club, who decided to build a state-of-the-art schooner to compete against British ships in conjunction with England’s Great Exposition of 1851. Designed by George Steers, the 100-foot, black-hulled America had a sharp bow, a V bottom, and tall masts, making it strikingly different from the traditional yachts of the day.

Hmm! 'State of the art schooner' and 'strikingly different' that is hardly the nice cuddly friendly view we might have in looking back. For all concerned in 1851 these were modern times! It was also cut throat trade as well.

I can imagine the USA thinking perhaps 'we will go and show them what we can do'! And who can blame them! The world was getting very trade conscious and that meant money.

The second outing to compete for the Americas Cup, as it was now known, was in 1870 and a lone GB entry competed against 14 other yachts, the yacht America came 4th. by the way. The history is all there on the Internet.

Another point from Nerys's post. Although we all accept countries putting on trade fairs now, the 1851 Exposition was the first and biggest ever seen in the world, and the world came to see it.

Many nations brought out their biggest and best to show off, it was a monumental sales drive. Nations were forced into realising that they did not want to be the only ones left out.

Also we must not miss the point that if it had just been Queen Vic it would never have happened! It was the German Prince Albert, and Henry Cole, who thought of it and promoted it.

Just like to say Nerys always enjoy your posts and builds, 'long may your chimney blow smoke!

Best regards

Roy

The Prada Cup to decide who races against the defending champions is over. Were we robbed? Our boat favoured the stronger breezes but it was not to be. So the Red Moon is triumphant and probably deservedly so..

The New Zealand team although lacking match race time have been watching carefully. They have been racing when ever possible. As ever, exploitation of the rules can lead a design idea down a nearly parallel path but....
In the case of the NZ boat if you look at the deck it is 18 inches lower than the other yachts. Beneath the deck below the mainsail the other yachts have put the mainsail hydraulics to clean up the design.

NZ have not done this, they have put all the mainsail hydraulics in the mainsail boom, looks a bit ugly having the bits on show but it was done with a reason. As this space under the deck is now redundant the deck has been lowered and this means the sail continues down to deck level giving an extra 18 inches of sail depth and when multiplied by the sail length is a considerable area, but legal!

It has another advantage as well, as it lowers the centre of effort of the sail and so for the same wind pressure she can stay upright for longer.

Another thing team NZ have done is that they do not lower the leeward foil quite as much, pushing the balancing point of the foil just 4 inches further out from the centre of the yacht. N.B. the fulcrum of the foil mechanism is not on the centre line of the boat.

The effect of this is a bit like lowering the lead further down on a keel yacht so making it stay more upright and stable. Now 4 inches about 20 feet out, is not a lot, but the weight of the boat acts upon this point so it has to be multiplied by the 7 1/2 tons of boat!

These two innovations for a given wind speeds give a 7 1/2 % advantage in speed. Back in the day of the big monohull yachts half of 1% would give you victory!

The rounding of the gates is getting more sophisticated for all. There are trim tabs on the rudder foil acting a bit like the elevators on an aircraft. There are similar tabs on the main foils a bit like the ailerons etc. However on an aircraft they bank into a turn, this would be disasterous on the AC 75 yachts.


They need to stay flat, so the foil 'ailerons' are used in the opposite way, this keeps the hull level. The elevator on the rudder is used to slightly dip the bow and lower the hull when rounding the gates this is to ensure when turning that the bow does not rise should the wind speed suddenly increase. Well that is what we are told! Just watch what they do!

So this maybe a one horse race but Luna Rossa will be well aware of the NZ boat and its capabilities and probably has a few tricks left yet to play.

I watched a practice start and 4 lap race and Team NZ just sailed away from them. Or did they? Tactics are very much the name of the game in match racing.

Should the Team NZ win the Americas Cup it is almost certain that the races for 2025 will be held elsewhere. This leads on to thinking where this might be? As for example should it be in European waters then the North Sea presents a far different environment with short steep seas against sailing off the Americas.

Aukland has relatively sheltered waters and there are 8 race areas, chosen partly depending on the wind direction, basically it has to blow down the course forcing tacking manoeuvres. One Prada race was called off as the wind veered 90 degrees and then it becomes a straight speed test on a beam reach.

Designs would be different, this current design was a logical development of the AC72's of 2017. They were catamarans with foils but one hull was always redundant as they changed tack, and the crew moved across the hull, but it still took a genius to work this out and come up with the AC75's.


If you want to see for yourself, the above is an evenings You Tube watching. Try, americacup.com, Planetsail (v.g.) Mozzy Sails, very technical.

The Americas Cup starts on the 10th. March a delay due to some local covid infections and may still need special government permission to commence the racing.

regards

Roy

Hi, the Elke 408 is a Graupner kit now out of production, and the hull is ABS plastic, so no hull drawings to build from.

Does it have to be this boat? The Billings Mary Ann is a slightly smaller but similar fishing boat. The kit is still available.

Alternatively if you go on-line to Sarik model boat plans you will find a lot of fishing boats from several eras to choose from.

Good luck

Roy

Hi Colin, if you need to buy 40 Mhtz crystals make sure they are FM. The only use for 40Mhtz AM crystals is for the 2 ch sets. All else at this frequency is FM.

Roy

Hi all, The 40 Mhtz and 35 Mhtz frequencies are quite close electronically. This means that if you put a pair of 40Mhtz FM crystals into a 35Mhtz set it will work at the new frequency of 40 Mhtz. The receivers with dual conversion will need a dual conversion rx 40 Mhtz crystal.

So is this a bodge? No, it isn't!

My Fleet 40Mhtz RC sets one of which was bought by myself from the shop is labelled 35Mhtz underneath. The box it came in is labelled 40Mhtz.

The 35 Mhtz. Futaba multi channel TX with a 40 Mhtz crystal operates Hitec and other Futaba receivers sold for 40Mhtz use. The same goes for my Fleet equipment.

With the standard Futaba 35Mhtz receivers with a 40 Mhz crystal fitted also work from Hitec dedicated 40Mhtz transmitters.

Remember that you do not have to match a 6 ch. Tx to a 6 ch. Rx. You can operate a 3 ch Hitec Rx from a 6 ch Tx also a 3 ch Hitec Tx will operate 3 of the 6 channels of a 6ch rx, well you may have fun finding out which ones but it is generally channels 1,2 and 3.

The only area I would be careful of, is bringing Fleet rx's into use as these have non-standard servo connections with the red and black transposed, a careless moment here writes off the rx. But a model boat fitted out with Fleet rx and and servos will operate from a Futaba 35Mtz Tx with a 40 Mhtz crystal fitted,

All the above I have tried out except the dual conversion rx and it is all interchangeable as I have described.

Newcomers, by all means go for the 2.4Ghtz sets but the old stuff still works! The crystals are all available on-line.

I do not recycle everything but please do not throw away these beautifully engineered transmitters as they still have a working life in them.

Regards

Roy

Hi, my experience is that assuming you wish to keep your model boat in visual sight then the aerial length is not critical.

Make sure there is some of the wire going along the length of the boat and that here is at least 6 inches of vertical aerial. I often have a fixed vertical scale aerial with a trailing wire and socket and plug the end of the aerial into it.

This means I can remove the superstructure and just unplug the aerial.

Sorry this is not a technical answer but I have a background of electronics and up to 200 or 300 feet range it is not a problem.

I have seen many model boats where the aerial has never been undone from new, they seem to work!

Let us not find extra things to worry about! We have enough on our collective plates already!

Best regards

Roy

Hi they must come out for replacement? I would get to them and put an extra wire between them i.e. centre tapped. Bringing it out so it is near the other terminals. This way you can charge them as 12 volt batteries.

If one of them goes down you will never know otherwise!

I would not charge them as 24 volts as there must be chargers around but 12 volt ones are more plentiful.

Roy

Hi do not worry about temperatures it does not vary enough to be a problem Trickle charging rate is one tenth the capacity of the battery, so 700 mA. You have to compensate for the inefficiency of the battery and so 10 hours times 140% comes out at 14 hours charging time.

Forgive me but I am not clear on whether you are charging a 7Ah or a 2Ah, battery.

As you know when charging SLA batteries they use taper charging so start with a 14/15 volt voltage from the charger with a max current limit of say 2 amps and as the battery voltage increases so the charge voltage decreases.

If you want to take the batteries out of the mechanism and charge them separately then Howes do a 12 volt SLA charger which you may want with crocodile clips on, to connect to the battery and just leave it until the green light shows.

They are very helpful on the phone just tell them you want an intelligent charger for a 12 volt 7 amp hour SLA battery. The intelligent bit is that it reverts to a trickle charge (sometimes called a float charge) when the charge is finished.

Good luck

Roy

Hi all a bit of background info.

You may well hear the expression Challenger of Record mentioned during the races.

This goes back to 1983, before then it was just the UK and the USA. It was agreed to include other challengers to agree on a yacht description, not a one design but these are my words, to race the holder of the Americas Cup.

Luis Vuitton put up the money for the Cup and a single Country was the official Challenger (of Record). Other countries could then compete with the C of R and so the winner got the Luis Vuitton Cup and then went on to challenge the holder for the Americas Cup which would be sailed in the holder's nominated water. This time it is Prada who put up the Cup etc.

The last time I saw money mentioned it was said that the race was worth 1 Billion £'s to the local economy and also the exposure of the area attracted visitors as well as a future holiday destination.

As an aside many years ago Australia was just somewhere a long way away. Then the film Crocodile Dundee came out and Oz shot up from number 22 on the holiday destination list to either 1 or 2 can't remember.

This film is the most successful non-Hollywood film ever made and later Paul Hogan had a National Award for the achievement. (He also married the girl and they stayed together for 20 years). Then as he says himself he screwed it all up!

So when asked what's the point in spending 100 M $ on a boat it does bring in lots of money to the countries involved.

Also had you ever heard of INEOS before a very large global company in the chemical industry. Well their name was blazened all over our yacht when it had its time in the sun. The advertising and exposure must be worth all they spent (£110M).

regards

Roy

Hi Ron and Tony, are your Dragen yachts static or for sailing?

Over 20 years ago now I was asked to build a Dragon Class yacht by Int. Mar. Modelling but using a ready made glass fibre hull about to be marketted. It was with a view to have a sailing model.

Don't get excited, when I received it the hull was very heavy with the hull about 5mms thick. I had an Inga IV hull at the time and it was 50% heavier than the much bigger Inga IV..

It was too heavy to have a lead keel and float any where near the waterline. I did give them feedback but no response, the model yacht was never built (by agreement) but I had done a lot of research including a visit to builders in Essex.

Most Dragons are open cockpit however there are a few non-racing ones with a closed in one. As you will know they are a Norwegion design from 1929 and were used in the Olympics as a class from 1948 until 1972.

Always regarded as a handsome design that has stood the test of time. Sarik carry a plan called Bluebottle which was the Dragon Class yacht which was presented to the D of Edinburough. The plans were in Model Maker many years ago together with a write up on building.

These plans show several sail plans and for a sailing model I would suggest the smallest set of sails as best.

I later had experience with a metre long sailing model of the UK Americas Cup Endeavour our 1934 entry. This was grossly over canvassed and benefits from cutting back the sails.

Sailing boats can look very nice heeled over but the most efficient way to sail is to be as upright as possible.

Regards

Roy

Hi all, the races just finished were for the Prada Cup which is an elimination race to decide who will challenge the holder New Zealand.

Up until the finals we were doing well but then Italy found another gear and dominated the races not only with a slightly faster boat but also in tactics.

The UK trailed 0 - 5 to Italy and then Sir Ben made a good tactical start and commanded the race so it was 1 - 5. Then The UK were out-manoeuvred once again to lose the next 2 races and so Italy and Luna Rossa won 7 - 1.

All things being equal 6th. March sees the start of the actual mericas Cup between Italy and New Zealand.

Considering how the USA then UK and ending with Italy all had a turn at domineering the racing events I wonder if NZ have been left behind as it seems to come down to tactics 90% at the start and the first time they cross as they head upwind to the first gate.

The trailing boat travelling in dirty air so never seemingly able to make better the difference.

Casual watchers may wonder at the computer graphics giving actual boat speed and then looking below to see a different speed quoted.

The lower speeds are Velocity Made Good or VMG. This is a computer calculation showing how fast they are achieving getting to the next gate.

The sailors will know that speed is one thing but with a destination in sight it is how quickly you are getting there.

One surprising thing with these yachts is the way they can convert a wind speed into 4 or more times that speed as they travel through the water.

Another is how the crews have mastered keeping these boats up on a or both foils all the time and going round corners at 40 50 mph!

Remember these yachts weigh 8 tons and are travelling on foils with maybe 15 square feet actually in the water between the 2 foils to balance on.

I look forward to the AC in March, probably the most exciting ever.

Roy

Sorry I may start a fishing boat one elsewhere.

I know they have Dragon boats wonder if they have Dragon fishing boats? 😇

Exit left chased by a dragon. ⚡😮

Roy

Hi as far as the Mary Ann model goes I am finishing the rigging and need to glue down a couple of items and I will post some pictures.

The boat is twinned with another Mary Ann so they can go fishing together! Tried to keep them a little different. I did need to match their speeds. One had a monoperm and the other a similar clone.

However on similar voltages they ran at different speeds in the water so the fast one had a down sized propellor and they run about right now.

The esc's I use for small motors are incredibly cheap and very small. Just 28mm x 19 x 8mm they do have different connectors as they use the same type as used for 2 pin rx to battery ones. They have an internal BEC. I bought extra made up wires to suit very cheaply.

I order them as 10 amp brushed W/O brake and the last time they were about £3.00 ea. I would not go above 5 amps but they run on 4 - 7 cells.

regards

Roy

Hi lovely as they are Taycol wound field motors are not good for RC due to electrical interference. There is a possible exception and that is with 2.4 Ghtz,

There is a big but, and that is the motor would still interfere with other RC model boats not on 2.4G.

Have you seen my reversing circuit using a full wave rectifier? I say my, I proposed it as an exercise about 20+ years ago on this site in its original form.

Regards

Roy

Hi thanks for the tip on using polyester resin I have not used it before. Is it a liquid and hardener and then thinned down?

I do kit rescues if I fancy the boat and have just converted a Billing Mary Ann from static to working but otherwise I now just build from plans.

I also only use the wood I have accumulated over the years, my last 2 boats were from this wood so only glue and paint were purchased.

I have many electric motors (close to 100) which I am using as well.

About 6 years ago I completed a model boat called "Dolphin" for a lady who had found the model with just the hull built and then left unfinished but with the plans.

Her husband had died and she wanted a memento. It is from the 1950s and I fitted a black and orange Hectoperm motor so that it was authentic if anyone knowledgable had a look inside. I said to her if the model ever has to be scrapped rescue the motor, it is quite rare.

I hope the photo is big enough!

regards

Roy

Hi always nice to see an old kit built. I have used old obechi or bass wood and the surface texture has dried out over the years.

It is fine for bulkheads and internal structure but getting a reasonable surface finish was difficult. I tried lots of filler etc but maybe using more viable wood was the real solution.

I would check some of the planking to see how it takes finishing and it may be worth using newer wood for the planking. However good luck with the build.

Regards

Roy

Hi NBT you are not alone I cannot come away from the smallest glueing job without sticky fingers.

Instant is the worst for me several times I have had to cut myself free with a knife. Also clear (bathroom) sealant.

I advocate this for sticking down electric motors, it holds them firmly absorbs some unwanted vibration and with a bit of easing you can release the motor unmarked.

Good luck with the build

Roy

Hi you should always damp proof a boat hull inside even as you are building and do not allow any spaces to be sealed off either.

If water gets into wood over a period of time it will swell up and it does nor matter what your finish is it will expose cracks and weak points in the hull.

Another thought is to balance the inner and outer surfaces so that neither one can expand or contract more than the other, varnish or the like inside will give the wood stability.

Nerys points out his method of building which is a purpose composite system and a good combination for a lightweight hull. No point in adding extra strengthening where none is needed.

I have seen Robob's hulls and they are an immaculate surface finish but which ever way you go it takes time and effort. But the finish will last and the model will live on!

Roy

Hi all, I have around me model boats and yachts that go back as far as 1960s and a restored one that must be 80 years old.

Not a sign of glass fibre on any of them. If you build in wood then a few coats of thinned varnish will toughen the surface, then just get rid of your old paints as you brush the paint on and wet and dry in between. With different colour paint layers you can see how deep you go when using wet and dry to get a good surface.

Most of my models have 10 plus coats of paint, well keyed in and have lasted well. I usually finish with an abrasive rub down of Vim (seems to have vanished from the shops) and then a couple of coats of good quality polish.

If you need strength in a hull start with thicker planking, just how strong does a hull need to be? I agree you can obtain a pristine finish but few full size boats are like that.

I also note that some go off into the realms of marquetary with deck planking. Most full size decks used teak for some very good reasons.

Over the years I may have refurbished a boat but one of my oldest has balsa planking and has survived very well.

By the way inside I sometimes use old stocking panels and varnish, just as good, also a good substitute for canvas. Many working boats from the 50s and 60s had canvass decks as well.

Regards

Roy

Hello Tica I see I have not replied to your kind upload of the building instructions. I apologise for my lateness. I managed to print off everything I needed and the printouts are held safely in the kit box.

It is nice to find help when you need it so thanks again.

Best regards

Roy