Yahoo! I met with my sail maker today and he has the time to build a couple of custom sails for my minis.
My problem: I don't know how to direct him. He is experienced at making windsurfing sails, canoe sails and sails for boats. He does not know how to make a land yacht sail. He re-cut my last sail and it works, but he was asking me questions about how to make the custom sail and I could not answer.
I was going to give him some photos from the forum and I also have the cardboard template for the mast curve made from the how to re-cut a windsurfing sail posts.
Does anyone have any plans for a sail or can you direct me to a place where I can get a template? I would like to have a 5.5 m sail given the light winds we normaly have.
Any help would be greatly appreciated.
Brian
Do a print out of the pages involved with the "How to re cut a sail board sail" www.seabreeze.com.au/forums/Land-Yacht-Sailing/Sail-making/How-I-recut-sailboard-sails-to-suit-landyachts/
Also give him a link to that on the forum so he can have a read through for himself.
When we had the "Sandpiper" sails made we actually went to a sail maker that was happy to come out for a sail BEFORE he started to make them..... that alone changed his thoughts towards land yacht sails and how they were constructed.
15 minutes sailing a land yacht for a sail maker might save you 2-3 sails of experimentation before he gets it right.
(put on a BBQ and a carton of beer, bring his wife / kids along if that's what it takes)
3x sails @ $500+ 
OR 15 minutes sailing + BBQ + Beer 
= GREAT day out Bargain !!!!!!
Great advice. We decided to recut one of my old windsurfing sails. Get the new mini sailing with that sail, then go out sailing. This will let him better understand the dynamics of the landyacht sail, before making the new sail.
I get the general gist of what you want and could suggest that you try what I had done to my sails both for the mini (Schrodinger's Cat) and and Occum's Razor.
That is I followed Paul's Formula though I had to use my own Judgement for the Sail Head s and Foot s. His curve has proved to be a very effective and as for any Looseness in the fore part of the sail pre-Luff there shouldn't be any. The sail should Sheet Down Clean and tight, any shape is gained through wind Pressure and Batten Taper. Least ways this is what I gleaned from Paul and my Sail Maker.
What I found under Sail is that these Sails become very active at around 12 to 15 knots and accelerate heavily. As a qualified Sail Maker you guy is used to making Sails that Require a great deal of power/Lift to overcome the Drag of the water, you have no such problem with a Land Yacht or very little to speak of. Therefore you require very little Power/Lift to move you and your sail gains it's power with speed i.e The Flatter the Faster.
Once again I take the liberty of telling you you should Print the pic out A4 and show it to the SM. He will get the idea. Flat as a Bed Sheet made of Silk.
Ron
PS The top one is for SC and the bottom one is OR.
Just remember that if you sail on softer sand you will need a fuller sail for power to drive you past the rolling resistance which is greater with softer surfaces
sabydent is wanting to start from scratch for a sail....... not go down the recycle path for sails (he's done that on his first yacht)
The conversion of sailboard sails is far from ideal, yes they work but a sail designed from scratch for the exact purpose works a hell of a lot better, and that's what sabydent is trying to do.
As I said get a sail maker involved very early in the project as we did with the "Sandpiper" and often a new person into the sail maker industry works better as they have very few preconceived ideas of how a sail should be and often has an open mind. There seems to be very few innovations in sail design over recent years of land yacht sails unlike whats happening on the water sailing area.
Do a google search on 'Speed sails' and have a look at some of the designs that are happening rather than the 15-20 year old sails that are being used from the tip currently use on land yachts.
Have a look at birds that soar the ocean, or sail plane gliders, or high performance prop powered planes and see if you can see any common things that exist in the shape and designs of the wings...... take your time research the subject and understand VERY well how a sail works.
Ignore jet powered plane as wing shapes often are that shape because they are nearing the speed of sound where other factors come into to play.
True TP1.
I did mention "The Flatter the Faster" So the opposite must be the Case.. The trick is to be able to judge the circumstances of the usage of you particular needs and build from there. For instance if trying to sail Quick Sand I think you'd require a Square Rigged Bubble. My point in this thread is your Sail Maker should have the experience to put together a Sail From Scratch based on your requirements. I had a little trouble getting across to mine that I required maximum speed and that power was not a prerequisite in my application..
If Brian is going to sail Car Parks he has only limited space to get moving before he has to slow down to turn (Sharp Turns especially) Then he is going to require a fair amount of Shape to give power to speed up again. Where to have an Airfield to sail he then would require another Sail to deal with that application.. I found that I need to sails per Craft. "Horses for Courses".
Think before you cut.
Ron
Ron the discussions you had with your sail maker was how to best use / re cut the sail you already had not build it from scratch.
Sail performance comes from many things including draft, the position of that draft, the aspect ratio, the overall profile and most of those things were already in place when the original sail was made.
Getting an open minded sail maker out to use a yacht early in sail development is virtually essential unless you wish to spend lots of $$$$ on sails.
If you are into SERIOUS reading on the subject I would recommend the book
aero-hydrodynamics-of-sailing by the author Czeslaw A. Marchaj (ISBN 0-229-98652-8) WARNING!!!! it is HEAVY reading
You might be able to down load an e-book version here
ww1.ebookbrowse.com
Well Gizmo I must have a good eye as I am not a great reader of Tech Spec's.. I tend to go Cross Eyed and Fall Over with Boredom.. My sails have been stood back from Eyeballed and then decide on the shape and then throw it out there for discussion. You should know this as I think you had some remarks at the time..
From there I take an average of thoughts and make my cut.. So far I haven't been to far off the mark. The last sail seems to be a little too much for me in 15 to 20 knots. Oh I can keep it upright all right but it is getting up around 70 that scares the Bejesus Outa Me. Hopefully I will get passed that problem.
To my way of thinking the end product should be the same regardless of whether or not it is a recut or scratch built. Again I at once the Luff Pocket was removed and the sail re-cut (Keeping the Leach) the sail was flat as a Bed Sheet but my purpose is to Run on Tarmac hard beaches and airfields and looking for everything can get out of the top end. So far I have managed in excess of 2.5 times the wind speed.
Ron
When you were wanting advice on re-cutting your sail the subject of new sails never came up..... The advice you were after was given, successfully.
So if you were going for a custom made new sail probably a lower CE would be more beneficial and probably an elliptical tip to minimise drag.... Just these 2 things would add to stability and slightly increase your speed.
sabydents request was totally different from yours.
No No No. I am not disputing anything. I can see no reason why a re-cut Windsurfer sail has to be any different than a purpose built sail.
I could have had the top radially re-cut and had I not been so excited and known how to work the formula correctly I reckon those to points could have been fulfilled as well.. 20-20 Hindsight is a wonderful if not frustrating thing. Also a Little Knowledge can make a person Dangerous as well. I guess however we all have a reason to be proud of our efforts and the results of said efforts..
Ron
PS: Does Generated Wind Speed Less GPS calculated Land speed + Actual Wind Speed??
