Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Yachts and Sail => Topic started by: Netleyned on June 23, 2014, 10:02:24 am
-
A club member who is not on line has recently bought a Moonbeam.
The sailwinch was faulty so he rerigged it with a sail arm.
Although using a Hitec sail arm servo it doesn't have the power
to pull in the mainsail.
Has anyone got a copy of the sailwinch setup as it is missing from the plans he has.
An emailed scan would be fine.
Ned
-
No one on MBM built a Moonbeam then?
Ned
-
I've never seen one on a thread Ned, so might appear as the answer is No. sorry.
neil.
-
Hi Neil
There was a thread where someone changed the winch for
a sail arm.
That's what this guy had done.
The arm will not pull the mainsail in.
He needs to go back to a winch but I would like
to see the original setup.
He is offering to pay me but I don't want that.
Every time he had a problem he would be back
to me >>:-(
Ned
-
hi ned ,
there is a build by dave abbott on model boats site, sorry I cant do links . hope it helps
david
-
trying to do a link but no good sorry
-
try dave Metcalfe for a plan...sure he could help...if its the boat im thinking of it was at brians open day and he bcame over to inspect....tony
-
Hi Ned
I am currently building a Moonbeam. The design uses a loop sail control system with the winch installed towards the stern of the boat. The control loop runs from the top winch drum rearwards to a pulley attached to the rudder servo mounting, then up to a pulley in the bow and back to the lower winch drum. The running rigging to the sails is attached to the loop and up through deck fairleads. The critical dimension is from the front pulley to the winch drum which needs to be at least 300mm so that it can have around 260mm travel on the running rigging. Unfortunately Dave Metcalf's plan is too big for me to scan, but I can have a go at doing a diagram if that would be helpful.
Rog
-
I am guessing this is the same boat mentioned in this article?
http://www.modelboats.co.uk/news/article/moonbeam/4457
If so, it is a large boat (1320mm / 52 inches long) - an arm winch would be totally impractical for something that large in anything but very light conditions.
In my opinion, if it needs 260mm of travel (as mentioned by RogerB), this would be impractical to achieve with an arm winch, even with double or triple haul to result in both sufficient travel and sufficient torque.
I would think the loop winch setup mentioned would do the job. Here is a video of a smaller (800 mm) boat with a similar setup that may help from a mechanical point of view... This boat was modified for another reason - the jib sheet kept catching below deck with the original setup.
https://www.youtube.com/watch?v=JWhI3F_MY74&feature=player_detailpage
-
Thanks Roger and Mr P.
I have done a drawing of your plan
[size=78%]Roger.[/size]
Just one question, does the drawing mention any kind
of tensioning i.e. a spring in line to keep the lines from
coming off the sail drum?
Hi Slug,
Correct :-))
Thats the one.
He tried it out with a T7 radio at home and the radio must have gone into failsafe on switch on.
The drum just spun to its limits and was then ripped off,
Thats why he went the sailarm route.
He is not the easiest of guys to point out his errors to as he does exactly the same next time at the pond.
Whatever advice he is given, he modifies it, gets it wrong and then blames the advice.
I'm sure every club has one {-)
Ned
-
Hi,
If a lever arm will not pull the main in you might consider using a pulley on the lever arm itself.
Something like a Pekabe (?)
Regards
-
@NetleyNed:
From my experience there should be no need for a tension spring in the loop. The loop tends to go a bit tight at both ends of the travel as the loop line piles on the drum and is a little slack in centre of travel but should stay in the drum ok and will stay on the pulley on the other end of the loop unless the pulley has a very shallow groove. If you use a pulley with a sheave as in the example video I posted it is not a problem.
-
netleyned some of our club members tried to point out a few things to him...a nice boat all the same...we have a member with one and he uses a planet tx and on the sail control on the tx he has taped a restrictor so he cant use the full throw of the lever....seems to work o.k tony
-
Although the original design hasn't got a tension spring, I have put one in on the bow pulley on my build. I tried without a spring with some thick(ish) cord for the control loop and it was too slack in the middle of the travel. The spring made it better. I subsequently changed the cord for some thinner nylon covered wire which makes the whole set-up run smoother. On reflection a spring is probably very desirable with a wire loop as there is no elasticity in the wire to even out the slight changes in tension as the loop winds on to the drum (as posted by MrP )
Regards
Rog
-
Hi, I have a Moonbeam yacht bought second hand on EBay, it is fitted wit two Hitec HS_765NB servos for the mainsail and the two fore sails. The mainsail is sheeted about a third of the way along the boom from the mast and appears to work satisfactorily.
I had problems setting up the mast at the pondside so altered the mast case so that is was through the deck and resting on a mast jack, this allows me to set up the mainmast and top mast and then raise the whole mast by about 1/4 inch.
It seems funny not having backstays on the topmast, has any one fitted these?
Regards all Les
-
Hi Ajax,
Could you post a picture of the rigging?
Several of my yachts do not have backstays.
Regards
-
The Peak of the topsail is higher than the topmast so a backstay cannot be used.
The after pair of shrouds are led aft of the mast for support from aft.
In real life a yacht with a boom too long to allow a backstay would be
rigged with a runner going aft each side and on going about the windward runner
would be set up and the lee runner slacked off.
Ned
-
I have never had anything to do with the Moonbeam but my J Class has a neoprene O ring about 30mm diameter tied in to the main loop. With just slight tension on it at the loosest part of the travel it has enough stretch to allow for things tightening up at the ends of the travel. All this is mounted on a board under the deck with the winch at the stern end and a pulley at the bow end. Sounds like if you need 260mm of travel then the distance between winch and pulley needs to be about 280mm. The sheets for the sails are attached to the loop at the O ring but go out through the deck through two differnt small copper pipes. Each sheet moves the same distance but you can vary the travel of the sails by varying the position it is clipped to the boom. Hope this helps, Ian.
-
Thanks Ned for the reply, my mistake I should have said runners. The after stays are to the mounting on the mainmast and I have noticed the two forestays are less than tight
Regards Les
-
I am not familiar with the Moonbeam. Is the mast stepped in the deck or keel?
If the mast is stepped to the keel, then the shrouds are largely for scale appearance. They will stop the mast and sails from lifting out, but provide little lateral bracing for the mast. Most of the lateral support comes from the deck. The mast will flex very little, and effect of scale perhaps. On most scale models the back runner/stays are omitted, or made of elastic so that they can be pushed out of the way.
-
Hi Tigert.. Moonbeam has the mast mounted on the deck but when reviewed in MMI magazine John Cox recommended taking the mast down to the keel. If I were building her this is what I would do as well, clearly the mast has to be made longer to accomodate.
In doing this it does not make the shrouds redundant, it just makes the mast a bit stiffer when under wind pressure and the yacht easier to assemble at the pond side.
regards Roy
-
Hi all,
I would presume that there is a fixture between the underneath of the deck and the keel if the mast were deck mounted?
It is this way on our Marbleheads and I have never had a mast slip yet.
Regards
-
On my Moonbeam, the mast fits into a U shaped metal bracket on the deck, and a retaining pin goes through the bracket and the mast itself.
Pulling the pin out, and releasing the sail connection at the bow allows the mast to fold down flat
-
On my Moonbeam, the mast fits into a U shaped metal bracket on the deck, and a retaining pin goes through the bracket and the mast itself.
Pulling the pin out, and releasing the sail connection at the bow allows the mast to fold down flat
Is that a tabernacle arrangement?
-
Pretty sure thats what its called used to have one on my old Y2k
-
There is nothing impractical about replacing the winch with a sail arm. I have done this mod on 2 Moonbeams and have had satisfactory results with both and they sailed like a dream! I admit the arm is not as powerful as the winch but it will do the job and unless the wind is very strong it sheets the main in easily. I found access very difficult when trying to replace lines that had broken prior to my purchase. It is a nightmare trying to work the rigging lines through the tiny hatches, hence my use of the sail-arm which is much easier to install, albeit at a loss of some torque. Moving the rigging-point on the main boom a bit further aft gives a bit more 'leverage' and assists sheeting.
https://www.youtube.com/watch?v=hsQCWU5IreQ&feature=youtu.be
Bob.