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Soldering tip

The basics in sailing - Beginner's Guide to Sailing

Introduction in the parts of a sailing yacht – yacht cockpit – mast, boom, sails – intro of the mainsail and jib sail (or genoa), windward, leeward side, telltales, winch etc

If you are having trouble soldering your copper wires,especially when nearer the motor where they may be coated.

Mix some white vinegar in an empty yoghurt pot and a spoonful of salt.

Stir until the salt is dissolved.

Then place your wires into the solution and leave for a short period. I normally leave it for 30 minutes.

Then remove and dry completely, I use a hairdryer.

You will then find that the wire coating has been removed and soldering becomes easier.

New version rigging instructions for

DF65 V8 & DF95 V3

Beginner Nautical terms

(Contributed by Kenneth Thompson)

DF65 DF95 dragon force tuning tips

What do you do to fix moving or creeping winch servo

Ensuring your winch servo on your DF yacht is correctly positioned after each race involves a few practical steps….Here’s a simplified approach:

1. Mark a Positioning Indicator:
Mark with a black permanent marker at the end of the winch sheet a black mark which allows you to visually confirm the winch’s position after each race. Use this as a reference to adjust the winch.

2.Manual Calibration After Each Race:
After each race, I manually adjust the winch line using the fine tuner on the transmitter to the marked position.What do you do to fix moving or creeping winch servo ? 

Ensuring your winch servo on your DF yacht is correctly positioned after each race involves a few practical steps….Here’s a simplified approach:

1. Mark a Positioning Indicator:

Mark with a black permanent marker at the end of the winch sheet a black mark which allows you to visually confirm the winch’s position after each race. Use this as a reference to adjust the winch.

2.Manual Calibration After Each Race:

After each race, I manually adjust the winch line using the fine tuner on the transmitter to the marked position.

Fuse Removal Tip

(Contributed by Kenneth Thompson)

Got water in your boat?

How often do you find water in your boat and pull your hair out trying to find out why, for some reason brass tubes very often become unstuck from the epoxy so water passes between the tube and epoxy so to stop this from happening fit rubber o rings before you glue them in.

(Contributed by Richard Williams)

Storage of batteries

COLD WEATHER WARNING. During prolonged cold spells, if possible I would store any model batteries in a warmer environment, especially if your models are stored in a cold shed or garage without any form of heating, the cold weather will affect them, if a battery has any type of weakness, eg a cell losing its activity, the cold weather will find it and you could end up with no power or less power from a battery.

During use in cold weather batteries will also not perform at their maximum power, and the useable capacity will be less. Hope Im not offending any one in posting this, just trying to save any unnecessary replacement of batteries, they are not cheap nowadays.
(Contributed by Andrew Wright)

While we're on the topic of lipo batteries, most good chargers come with a temperature sensor port but you usually need to buy the sensor. If you use the sensor set to a low temperature then the charger will switch off if the battery starts getting warm.

(Contributed by David Bridge)

Props and how to use them

Your propeller or propellers are one of the most important components of your boat. This is what transfers your power into motion.

If it’s not the right size or is poorly balanced you have vibration and cavitation which drains your movement.

It’s like building a car and leaving one wheel off.

If you are using plastic or nylon props they flex and so they are almost impossible to balance.

Unless you have ordered a sharpened and balanced piece all metal props need balancing.

Unbalanced metal props can also destroy your motor bearings.

In order to balance you need a couple of fine files, a prop balancer and fine sand paper, wet or dry.

I also use a jewellery digital weighing scales, as this gives you your starting point.

I use a tfl magnetic balancer as it doesn’t need a perfectly flat surface, and comes with varying shaft sizes.

Once weighed I place the prop onto the shaft and spin it.

The shaft ends are pointed and hold the prop in exactly a neutral position. When the prop stops mark it , I use a very small pencil.

The heavier part of the prop will point downward. Carefully sharpen the front of the prop blades, ( those that face the water). Taking a tiny bit more off the heavier blade. Measure twice cut once is a very good analogy for this part. Take your time. Keep checking the balance by spinning the prop and watching where it stops in relation to your pencil mark. If the prop stops in random places it is balanced. Then you can use the fine sandpaper to finish. There are two different schools in relation to polishing props, one too leave it dull and the other to shine. I polish my props but that’s just my opinion. There are plenty of other makes of balancers out there, including the octura one which is also very good.

One word of caution if you have a beryllium prop use breathing apparatus as it’s terrible stuff for your health.

Understanding brushless motors

Brushless motors have two types of windings.

Delta and wye.

Delta winding motors have high torque.

Wye winding motors have higher revs.

Most boat motors have a timing of “0”.

By increasing the timing on a delta winding motors you are adding more revs, and more heat.

By increasing the timing on wye winding motors you are adding more rpm to an already high reving motor.

Conversely if you lower the timing on a delta winding motor you reduce torque.

And on a wye winding motor you would reduce the revs.

On a delta winding motor the maximum timings are between 2 to 6 degrees.

On a wye winding motor you can go to 8 to 16 degrees.

As a rule of thumb it’s 0 degrees for delta winding motor, and 15 degrees for wye winding motors.

Remember the higher the timing the hotter the motor runs.

Always check the motor’s specifications before adjusting the timing.

Similar with props , the larger the prop the more heat is generated.

Clear as mud, lol.

The difference between parallel and series batteries

Rescuing lipo batteries 

If you have a problem trying to charge a lipo battery,either because you have left it on or not used it for some time.

Then when you try to charge it through your charger it comes up,

“0 voltage “,or balance not working etc.

This will work.

First let me emphasise that you cannot leave it ,you must stay with it. 

Do not do this anywhere but outside.

First remove the balance charging port.

So that the battery is only connected by the socket ie xt90, xt150 , eq5 .

So just one lead is connected to the charger.

Then you move the type of battery over to nimh.

Then reduce the charging current to 1000mah, not what it says on the battery.

Never more than 1000mah.

Plug it in (one lead), and watch it charge.

It will start charging immediately.

Stay there with it.

Once the current gets to 3.2 volts per cell.

Remove it.

Your battery should now be able to receive a balanced lipo charge.

You cannot do this if the battery is in anyway compromised or puffed up.

If you are unsure come and speak to one of us and we’ll help you.

(Contributed by Richard Williams)

Estimated speed

How to read Octura props

The first two letters or numbers give you the pitch

So an octura X438

Equates to 1.4 so the pitch is 1.4

Then 38 is the diameter.

So this prop is a 1.4 pitch with a diameter of 38mm.

Propellers are not 100% efficient 

As a guide mono or deep v hulls lose 25 %, hydros 20% and riggers 15%.

Estimated speed - see other

Propellers Explained

Low , medium and high lift.

Place the prop on a flat surface with the dog end down.

A low lift prop will have a bigger tongue,a high lift prop will not have a tongue.

The more tongue you have the better the acceleration,the less tongue you have the better your top speed.

similarly the more pitch you have the higher top speed. 

Rake

Again with the prop laid on a flat surface (dog end down) rake is the part of the prop which comes up from the top at an upward angle.

A cat hull will be better with a high rake prop and a monohull will be better with a low rake.

Cats are better with a high lift and high rake.

These are the basics on from there is the stock, thinned and modified props.

There is always the exception.

(Contributed by Richard Williams)

Propellers and speed

Octura props as previously stated are X 438

that gives a pitch of 1.4 and a size of 38mm

Other makes use a different way ie 3819 

this gives a size of 38mm and a pitch of 1.9 

Don’t ask me why it’s just a different way of sizing them.

To begin to get your maximum speed you multiply your pitch by the size so in this case 

38x1.9=72.2 

This gives you a theoretical speed of 72.2mm per prop rotation .

Then you take away the percentage of loss as per your hull, 25%, 20%,15%, for deep V , hydro or rigger.

So for a deep V 72.2mm minus 25% gives you a speed of 54.15 mm per prop rotation.

Working out brushed and brushless motors combinations

Motor information

Manufacturing rpm on motor(kv).

So if it’s a 1600 kv motor you need to multiply that times the motors efficiency.

70% for brushed motors

80 to 90% for brushless motors depending on manufacture,ie leopard motors are 90% whilst cheaper ones are 80%.

So 1600(kv) x 90% ( leopard) is 1600x 0.9=1,440 

So that’s 1,440 rpm under load per volt

Batteries-Voltage 

If you battery is 14.8 volts

Then the number of cells ie 4 

So the volts per cell are 1.2 volts for nimh or 3.7 for lipo

Therefore it’s a lipo that’s 3.7 x 4 =14.8 

You then multiply 14.8 x 1,440 =21,312 

This will then give you your estimated rpm .

I hope this helps.

Greasing your shaft tutorial video

(Contributed by Richard Williams)

Boat Set up

(Contributed by Dave Williams)

Lithium Polymer cells (LiPo)

Unfortunately, in the past, these cells have had bad reputation for safety, exhibiting a tendency to catch fire. LiPos will usually not explode but the fires, if they happen, are quick and intense. The current crop of Lipos are much more stable than the early ones and as long as you look after the cells and follow the safety recommendations, you should not have any problems. I rather suspect that the reasons for fires in the early days was that people were not aware of the best way to handle these cells.

In all the time I have used LiPos I have only seen one LiPo fire and to be honest that was the fault of the user. He had left the battery on a higher charge than was recommended, gone to do something else and forgot about them. The inevitable happened and it caught fire after being totally overcharged.

Things you need to know.

Voltage and cell count.

I am not going to delve into complicated details such as the chemistry of the cells, or the construction of them as I don’t think you really need to know that to get the best out of your cells. The nominal (average) voltage of a LiPo cell is deemed to be 3.7volts but in actual fact a good quality fully charged Lipo cell is at 4.2v, sometimes 4.23v if it’s very good. The lowest you should ever discharge a Lipo to is 3.0v. That is the absolute lower limit! Below that damage will more than likely occur and this is where problems arise with scale boats mainly.
Now I’m not suggesting that scale boaters are any less careful than FE racers.
It’s just that the racers have to be into the technology to get the best out of their boats! So here’s the thing. Most scale boaters are used to using brushed motors because you often don’t need the power of a brushless, but want to use Lipo batteries for their advantages over NiMh cells. But here’s the problem, ESCs for brushed motors almost always have no Low voltage cut-off (LVC). This means it will be easy to run your batteries down to a dangerous level without you knowing. So if you don’t want the hassle and expense of getting brushless motors and ESCs and still want Lipos with your brushed controllers. I suggest that you buy one of the devices shown below (picture 1).  This a low voltage alarm that plugs into the balance lead of your Lipo battery
and makes a pretty loud noise when the voltage drops to a pre-set level. I would
suggest you try and find one with an adjustable voltage. These devices are cheap as chips and there are loads of them on
EBay. The type shown here is usually set at 3.3volts which is ideal. Final word here! If the alarm does go off DO NOT try to eke out just a little more time.
Bring your boat slowly straight to the bank and remove it from the water.
Here is a very simple explanation of what happens to a Lipo cell under load.
Assuming a full charge, the cell will be at 4.2v which will then quite quickly drop to about 3.7v for the majority of the run. Once the voltage drops to
around 3.4v it is to all intents and purposes flat and will give very little usable performance. So it is to be hoped that your ESC has a Low Voltage Cut-off(LVC).
Many are set at 3 volt, I prefer to have mine at 3.2 volts so if this setting can be reprogrammed on your ESC, I would suggest you set it at around this value. Many of the cheaper brushless motor ESCs and virtually all ESCs for Brushed motors have no LVC, so avoid these like the plague. (See
Above)

Capacity and charging

The capacity of a battery is basically a measure of how much power the battery can hold. Capacity is measured in milliamp hours (mAh). So if you seensomething like 5000 mAh as the battery capacity, this is telling us that the battery can support a discharge of 5amps (1000mAh = 1 Ah) for one hour, 10bamps for 30 minutes, 20 amps for 15 minutes and so on. In fact, all this is never going to actually happen! As soon as you apply a load to that 5000mAh battery, the actual capacity is going to reduce. To make matters worse the more load you put on the battery will mean that the actual capacity will reduce in proportion. However, assuming the battery manufacturers’, or the battery resellers’ honesty, the stated capacity is a reasonable guide.
Now we come to the other part of that capacity figure, the charging rate. This is the same as the capacity. So that 5000mAh battery (5 Amp) should be charged at 5 Amps. Some suppliers will say that their batteries can bencharged at 3 or 4 times the capacity rating. Take no notice, DO NOT be tempted! Always charge at the Capacity rating for best and safest charge.

Another thing should be aware of is the ‘C Rating’. This just a measure of how much current the battery can safely provide on a continuous basis.
The C rating is arrived at by multiplying the capacity (5000mAh in the example used previously) by the ‘C’ number printed on the label attached to the battery. It could be anything from around 25C, 40C, 60C up to 100C plus. Take 60C as the example: 60C x 5 amps = 300amps. So that 300 amps is the maximum safe continuous current that the battery will supply. Once again this a theoretical figure and won’t hold up in actual use. As previously mentioned, as soon as that battery is under load, the actual capacity will reduce and so that calculation goes out of the window. You may notice two C ratings on a battery label. One is the normal C Rating the other (the higher one) will be a ‘burst’rating. The burst will probably allow for perhaps 20 to 30 seconds at that higher rate.
Now unfortunately manufacturers are sometimes a bit ‘liberal’ when it comes to rating their batteries. So it’s not unheard of for the quoted C rating of a pack to actually be the burst rating which is a bit naughty and often why packs destroy themselves when operated continuously at, what is in effect, a much higher rate than the pack can handle.
As previously stated, batteries will experience a reduction in capacity and voltage under heavy load and a battery with a higher C rating will give you greater head room. Here is a simple example. A 20C 5000mAh battery should be (at least in theory) provide a constant 100 amp discharge. In practice it will probably be less than that. So if a motor draws 40 amps that is 40% of the theoretical maximum the battery will support. So if you use a 40C 5000mAh battery the same motor would only draw 20% of the maximum and would therefore stress the battery less than the previous example. This means of course that the battery would be able to maintain the 40 amp discharge for a longer period, but given a fixed running time the battery should perform well for a longer period,
i.e. its service life will be longer.
This is of course the basic premise behind the design and use of Limiters for Fast Electric racing!!
Of course you need to consider the power draw your motor has when picking out the right C-Rating for your battery, but does more equal better? Well, yes it does for the battery’s life, But, there is also a tenuous correlation between the C-Rating of a battery and the internal resistance of that battery. In general, batteries with a higher C-Rating also have a lower internal resistance. Obviously this isn't always the case, because there are always variables in the manufacturing process, but in general it seems to hold true, and a pack with lower IR, all else being equal, will allow a model to go a little faster. This is because, simply put, the lower the resistance, the less restriction the battery encounters in delivering the needed power

So to be clear, it's really the internal resistance making a battery perform more efficiently, not the C-Rating.
Also interesting to note is the fact that some of the newer batteries on the market are including the Whr
Watt hour) equivalent of the C- Rating on the label. Such as this Redzone racing battery.(21.6 Whr)

Internal Resistance (IR)

This is the last detail I will give you about LiPo batteries, other than the safety guidance. But it is a very import detail and one which surprisingly few people seem to consider when buying, or even talking about Lipos. The manufacturers don’t print the IR on the battery label. That's because the internal resistance of abattery will change over time, and sometimes because of the temperature of the cells. I’m not going into the calculations, but as resistance is involved you need to know Ohm’s law.
Simply put, Amps = Volts /Resistance. Even more simply put it means that the higher the internal resistance in a cell, the less current it can provide and also the output voltage will be reduced. Although you can use Lipos without ever knowing the IR, it is important that you know it, because this is a good indicator of the health of the battery. Better yet if you can find out the individual cell resistances.
So what is a good IR? I think that anything under 10mΩ per cell to be great cell condition, 10mΩ to 15mΩ to be fine, 15mΩ to 20mΩ to be old and it’s probably best to use these for practice or fun running. Anything over 20mΩ to be “time to retire”. But if the cells are in good physical condition you could maybe use them in a scale boat drawing less current than in a race boat.

Testing for IR

Some battery chargers on the market will include an IR testing function. Most of these will give individual cell values, some possibly only the pack IR. Even that would be useful as it could still alert you to a failing battery. You can purchase stand-alone IR checkers and these would be a good piece of kit to have.
If you can test IR, my suggestion would be to test new cells as soon as you get them, then record the figures. Test the cells regularly and keep recording the results. That way you can easily see signs of the battery starting to age. At the end of this article I will be giving you hard and fast safety rules, so read on please.

Battery Chargers

Most chargers are very comprehensive these days and will charge virtually all rechargeable batteries you are liable to use in a boat. Including of course NiMh cells and Lipos.
Excellent mid priced chargers that have individual cell IR readings are available.
My first point is not to go cheap. Really cheap chargers are a total waste of money. But that doesn’t mean you have to go mad and spend a fortune.
See what others are using to charge their Lipos.

I would suggest a charger that will charge LiPo batteries from 1 to 6S with a charge rate of up to 10 Amps at least. Buy a charger that will have a storage charge facility as Lipos need to be stored at around 3.8v if left for a prolonged period.
Some chargers will measure internal resistance. Often this may not be very precise, but it can still be useful for monitoring the health of your batteries over a period of time.
The functions you really need are, Balance Charge, Discharge and Storage Charge. The other modes may be useful but those three are the ones you need.
There will be one mode that I would especially advise you not to use unless you are charging NiMh cells. This is ‘Fast Charge’. This mode does what it says, but does not balance the cells in the pack. Which is not a good idea with LiPos.
Skyrc T100 Lipo Charger. Good mid priced Dual charger It’s a good idea to get a couple of these.

Lipo safety bags will contain flames long enough to get rid of the bag to a safe place outdoors.

Everyone should have one of these battery checkers. Cheap to buy and almost essential for Lipo users
Almost the same as the one above, but these blue smart meters add IR checking to the list of functions.
Handy if your Charger does not include IR checking.

Balance charging

Balance mode is the safest and best way to charge your LiPo batteries. You have to plug in both the main lead and the balance lead, so the charger can read the voltages of all the cells, and can then automatically balance the cells during charging to avoid problems.

Storage
The Storage charge mode is also important as you should leave Lipos at storage voltage when not in use for a while.

Number of Outputs/Channels
Most chargers are single output, which means only one battery can be charged at a time. A charger with more than one output can charge several batteries at the same time. As each output acts as a self-contained charger in its own right, you can charge different batteries regardless of capacity, voltage level, cell count and even different cell types. They are more expensive, but more flexible and will make charging faster if you have different types of batteries.

How to Choose a Power Supply
Some chargers have a built-in power supply that allows you to power them directly from an AC wall socket and some have the facility to be powered by car batteries.With this type of charger if you want to be able to charge easily in the workshop you will have to purchase an external power supply (PSU) which will provide that voltage when under load.
The rated output of the PSU should be well above the power demand of your charger if you want to get the most out of it. For example if you have a 100W charger, you will need a power supply that is rated higher than 100W. The more headroom’ the better really as it won’t damage your charger and it’s going to be more future-proof in case you later get a more powerful charger.
Finally, as I explained earlier, Internal Resistance of the cells/battery pack is important. So if you can get a battery charger that has this function, even if it only provides the overall IR of the battery and not the individual cells, it is a good function to have and a good way to check the health of your batteries.

Safety, Do's and Don’ts

Do
• Only ever use a charger specifically designed to charge Lithium Polymer cells.
Failure to do so may a cause fire, which may result in personal injury and/or property damage.
• Make sure the correct voltage and the maximum current does not exceed the stated charge rate (normally 1C). If using an automatic charger, check that it has detected the correct number of cells. Check it again through every stage of charging. Do these checks for EVERY charge. .
• Check the voltage of your LiPo pack before charging with a voltage checker that plugs into the balance leads. Only charge if it is 3.30V or greater per cell
(e.g. 9.90V for a 3S pack).
• Only charge in an isolated area away from other flammable materials and on a non-conductive and non-flammable surface.
Use a fireproof container such as a ‘Lipo Safe’ bag or a lidded tin.
LiPo battery fires cannot be extinguished. If a fire occurs, contain it by covering it with sand or a fire blanket until it burns itself out.

ALWAYS
use the "Balance Charge" setting on your charger. If your charger does not have this feature then don't use it and invest in one that does.
• When connecting 2 packs in parallel always make sure they are from the same manufacturer, have the same capacity, are the same age and type and that there is a voltage difference of 0.03V or less, otherwise the higher voltage pack
will discharge into the lower voltage pack, which may cause a fire. •
If you plan not to use your LiPo cells for an extended period (more than 4 days) then use the "Storage" setting on your charger. If your charger does not have this feature then don't use it and invest in one that does.
• Ensure connectors are insulated correctly to prevent short circuit in handling
or storage.
• Always check that batteries are physically and electrically undamaged before charging or discharging.
Don’t
• NEVER leave charging batteries unattended and keep all batteries out of the reach of children.
If at any time you notice a cell "puff up", disconnect it immediately and cover it with a fire blanket, or put it in a non-conductive container and place it outside away from all flammable objects for at least 30 minutes as chemical reactions can take this long before a fire starts.
• Don’t overcharge or charge LiPo batteries at higher than the ‘C’ rate. This may well damage them and possibly cause a fire. (Above 4.20V per cell is considered overcharged)
• NEVER use water to try and extinguish a LiPo fire. Water acts like pet-
rol on a LiPo battery fire.
• Do not charge LiPo batteries in the model as you cannot successfully monitor and move them quickly if necessary.
Do not charge LiPo batteries in a vehicle or in the engine compartment of a vehicle.
• Do not carry LiPo batteries in your pocket. They have been known to short against coins and keys and cause fires.
• Do not puncture the cells as this could cause a fire.
• Do not place LiPo batteries in a fire.
• Do not short the wires of your LiPo battery. This is very dangerous and can cause a fire or even an explosion.
• Do not store your cells in a hot place (i.e. in your car on a hot day) as this may cause them to catch fire or even explode.

Cap packs on your ESC

In basic terms your motor pulls amps (there not given rather taken) your esc will give the motor what it asks for sometimes the esc is giving more than the battery can supply for a moment causing a ripple current.
The cap pack will pick up the pace for that moment. It's makes your system more effective and efficient.
Esc temps go down , lipos will have a longer life span .

Couplings and shafts 

When installing a new collet, just as with the drive dog & strut, leave a small 1-2mm space. At the same time, you want to make certain that grub screws are fully seated on the flat of the motor shaft, so the collet can't be too far out. Here's what I do: 

I insert the grub screw further from the motor to the point that the collet stops when the grub screw hits the end of the motor shaft. I note where the motor end of the collet is, loosen the grub screw, and slide the collet back by whatever the grub screw diameter is, plus an extra 0.5-1mm, then lightly re-tighten that grub screw. If the cooler can go back a little further, that's ok...as long as there's still a space between the motor & collect. Next, the other grub screw gets installed/tightened using threadlocker. Once that grub screw is tightened, I under the first, apply threadlocker, and reinstall/tighten.

Something I've had a few others tell me they do is that they also slide the flex shaft up the stuffing tube, and into the collet, before tightening the grub screws, which helps to make certain the collet is perfectly straight on the motor shaft. Personally, I haven't tried this...but, on my next collet swap, I'm going to give it a try, to see if it actually helps.

Building models from Scratch Tips