I already have some more rather basic questions about RC yachts that may help others, so I thought I’d rather put them all in this thread as I go along.
Hopefully this will keep things neat and stop me spamming the main board with threads.
It’s all rather practical but I greatly value your input.
As this is my first attempt at building a yacht as close to plan/spec as possible I have been keeping an eye on the weight.
Everything was looking acceptable (for my skill level) until I thought I would try and weigh the electronics etc.
I have these 2 questions about weight.
Electronics
The weight allowed for the Electronics is 210g.
The Hi-tec 2N transmitter I was going to use has the following weights:
receiver - 28g
Servos (hs-311 rated for 3kg) 42.81g each. I’ll use 2 so it’s 85,62g
4AA batteries (I have Orion NiMH) roughly 31g each so a total of 124g
Total Weight : 237,62g
If I put a micro servo in it will save me about 30g. That will put me into spec but what strength servo am I looking for? And do I need a fancy one or can I get a cheaper, no bearing, nylon gear option?
Could I not use 4x AAA batteries instead of the 4x AA? That saves me 64g. What are the implications of this other than weight loss?
I have found my AA Orion 2700mAh batteries last forever on my RoundRanger so I’m assuming runtime wouldn’t be a huge issue?
I don’t race and this is my daughters boat so if we get 30 - 60 minutes of runtime that will be fine.
If those 2 options are viable it will give me an extra 102.81g which seems massive to me.
The Bulb
The Bulb weight is specced at 500g. I bought myself a huge 600g lead weight from my local fishing shop and shaped it with a rasp and got it to 500g.
My question is this… If I get everything built and I am overweight, is it better to have a boat that is overweight, or does one shave more weight off the bulb and make it lighter and thus in spec? Which is the lesser of the evils?
I am aware that Im not racing so it’s a mute point really but I just find these kinds of things interesting
Hi,
I do not know where you picked up 11kg for a rudder, but in any case, here below a typical Weight Budget for an RG65 of 1050g total displacement.
Of course if the available total displacement is lower, you need to reduce the weight of the construction and at the end reduce the Bulb weight.
The general assumption is to have a Bulb that represent as minimum 60% of the total weight.
eg, if the total weight is 950g , the bulb should be 570g but the full construction shall be kept within 380g and this may be difficult to achieve. This is not a strict rules of course but better to stay as close as possible !
And to clarify once again, I’m only logging this so if anyone else is worried about trying a scratch build they can see that If I can do it, any eedjit can
At this point it is weighing in at 895g without the deck. I am thinking I’ll use 1mm balsa with what they call “Surface matt” out here.
It’s a very lightwight fibreglass I had lying around and used on the hull - it seems to work quite well. Weighing 3mm balsa added 15g so I am reckoning I can easily get it within 30g using the 1mm glass/epoxy.
Silly things that I have found out so far to avoid for the next build…
The rudder:
I got my wife to enlarge the image to 1:1 and cut out the shapes. In my infinite wisdom I used 1mm ply and made the grain run vertically on one side and horizontally down the other.
It took the correct, foil shape on the vertical side and is as straight as a ruler on the other side… hindsight is awesome.
I also have some play on the rudder post inside the tube. I have no clue how it happened and I’m not sure if there’s a way to do a fix?
KeelFin:
I rushed and it has a warp to it
Electronics:
My sheeting servo is horribly underpowered apparantly. I need to get a more powerful one. The stock unit is only 3.8kg so I shall be searching for a new one.
I pondered using the winch from my Round Ranger but that was double the weight, so as this was a lesson in weight I’m skipping that for now. Possibly if the more powerful servos are heavy I shall revert to that.
Sheeting…
Can someone please chime in here. For the mainsheet, i have made a servo arm that gives me just under 9cm of sheet travel. I was going to make the sheet line come out on the deck at the point that allows the boom to swing out to 90Degrees using my 9cm of travel. this doesn’t necesarilly co-incide with the plans’ attachment point on the boom. I cant think that this would be a problem but am I missing something? Surely the only thing to watch out for would be the amount of power needed as I’m moving the attachment point closer to the fulcrum? And Make sure that the Jib has the same changes made?
So far I’m happy that I’ve improved since my last attempt.
I really need to take more time in the “fin building” stages. Those are less than satisfactory but I’ve decided to just keep going. I don’t race at all so this is just really fun for me - and my daughter has now moved on to saying that she doesnt care, she just wants her boat. Can’t argue lol.
Here in attachment the classic Servo Arm circuit. You need an anchoring point and one pulley on the arm. Some use a simple eyelet screw .
With that system you double the sheet length.
You can play with the arm length and with the degree of swing in order to get the right length you need.
This operation can be drawn on a paper to scale 1:1 before do some hardware work. Little detail the pulley, if used, consume the equivalent of half circumference, so this need to be taken into account. Further you need only to open the main boom at 85° max. Please avoid to use ‘sir’, I’m not ! heheh!!
ClaudioD
If you haven’t already done so - visit the AMYA website and download the three parts of construction info. Although it is a 1 meter, much of the info is relative to many other size of boats. Here is the link that will probably answer many general questions - but not necessarily CLASS questions. http://www.theamya.org/boats/us1m/us1mcons.php
If you are building an RG65 - I have used a Hitec HS645MG arm servo for my main and jib sheets. At 6 volts, it is rated at 9.6kg/cm Before you go and buy a different servo - try running alkaline batteries in your receiver. If you are using NiMH batteries, you are only getting just over 4 volts. (4.8 V) you may find with a bit more battery, your winch will be OK - but the Orion is not carrying the same sail area as an RG65 (not a Dragon Force).
Since there are no minimum weights for the RG65 class, why not build and get all things sorted out (sheeting, foils, rudder, mast/booms, etc.) and get it sailing. You can then build to a lighter weight. If you are weight conscious, skip all glass and heavy wood, build with very thin and light balsa, and coat inside and out with good, MARINE GRADE epoxy.
I was unaware of the voltage difference between the alkaline and niMh.
And so far I have used 1mm balsa and the epoxy I had available. I am amazed at how strong it is. There is definitely more give in the styrene hull of the round ranger. But that could be due to the lack of the stringers on that?
And I agree about the need to get it going now:)
I just need to epoxy up the hatches (which will be held on via tape) and glue the deck down and finish things off.
I weighed it at 980g but that excludes the final rigging etc.
I have used AA batteries to help balance out the boat, I got something wrong somewhere and needed some more ballast to get the bow down a bit.
Things I’m chuffed with…
When I cut the deck, its almost identical if I flip it over so the hull is relatively symmetrical - small wonders will never cease
My friend got a 3d printer. So I used Sketchup and got him to print some bits for the mast attachments for the kicking strap and some boom bits. None of the bits are glued yet.
The bulb ended up pretty well shaped I think. It’s a big fishing lead and I just rasped away at it measuring the weight as I went. I now have lots of shavings to use as ballast for future things.
But most importantly… I’ve almost finished building a yacht from scratch!!
The sails are rather ruff and rugged but I just need to put in the holes and finalize how to do the jib luff easily for this first set (questions incoming soon)
Thanks for reading and all the guys who design/do the involved build logs. Its appreciated.
If your images are the attachments - you need to save the images in a personal file or an off-line site since a URL is needed if you are trying to insert ----then select and attach. Don’t forget to include the file type also.
Add an Image from Url Allowed Filetypes: jpg, jpeg, png, gif
Dick: yes, but the server will delete the file after some months… look at older threads…
What I do is that I upload photos on flickr, and then post here using the image URL.
flickr saves them forever.
If I recall correctly I got logged out as I replied, so that’s possibly where the issue came in.
I did the same operation now and its all working. oh well
Thomas, - good point. I haven’t noticed the files dropping off, but will forward your comment to site owner to see if by chance an older “library” can be loaded and made accessible.
I have 2 different exits for the sheeting to the jib and main which is wreaking havoc because they now appear to have different ratios - that’s why all the plans etc. have them exiting at the same place… DOH.
The sheet exits are snagging the line as they are vertical and extend beneath the deck… DOH.
Kicking straps are tricky lol.
Kicking straps stop the boom lifting up as the wind hits the sail and pushes it out (obvious once you’ve seen it happen but I was always a bit unsure on that point)
I used a Scrap-booking eyelet gun that crimpled the sails.
Please excuse the Electrical tape, it works well and I’ll get nice vinyls cut.
As you will see the sails are completely out of whack with each other I twiddled with the jib pivot point and got things better but there is much to be improved on in that regard - Any pointers will be appreciated.
But my daughter and I are having a blast anyway and when the wind picked up things went very well and it motored accross the pond.
It might be the angle of the photograph, but the bottom tip of the rudder “looks” like it extends beyond the transom. Might want to check and review - especially if you want to race the boat. If not racing, don’t worry about it.
