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Author Topic: Same transmitter for power and sail? Centre-sprung left stick.  (Read 1743 times)

clockworks

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I've got a few electric boats, and I've just bought a Graupner GR65 yacht to play with. Having a frustrating time putting it together (got a post running in "Yachts & Sail"), but a thought just occurred to me:


What type of transmitter do the sail guys use? Specifically, the stick configuration.


I'm using my old 7 channel Futaba T7 2.4GHz 'plane transmitter, which originally had a ratchet on the left stick (throttle channel on a plane, full down for off). Because electric boats have reverse, I took the ratchet off and added a spring, so the stick now centres. I'm guessing that is how most powered boat transmitters are set up, same as they are for RC cars.




How does this relate to using the same transmitter with a yacht?  From what I understand, the sail arm servo goes from sails fully in to fully out, so a plane-type ratchet stick setup would work better than a centre-sprung stick.


Does anyone sail with a centre-sprung stick? If so, do you just use the "stick up" portion to control the sail arm servo, and how do you get full travel on the servo?
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aeronut

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #1 on: April 29, 2019, 09:27:57 am »

I have a very similar dilemma, as I fly quadcopters, aircraft and sail boats.  Most of my boats need a self-centering throttle, the aircraft don't.  I've solved this for now by having two transmitters, one for aircraft and one for boats.  However, you may like to take a look at the latest Spektrum DX6e, which has a switch on the back to allow changing  stick types without even taking the back off.  Were I not so heavily invested in my current systems, that is probably what I'd be buying.


Gordon
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #2 on: April 29, 2019, 09:50:33 am »

That Spektrum Tx looks like the ideal choice for someone starting out. I've got a lot of Futaba gear, and it would be a pain to have to start again just for one sail boat, especially since I've never tried a yacht and might not get on with it.


I wonder how often the sail arm servo gets adjusted when just cruising around the lake?  There are a couple of options that I could try on my existing Futaba Tx:


Use the rotary knob (ch6) to adjust the sail servo. Might be a bit fiddly, as the knob is quite small.


Put a ratchet on the right stick up/down (ch2?), and sail with both servos controlled from the right stick.




I think the second option might work best, as the right stick up/down isn't likely to be used on any other powered boats - is it? Possibly not the ideal solution if I decide that I like sailing, but good enough to get me started?
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DaveM

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #3 on: April 29, 2019, 01:58:06 pm »

I'd suggest you consider buying a cheap 2-channel set - it's all you need for the yacht - and set the throttle stick to ratchet (if it's not already set there). I've heard a good report of this one https://howesmodels.co.uk/product/absima-sr2s-2-4ghz-2-channel-stick-radio/
DaveM
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malcolmfrary

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #4 on: April 29, 2019, 03:00:20 pm »

Having a stick that doesn't always want to set your sails half way out is good, as is deciding on your sail setting and being able to take your thumb off the stick, rather than feeding it a setting then having to concentrate on keeping it there.  Unless you are running a non-proportional winch control.
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #5 on: April 29, 2019, 03:29:03 pm »

If I decide that I enjoy sailing, I'll get a second transmitter - and make sure it has a ratchet on the left stick.


I was speaking to a friend who is into his RC yachts earlier, and he has a spare basic radio set that he will let me use to try my boat.
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roycv

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #6 on: April 29, 2019, 04:17:38 pm »

Hi just a thought, I have several (7+) yachts and always use a ratchet, remember stick towards you and the sails are tight in. But make sure the servo adjust on the transmitter when fully down is not going to break anything.

 If you use a centred stick then the position of the sail servo will be hovering at the general setting you want but also receiving the odd twitch from your hand and so the servo motor will be constantly adjusting and using extra power in doing so.

If you need a physically smaller sail servo lately then lately I have been using a 'cheap' metal gear servo that will rotate 170 degrees, most will, with a servo stretcher to give you most of 180 degrees movement.  I found a UK made piece of electronics the size of a pair of servo plugs that sits between the servo and receiver and does the job nicely, no adjustment though.

I pay less than 4 for a 10 Kgrm pull per cm servo and 8 for the stretcher and you have a small sail arm servo.  Howes do some small rotating drum servos about the same price.
regards
 Roy
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #7 on: April 29, 2019, 04:21:47 pm »

That's something to bear in mind if I buy a cheap radio without adjustable endpoints.


If only I could figure out how to rig this thing - instructions are useless, and some of the lines aren't even shown.
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #8 on: April 29, 2019, 04:58:59 pm »

Radio problem solved - just found a 6ch Futaba Tx on eBay that will work with all my existing receivers. I'll keep that one set up with a ratchet left stick.
It's not quite as fancy as my T7 Tx, but it has adjustable endpoints and dual rates, so will do everything I need for sailing, and not too much more expensive than a cheap radio.
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grasshopper

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #9 on: April 29, 2019, 08:05:26 pm »

I was in a similar situation having converted to steer wheel radios for racing cars, had a couple of new 5 and  channel sets for flying so have dug out and using an old Acoms 27MHz 2 channel set with the centring spring removed....works for me as everyone else has gone 2.4...
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malcolmfrary

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #10 on: April 30, 2019, 08:51:30 am »

That's something to bear in mind if I buy a cheap radio without adjustable endpoints.


If only I could figure out how to rig this thing - instructions are useless, and some of the lines aren't even shown.
Rigging is generally a simple matter - you have standing rigging to keep the mast upright, and running rigging that controls the sails.  Which bit is giving the trouble?
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #11 on: April 30, 2019, 09:16:01 am »

Rigging is generally a simple matter - you have standing rigging to keep the mast upright, and running rigging that controls the sails.  Which bit is giving the trouble?


Basically all of it. Problem is this is my first yacht, and I didn't have a clue about the end result I was trying to achieve - how the sails/booms should move, how far they should move relative to the servo arm and each other, and what stopped the whole rig falling off.
The poorly translated and badly illustrated instructions just confused me, although they would probably be sufficient for an experienced sailor to work from. The most helpful thing was the pictures on the box, but even those were spoilt by having bits missing.


I found a diagram on this forum yesterday that explained the basics of yacht rigging, and the Dragonforce 65 instructions that were suggested on my other thread have filled in most of the blanks. I will have another go at it later today.


From what I can figure out, I need to tie the top of the mainsail to the front end of the backstay arm, then run the line to the end of the arm and down to the eye on the back of the deck. That will hold the mast in place and brace it.
The bottom corners of the mainsail are tied to the boom. One of the lines runs back to the middle of the boom, through a guide on the centre line, and then to the line (sheet?) that's connected to the servo arm.


The fore sail is hung from the mast, 2 lines connect the jib to the deck, and another line runs back to the servo arm. Looks like the jib should pivot about a point between the 2 lines that tie it to the deck? Or is the front line fixed, and the rear line running? This bit isn't that clear to me at this point.


A couple of overall line drawings in the instructions would have made it so much simpler.
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roycv

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #12 on: April 30, 2019, 11:19:48 am »

Hi you seem to have worked out most of it OK.  The jib should pivot close to its front end at the bow.

 The Main and jib move in and out in parallel.

This means that the distance from the pivot points of jib boom and the mainsail boom to the place where the sail servo connection is should be equal.  e.g. if the distance from the gooseneck of the main to the servo connect point is 20cm then the distance between the jib pivot point and its connect point should also be 20cms.

It would be a good idea to have a bowsie adjustment to either jib or main boom to make some fine adjustments when sailing.
The sails with wind in them will try and lift the main boom.  There is probably a wire or string near the gooseneck connected to the deck or base of the mast to stop it rising too far, also known as a boom vang.

When the sails do fill with wind, the top of the sail will be out at a greater angle than the boom there is no point in letting the sails out too far as the wind will spill off them.
You may need to adjust the angle of the mast either forward or back to allow for adjusting the centre of effort of the sails and you should have bowsies on the fore and back stay.  You may be able to copy an existing similar yacht as a starting point.
As a point of appearance you will have several bowsies in the strings holding up the mast so try and get them all at the same level and as low down as possible.

Hope this helps,
regards

Roy
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #13 on: April 30, 2019, 12:12:01 pm »

Very helpful, thanks Roy.


It's the adjustable bits that are causing me the headaches. I've got the mainsail pretty much sorted now I think - tied to the boom at both ends with adjustments to change the slackness. Boom sheet is connected up, again with a sliding fitting on the boom for adjustment. Just the back stay left to fit - it does have a bowsie. I'll have a go at the foresail after lunch.


There doesn't appear to be any provision for a fore stay - no eyelet on the deck as an attachment point.
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #14 on: April 30, 2019, 06:45:33 pm »

Everything fitted, and seems to work as it should. Both sails move in and out together, and stay parallel to each other. I can pick it up by the masthead, so hopefully nothing will fall off.


If my spare transmitter turns up, and the weather is OK, I'll take it to the lake on Sunday, get someone else to check it over for me.


Thanks for everyone's help - I would've given up if it wasn't for you guys.
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malcolmfrary

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #15 on: April 30, 2019, 10:02:16 pm »

Very helpful, thanks Roy.


It's the adjustable bits that are causing me the headaches. I've got the mainsail pretty much sorted now I think - tied to the boom at both ends with adjustments to change the slackness. Boom sheet is connected up, again with a sliding fitting on the boom for adjustment. Just the back stay left to fit - it does have a bowsie. I'll have a go at the foresail after lunch.


There doesn't appear to be any provision for a fore stay - no eyelet on the deck as an attachment point.
This type of rig has a "virtual forestay"around the sail, two lines, one at the leading edge that keeps the front edge straight, the one at the back (luff line, topping lift) provides tension to keep the trailling edge just loose enough to give the sail shape without losing the shape as the sail swings.  These two lines fix to the ends of the jib boom, making a triangle.  A line about 25% in from the front of the boom to the deck provides the swivel.  The other line to somewhere further back is where the running line connects.  As Roycv says, the distance from the swivel point to the connection point should be near enough the same for both sails.  My personal preference is that the fore, when pulled in as far as it goes, should be a few degrees further out than the main, which in turn should not sit on the center line.
How far out should thet swing?  Stopping just as the main sail touches the sidestays is the max, but within 10 degrees of that is fine.  With set travel from the winch and transmitter combo, tweaking the geometry by moving the deck points and boom connections does the job of adjusting travel.
Looking at advert pictures, when done correctly, everything will be adjustable*, which means that you have a long and fascinating learning curve before you.  If its any consolation, the instructions for a Micro Magic are no better, a lot being left to the builders intuition.  It might be that they didn't change a lot in translation, the instructions might be just as horrible in German.

*I didn't see a third line on the bridle ring, so its position fore and aft is set.

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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #16 on: April 30, 2019, 11:13:47 pm »

Sounds like there's a lot for me to learn. First time out I'll be happy if it floats and comes back to the side of the lake when I've had enough. It actually sounds more complicated than flying.
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roycv

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #17 on: April 30, 2019, 11:42:57 pm »

You have a point about the sailing, you have to keep your eye on the boat and also ahead of the boat to work out what the wind is doing. 

Look for the ripples on the water or 'cats paws', this is where the wind is.  After a bit you get to see that if you place youself on the boat then there is a virtual or apparent wind which is a combination of the speed and direction of the yacht and the actual wind.
 i have rarely gone in for racing, just no oportunity but when I did the concentration is very real, trying to get that little bit more out of the yacht.
It is easy just to fololw the boat, so to speak but if you can put some buoys in the water you get a better idea of how to steer a course., when to tack etc.

I liked full size sailing and passed it on to my son, he is an Off Shore Yachtmaster now so I happily place my confidence in him when we are in his yacht, I am just past 80 now, so do not move about so quickly.

 Should you go on and take an interest in scale yachts then try to get yourself on a full size yacht and help crew the boat you will learn a lot.  You will also see all the extras there are on a full size yacht that are not on the models.  The easy and most pleasant way is to go on an RYA course and live on a yacht for a week, it is a great experience.

good luck with your first sail.
Roy
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clockworks

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #18 on: May 01, 2019, 07:30:14 am »

No chance of me crewing a yacht, or getting on any small boat. I don't like the water, never learnt to swim.
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roycv

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #19 on: May 01, 2019, 07:58:47 am »

Hi clockwork, takes all sorts etc.  but you are in the right place to observe yachts.  For me I like looking at a yacht sailing, and actually prefer to see my model yachts sailing than being on a yacht when sailing.  But I do like standing at the wheel and looking up 50 odd feet at the mast checking the luff of the sail to see if it is set right for the course we are on.

 Earlier in the year I was sailing with him (Australia so summer time) just the two of us and I had instruction on self steering.  Just choose the course press a few buttons and sit back with a tinny or whatever and put the world to rights.

There are little threads on the surface of the sails (tell tails) that show the direction of the wind on the sails and you can see where it may have 'stalled' or caused whirlpools of air this is where the wind is not doing you any favours.  It is all very much like an aircraft wing producing lift.  You may need to flatten the sail or adjust the tightness of the sheet.

One thing with the model yachts you may have heard mention of balancing a yacht?  This is getting the sails in the right position on the boat and set for the wind and the yacht following a course without use of the rudder.  The rudder if used to steer the boat is a small drag and slows the boat, so getting the boat balanced gives a bit more speed overall.
I have a yacht where I set the sails (gaff rig) and she sails hands off in a straight  line and being balanced like that she turns on a sixpence.
all the best.
Roy
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Hotglove

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #20 on: May 03, 2019, 03:52:19 pm »

As a rank novice to RC sailing boats, just wanted to say thanks for the helpful info added to this post.  :-))
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rickles23

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #21 on: May 03, 2019, 05:39:58 pm »

Have a look around for Model Yachts by Vic Smeed.


It deals with all things model yacht.


Regards
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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #22 on: May 23, 2019, 11:35:01 pm »

Not sure how you finally rigged for the original problem, but I simply plug the motor esc into the elevator channel ( right hand up/down stick here in the US ). The sail control is on the throttle channel ( left unsprung up/down stick ) and the rudder is in the aileron channel.  Works well for me.  Hope this helps.
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malcolmfrary

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Re: Same transmitter for power and sail? Centre-sprung left stick.
« Reply #23 on: May 24, 2019, 10:16:15 am »

A conversation last night reminded me of a useful tip from a magazine in the late '80's.  Graham Bantock had just won his umpteenth pot, and there was a picture of his transmitter.  A perfectly standard 2 channel set of its day, except that the "throttle" stick had a hinged quadrant alongside it, notched to give fully in, a bit out, half out, full out, which is all that is needed.  The stick, possibly sprung, possibly not, could be latched into any one position without looking and left there.

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