Simple steering gear – will it work?

[Brian MuirParticipant @brianmuir84327]

[Brian MuirParticipant @brianmuir84327]

As this is a protoptype, and I want to see how it sails if possible, I have adapted the Braine steering gear design – I don't have a "proper" drawing package on my Mac so this is a child-like paintbox representation. Will it work?

The main problem is this boat has a very steeply angled stern post, so the rudder post will also be angled steeply backwards, this means the "quadrant" would turn and tilt at an angle as it does so.

I don't have any metal to make it, so I thought I'd use hardwood.

[ashley needhamParticipant @ashleyneedham69188]

Brian, what are you aiming for exactly? straight line stering?

Ply better bet for the quadrant. What size are we looking at here?

Ashley

[Brian MuirParticipant @brianmuir84327]

Hi Ashley, yes straight line sailing, the boat is 720mm long, 210mm beam and the draft will be about 120mm.

[Malcolm FraryParticipant @malcolmfrary95515]

That is pretty much exactly how Braine gear works. You will need some way to adust the tension on the elastic, because its strength will vary day to day, and the strength required will also vary. When I say day to day I really meant launch to launch, going from memory.

[Brian MuirParticipant @brianmuir84327]

First attempt at the gear, now to run up some sails and fix the rigging…..

[ashley needhamParticipant @ashleyneedham69188]

Brian, that looks very nice, what a nice sinuous curve you have there. I always like a boat "in the wood" as it were. several things I have built look just fab "au natural" and then I paint them.

I hope it works ok, A drop of varnish and everyone can croud round an ask "wotsitfor".

Ashley

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Hello Brian and Ashley,

I can now state that I sail Braine controlled yachts. We use them for vintage 36R racing. Now, this racing is done up wind and down wind, that is a beat and a run.

The Braine gear quadrant is locked with the rudder amidships for sailing up wind, the sails being set to claw as much up wind distance as possible.

The diagram you show on the first thread post is as for a down wind/run, where pressure in the sail is offset by the elastic band to hold a (pre-planned?) course. As all yachts are set up to have weather helm (when over pressured with a gust of wind their head points up into the wind, hence dumping wind and pressure, which then allows the head to fall off again) a gust will cause the sheet to pull the quadrant hence giving some helm opposte to the weather side. Now the trick is to set up such that the yacht sails a stright line down the wind. Sometimes it works very well, but sometimes you end up chasing your yacht back up the way it should be going.

Good luck, it's great fun trying to achieve the balance. Different elastic bands, and the quadrant usually has a series of holes radiating out along the arms so that leverage can be adjusted too.

See the thread "Vintage yacht 36R" for some pictures of a quadrant.

Kimosubby

Edited By Kimosubby Shipyards on 27/08/2013 18:03:37

[Brian MuirParticipant @brianmuir84327]

Thanks for this info, if the rudder is locked for sailing upwind, does the boat not keep turning into the wind and stalling?

I will have to run a lot of trials to try and get this to work (so much for a simple steering gear!).

I will only connect the aft (mizzen) sail to the tiller, the main sail and fore sail will be on a fixed length sheet, does this sound OK?

Cheers, Brian

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Brian,

if the sails are set for the wind, then she will sail the straight line desired – only gusts will force her into the wind, and then she should fall back to her course.

Yes, lots of trials are required, but once you've established basic settings things inproove!

And now I'm intrigued, I've not come across a Braine being driven by the mizzen sail, which is the steering sail anyway. It can be used to give the boat windward characteristics by setting it in tighter than the main thus pushing the bow up to the wind. I'd be delighted to know how it works out. Most Braine gears are connected via the main sail, and some to the foresail as well (without crossed sheets for the fore sail).

I sail a Thames barge in coastal rig (no bow sprit) and she free sails well, just using the "Mule", a mizzen sail, to keep her slightly windward. I do use radio gear on her, but only for the rudder, and only to gybe, and tack or ware, as she is slow to come about and usually ends in irons!!

Kim

[Brian MuirParticipant @brianmuir84327]

Hi Kim, as you can see from the pics, the mizzen is the largest sail, so I thought it would be the best to link to the steering, but I could rig it from the main sail on the fore mast.

[Paul TParticipant @pault84577]

Brian

What a sweet looking sail boat, you have done a first class job in building her and I hope that she sails as well as she looks.

Paul

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Brian, I agree with Paul, she does look dandy. Seeing her full rigged now I can see your point in using the mizzen.

To be honest, I've no experience with your rig, so as a true modeller, try it and let us know. At least the apparent physics looks as if she'll be weatherly, but tell us how she behaves on the pond.

Kim.

[Brian MuirParticipant @brianmuir84327]

Now with temp rigging (replacing masking tape)….

The steering rig is shown below. I can move the fixing point on the boom for the crossed lines to the quadrant, in order to get more movement on the rudder.

Does anyone know how to work out the size of rudder needed? I have made this one about the size shown on the plans, but I have noticed that many sailing models the rudder appears to be much larger in proportion to the boat….. Don't tell me its trial and error, how do you adjust rudder size?

[Paul TParticipant @pault84577]

Brian

I am sorry but I don't know of any set calculation that can accurately predict the performance of a model boat rudder.

There is an interesting article by Petter Blix on the subject.

**LINK**

Paul

[Brian MuirParticipant @brianmuir84327]

Cheers Paul, very interesting article, it looks like I may have to increase the size of the rudder.

[Paul TParticipant @pault84577]

Brian

A general 'rule of thumb' is to start by increasing the rudder surface area by 50% but eventually it does come down to trial and error.

Paul

[Brian MuirParticipant @brianmuir84327]

I did add a rudder extension for the maiden voyage and in very light winds she did sail well, but the steering settings are very sensitive. The wind wasn't steady enough to try out many settings, but it did sail into the wind (tacking once or twice!)

Sailing downwind it tended to come around into the wind and I struggled to get the rudder to respond to the crossed lines, I will have to use quite weak elastic I think.

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

Hello Brian,

difficult to see the true sail shape in your images, but she does look quite nice on the water. From what you have said your boat likes to sail up wind, which is good.

To run down wind you will really need to pay out the sails quite a bit. There's two things could be happening for her to come back up wind when on a run. The elastic not strong enough, so the sail is always pulling the rudder hard over putting her right round, or of course, too strong and the rudder not coming into use at all.

Looking at the set up in your image 1020194 the rubber band appears to be very short? and a long way from the tiller arm. On a normal Braine quadrant, the band passes beneath the quadrant, so that the turning moment of the quadrant (your tiller) is through the band itself. The rubber band is NOT attached to the Braine quadrant at all, it is strechted along the fore/aft centre line and the quadrant is over it, with the rubber band passing through the quadrant's loop. Secondly, the running sheets are attached at the outer ends of your rudder quadrant, which will give a very big turning moment for very little sail pressure.

Try attaching the sheets closer to the rudder stock and record what happens. Then increase the rubber band size and tension. It's quite surprising just how much band tension is required to hold the rudder dead ahead, especially in your system with the large lever force supplied by the tiller arm.

NOTE take care that over tensioning does not break the tiller!!! I suppose thats why we set the band through the Braine quadrant passing it through a brass loop, a rubber band will hardly break a brass/steel quadrant.  You may have to try that too, and just have a down peg under the tiller arm that has a hole for the band to pass through such that the tiller stops up against the band from either side. This can also assist in keeping the tiller midships on a beat. (it's how my own yacht is operated, I do not lock the rudder, but increase band tension for a beat.)

Kim

Edited By Kimosubby Shipyards on 06/09/2013 11:15:26

Edited By Kimosubby Shipyards on 06/09/2013 11:21:55

[Brian MuirParticipant @brianmuir84327]

Cheers Kim, I did lengthen the elastic band as soon as I saw how "stiff" the rudder was. I like the idea of the pin on the tiller between the rubber band.

[Brian MuirParticipant @brianmuir84327]

I lengthened the elastic

and doubled the size of the rudder

She now sails like a dream, in a light breeze, she sailed out on a broad reach, with a little bit of weather helm fixed. I had a line attached (floating polypropolene) which gave a bit of added drag I suppose, and about 50m out I was able to pull the line and make her gybe, then sailed back, but this time trying to come into the wind a bit more, pulling on the line pulled her away from the wind and she sailed happily all the way home!

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

There you go Brian, we'll be reading of your new job in yacht design soon…………

Glad your yacht is starting sail nicely, you did what I did the first time I set my free sailer loose on the water – I used floating fly fishing line – some effect and the same ability to gybe her when wanted to returned.

Now I'll read your ballast post.

Kim

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