How To: Insert Runners

by: Paul Goodwin- DN 4061

This information is provided for the use of sailors who wish to build their own insert runners. Over the last few seasons a lot has been learned about what it takes to assemble an insert runner which can stand up to all ice and wind conditions. The construction described here is not the only acceptable design, but is easy to build and will give good results. The basic design is for a 36" long runner with a 1/4" thick blade. The changes required to accommodate thinner steel and/or shorter runners should be obvious.


Many materials are available to the builder for this type of runner. Recommendations for specific blade materials will not be made, since this information has been covered in other newsletters.

Blade shape

In order to determine what shape the blade should have, make a full-scale drawing of the complete runner (fig. l). A good starting point is to use the same nose and tail contour as used on the Sarns bull-nose runner. I prefer the appearance of a runner body which drops in height from the

inserts_1c.gif (16372 bytes) fig.1 COMPLETE RUNNER

chock to the nose (about 1"), and from the chock to the tail (about 2"). Don't forget about the 5/8" minimum radius on the front of the runner (see fig.2). Once the overall shape is drawn, add two lines to the drawing, one at 1-1/2" from the bottom and the other at the same height as the width of the blade material (2-1/2" to 3"). This drawing now shows the outline of the steel blade and the wood body. This is important since once the steel is hardened it will be difficult to change its shape.

Using this drawing as a guide, cut and shape the steel so it matches your desired outline. Drill six 1/4" holes through the steel 1/2" above the lower edge of the wood body for reinforcing screws (see fig. 1). Sharpen the bottom of the runner to a 90° edge. The blade is now ready to harden. 

inserts_2c.gif (8020 bytes) fig. 2 RUNNER NOSE


Spring steels are often purchased hot-rolled, which bas a rough surface. If the hot-rolled steel also has scale on it, sand blasting is required before it can be heat-treated. Most other types of steel are usually purchased either precision ground or cold-rolled, both of which have a smooth clean surface.

Steel that is already ground to the final thickness must be heat treated in a controlled environment so that no scale is formed on the surface. Steel that is thicker than desired should be ground to thickness after hardening. This final grind will help remove any warping.

Blades can be flame hardened which allows holes to be drilled and modifications to be made in the unhardened areas. Most other types of heat treating harden the entire blade, so be sure to complete all of the desired machining before hardening.



The type of wood used for making runner bodies must have several properties in order to be successful. The wood must be hard in order to keep it from being dented by the chocks (this will make the runners loose), it must glue well with epoxy, and it must be resistant to splitting. If a chart of wood properties is available, look for wood that has high hardness perpendicular to the grain, and high tensile strength perpendicular to the grain. White ash and hard rock maple are good choices. The issue of gluing is more difficult. Two woods that I know of which can be difficult to glue are oak and teak, and I'm sure there are others. The body may be one piece of wood, or may be laminated butcher-block fashion. The laminated body will be less likely to warp.

Body shape

Start with a piece of wood (for each runner) which is 36" long, 7/8" thick, and 3-1/2" high. Cut a slot in the bottom edge for the steel insert. The dimensions for the slot will be determined by the size of the steel. The depth of the slot should allow 1-1/2" of tile blade to be exposed. Cutting the slot is best done on a table saw, adjusting the rip fence by trial and error to get the right width. Place three thicknesses of 8 oz. or 10 oz. glass cloth over the blade and try to insert it into the body. The perfect fit will allow the glass cloth and steel to slide in snugly without putting too much strain on the wood.

Using the steel blade as a template, mark the location of the reinforcing screw holes on the side of the body. Drill these holes out to 5/16" diameter.

Using the runner drawing cut the body to the desired outline. Trial fit the blade into the body to insure that everything lines up properly. The runner is now ready for final assembly.


If the slot in the body is the correct width, the steel insert will be self-aligning when it is glued in. If the fit is too loose, consider adding another layer of glass cloth to adjust the fit.

Support the body with the slot facing up. On a flat surface, spread out a sheet of plastic to wet the glass cloth on (a garbage bag works well for this). Cut three pieces of glass cloth (for each runner) 38" long and 5" wide.

Coat the inside of the slot with epoxy. Wet out a layer of glass cloth on the plastic. Add another layer of glass on top of the first, wet it out, and repeat for the third layer. Coat the steel insert with epoxy (where it will be glued into the wood) and sand with 80 grit sandpaper. This is similar to wet sanding, but with epoxy instead of water.

Lay the three layers of glass cloth on top of the body, centered over the slot. Set the top edge of the blade on the glass cloth and push it down into the body. Epoxy should squeeze out as the blade is inserted into the body, guaranteeing that the joint is not glue starved. Make sure that the blade is properly aligned with the body, and leave it positioned vertically to cure.

After the epoxy has partially cured, use a razor blade to cut off the excess glass cloth at the bottom of the body.

inserts_3c.gif (9109 bytes) Fig. 3. SECTION

Once the assembly has reached a full cure, drill out the reinforcing screw holes with a 1/4" drill. Cut pieces of 1/4" threaded rod to the width of the body. Put tape over the holes on one side of the runner body and fill the holes with epoxy. Coat the pieces of rod with epoxy and drop them into the holes. Wipe off any excess epoxy and allow to cure.


Sand the body to its final shape and round off all edges except the bottom. The body should be reinforced by adding layers of fiberglass to the sides. If the top edge of the body is rounded, then the glass cloth can he wrapped over the top and down both sides, laminate the layers of cloth one at a time, being careful to squeegee the cloth well in between layers. Allow each layer to cure and sand lightly to remove any bumps and irregularities. Measure the overall thickness and add more layers of cloth to build up the thickness to 1". A layer of carbon fiber can he added with the fiberglass for additional strength and stiffness, but is not required.

Drill the 3/8" pivot hole 15" from the back of the runner and 1" from the top. Coat the inside of the pivot hole with epoxy. After curing, carefully drill out the hole to 3/8' again.

Sand the runner smooth with 80 grit sandpaper and apply a final coat of epoxy.

Many sailors add stiffeners to their insert runners. This can be done several different ways. Stiffeners can be made of aluminum angle, but they must be bolted very tightly to the runner to be effective. A wooden "wing" with carbon fiber glued to the outside edge also makes a good stiffener. A stiffener might make the runner faster by keeping it from bending under load, and also adds strength.

The runner is now complete except for sharpening the edge. Henry Bossett's article in the last newsletter outlined a good method for measuring the crown on runners. The epoxy coat will hold up fine for several years, but an additional coat of varnish or paint will give a more durable finish.

Many people have had problems with runner bodies breaking (usually just above the top of the blade). The reinforcing screws and the layers of glass cloth should provide adequate strengthening of the body. I have a set of runners built as described in these plans and have sailed them hard for three seasons. So far there are no signs of any problems. Other sailors in my region have runners of similar construction, and I’m not aware of any failures.

Most people that have made insert runners were surprised at how easy they are to assemble. I hope this has provided some useful information and the inspiration to start building.

Iceboat Runner Blades - 3 steps to help you get the most out of yours this season

By Jan C Gougeon

Iceboat nuts agree: when you increase the speed of your DN Iceboat, there is a snowball effect on the amount of fun to be had during the chilly winter season. If you want a faster, more enjoyable sail out of your DN, it is very important to get the runner blades parallel to each other. Proper alignment requires a little extra work, but can mean the difference between first and second place in this season's DN iceboat races. Here's how we do it in the icy Saginaw Valley.

Step 1

Mounting the Chocks

First, create a bend in the runner plank that simulates being on the starting line in light wind. With the plank upright and the ends supported by small wooden blocks, stand on your plank with 30 to 50 pounds of weight in your arms. Note the amount of deflection in the plank by measuring the height above the floor at the center and the ends of the plank. The runner chocks will be mounted on the plank so that the runners will be perpendicular to the ice in this position. Duplicate the bend by clamping the plank upside down to a 7 ft long 4" x 4" beam with "C" or bar clamps placed 6" from each end of the plank. Draw the ends of the plank down until the bend is duplicated. Sight across the ends of the plank to measure the amount of deflection and assure that the ends are parallel to each other.

Measuring plank deflection

There are different methods of lining up the chocks to make them parallel. We use the triangle method. A jig, made of three pieces of 1" square steel or aluminum tubing, is welded together in the shape of an equilateral triangle. The base of the triangle (about 4' long), bolts into the runner chock. (A 1" section will fit into the runner chock, just like a runner.) The two equal length sides of the triangle (a little over 8’ long) should come to a sharp point at the peak and almost touch the chock on the opposite end of the plank. The point should fall on a centerline that bisects the triangle equally, and is exactly perpendicular to the base. Drill a hole through the middle of the base tube in line with the perpendicular centerline for attachment to the chock. (Lay it out on the floor to get it perfect.)

Dry-fit the chocks in position. One through-bolt holds the tang for the shroud on top of the plank, passes through the plank, and then threads into the middle outer hole of the chock. One-inch Allen head set screws are threaded into the other five holes in the chock. The through-bolt hole in the runner plank is drilled to size. The holes for the set screws are drilled slightly deeper than the screw length, and oversized to allow for adjustment and better bonding. A 7/16" hole will do. The chock should be able to pivot slightly around the through-bolt.

After the plank, jig and chocks have been prepared, wet out the holes and the surface of the plank under the area of one of the chocks with WEST SYSTEM epoxy. Follow with a generous amount of epoxy/406 Colloidal Silica mixture. Carefully place the chock on the plank end with the triangle-jig bolted firmly in place. Align the triangle point with the center of the runner bolt hole in the opposite chock. Shim the triangle point so that it rests with the center of the 1" tubing even with the center of the hole.

Alignment Jig

Epoxy should squeeze out everywhere. With the chock tightened down on the triangle, and the triangle end centered in both front and top view on the opposite runner bolt hole, the chock will be correctly positioned from both front and top views. Note that the inner edge of the chock may be slightly raised. Clean off excess epoxy, and allow the epoxy to cure thoroughly with the chock in this position.

Thixo wedge

After the epoxy cures, mount the other chock in the same manner and allow to cure thoroughly before proceeding.

NOTE: Do not turn the aluminum triangle over. Mark the surface that is up and always keep it up. This way, even if there is an error in the triangle, the chocks will still be parallel to each other.

Step 2

Tuning the Runners

Now that you have the chocks on the plank, the next step is to fine-tune the runners. With the runner plank still clamped to the 4x4 with the same deflection used to mount the chocks, bolt the runners firmly in the chocks so their edges are parallel to the bottom of the chock. The runners should also be parallel to each other. Put two marks on each runner, 6" fore and aft of the runner bolt. Use a stick about 9' long and about 3/4" square to measure the runner alignment. Lay the stick across both runners on the aft mark. Press the stick against the edge of one runner to make a V-shaped indentation in the wood. With the indent resting on the runner edge, squeeze the stick against the other runner edge at the aft mark to make a second V-shaped indentation. Slide the stick to the marks on the forward end of the runners to check the difference in distance between the fore and aft edges of the runners.

NOTE: It is important not to push down on the stick, but to squeeze the stick against the runner with your hand. An inaccurate reading can result if the runner and plank are even slightly deflected when marking the stick.

According to Murphy's law, the runners probably won't be perfectly lined up. There are two ways to get them into line. The usual method is to grind the running edges to the correct alignment when you sharpen the runners. If the runner edges are sharpened so they are in the middle of the steel that makes the runner body, and there is still considerable error, the runner stiffener can be modified to correct the problem. One method is to sand the appropriate areas of the stiffener where it contacts the chock. Remove enough material to allow the stiffener to move to the desired alignment when the runner bolt is tightened.

If you have a little clearance between the runner and the chock, there is an easy way to remedy the situation. Remove the runners and coat the inside surface of the chocks with an automotive paste wax. Remove grease from the runner and sand the runner stiffener in the area that goes into the chock. Mix up a small batch of WEST SYSTEM epoxy and coat the runner stiffener on both sides where it fits into the chock. While the epoxy is wet, wet-sand it into the metal. Add some 406 Colloidal Silica to the batch of epoxy and apply the thickened mixture to the runner stiffeners in the same area. Place the runners in the chocks, with the runner bolts in place, but not tight.

Use thin wedges of wood between the side of the runner and the chock to get the correct alignment, tighten the runner bolt a little to squeeze out some excess epoxy, and then check the alignment one more time.

When the epoxy cures, trim off the excess and you'll have a well-fitted and correctly aligned surface that, when greased, will last a very long time.

Step 3

Mounting the Runners

The last step is to mount the runner plank on the iceboat. You want the plank to be centered and at 90deg to the centerline. The plank should also be mounted so that (from the side view) the bottom edge of the runner chocks are parallel to the ice when the boat is in powered-up sailing trim. To simulate this powered-up sailing trim, place about 400 pounds of weight in the cockpit in the area of the runner plank. With the three runners installed (place 1/4"-thick plywood under each runner), measure the bottom edge of the chock to see if it is parallel to the floor from the side view. Shim the front edge between the hull-to-plank fitting and the runner plank as necessary to get the chock parallel. Bond the shim to the hull-to-plank fitting when you are satisfied with its position.

Shimming the plank

These steps will help you to get the most out of your runners under the widest range of sailing conditions.

Note: This article is from the Fall 1989 edition of The Boatbuilder (Number 27).
The Boatbuilder is published by Gougeon Brothers Inc.

updated August 22, 1999

Runner Alignment

by: Henry Bossett - Decmeber 10, 1984

Speed in a DN is produced by a combination of the following factors: Runner Alignment, Runner type, Plank type, Mast/Sail/Boom type, Hull type, Tuning factors and Sailing technique. An adjustment to anyone of these areas.will have an affect on the performance of the boat and your final position. Each of these areas is important and large enough in scope that you must study and understand them individually, before you can hope to improve your results.

My discussion is going to be about Runner Alignment. Even if you have achieved perfection in all the other areas, improper alignment can actually keep you from sailing around a course, let alone trying to win a race. Everyone seems to have his own idea of how best to align their runners. To discuss them all would fill a book, so 1 will just relate the various areas that I check to be sure of my alignment.

The first step is to get your chocks set up on your plank so that they are parallel and capable of moving enough to align your runners. Thus, although it would be nice to just drill exact size holes for your bolts, it is better to drill oversize holes. You do not need a fancy set up to do this. Simply drawing a line across the plank end at the bolt hole locations with a carpenters square placed along the front or back aide of the plank will do. If the mounting surface on the plank is uneven you will have to smooth it with an additional layer of wood or epoxy with filler. The point here is to be sure that both the left and right surfaces are parallel to each other. If not, then your runners will change alignment as the plank bends, check for this with an adjustable level. Look at both the fore and aft direction and sideways.

Next you need to take a good look at the actual edge of your most reliable set of runners. Use these to align your chocks since they will be from front to back. It may be straight for a short distance under the pin, but most that I have checked will then wander to one side or another at the front and back. Usually the edge will also not be aligned perfectly with the stiffener. This is why you have to shim each set of runners individually on a given plank (unless you machine your own runners and have built them to perfection). I started using a small rifle scope three years ago, and was amazed at how far the edge wandered. I am not convinced that this degree of perfection is needed, but it is just one more tool that I use to be sure of proper alignment.

Once I am sure of a good edge on my all around runners, and have drilled the holes in the plank for the chocks, I drill a lot of small holes into the flat surface of the chock to help it glue to the plank. These are randomly spaced, and I also rough up the surface with harsh sandpaper. Now when you glue your chocks on (the only way to be sure of continued alignment throughout the season), they will have a very difficult time breaking free. When I finally mount the chocks, I fill all the holes with a mixture of "Gougeon" and filler, plus spread a small amount on the entire surface. This mixture will bold your cbocks in place until YOU. decide you want to change them.

I align my runners using triangle plates. The plank is mounted on the boat, and weight is put in boat to approximate my weight, the rig weight, and a small amount of downthrust such as a sma11 puff would generate. This all makes sure that I am in the most perfect alignment when the boat is coasting. It is at this point that both runners are firmly planted in the ice and thus need to track together. Any more wind and your windward runner starts to get light and alignment becomes less important.

The triangle plates that the runners sit on have their runner supports only 10" apart so that any bend in the front or back of the runner will not result in bad alignment. After all, that is the portion of the runner' that is most deeply imbedded in the ice. Plates seem at first to need machine sighting thru string set up as a large "T" on the floor, using the easy method of swinging two arcs to get the right angle "T". I then glued the supports in place and after they dried, screwed them in place for added safety. It worked perfectly, since anyone who uses my plates seems to glide quite well.

The fina1 step is to check it all on the ice. On those no wind days when most everyone is sitting around the bar waiting for the wind to come up, you will find me out on the ice "Test Gliding" my boat. You need near perfect ice to do this, but that is what we usually have at the beginning of the season anyway. Push your boat up to speed, then hop in and listen to it, as well as watching the runners. If you are out of alignment, the runners will be pulled further out of alignment and then spring back with a scratching noise severa1 times during your Glide. In springing back, they will throw ice chips, and this will tell you if you are toed in or out. Use thin shims to finally align them to the point that the boat glides further and is quiet. Now you are finally ready to beat the pants off of your buddies when they finally get back on the ice after all their Elbow exercise.

The one thing that bas become apparent in all the work that I have done to make my boat fast is that if you use your own senses and do not worry too much about Space Age Technology, you WILL. be fast. Don't get me wrong, you do have to investigate everything that promises to be a breakthrough, but the biggest breakthroughs in your own performance will come from straight forward practice, and keeping your eyes and ears open to what's right there in front of you. Good Luck this Season!