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Post by Village Idiot on Aug 9, 2008 14:13:23 GMT 10
I ran into Tim (the pie eater) at the pattiserie this morning. He got talking about his new high mod C-Tech and the differences from his old rig.
For us plebs who just blindly buy masts off the shelf can anyone explain what the general trends have been in the development of the C-Tech from the beginning to now?
Even better would be a time-line of sorts listing the changes and developments over the last 5 years or so?
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Post by Deleted on Mar 25, 2009 6:25:13 GMT 10
I thought my design progression was unique then I ran across a Diick Batt article on OK rigs from the early seventies.....turns out this guy had beaten me to it by 36 years!! ;D Which just goes to show there is nothing new in yacht design, it's all been done before. The difference is that with carbon fibre we now have the ability to make those old ideas work better. I'm working on a new concept now which hopefully Alex will have finished very shortly. Don't know if it will make the container in time for Sweden though unfortunately . Would be interesting to hear what other peoples ideas are though.
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Post by Deleted on Mar 27, 2009 9:58:13 GMT 10
Thanks Karl. I wondered why you had typed Diick Batt until I first tried to send a reply. Talk about "political correctness" as I could only get the text to read "thingy Batt"! Anyhow, we'll call him Diick, is a well established UK sail-maker. He sailed OKs in the 1970s and was GBR National Champion in 1975 & 1977. He also finished 8th in the 1974 Europeans, 5th in the 1975 Helsinki Worlds and 35th in the 1977 Takapuna Worlds. (Courtesy of "Completely OK"). From his website; www.battsails.com it tells us that "He still has his OK, one of his favourite boats". See Diick's article on the birth of the metal OK mast on page 160 of "Completely OK". Diick is also the brother of Mike Batt, the founder of the successful UK children's TV show, The Wombles, from the early 70s. You might be a little young to remember them! I'm not certain that this is fact but I recall that Patrick Whittington once told me that Diick Batt was the original Wellington Womble when the show first started on UK TV. Maybe someone from the UK can confirm this? Yes what you have said is correct, everything old is new again. Diick was obviously a progressive thinker with his OK rig development. Back in the old days, blokes use to work on their timber masts from week to week, gluing pieces on and then shaving more off searching for the "perfect" shape. Here in Sydney, Penguin now does much the same using carbon fibre! This is a good "positive" topic. Hopefully members will respond to Karl's comments with their ideas.
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Post by Deleted on Mar 28, 2009 5:42:23 GMT 10
Well for your info it appears Mr Batt may well be our new International Measurer so we keep him in the class. He was chief measurer at the last olympics and will be again in 2012 so he knows what he is doing. with the masts they have changed over the years. The newest or MK2 masts are from a smaller mandrel which makes them thinner. This has the advantage of more carbon being required for the same stiffness so they are heavier. Not good is that they cost more. You can of course get a cheaper one from the MK1 mandrel still. The bend characteristics have also changed a bit as they now bend more below the deck to get a bigger f/a tip deflection. they are stiffer sideways down low as well which helps with height and as the tip is very thin it works hard and fast with the high mod carbon so even the light guys can use them in a breeze. essentially they have just developed and improved. having said that though there are still plenty of guys who use the older ones and are quick. last year Nick used mast number 6 in the NZ nats and got 2nd. He said it was just like his celidh mast. (a lamp post). If you are not sure what is the best just ask Alex for a mast for your weight. He has now made over 180 masts and has a lot of data and can produce a good mast for you.
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Post by Deleted on Mar 31, 2009 6:23:45 GMT 10
Yeah I remember The Wombles! Greg basically has the c-tech design progression right. The one thing I'd like to add is that too often people look at the mast and sail in isolation to each other. People think for instance that if they can get a certain mast they will be fast even tho they'll still be using their old sail.....wrong! I think you have to decide at the outset what sort of conditions you are targeting, then get a sail built for those conditions and then get a mast to suit the sail. This idea is different to the normal lets get a mast and then get a sail to fit the mast routine. Having experimented a bit with different sails now I think perhaps this is the way to go. What does everyone else think?
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Post by Glenn AUS 719 on Mar 31, 2009 7:16:51 GMT 10
Mmmmm, I agree we need to stop thinking of the mast and sail as separate individual items and instead look as they should be an integrated whole. The need to take into consideration body weight and sailing style should also be a factor. As for the zone we would like to aim for? I can see where you are aiming for new mast/sail for different conditions and while I agree this is the ultimate way to go it will be expensive. As mentioned above, none of this is new but how much of a gain in real terms would you achieve?
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Post by Deleted on Apr 1, 2009 7:14:43 GMT 10
Altho you can obviously have different mast/sail combinations which are fast for different conditions I agree it would be expensive and actually very difficult to implement accurately over a regatta. We are currently allowed 2 masts and 2 sails for a worlds regatta, hence one rig could be oriented for light/heavy airs (what goes fast in the light also goes fast in the breeze) and the other for moderate. The problem would be choosing which to use on any particular day given that lately at world contests we have 2 and sometimes 3 back to back races. Invariably over that period the wind changes quite a lot which would necessitate a rig change out between races. Unless you've got a good on the water pit crew and accurate weather forecasting this is a risky business I think. The safest (and cheapest/most hassle free) choice is the one rig for all conditions option. I currently have a rig which is very fast in the light and very fast in the breeze, my new mast will hopefully bring the moderate air and reaching performance up to that same level. It's a rig concept which has been around for a long time, it's just that now with high mod carbon I think you may be able to get it to work. Anyway will keep you posted as Alex has just finished it and done an awesome job on achieving the bend nos needed. I think it's the next logical progression from what I've done before however the proof of the pudding....I should be sailing with it in about 2 weeks. Unfortunately it will now miss the container for Kalmar By the way during the development of this mast I found out that a 19-20kg weight off the top of the mast is what is needed to simulate mast bend when you are sheeted with the boom nearly on the deck. Using this weight, differences which aren't obvious between masts using the standard 10-12kg stand out like dogs balls. And lets face it prob 75% of the time this is your normal sheeting position....well in Wellington it's prob closer to 90% ;D
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Post by Deleted on Apr 1, 2009 11:12:38 GMT 10
By the way during the development of this mast I found out that a 19-20kg weight off the top of the mast is what is needed to simulate mast bend when you are sheeted with the boom nearly on the deck. Using this weight, differences which aren't obvious between masts using the standard 10-12kg stand out like dogs balls. And lets face it prob 75% of the time this is your normal sheeting position....well in Wellington it's prob closer to 90% ;D Interesting to hear this. The method that Bruce Ashton uses in Vic is to measure mast bend with 24kg of tension down the leech (more specifically, measured by pulling 24kg of tension in a line to the mast head from the end of the boom), then scaled by the sailors weight(kg)/100. That suggests around 21.5 kg for a 90kg sailor - not too far off what you are saying? Although that's not a weight hung off the tip. It seems to work quite well.
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Post by aus729 on Apr 1, 2009 14:36:05 GMT 10
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Post by Deleted on Apr 3, 2009 6:35:49 GMT 10
I think if you do some rough trig on the 24kg leech tension no. you'll get a horizontal figure (mast tip weight figure) of about 11kg. I did this using 5.4m as the boom to tip height and 2.68m as the mast to boom end figure and approximating them as being at 90 deg to each other. So this then is where we prob get the 10-12kg mast tip weight figure from. Always wondered about that.
What would be very cool is for a sail maker to have a program which could calculate exactly how a mast of known bend characteristics altered the shape of a sail (ie depth and draught position) (also with a known shape) as the mast was bent f/a and s/w. Imagine the guess work that would take out!
I think the current status is that you get a sail which typically has luff round and seam shape built into it and which is designed to provide a specific shape at one particular mast bend figure It would be bloody interesting to then know how exactly that shape altered for (a) different mast bends from the same mast and (b) when put on another mast of different bend characteristics. I guess the only way you can currently do that is to stick a camera on your mast tip looking down (like on the WB sails site) and analyse the photographic data produced.
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Post by Deleted on Apr 3, 2009 6:59:12 GMT 10
As mentioned above, none of this is new but how much of a gain in real terms would you achieve? Actually surprisingly it is a hell of a lot. My new sail is hugely quicker than my standard sail in winds below 10 knots. (check out Kalmars Predictwind forecasts....0-10knts in the morning typically rising to 10-15 knts in the afternoon). The thing is to get it going in the 10-15knt range. No good winning the first race if you finish last in the second race!
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Post by Glenn AUS 719 on Apr 3, 2009 11:33:02 GMT 10
You are quite right regarding the advantages of getting the sail mast combo right and I stand corrected on that. So in summary while it would be ideal to have a mast/sail that would work through the range of conditions but as we have yet to figure out how that can be achieved it is best to have a combo that works in the mid wind range.
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Post by aus729 on Apr 3, 2009 11:53:50 GMT 10
I think if you do some rough trig on the 24kg leech tension no. you'll get a horizontal figure (mast tip weight figure) of about 11kg. I did this using 5.4m as the boom to tip height and 2.68m as the mast to boom end figure and approximating them as being at 90 deg to each other. So this then is where we prob get the 10-12kg mast tip weight figure from. Always wondered about that. The only real difference in using the leech tension, is that we get some compression bend as well, which probably contributes to a little extra bend. But who knows how much of this actually occurs, as as soon as it gets windy the leech opens up due to sideways bend. We have found over the years, the leech tension method works for us, when getting G & R sails. But none of this helps if you don't train, start correctly and go the right way. Looking forward to seeing all the new developments in Sweden.
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Post by Deleted on Apr 6, 2009 6:14:09 GMT 10
The only real difference in using the leech tension, is that we get some compression bend as well, which probably contributes to a little extra bend. But who knows how much of this actually occurs, as as soon as it gets windy the leech opens up due to sideways bend. We have found over the years, the leech tension method works for us, when getting G & R sails. But none of this helps if you don't train, start correctly and go the right way. Looking forward to seeing all the new developments in Sweden. Interestingly Stech and I investigated this and the bend was exactly the same whether you used leech tension or an equivalent weight from the mast tip ie leech tension induced no extra bending due to compression. Picked up the new mast on saturday and dropped the old one off with Al for container loading for Kalmar next week. Well I guess I'm committed now!
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Post by tim on Apr 6, 2009 12:53:56 GMT 10
I am not a big "pie eater", Paul just caught me having a weak moment. I have just finished a bowl of hot vegetable soup, and this was also very good!
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