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New to the class

Postby Alan Bessell on Sun Oct 24, 2004 1:26 pm

Hi, I am new to the class. I've just bought an old boat 1177and have sailed 2 races, one in 5-8 knots, and yesterday in 20-25 knots.
I've sailed 505 and sharpies for years, and never having sailed a single hander before, and not having a jib, I need a bit of help please.
Yesterday in 20-25 knots, I was killed upwind. the boat was choked and bobby if I tried to point with the others in the fleet, and when I did sail for speed, my height was very low, and I could not find the happy medium.
I did notice that the leeward side stay upwind was waving around in the breeze, and downwind the forestay was v. slack.
I would like to know please;
1. Rig tension for various breezes, as measured on the Loos gauge.
2. Heavy air sail trim, end of boom position, vang tension, cunningham eye tension, foot outhaul tension, traveller position
3. Should the centrebrd be raised up wind ?
4. Heavy air steering technique, ie it seemed that if the boat was sailed high and slow it went sideways moreso ?
5. I did notice upwind yesterday that no matter how much vang, the top batten was mostly inverted, or the top 25% of the sail was back winding,
is this ok ?
All assistance will be greatfully received, I'm new and keen.
Thanks, Alan, acbessell@primus.com.au
Alan Bessell
 

rig tension

Postby fitzwarryne on Sun Nov 14, 2004 6:05 pm

I use the following settings for sidestays measured on a Loos Model A for 2.4 mm 1x19 wire

wind- knots---------- condition---------- scale------- tension - kg

------ 8 ----------- underpowered -------- 20 --------- 91
-----12 ------------- optimal --------------- 22---------- 104
-----20 plus------- overpowered--------- 25---------- 113 after max downhaul tension applied

The concept is to keep slight tension on the leeward shroud going to windward.

Replicate the tension by datum marking the forestay tensioning cord.
fitzwarryne
 
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Joined: Fri Jul 09, 2004 12:18 am
Location: St George, Bermuda

Heavy Weather boat set up

Postby Alan Riley on Mon Nov 29, 2004 9:54 am

Hi Alan,

Glad to hear you have joined in the fun of Sabre sailing. I go reasonably well in heavy weather, so I thought I'd share my thoughts on making a Sabre go fast in these conditions.

1. Rig tension: I don't have a Loos gauge (I've made my own rig tension gauge, but how it calibrates to the Loos settings I don't know!), so I can't help you with specific settings, but I can tell you that I sail with a very tight rig all the time. The more rig tension you use, the more mast bend you get when you apply mainsheet or vang tension since the mast is already under a compression load. How much tension you actually use depends mostly on your mast-sail combination and is a balancing act between upwind and downwind sailing. A fuller sail will probably benefit from a higher rig tension so that it flattens more for upwind. Beware of too much tension because when you go downwind all that happens is the vang bends the mast sideways too much which gives you a very flat sail and little leech control! I use the same rig tension for all wind conditions (so does the national champ, Wayne Bates. Wayne is heavier than me, so he doesn't use anywhere near as much rig tension).

2. Heavy air sail trim: everything should be on very tight, except the outhaul and the traveller. The downhaul should be on to the bottom black band (make sure the sail hasn't sagged down from the top black band though!). The vang should be on so hard that the sail is just on the edge of inverting due to overbend on the bottom half. You are using vang sheeting in heavy conditions, so the mainsheet really only controls the in/out movement of the sail. The outhaul should be on tight, but not so tight that you pull a crease in the bottom of the sail. Particularly in waves, I find that a little bit of shape is still needed in the bottom of the sail so there is still a gap of about 1.5 - 2 inches between the boom and the sail at its deepest point. However, if you are a real lightweight I'd pull it on as hard as I can get it! The traveller doesn't really do much on a Sabre, most of the good skippers have it set fairly high in all weather. Just make sure that in the lulls you can get enough mainsheet tension to stand the leech up if necessary.

3. Centreboard: I don't raise the centreboard when going upwind. The Sabre centreboard is relatively short and very thin board. I find that if I raise it a bit, I start making too much leeway and can't point as high as other boats. Most of the time I have the centreboard in the front of the centrecase and I use a piece of shock-cord to ensure it is vertical. When it is really windy letting the board rake aft balances the boat a bit better.

4. Steering technique: The most important thing is to always keep the boat FLAT and moving. The centreboard is small, thin and flat so it is easy to stall it. Similarly, the bow of the boat is very full so it tends to slam into waves. So don't concentrate on height, concentrate on keeping the boat FLAT and moving. If you have good speed, good height will generally follow because the centreboard will be working better - otherwise you get a good dose of the slow, sideways bob-up-and-downies! You can also help the boat in waves by steering up and leaning back as you punch through a wave, then bear away and lean forwards as you go down the back of it.

5. If you were in 20-25 knots you were doing well getting only 25% backwinding. When the wind is that strong you can't use all the sail upwind so flatten it as much as you can, sheet in as much as you can handle, and let the rest flap. You might benefit from a stiffer top batten. I use a Hooper sail and these seem to need 2-3 pound battens. Irwin sails use stiffer battens, but I don't know what weight. I have found it best to use the same battens in all conditions.

Will we see you at Eden for the Nationals?

Alan Riley
Sabre 1564
Alan Riley
 

Postby fitzwarryne on Mon Jan 31, 2005 5:16 pm

I have tried Alan's advice on strong rigtension, as the new national champion it must be sound. However, I am having a major problem. When I apply tension, the mast inverts giving significant fullness in the middle of the sail. It is only cured by massive vang tension which at least bends the mast the right way but with a hooked leech. Real deag in light winds.

What am I doing wrong, and what is the solution?
fitzwarryne
 
Posts: 58
Joined: Fri Jul 09, 2004 12:18 am
Location: St George, Bermuda

Postby Alan Riley on Mon Feb 07, 2005 10:24 am

Hi,

I think you might have over-done it. My rig tension never causes the mast to invert. In fact, I wasn't aware you could invert the mast on a Sabre! I tried it on the weekend and by pulling it on as hard as I could, I could get about 3mm reverse bend. But that was way too much tension. Although I use a "tight" rig - tight is a relative word. It is tighter than most other Sabres I have seen on the beach. However, it is not super tight. The forestay goes slack downwind in 15+ knots!

Also notice that I said "How much tension you actually use depends mostly on your mail-sail combination and is a balancing act between upwind and downwind sailing". Sails react differently. The sail I used at the Nationals this year needs less tension than my old sail. Both are Hoopers, but they are cut differently.

Keep trying the rig tight, but not super tight. The main indicator that I have too much rig tension for the sail I'm using is actually down wind. If the rig is too tight you cannot control the leech tension properly because the mast bends too much. Pulling on vang tension to straighten the leech just bends it more and makes the sail way too flat.

Hope this helps!

Alan Riley
Sabre 1564
Alan Riley
 

Postby fitzwarryne on Mon Feb 07, 2005 3:38 pm

Yes I was overdoing it with some 140kg tension on the forestay. I ended up with some 10mm inversion while trying more I got an inversion in the foredeck! I had shifted the mast step right aft where it was no longer being supported by the bulkhead.

I tried maximum vang to prevent the inversion, when slacked downwind the mast straightened and kept the forestay tight even in a 20 knot breeze. On the wind the sail lacked gust response. End of supertight experiment. As Alan said it is all relative, obviously a Sabre does not need the forstay tension of a dinghy with a jib such as the Mirror.

More notes for my little black book on the trials and tribulations of a new Sabre skipper.

Paul Fitzwarryne Sabre 266.
fitzwarryne
 
Posts: 58
Joined: Fri Jul 09, 2004 12:18 am
Location: St George, Bermuda

Postby fitzwarryne on Tue Feb 08, 2005 5:27 pm

Another aspect I have only just noticed is the stiffness of the mast. I have two which are both within class dimensions. However, the one I have been using is the original from 266 and is softer and has more bend when checked against a weight suspended from the hound position. I presume over the 20 years there may have been a variation in the alloy used.

Bing 80+kg I will go with the stiffer one.

Paul Fitzwarryne Sabre 266
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Posts: 58
Joined: Fri Jul 09, 2004 12:18 am
Location: St George, Bermuda

Postby andymac on Tue Feb 08, 2005 6:59 pm

Perhaps one of our metallurgists can help out with this one...is it true that the process of anodising has some effect on the alloy that will alter its stiffness? Someone once told me it did. In my old Mirror days we used to try and get very stiff bottom sections without increasing wall thickness...as I recall by ordering some kind of temper that was designed for ultralight aricraft spars (it was just 50mm tube). The spec was T6061...or something like that.

All too much like rocket science for me...

Andy Mac
S1670
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Anodising

Postby Barry Eastgate on Tue Feb 08, 2005 7:48 pm

Andy,
Many of the top boats double anodise to thin the wall thickness.
Stephen Early has a metalurgical background and I seem to recall him saying that over time, anodising will actually stiffen the mast.
I started sailing Sabres in 1991 and I think there was a great deal of controversy at the Tas nationals that year regarding a couple of boats having illegal sleeves inside their masts down near the gooseneck and above.
The idea was to stiffen the mast down low and bend at the top half.
I think the main culprit was related to one of our leading sailmakers.
Needless to say, heavy penalties were applied.
Barry Eastgate
 

Postby fitzwarryne on Tue Feb 08, 2005 8:16 pm

Another trick tried in a certain international class is to chemically etch the inside of the topmast to gat more bend there yet still satisfy the external measurement requirements. The top cms are waxed so the wall thickness looks normal.
fitzwarryne
 
Posts: 58
Joined: Fri Jul 09, 2004 12:18 am
Location: St George, Bermuda

Postby andymac on Wed Feb 09, 2005 3:53 pm

Wow...rocket science indeed. I just anodised my mast so it looked pretty.

But seriously, all of that does make good sense. Further to the mast bend/control issue...did anything progress on the vang strop positioning suggestion that was raised at the AGM? I would have thought the lower the better from a control perspective.
andymac
 
Posts: 23
Joined: Mon Jun 14, 2004 9:01 pm

Postby Stephen Early on Fri Mar 04, 2005 4:21 pm

Well as my name has been mentioned I will put my 20 cents worth in. First Annodizing is a cold chemical process. It does eat away a very small layer of aluminium but I suspect the softenning effect is more rumour and story than fact. I wont suggest other ways of changing the thickness in fear of upsetting someone but anything done to an existing mast is most likely to lead to failure at week point.
The second point is what happens to a mast with age. Aluminium is made stiffer and harder by causing a large number of small impurities to precipitate out. The ease of doing this and if it can be done at all depends on the chemical composition. One batch of masts were made up out of the wrong grade of aluminium and were fantastic for sabres (Xstatic won a number of titles using these masts). They were all sold cheap as considered too soft and some people bought a number. To harden alumiium the normal method is to heat it (or do it when hot) and rapidly cool it. To then resoften it all you need do is heat it and allow it to cool slowly. Aluminium that is mad hard and stiff this way is more prone to cracking and failing and most who have used an old laser top section for a boom will have experienced this.
With normal aluminium you would with time expect it to slowly temper and get a bit softer. However if it is bent or deformed in any way that area will get harder and more brittle. This is where you would expect cracking.
The main problem with aluminium is stress corrosion. This is where a small mark can turn into a crack and oxygen defiiciencies in this area along with stress at the point will cause the crack to grow. If the material is soft then it can blunt the crack but if hard (see laser top section) the crack can grow quite rapidly. The solution is to keep corosive materials such as water (in particular salt water) away from the aluminium. I have just never worked out how to do this on a boat.
Well now that you wished you never asked I will say goodbye.
Stephen Early
Stephen Early
 


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