I sailed my new Ice Flyer today for the second time. It was on clear black ice with light winds. As with my first time out, I was disappointed with the way the boat powers up...especially in light air. Also my top end isn't what you would expect. I was sailing with DNs and wasn't even close to keeping up.

The sail I use is a Sailworks Retro 8.0M which is a RAF sail. Works well for windsurfing, but I was wondering if a fully cambered sail might hold it's shape better and power up better. Of course, it might be I just need a bigger sail in light air. Let me know what you think.

Roger Livingston

My experience has not been that good with RAF sails in very light wind but I would expect your sail to be pretty fast in a good breeze like 20 mph. The current sail I use can be run without cambers and the one time I ran without cambers, it just wouldnt go in the real light wind (and its a 9.0).

I dont think in general you build the Iceflyer expecting to beat DN's but my experience with modified windsurfing sails has been opposite yours especially for very light winds and to some extent peak speads also. My modified 9.0 has been working very well in the light winds (given good runners) and at least in the land sailing world, seems to be right up there with the best (and the best are better than DN's).

Here is a picture of my sail set for very light winds http://groups.msn.com/ICEFLYERPictureForum/11yearoldlightairmaster.msnw?action=ShowPhoto&PhotoID=62

This sail is a Windwing Synthesis 9.0 with 2 camber inducers in the lower portion of the sail. I use an adjustable outhaul and it is let all the way out so the sail is very full. However, one thing to notice in the picture is that even though the sail is full, it still has a flat entry behind the mast and that seems to be important. This sail is also rigged with the top part of an extra windsurfing mast inside the lower portion ( http://iceflyer.com/mastiff.html )and this can cause some sails to have a lot of curvature near the mast when the sail is set full. This is good if you want to develope power under 20 mph but in my experience, it is not fast.

I started flatening the front of the sail somewhat by accident but after a while I was trying to go for an Eppler 376 foil shape by stiffening the battens near the mast end only on the ones which had camber inducers. This web page needs to be updated but the details are here:
http://iceflyer.com/ptb2.html One thing about this mod is it seems to give a better foil shape when the sail is run full and you need to run full to get the potential performance in the very light wind. I think in general I can also run the sail fuller with the mod in any sort of wind and after all these years of using this, Im pretty convinced that it does in fact make a faster windsurfing sail. The only time I make my windsurfing sails very flat is when Im for example using the 9.0 in 25 to 40 mph winds.

The next thing Im running is either cutting edge or pretty far fetched but I think it makes a difference in some conditions and doesnt hurt in others. I beleive one of the benifits of a wing mast is that it is good at keeping attached flow in the region around and just behind the mast and this is where the highest pressure gradients on the sail occur. If you cant keep attached flow, you get seperation bubbles which is sort of the air flows way of going over an area that it cant stay attached to but you loose the lift created by the higher pressure differential this is available if you could keep the flow attached. For a couple years, I did some experiments and my criteria was simply trying to keep the tell tails behind the mast more attached and I tried a bunch of things but the one which so far seemed to give the best results is a peice of PVC pipe run through a table saw. The details are here: http://iceflyer.com/hybridfoil.html (see experiment #3). As I mentioned, its either cutting edge or lunacy for a round mast leading edge but what I beleive is happening is that there is a columb vortice shed off the PVC leading edge which has a positive influence on the flow remaining attached but it doesnt seem to have any negitive drag effects. It seems to make a difference to me. http://iceflyer.com/experiment/windsurf_vortex.html

Finally, Im also using a end plate fence on the sail http://iceflyer.com/experiment/end_plate.html which I think there is a "reasonable chance" that it also is making a difference.

Unfortanately, I never get around to for example removing one of the implementations at a time and trying to measure the results but with all these mods, I seem to be able to beat any other Iceflyer in most conditions (in some conditions, I will be about equal, once in a while, someone will pass me but I think in general, my sail is fast).

So I think your sail as is will probably be overall pretty fast in winds over 10 mph (how high were the winds on the day you sailed?) and probably will be real fast in winds over 20 mph but will be fairly poor in say 3 to 10 mph winds. Unfortanetly, I think you have to start messing with the windsurfing sails to really get some speed out of them and some people like that (I do) and some dont.. But if you just wanted that boat for high wind days (might make a nice complement to your DN?), just about anything will be pretty fast.

Thanks Wally for all the information.

The winds today were only 3 to 8 mph. My runners were freshly sharpened and aligned so I knew the problem had to do with sail shape. I'll pick up a cambered sail for light wind days and try some of your other ideas. I like how you closed the gap under the sail. I've seen this done on some of the larger ice boats and it seemed to make a difference.

I know I shouldn't compare the Ice Flyer to a DN, but should judge it on it's own merits. My frustration today had more to do with a sensation. I've sailed many different ice boats over the years and there is always that change you feel when the sail developes lift as it starts to accelerate. It wasn't there today and I knew it was just a matter of making some adjustments to the boat. One of the reasons for building an Ice Flyer was to have a platform I could experiment with.

I'll keep you informed of my progress. Hope to sail Saturday.

Merry Christmas to all.

Roger Livingston

Picked up a used Gaastra 8.5m 4 camber sail yesterday. Sailed this morning in very light air with it. Wow...what a difference ! The boat was moving in virtually no wind and as the wind increased the boat accelerated rapidly. I had a great time. I had to quit at noon since the temperature was in the high 40's and the ice was rotting fast. I'm anxious to try it again.

Roger

I got in a few days sailing with a variety of boats and think the sail described above in this thread is very interesting... Im looking forward to when someone else tries the Eppler 376 foil shape and the 3/4 PVC pipe leading edge to see if they are getting similar results. For the rocket scientist, I think what I have described is a good baseline to implement and then modify. Here is the Eppler 376 foil shape that Im trying to approximate: