Here is my finished 4.6m sail. Just a bit smaller than my airtrack sail.

Thank you land yacht for helping with the design and construction tips.

Ben.

Finished a fat 5.0m sail for dad.

Wow!!!

Looking very professional Ben. Well done.

Thank Chook,
The 4.6m sets nice and looks fast.

dang boy that looks better than mine,Id better get my game face on

Tested this sail today on a mini vs my production blokart. Wind was 8-12knt S-SE, Sail looked and performed really good on a soft mast ( about the same as Production blokart or a bit stiffer) with stiff tip/extension. I would like to see how this sail performs on a stiffer mast. Soft mast has a lot of sail twist.

The mini was the faster yacht and dad loved the VHS tape tell tales he sad " I can see how to trim the sail" most of the time he chokes/stalls the sail and complains there is now wind but not now.

To catch up or pass dad I had to wait for him to make a mistake ( he is getting faster) .

Only problem is I need to make another sail as dad now wants this one.

Might make him a 5.0m^2.

Ben.

couple of minor puckers, but looking great. i would have had a tad more mast rake.
Im rather jealous that you got out to the secret claypan on such a nice sailing day. that windsurfer board is still waiting for pickup
hows that 5 looking,mine s starting to happen

Sail sets better on test chassis with centre sheeting. Dad runs a unique sheeting arrangement.
Class 5 is happening slowly. Better late than never. Just assembly recut, re-weld, re-align components. Seat is comfortable. Hopefully get a test sail this break. I would like to be working on a flat y mini though.

You guys have one up on me i still do have not got a clue how to make a good sail

Ben where did you cut the shape in the sail?.Was it under the first batten from the foot of the sail?

The shape in the sail comes from the 20mm constant curve on the back of luff panel in the middle. The radial rear panel is completely flat.

Here is the sail plan if you want to have a go.

Ben.

Hi Ben, what a greatlooking sail, thanx for posting the plan!
Did i get it right: just a 20mm curve, peek at 50 percent hight, for chamber?
Why is the rear panel cut radial, when its flat? Wouldn't it be easier to use a single one, as on the Airtrack-sail?
Same cut for Mylar and Dacron?

I have to make some small sails for the Kids...
Cheers, Joe

Landyacht may correct me if I'm wrong. My understanding is that the radial cut suits the properties of the material by reducing the amount of stretch. If you look at the laminate we were using you will notice the direction of carbon and dacron in the laminate.

Draught depends on the surface you sail on. I found my airtrack is cut to full for high speed smooth salt lake but has lots of grunt for a french beach.

Smooth and High speed= less draught 20-25mm
Lumpy Power Sail with Grunt= more draught up to 50mm?

If you look at Chook with un-cut windsurfer sails the Sverene Reflex is a multicam powerful and stable sail and has a deep draft.

Have a look at www.seabreeze.com.au/forums/Land-Yacht-Sailing/Sail-making/tall-skinny-class-5-homebaked-sail/

This is a similar type sail with same design principles. Flat rear panel.

Different sails but both work.

Hope that helps.

Ben.

Yeah, that helped, thank you!
Sailmaking seems to be a bit more art than witchcraft now!

Select to expand quote

BenBoulder said..
Landyacht may correct me if I'm wrong. My understanding is that the radial cut suits the properties of the material by reducing the amount of stretch. If you look at the laminate we were using you will notice the direction of carbon and dacron in the laminate.

Draught depends on the surface you sail on. I found my airtrack is cut to full for high speed smooth salt lake but has lots of grunt for a french beach.

Smooth and High speed= less draught 20mm
Lumpy Power Sail with Grunt= more draught up to 25mm

One thing that I have never been able to make successfully are sails , can not get my head around the whole process
Well done ben

sail making is good fun vic.

I'm just lucky I have a good mentor and I am motivated to learn. Your sails give you the best performance advantage by far.
But the most important factor in sailmaking that I have learnt from studying the windsurfing sails industry is "what colour do you think it should be?"

sail making is labor intensive. I love reverse engineering windsurfing sails. Each brand and sail designer is different.

Just takes time researching the why and practising the how.

Ben.

Select to expand quote

BenBoulder said..
The shape in the sail comes from the 20mm constant curve on the back of luff panel in the middle. The radial rear panel is completely flat.

Here is the sail plan if you want to have a go.

Ben.

Ben

I recreated your sail plan in EXCEL but have a few questions on the layout. The dimensions match your sketch.

The sail was oriented on the grid with the line joining the head and foot of the luff pocket trailing edge angled 71 degrees from vertical. The leading edge of the curved part is at 10 degrees.

The angle of the foot with respect to the line joining the head and foot of the luff
pocket trailing edge was drawn with 61 degrees between them. This puts the foot
at 10 degrees in the grid. What angle did your sail have?

The dimensions of the radial panels are for a flat surface. If I were to draw them on the sail, their leading edges would overlap the trailing edge of the luff panel. I believe that this is where the draft comes from.

The back of the luff panel was modeled as a straight line. Can you confirm that the
20 mm curve is to the rear and is centered on the panel trailing edge?

Thanks for your patience, I am very new at this.

Dave

I think you got that right

Dito

I am just about done with the Sail model that I have been working on. I have plenty to learn and figure that the best way will be to create a new topic and break the design down to discuss it further. I was pleased that I caught the attention of Landyacht and BenBoulder over here. I look forward to their input.