Collective Wisdom – The DN Iceboat

Seven Years of Internet Archives

1998-2004

Edited and Arranged for Easy Reference

PLUS

Selected Reprints from Runner Tracks

Racing Rules

DN Class Specifications

Ken Smith

Editor

Contents

Click on a page number to go to that page. (Control – Click in WORD) Use your Back arrow in the top menu to return to this table.

What is a DN?............................................................................................................................... 4

History and sources.................................................................................................................... 6

Buying........................................................................................................................................ 8

Used boats and repairs............................................................................................................... 8

Thinking about building............................................................................................................... 9

Hull Kits................................................................................................................................. 9

Opti DN for kids...................................................................................................................... 13

Think about this first................................................................................................................. 13

Love this boat...................................................................................................................... 13

Helmets................................................................................................................................ 18

Down forces........................................................................................................................ 19

Racing.......................................................................................................................................... 21

“Buoys”................................................................................................................................... 21

Starting.................................................................................................................................... 23

Shop Stuff.................................................................................................................................... 25

Hull.............................................................................................................................................. 26

Hull Plans and Options............................................................................................................. 26

Hull shape and modifications..................................................................................................... 29

Concave Hull Bottom........................................................................................................... 29

Hull Materials........................................................................................................................... 31

Side boards.......................................................................................................................... 31

Plywood.............................................................................................................................. 35

Hull Repair............................................................................................................................... 36

Cockpit Floor Thickness.......................................................................................................... 37

Cockpit Footrests.................................................................................................................... 38

Hull Finish................................................................................................................................ 41

Steering.................................................................................................................................... 47

Caster (Tilted pivot)............................................................................................................. 47

Front pivot loose.................................................................................................................. 48

Tiller........................................................................................................................................ 50

Runners........................................................................................................................................ 54

History................................................................................................................................. 54

Rules.................................................................................................................................... 56

Insert vs Plate Runners............................................................................................................. 59

Plate Advantages.................................................................................................................. 60

Alignment................................................................................................................................. 63

Plate runner construction........................................................................................................... 83

Runner body construction......................................................................................................... 84

Pivot Point............................................................................................................................... 85

Angle Runners.......................................................................................................................... 87

Insert Runners.......................................................................................................................... 88

Insert Design........................................................................................................................ 88

Runner Construction............................................................................................................. 90

Insert Bodies – Wood.......................................................................................................... 92

Insert Bodies -- Reinforcement............................................................................................. 95

Fixing broken inserts........................................................................................................... 102

Runner steel........................................................................................................................... 103

Building Runners................................................................................................................. 104

Hardness............................................................................................................................ 105

Runner Crown and shape................................................................................................... 108

Sharpening............................................................................................................................. 112

Snow Blades.......................................................................................................................... 113

Straightening Bent Runners..................................................................................................... 113

Brakes................................................................................................................................... 117

Articles.................................................................................................................................. 117

Masts......................................................................................................................................... 118

Getting started in the class....................................................................................................... 118

Shipping a mast.................................................................................................................. 122

Rules and Discussion.............................................................................................................. 122

Aluminum masts..................................................................................................................... 128

Internal reinforcement......................................................................................................... 128

Composite Spars.................................................................................................................... 129

Mast Bend............................................................................................................................. 129

Measuring Mast bend (deflection)....................................................................................... 131

Tuning Mast Bend.............................................................................................................. 134

Selecting a material................................................................................................................. 136

Fiberglass construction........................................................................................................... 140

Mast minimum weight............................................................................................................. 142

Luff tube................................................................................................................................ 146

Alternative materials for luff tubes........................................................................................ 149

Cutting a slot...................................................................................................................... 151

Other Wood Masts................................................................................................................ 152

How to modify (tune) a wood mast..................................................................................... 153

Strengthening Wood Masts................................................................................................. 154

Glass Mast Repair.................................................................................................................. 155

Booms....................................................................................................................................... 157

Goose neck............................................................................................................................ 157

Plank and Chocks...................................................................................................................... 158

Plank construction.................................................................................................................. 158

Wood Sources................................................................................................................... 158

Where you step.................................................................................................................. 159

Building a plank.................................................................................................................. 159

Laminations, thickness, and wrapping the plank in glass....................................................... 164

(Caution: Strong Engineering language may not be suitable…).............................................. 167

Using glass or carbon – The rules........................................................................................ 171

Plank Stiffness and Crown...................................................................................................... 172

Changing stiffness............................................................................................................... 172

Twisted Plank?................................................................................................................... 175

Crown............................................................................................................................... 176

Spring back, Gluing layers.................................................................................................. 177

Hollow Planks.................................................................................................................... 179

Bottoming out-Advanced Tuning......................................................................................... 180

Plank Profile and Drag............................................................................................................ 189

Chocks.................................................................................................................................. 191

Alternatives........................................................................................................................ 192

Mounting chocks to plank....................................................................................................... 194

Which end forward?........................................................................................................... 196

Alignment of Chocks.......................................................................................................... 197

Sails........................................................................................................................................... 204

Battens................................................................................................................................... 204

Tell-Tale Streamers............................................................................................................ 205

Mast Rotation.................................................................................................................... 207

Rigging....................................................................................................................................... 208

Sources for Hardware........................................................................................................ 208

Rigging a Hull (Putting on hardware)....................................................................................... 209

Springs on Front Chock..................................................................................................... 210

Plank to Hull.......................................................................................................................... 211

Bobstay................................................................................................................................. 211

Blocks (pulleys)...................................................................................................................... 212

Main Sheet............................................................................................................................. 215

Shrouds................................................................................................................................. 219

Shroud lengths.................................................................................................................... 219

Head Stay.......................................................................................................................... 221

Head stay length by other measures.................................................................................... 222

Forestay hardware for mast rotation.................................................................................... 225

Problems and solutions............................................................................................................... 229