Insert runners part 1

Modern insert runners for DNs are very expensive. If you have ever tried to make some you will quickly find out why. Being the DIYers we are, my cousin Les and I decided to make our own. We're starting with 2 sets, 4 side runners and 2 steering runners.

The only 440C stainless steel supplier we could find was KnifeMaker.ca. We purchased 6 pieces 36" x 2" x 3/16". The bill made our eyes water! This was right in the middle of that trade spat over steel with the USA. Friends with machine shops cut the shapes and edges. We also incorporated 5 "key holes" in each blade. The blades also underwent a thermal hardening process at a specialty shop in Hamilton.

I used a CNC router table to cut corresponding body halves out of 1/2" Baltic Birch plywood. This was a 2 step process where I first cut 3/32" pockets in each half and then cut the over-all profile. When glued together the "keys" left in the birch project through the "key holes" in the steel.

NOTE. After cutting 12 body halves we discovered that the 3/16" steel was not 3/16" thick! Who knew! The steel was thicker than 3/32" so all our pockets were too shallow. Back to Exotic Woods in Burlington for another sheet and back to the router for a few more hours of noisy fun! Remember - measure twice - cut once!

We also added 7/16" holes at the front end of each key. We made each hole blind by bunging in a 7/16" x 1/4" long dowel on one side. When we glued the two halves together we could pour epoxy down each hole to insure all the nooks and crannies around each key was filled. The exposed steel is coated with furniture wax to prevent the epoxy from sticking to the blade. The steel surfaces that are inside the body were scuffed up with a dremel and a grind stone to help the epoxy stick. Later, when we skinned each runner with carbon fibre we redrilled each hole and glued in 7/8" long 7/16" threaded rod.


In this photo you can see the keys along with the 7/16" holes. We scored the inner faces to add more "clingy spaces" for the epoxy. We use West system 105 epoxy, 207 hardener and 404 High Density filler as recommended by iceboat builder Bob Intini. 

Singly or in pairs the runners were glued up between two pieces of granite kitchen counter on a flat bench to insure straightness.

This photo shows 2 runners fresh off the granite. I like to let epoxy set for 2 days minimum. 

We also discovered that 1/2" plywood is not 1/2" thick. Good thing it is slightly under. There's just room left to add carbon fibre to add strength and looks. That's in part 2.

If you are interested in the .stp or .dxf files send me an email. mdruiven@gmail.com.

DN Canadian Championship March 17 2019 Kingston

Neck Brace for DN Sailing

   Whenever I am cruising my DN I tend to steer with my knees with one hand on the sheet and the other holding my head up so that I can look forward. Sailing a DN is tricky on the neck. You lay down in the hull and end up looking at the top of your mast. In order to look forward one must crane their neck down towards their toes. The older I get the more this hurts. Thanks to John Curtis for this design suggestion. Many DN sailers use a rig to ease neck strain during races.

Parts
1 Grippie Rope Tightener (sku 061-0044-0 at Canadian Tire)
6 ft x 2 inch cotton webbing
3 ft x 3/16 inch Bungee cord
3 ft x 3/16 inch cord
several small cable ties

Step 1
Sew the webbing into 2 loops 32 to 36 inches long. Make sure to put each loop through the Grippie first. Use several passes of zig zag stitch.

Step 2
Determine how to fasten the bungee cord to your helmet. This will depend on helmet type and construction. Make sure you have enough "stretch" to be able to raise your head (flatten your body) when you tack or jibe. I was able to pass the bungee cord right around the helmet through built in loops to give plenty of stretch.

Step 3
Fasten the bungee cord ends to the cord using knots and/or small cable ties.

Step 4
Test everything out in full gear. With your legs through the straps the Grippie should be near your waste. Feed the cord through the top half of the Grippie and cinch it up just before the race.

Step 5
Have fun and be safe.

Dual DN enclosed trailer part 1

My cousin Lester Druiven and I build and sail DN ice boats for fun and the odd race.

A couple of years ago we purchased a 15 ft. 1000 lb single axle boat trailer with no bunks or winch. The long tongue makes for some interesting times backing up the trailer but made it easy to strap on our DN Ice Boats. I sewed a couple of bags out of heavy cloth to help protect the hulls from stones on the road. With an added cross brace and some kayak brackets we were able to trail our boats cross country. It would take us some time to strap everything on and the hulls still sustained damage from stones and from rubbing against other parts.

We always planned to make an enclosed trailer that could house everything, 2 hulls, 2 masts, 2 runners, skates, sails and booms, tools and clothes in a "ready to go" state. The method seen above to clamp the cross member to the tongue worked well. Les welded up a 4 ft by 8 ft frame out of 2 inch square steel and we clamped that onto the tongue by welding 5 1/2 inch x 5 inch plates to the frame using a second set of plates and 1/4 20 bolts. We brought out the marker lights and skinned it over giving us a 4 by 13 foot base.

The base is 3/4 brown plywood and the sides are 3/4 sanded plywood, 2 feet high. We used 2x2 offset from the edge to attached the sides. Everything is bolted down with plenty of 1/4 20 bolts and nyloc nuts. Joints are glued and screwed with 2x2 and 2x4 reinforcing backing.

Next time I will discuss the construction of a lid. The ribs are done and final assembly of the lid will start soon. You can see a quick mock-up below.

The trailer will look like and open like a giant coffin. The 6 inch pipe will project forward and aft to house the 16 ft masts. I thought it might be best to make the 2 bottom outside stringers out of solid 2x2. It turns out you can't buy a 16 ft 2x2 so I bought a 16 foot 2x4 and split it in two. It was amazing to see a straight 2x4 go into a table saw and watch the 2 twisted and warped 2x2s emerge!