closed loop sail control

[LARRY WHETTONParticipant @larrywhetton68737]

Hello All ,

Feeling little better now , so picking up the odd model to carry on and complete ……

So first in line my Brixham Trawler ,

Need some advice how to design a loop sail rig using a sail winch ,

for main and missen sails , have some ideas but not quite sure of set up,…

so can any body help ,

want to get set up before deck is fitted,

cheers Larry……..

[LARRY WHETTONParticipant @larrywhetton68737]

[Paul FreshneyParticipant @paulfreshney24971]

There was an excellent description and diagrams of how to have a closed loop method of operating a number of sails, by Dave Petts in July 2013 MB, pages 36, 37 & 38.

Paul Freshney – Editor.

[LARRY WHETTONParticipant @larrywhetton68737]

Thank you Paul ,

Have a copy of that issue , very good, bot struggling a little with diagram ,

and rig will have another look at it ,…. cheers Larry…

[Tony HadleyParticipant @tonyhadley]

Larry,

Why not make your own based on the old screwed rod system, which pre-dates the modern lever arm/winch controls. Time consuming and needs quite a lot of setting up, but when done, they work fine. Slower sail control than a winch, but you aren't in a race.

A rough sketch (obviously not detailed) for thought.

[LARRY WHETTONParticipant @larrywhetton68737]

Good morning Tony,

Thank you for drawing , very inventive will give it a dummy run ,

but trying to make it a removable unit,……Larry…

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Hello Larry,

I use a removable closed loop system on my IOM and other yachts. I'm just renovating one now so have some images which might be of use – I actually glued the deck on this morning so cannot get more inside, but could take out the whole unit once the deck has set.

It is definitely much easier to set this up with a servo tester, 1) because you can find the mid point and mark the drum and 2) slowly control the winch to its end points (and program if you have that capability.) Using the r/c kit is possible, but remember that sail winches are very powerful.

Here's the hull with the lid off, the sail winch drum can be seen just top of midships through the deck and keel box support beams. The winch is bolted to a length of square profile aluminium tube (from B&Q) and is slotted onto two captive bolts on the keel box side. These can be tightened/loosened with a box spanner or socket.

The closed loop consists of two lengths of braid, each ending on the winch drum and joined together on the long side with a small swivel. The deck sheet attaches to this swivel with a closed clip. At the stern end the closed loop passes through a pulley that is held to the tube by a strong spring. This ensures that the loop is always under tension and so does not drop off the drum. The foreword loop end runs about a fixed pulley. The loop I use is made from braid fly fishing backing line, 35lb. NO KNOTS, use crimps, believe me when I say you have to know your knots to tie braid and for a closed loop you need to tension the loop at the same time!

In this picture I've added some coloured lines, to assist with the description. The red line indicates the length of the aluminium tube, the blue squares are the deck access hatches, the red arrow shows where the sheeting line emerges. The sheeting line passes through a loop on the aluminium tube end which guides it to the deck access slot. This ensures the sheet is pulled lengthwise along the boats length. The sheeting line is the same material as the closed loop line. The opposite side in the hull has the rudder servo, again attached to the keel box, and connected to the rudder by a solid strut and ball mounted arms.

The length of travel of the closed loop, pulley to pulley is greater that that required to pull the sails from full out to full in. If you cannot get this length in your hull you will have to utilise a 2:1 purchase out on the deck. It is simpler to work there than within the hull and getting tangled.

Here's the deck (actually before glueing). As you can see the deck has several access hatches enabling access to sail winch, rudder servo, battery box, insertion hole for closed loop winch and behind a small hole for rudder access.

As I said earlier, a SINGLE SHEET comes up out onto the hull via the slot at the stern. [This is a double roller ball deck insert available from model yacht bits suppliers.]

This single sheet, for me, runs to just before the mast slot (small rounded square hole) and is tied to a small swivel. TWO sheets and a length of elastic are attached to this swivel. One sheet goes forward and is the foresail or jib sheet; the elastic is taken foreword and is tied off to the jib foot swivel with slight tension; and the main sheet is passed through a deck mounted single pulley and travels back to the main sheet post seen sticking up through the deck. The elastic must be long enough to stretch back to the deck stern sheet hole. It keeps the sheeting line under constant tension which stops hangs up within the hull (and ensures the sail sheets only have the sails to deal with on windless days.) The sail sheets are again braid, but this time only 20lb breaking strain (they fail before the under deck system does!)

The distance of travel from the deck mounted single pulley at the mast back to the stern slot where the sheet comes up through the deck is greater than the sheet length required for full out to full in (about 11.5 inches on a IOM). If you do not have sufficient deck length, establish a 2:1 pull by passing the two sail sheets through the swivel and tying them to a fixed location. The pull being from the "centre" of the sheet will in fact impart a 2:1 pull.

One final tip. Try and make the sheeting length for each sail the same, that's the distance from sail foot to the attachment point of the sheet. it then enables both sails to move together in tandem.

I think that should be meaningful, but come back if you need more. Meanwhile I'll see if the glue has dried and lift the winch out again, complete on its tube, and take a picture for you.

Gosh it's much easier to build than to describe.

Kimmo.

 

Edited By Kimosubby Shipyards on 03/02/2014 15:38:49

[LARRY WHETTONParticipant @larrywhetton68737]

Hello Kimmo,

Thank you for input, nice to here from you you no your sail bits a great tutorial , hanging on to every word,..

using Hitec winch , will build test bed first, when i get the use back in my shoulder ,

got little beat up having pace maker fitted , but on the mend,….

mast and rigging is sorted , sails there a lot of them , light weight rip stop used by gorg ,

but i may go for cotton on mine ,

are you still making your own sails ,.?…..

still trying to master the art,……..

a very big thank you again , for info ,…..cheers Larry……..

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Hello Larry, great to read you are back on the circuit, just take it easy me ol' mucker!

Now, yes, I'm making sails still. Just done a Marblehead set for a vintage, started a Thames barge set for me and I have a top sail schooner set on the way plus I'm about to start 49 cotton sails for a "1/8th to 1 inch" Thermopylae.

I'll send you over some of the braid I use (comes on a 100m drum so much to much for me!) as I still have your details.

Here's the set-up, exactly as she emerges from the hull, just been up to a very cold workshop and took it out as the glue has set – good old Stablit !

The spring attached pulley first (just see the swivel too), followed by the winch below (see the two mounting holes below the drum?)

And here's the foreword end, the captive pulley.

And the whole looks just like this, about 26 inches overall length.

You can just see the sheet loop guide at far top end (brass loop),

Kimmo

Edited By Kimosubby Shipyards on 03/02/2014 16:49:09

[LARRY WHETTONParticipant @larrywhetton68737]

Hi Kimmo,..

Thank you again for info ,… picture paints a thousand words,

are the blue pulley wheels a purchase or scratch built.?..

busy with sewing machine are you not ….…

any more light you can chuck at me is all ways welcome ,

can not drive at the moment so , so pc shopping is my only link

plus flooding is a pain……….cheers Larry………..

P/S  is the sticky up bit sheet exit.?…

Edited By LARRY WHETTON on 03/02/2014 17:28:14

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Larry,

I get stuff like this from Technobots, and a lot of electronic stuff too.

The sheet comes out the deck from the slot hole and goes foreword. The sticky up bit is the sheeting pole, the sheet enters about 3/4inch from top and exits at top to sail boom.

Have fun, Kim

Edited By Kimosubby Shipyards on 03/02/2014 18:21:40

[LARRY WHETTONParticipant @larrywhetton68737]

kim,

thank you again for info, picture of build so far ,,.plus the handy cap picture….Larry..

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