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Author Topic: Britannia rigging  (Read 1846 times)

ted

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Britannia rigging
« on: May 11, 2007, 03:20:07 PM »

The sail plans for the Britannia Racing Yacht 1893-1937 show forward and aft backstays which extend to either side of the rear of the boat. They would appear to restrict the movement of the mainsail to about +- 20 degrees of the centre line, and yet actual photographs of the Britannia when racing show the mainsails well out over the side. Are the backstays removed for racing? Why are they there if they can be removed?

Ted - a complete novice as far as sail is concerned.
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Colin Bishop

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Re: Britannia rigging
« Reply #1 on: May 11, 2007, 03:43:14 PM »

I think what you are referring to are "Running Backstays" which are used to tension the mast. Only the windward one is in use at any one time. The leeward one is slackened off so as not to obstruct the sail. When tacking the sail is brought amidships and one backstay is tensioned as the other is slackened. There are references to levers being used to do this. Otherwise you need several pairs of hands! Not sure how you'd do this using RC though!
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roycv

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Re: Britannia rigging
« Reply #2 on: May 11, 2007, 07:06:23 PM »

Hi I had this problem when building the J class sailing yacht Endeavour. (1 : 35 scale about a metre long)  I could not see a solution to slackening off the leeward backstay so I shortened the main boom so that it did not foul the backstay.  Sometimes you just have to adjust things to get a model sailing.

Just a thought but if you could slacken the appropriate backstay and have an elastic cord pull the backstay down and under the boom and closer to the mast, that might work.  You can get a transparent elastic about 1 mm dia. in craft shops.

Let us all know how you get on please.
regards Roy
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tigertiger

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Re: Britannia rigging
« Reply #3 on: May 12, 2007, 03:15:07 AM »

My first real build (Mary J Ward) has the mast passing through a deck beam and is then footed in the bottom of the hull. The shrouds are largely decorative.


Looking at the plans
Also if I am misreading the plans please advise me.

On Sheet 2
On the side elevation of hull.
Just forward of frame 10. The mast seems to foot into a tube of about 9cm.  If this is strong enough, and the mast strong enough, you will not need stays or shrouds.
This would make the back stays decorative, so you either omit them, stow them (see below) or make them out of elastic.

On Sheet 4
On the side elevation
Just aft of frame 14, and directly behind the saloon roof, there is a 'Hook for aft backstay when sailing'. In line with what Colin said earlier. In this case you could stow both of them for sailing and use them to stop the boom from swinging out when on display or moving.

Vaughan Williams book mentions the compromises of scale vs practical sailing, with standing rigging.

Please feedback on this as I will have the same issue in the future.

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ted

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Re: Britannia rigging
« Reply #4 on: May 14, 2007, 09:11:20 AM »

Hi all, Thanks for the comments about the rigging. It sounds as though the crew would have been quite busy when tacking. I think I will simply leave the backstays off for sailing.

Re: the mast, yes I set a 15mm brass tube into the hull to take the mast.

Re: the hook. I had not noticed the hook on sheet 4 for the backstay when sailing.

I found the method of covering the hull with card and thin ply quite tricky. The author of the original article quoted 4 pieces either side with a few cuts to cover the hull. I ended up eventually with five pieces and many cuts to get a reasonable finish. It has the advantage of speed, and I was able to cover the hull in a couple of sessions., but I suspect a better finish could be achieved with planks.

Ted
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tigertiger

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Re: Britannia rigging
« Reply #5 on: May 14, 2007, 02:18:50 PM »

Hi Ted,

There is an interesting comment in Phillip Vaughan Williams book, Scale Sailing Models. Page 128

It discusses Phil Anstiss' (It mentions some journal US no 20 1996) build of Britannia. He upped the scale from 1/32 to 1/20.

Interesting comment.
"This is a very light model and the strain on the sails, rigging and servos is quite considerable. The heavy duty servos handle the job, within the limits of the backstays which keeps sail travel to within safe limits"

In truth it would sail within the limits of the backstays, it just means that when running you would not get the full advantage of letting the sails out. Also she is more prone to being knocked down, as you cannot spill air from the sails when broad reaching.


Also
The other thing it mentions is that Phil Anstiss also increased the size of the rudder to improve performance.


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