Greetings - I am building a craft similar to an ice boat but much smaller in scale. When I tried it out for the first time, I suffered from excessive side slippage, and as a result couldn't get much speed. Somebody mentioned my blade sharpening was all wrong, and recommended to try an edge profile similar to an ice boat runner. What is the preferred runner edge profile? I've heard it's a simple V, but at what angle?
Curious,
Dave

I have never built a set of runners - only used Sarns so keep that in mind and you will might also take a look at the the DN bulliten board http://www.laser.org/DNboard/DNmain.html

My advice also is pretty close to just go buy a set of Sarns runners your first time because it gets rid of a huge varaible in building a boat but they may also be too large for your application.

Anyhow, the angle on runners is 45 degrees (forms a 90 degree angle at the edge) - one single point. Ive heard of higher angle and lower angle but they tend to be for very specific conditions. For example, a higher angle edge might work better on very hard ice but will likely "dig in" and have higher drag on softer ice. 45 degree works well all around. On very hard ice, keep it sharp, on soft ice, let it get dull. It also seems to be important to have a smooth transition from round to sharp on the leading and trailing edge and as you get more complex with them, you can start to put a little bit of "rocker" in the runner. Sarns is supposed to have about .008 inch rise on each end and Ive heard that the "bottom" of the rocker should be just behind the runner pivot point in the chock. I guess even the amount of rocker gets adjusted for the different ice conditions but I tend to just mess with sail size and shape rather than get exotic with runners (I sail an ice flyer). I usually carry around 2 sets of Sarns runners only - one sharp set and one dull set. The sharp set gets used mostly early season, the dull set late season. You can get more complex than this and the DN web site and bulliten board is a good place to research or ask questions.

Iceboat runners are sharpened to a 90 degree angle creating the V you mention. Some ice boaters increase and decrease this angle to accomodate different ice conditions. There is also a slight rocker to the profile of the blades. For instance, on a 30 inch runner, I have 3 1/2 inches of flat under the hole where the blade attaches. There is a slight curve upward to each end (about .011 inches). Without this curve, there is too much blade on the ice and the boat side slips.