sail winch replacement

[glenn meekcoms]

We have an every growing fleet of DF's currently numbering around 15 in our club. There have been several winch failures, including one which lasted less than 10 mins on its first sail & have heard of many others suffering failures. Whilst I am the first to defend the strict rules of the DF class to keep everything fair, I wonder if it isn't about time the rules were changed to allow different winches to be used? Perhaps the same rule as the rudder servo could be used, i.e if it fits in the hole you can use it. Looking at the specs of the winches for this size they all seem around the same speed & torque, so appears no advantage would be gained. At around £30, replacements winches are not cheap, especially when alternatives are around half that price.

I did hear Mike Weston say he was looking into alternatives, as he was aware of problems with the winches, & appreciate it takes time to evaluate them. I was just wondering what the general opinion of the other skippers was?

Glenn

[tony...@elmclose.co.uk]

Hi Glenn

I have just completed testing the sw4805-1.5pa servo from Component Shop. It is the same as the existing Dragon servo except that the drum/housing is different. Full details found rg65.co.uk/controls.html.
The photo on their website shows the existing black high 20mm drum used in the Dragon but they supplied the newer version with a white low housing and 25mm drum.
The 2 turn servo from Howes Models looks the same but would not be permissible.

I have been selling this style of drum/housing for the last 2 years on 4 and 6 turn servos from the same supplier with only a 6% failure rate. I invented the term "Captive Drum"
The old style housing (20mm drum) will fit onto the new servo with a little force so no mods are necessary to the housing tray.
If you fit the new housing (25mm drum) you will need to cut the top of the wooden tray as the top of the housing is exactly level with the ply.
The new Dragons Mk3 have a plastic servo tray, has this been done to support the new 25mm drum/housing servo sw4805-1.5pa?

Comparisons.

1. Using the larger drum does reduce the sheeting in time from 2.5 to 2.2sec at 0.5kg sail load which is insignificant when compared to 0.4 sec for my digital version. (Note the box gives 0.7sec/360)

2. As all drum servos reduce speed as the load is increased, it is good practice not to use them below a 20% speed drop. Never below 40%. All my data is banded by speed drops. 0.5kg load is used as a guide to the sail sheet upper limit load.

3. You will note the stall torques measured 1.5 and 1.9Kg.cm bear no relation to the 6.13kg.cm on the box. This is common to all drum servos.

4. You may not be aware that all drum servos do not pull fully back in under load. Both drums give a shortage of 7mm at 0.5kg load.

5. The current ratings are similar 0.3A at 0.5kg load.

Hope this helps

Tony

[David Foster]

Tony.

I wonder which of the words "Do not plug your commercial website on the Forum" you repeatedly have trouble in understanding?

Apart from that, the suggestions you make are misleading. Whilst it is quite possible to do what you suggest and fine if you have no intention of ever racing, your suggestions make the boat 'Out of Class' as far as racing under the Dragon Force Restricted Rules (v1.3) currently allow. By commenting on the fact that the Howes 2 turn servo is illegal, you are implying that it is legal to use the Component Shop 1.5 turn servo if you use 'a little force' to fit the original winch drum. Your comments about using the larger drum, or your digitasl servo that you just happen to sell are also misleading.

It would be better if you didn't suggest illegal modifications in a forum that is intended for Class compliant boats/subjects, but if you are determined to post suggestions of modifications that take the boat out of Class, then please state the fact clearly.

I am sure that one or two winch servoes have failed for no obvious reason, but the only ones I have come across have either been wet because of a sinking or partial sinking, or as a result of the boat not being left open to air when not being used. I accept the servos aren't the ultimate in water-proofed equipment, but can you really expect them to be when the whole boat, complete with radio costs not vastly more than a top quality winch servo for a larger racing boat!

My boat has been sailed for somewhere between 4 and 5 hours a week for well over 8 months (certainly well over 120 hours actual use, in all sorts of conditions) and is still on its first winch. The steering servo failed a few weeks ago for no obvious reason, but that is the only problem I have had with servos.

All the talk about stall values, speed etc is totally irrelevant if you wish to keep your boat compliant under the v1.3 rules, where all you have to do is use a servo supplied by Joysway. In any case, far and away the most important point is to spend more time sailing and become a better sailor. The speed of the winch is only really an issue if you weren't thinking ahead and anticipating what was going to happen before it actually happened. Winches can actually be too fast, resulting in over-controlling if you aren't careful!

David.

[tony...@elmclose.co.uk]

Hi David.

My basic objectives with my posts is to educate and to reply to Glenn's question. I am not plugging my site only my vast knowledge on these servos. The profit margin on these servos are so low as not worth selling.

You will get 5 - 10% failure with these servos.
Component Shop sw4805-1.5pa must be legal as it is exactly the same servo as fitted by Joysway. Howes sw4805-2pa is not the same therefore not legal.

I pointed out that the two drum/housing are interchangeable so the user can decide which one they want to use and why. Benefits/disadvantages.

The new versions of the Dragons open up some interesting questions.
The "Captive Drum" winch servo now comes with a low height drum/housing. Please confirm that it now has a 25mm drum diameter. If so, this is different to the original spec of 20mm in the restrictive rules. It does have an advantage as it gives a longer sheet travel making sail setting easier with the Joysway Tx/Rx. It does make sheeting in a little slower and makes it work harder.

I have been told that the slide switch has been removed from the deck side to a piece of wire exiting between the sail sheet/rudder rod bellows. This major modification now legaleses my positive action toggle switch positioned just in front of the rudder.

Tony

[Joanne Sharpe]

Hi Tony,

I must say that I agree with David, with the one caveat; that we are discussing a DragonForce that is to be raced under the Restricted Class rules.

You say in your post:

"Component Shop sw4805-1.5pa must be legal as it is exactly the same servo as fitted by Joysway". This is not true and obvious to anyone who has read the rules ...

B.1 Sail Winch

The Sail Winch shall be supplied by the Builder. No sail winch shall be modified electronically or

mechanically from its factory default performance torque, speed or revolutions, except for those

adjustments available through a transmitter

By definition, Component Shop sw4805-1.5pa is not supplied by the Builder ergo not legal.

I also feel I should echo David's views about misleading others, particularly new participants in this sport of ours. Posting with an air of expertise is a responsibility, not a free shot at pedalling stuff that any / all of us might sell from time to time. I have written to you before privately suggesting that you get our material Peer Reviewed before expressing such dubious opinions, but you've taken no notice. A cynic might conclude that you are not interested in being right, but merely in being heard.

And on that subject, what is all this 'Captive Drum' business? You seem to claim to have invented a cure to a problem that doesn't exist !! Look up closed loop systems some time.

Joanne

[David Foster]

Hi Tony.

You seem to miss the point every time.

If the boat is to qualify as a 'Dragon Force' it has to use parts supplied by The Builder and unmodified, unless alternatives, or changes, are specifically allowed either in the Rules, or the 'Hints & Tips' on the official website. If you use parts from elsewhere, or modify the standard parts, you no longer have a Dragon Force - You have an RG65 compliant yacht, assuming your alterations haven't conflicted with the RG65 rules, of course!

I am sitting here with one of the low height drum winches supplied by Joysway and can confirm that the drom is 20mm diameter, not 25 mm as you suggest. I also have to disagree with  your statement that the 25mm drum winch is both slower and makes the servo work harder. Work harder, yes, definitely, but slower - Definitely not. If the diameter is larger, then the circumference is also larger, resulting in more line being wound in for a given amount of rotation of the drum. Therefore, for the same amount of line to be wound in, less rotation of the drum would be required, which takes less time!

No, you cannot choose which size drum you want to use if you want the boat to remain a compliant Dragon Force, for all the reasons already explained.

As you say, the switch has been relocated inside the boat on the latest versions and is activated by a wire. I assume the reason for this is that it was possible for the electrics to be switched off whilst sailing if another boat rode up onto the deck and slid along (It has happened to me. OK, they fouled me, but that makes no difference to the fact that my boat then sailed off on its own! This change to the Dragon Force does nothing to enhance performance and, in my opinion is a well worthwhile change, but it does NOTHING to make your modification legal, as your modification does not use parts 'Supplied by the Builder'.

Incidentally, there is nothing particularly new about a winch with a cover round the drum to keep the line safe. Thunder Tiger have supplied a winch for their yachts for a long time with a cover that fits over the top of the drum to achieve the same result. The only real benefit to what you refer to as a 'Captive Drum' occurs when/if the tensioning arrangement, whatever that might be (elastic, spring etc) fails and the line would otherwise be free to foul up inside the boat. Your suggestion in an earlier post that there is no need for the elastic tensioner as the line can't escape, is only partially correct, Whilst the line might remain captive, if you want the sheeting to work in a constant and linear fashion it needs to be kept under tension.

David

[tony...@elmclose.co.uk]

Hi David.

I have been looking at another forum relating to this new winch. They say it has a single drum slot not two as previous. Is this correct?

[David Foster]

Yes Tony.

The winch servo I have here, supplied to my local model shop by Ripmax, Joysway packaged and labelled, has a single drum with a 20mm diameter. This was apparently done to eliminate the original problem of deck patches sticking to the winch drum on the earlier double drum winches.

David.

[Dave Pickett]

Just to add my thoughts on the winch situation. I have only sailed twice so far and my rudder servo has failed and I have replaced it with a savox one of similar size. It does seem the servos are a weak point but this is only to be expected at the price. Winch failure seems fairly common and to force people into buying an original at £25 rather than a supposedly identical one at £11 appears to go against the objective of making the class affordable.

Personally I would support the idea of any winch that fits in the radio tray, in a similar way as is allowed for the rudder servo. Perhaps it is worth looking at the Micro Magic rules which have proven successful within which any servos are allowed...........

I think the situation is made more complex with club racing vs National. At a club meeting you will not b turned away for making changes within the spirit of the rules whilst at a national event rules are more strictly applied - This can cause issues with people turning up thinking their boats are OK only to be disqualified.

Anyway I am sure the rules will progress as the class expands in the meantime lets continue to enjoy these great little boats!

[Gilbert Desclaux]

hello,
totally agree with you.
Why a winch, having the same size and costing € 9 will be outsized compared to a winch original costing € 29?
'google traductor)
gilbert
FRA 111

[Tony Bell]

I have at last been able to compare the Dragon Winch Printed Circuit Board and components against the available 1.5t winch servo.

Even the copper tracks and holes are identical. As the load/speed performance is similar, it has been shown that these two servos are the same except for the drum diameter. That’s not a problem as the drum and housing can be swapped over.

My experience in rigging 5 Dragons is that the sail sheet travel is critical in setting up the sails, especially the main. I found that 105mm was a happy medium allowing the sails to be adjusted correctly with the main at 90deg.

To increase the main sheet travel you move the main sheet boom attachment point towards the mast. This is problematic if the winch is only giving you 80mm travel as the attachment point hits the fixed vang attachment point and will not allow 90deg boom angle.

My first Dragon used the Joysway Tx/Rx and I had to add an End Point Adjuster to get 105mm travel as it was only giving me 80mm. My last Dragon had the latest Joysway Tx/Rx and this gave me just enough travel to set the main at 90deg so avoiding fitting an EPA.

Why?

Variables

Each servo has a different sheet travel varying from 97 to 110mm @1.0ms PWM range. 20mm dia drum. (batch of 10 tested)

Receiver outputs vary for different manufacturers. (channel 3)

655us for 35hz Skysport to 1026us for 2.4Ghz Multiplex Light

This gives a possible travel range of 60 to 110mm

To show how different Tx/Rx and servos alter the servo sheet travel.

Joysway Tx/Rx versions with different 1.5t servos

Early  800us travel 77 to 95mm travel

Latest 980us travel 95 to 112mm travel

What is my point

The 25mm dia drum should be permitted as it levels the playing field for those who want to avoid the additional expense of buying a computer transmitter with End Point Adjustment.

Early  800us travel   97 to 109mm

Latest 980us travel 118 to 134 mm

It is easy to reduce the main sheet travel with a 25mm drum by moving the attachment point outwards, but difficult with a 20mm drum.

Tony