sail arm or winch?

[Jim Masson 1Participant @jimmasson1]

I am reviving an interest in model boats and I hoping to soon start building a Thames Barge which due to size constraints I need to build at 1/32 rather than the usual 1/24. This will be my first attempt at remote control sail (I've only built one other r/c boat, many years ago) and I would be grateful for some advice so that I know which set-up to plan for in the build.

I was initially thinking of fitting a sail arm but on browsing Howes Models web site the arms seem to be about 12cm long. Given the scale of the barge I have a feeling this size of arm is likely to be too big for fitting in the hold. If so would performance be affected if it was replaced with a smaller arm or would it be better to use a sail winch instead?

If so I am a bit confused as to the choice. Howes have 2 and 4 turn winches with the option of using a drum shroud and another which has 3.5 turns of travel. How do I determine which would be best and whether to use a shroud? From my, so far, limited reading on the subject am I correct that the set up would be a continuous loop of dacron from the winch to a pulley situated below the forward hatch to allow for access?

A novice would very much appreciate any tips.

Jim

[Jim Masson 1Participant @jimmasson1]

[Gareth JonesParticipant @garethjones79649]

Hi Jim,

I have fitted sail winches in a few yachts now and eventually will have to fit one in the Humber sloop I am currently building (very slowly)

I have tended to standardise on two types, both by Hitec. The HS815BB servo has an arm around 12 cm long and a travel of about 140 degrees which gives a working stroke of about 20 cm. If you just use the single arm supplied with the servo you can usually mount the body of the servo off to one side of the hull. If you shorten the arm to fit in the hull then the working stroke will be reduced accordingly. You will just have to juggle the stroke of the servo with the distance between the sail boom pivot and the point that the sheet is attached to. The sail arm type of winch is quite quick to operate and I have found them to be relatively trouble free. If you want to pull on two sheets in opposite directions you can extend the arm out on the other side of the servo. I have such an installation on one of my wife's yachts and I will try and get a picture of it tommorrow.

The other type of servo I have used is the Hitec HS785HB drum winch which typically has a working stroke of 45 cm, depending on your transmitter/receiver used with it. They are usually used to drive a loop of cord as you say, and if you want to use the full stroke you need to fit the return pulley around 50 cm from the drum. Again I have a work in progress example and I will post a picture of that tomorrow. Normally the sheets are attached to the loop of cord and you can pull in both directions by attaching sheets to both sides of the loop. You have to arrange the alignment of the sheets so that they are not likely to fall on top of the loop if they go slack or they will get snagged as it moves. It is possible to adjust the travel of the drum by using a Servomorph, available from Action Electronics/Component Shop.

I have tried the so called captive drum servos where the sheet is paid out from an enclosed drum. However despite using several different types of cord for the sail sheet I have not found them to be very reliable as the cord gets trapped between the drum and the shroud that encloses it.

There may well be some pictures of typical Thames barge installations on the AMBO website (www.modelbarge.info). Failing that I expect Kim Holland will be along shortly and be able to give you some more detailed advice and pictures of installations.

Regards

Gareth

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Jim and Gareth, hi.

Welcome to the forum Jim. I was just writing a reply when this website "had a funny" and re-loaded itself wiping out my reply. My response is to always shut down when that happens, you never know. This site was down earlier today as well.

Now Jim, as Gareth rightly states all your questions and many more you haven't thought up yet are all answered on the AMBO website. That's the Association of Model Barge Owners. There you'll find plans, builds discussion and several articles by me too. Sail control being one of them.

To start, I'd always use a sail winch, and one that has at least 10 inches of travel.

Some skippers use two winches as well, controlling the main and the vangs separately. The fore sail is chained to the fore horse and has NO sheet.

Hope to see how you get on, aye, Kim

[Geoff SleathParticipant @geoffsleath41411]

I had the same conundrum with my Veronica build. I haven't done much actual practical work in the past 10 days but a lot of pondering after my visit to the Warwick show and meeting a few experts like Kim.

Anyway I've opted for a Hitec winch (HS-785HB) for the main sheet. I already had a Savox high torque servo (SC-0252MG) in stock for an aborted quarter scale Avro Avian restoration so I made a long arm for that to use to adjust the sprit vang. The Veronica is 24th scale so she's a bit bigger than yours (approx 1metre waterline). I've almost done enough to make another posting on my build and I'll do it in the next couple of days with photographs so you can see the arrangement I've opted for.

I built a Rhythm 1 metre racing yacht about 15 years ago and that used a Whirlwind winch. On that yacht the continuous winch line has a small extension spring to maintain its tension and also to provide a take-off point fpr the sheets.  I raced that yacht quite a lot and IIRC never had any trouble with the sheeting and I'm intending to take the same approach with my Veronica.

Geoff

 

Edited By Geoff Sleath on 21/11/2014 00:57:35

[Gareth JonesParticipant @garethjones79649]

Hi Jim,

Here are the promised photos.

The first one shows a sail arm winch in a gaff rigged ketch that my wife restored about 4 years ago. There are two sheets running aft to the mizzen and main sails. I used a short length of 1/8 brass tube, gently bent to an approximate right angle as a guide for each sheet to come up through the deck.

This one is Scotsail which is slightly unusual in that the sail arm winch is mounted uupside down in the cabin superstructure which is all removable in one piece. You can see the servo arm has been extended as I described in my earlier post, one side controls the main sail and the shorter one the jib. It works very well as a sail control mechanism but is hopeless as an overall installation as the sealing between superstructure and cabin is not good enough. When the yacht heels over the hull soon accumulates a lot of water. This model is about to be revamped back into a more conventional yacht with the sail winch in the hull and a proper sealed hatch.

This one is work in progress for an 80 year old yacht that Elizabeth is currently restoring. It is designed to be completely assembled on the bench and then fitted into the hull through an oval hole about 5 inches by 3 inches. The ply plate with a small cutout at the bottom will be the attachment to the keel.

Here is another view showing the aluminium arm and return pulley, which is a Nylet supplied through deck pulley. I usually attach the sheets to the loop using a three hole bowsie which you can see towards the right hand end of the loop. Because the sheet will exit the hull behind the winch there is a risk that the sheet might drop on to the drum of the winch and get tangled. I plan to fit a thin sheet of styrene to the top of the ply mounting plate to shroud the drum. I also need to chamfer the edge of the ply plate so the bowsie cannot snag on it as it gets pulled towards the drum. All these detailed aspects of the design are much easier to implement on the bench rather than working blind through a small hole on the deck. With a Thames barge you should have plenty of access though.

Here is a final view of the servo mounting plate. The radio receiver, battery and servomorph will be mounted on the top of the plate. In this installation I need to limit the travel of the loop to no more than 400 mm because I cannot get an aluminium arm any longer than this through the hole in the deck. It also better matches the length of the main and jib booms on the yacht.

If you have any more questions just ask, there are lots of people on the forum who are very knowledgeable and keen to help.

Gareth

[Malcolm FraryParticipant @malcolmfrary95515]

Two years ago, for simplicity and reliability, I would have gone for the sail arm. To increase travel, if needed, you can always double back at the arm end. Since starting to use the shrouded drums, as sold by Howes and Component Shop, I would go for them every time now. Easy to mount, easy to fit the line, using a sensible line, no problems (30lb salmon backing, about 0.5mm diameter, braided). Work out the travel you need, reckon the drum is 1" diameter, that will give the number of turns needed. Too thin a line and it might slip into the very narrow gap between drum and shroud, too thick and there might not be room for it under the shroud, or if the sails do not pull out easily, it might push itself into a knot. You can get equivalent problems with an arm – loose line under the deck will find something to tie itself round.

I've been using mine single ended in a Victoria as a replacement for an arm, with a vast improvement in useability in heavy weather. In light airs, I use an elastic helper line above deck to make sure that no slack gathers outside of the drum but below deck to make it easier for the sails to pull out. Because it is a double drum, you have the option of fitting it as a continuous loop, if space is available, or two separate lines to different sails. Might be coincidence, but the battery life has increased enormously since moving over to the drum winch.

[Jim Masson 1Participant @jimmasson1]

Thank you all for your interesting and helpful replies I think I'll go for a winch. But now I have to get the plans organised. No doubt during the build I will have a few more questions.

Also thanks Kim and Gareth for suggesting the AMBO site, only had time for a quick look so far but it will certainly be very useful

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