Runner bags.

Now the runners have been sharpened I wanted to protect them from getting damaged! This resulted in a small side project making runner bags.

I started with buying an ordinary padded ski bag. The zipper needs to have two zipper heads so that when the bag is cut in two you end up with two bags with functioning zippers.

Unnecessary stuff is cut of and markings made where the bag will be sewed together.

The plan was to use a sewing machine to sew the bag ends together but the padded material was too thick.

So I ended up sewing by hand!

When the ends where sewed up the middle part was cut away resulting in two bags.

Handles where sewed to the bags with the sewing machine. I should have changed to a black sewing thread...

Runners in safe storage waiting for further refining.

Sharpening the runners.

 I was able to arrange so I could use one of the local sailing clubs runner sharpening machine!

This is what she looks like! I rigged the machine back on my trailer so the sharpening was done outside.

There are quite a few possibilities for adjustments. From runner point of view the angle is the most important. Pre adjusted to choose from is 100 degrees and 90 degrees angle. 

Ready to begin. First up is the front runner. I started with 60 grit sand paper and finished with 120 grit paper .

Quite a lot of material is removed. This is after first runner is sharpened.

Ready!

Below an attempt to show the how the runner is sharpened in a 90 degrees angle. My apologies for poor picture quality.

Back at home some oil was applied to the sharpened surface to prevent it from rusting.

Building the chocks.

Beginning to build the chocks. Cutting the parts needed.

Most of the holes drilled. 

Preparing welding.

Same procedure for front runner.

Welding outside in -10 degrees Celsius.

Front runner chock is still missing the "arms" to fasten steering lines in and hole for steering shaft. 

Rear chocks are basically ready. I'm still considering if I should build a bracket that would grab around the plank. The idea is that it would take up the sideways forces on chock during sailing helping to keep runners in parallel. Alternative is to have  a turnbuckle connected between plank and rear chocks this would also allow some adjustment if parallel alignment between runners is off.

This was how I planned to attach steering line arms  originally but the steering radius would become to big as the arms hit the springboard limiting the steering too much.

Determining how much the runner is able to turn before hitting the chock. The front runner is able to turn around its axis a a little bit more than 20 degrees (+- 10 degrees from level) in total and the rear runners about 17 degrees. Building instruction says that runners should be able to turn around their axis between 10 and 20 degrees so I guess this is OK.

Steering arms still not welded.

Front runner.

Front runner was basically made in same way as the rear runners! Location of shaft hole is a bit different and no stiffeners should be needed.

"Designing" the parking break that will be on the front runner.

Rear runners in the making.

After a couple of more trips to the scrap yard this is what I ended up with! Two flat iron bars. The wider one is 90 x 6 mm and will be used for blades and the other one is 30 X 5 mm and will be used for stiffeners. I would have liked to have gotten a higher flat bar for the blades for example 130 x 6 mm but that was not available. These runners wont allow much snow on the ice! Normal carbon steel is used. Stainless steel would be easier to maintain. I have read or heard that the frictional coefficient for carbon steel on ice would be lower than for stainless steel on ice. Although not confirmed I hope it is true since it should make the boat faster.

I started by cutting the bar in correct length (600 mm).

Next step was to shape the blade. The instructions state that blade should have a curve of 2 mm on a length of  400 mm measured from below the bolt of runner. I achieve this by taking of material of the blades with a belt sander with 40 grit sand paper.

Both runners were shaped at the same time.

Every now and then I checked the measures until I was satisfied. 

I made a small deviation from building instructions by leaving a 10 cm part straight below where the fastening bolt will come on the blade. This is how I know some of the DN sailors shape their runners when they sharpen them! Also good to point out here is that I'm only shaping the curve of the blade to desired shape now. The blade still has to be sharpened before it is ready.

Stiffeners. These are there for strengthening the blade in side ways. If and when the boat tips up on two runners during sailing due to strong winds, the sideways force on forward part of the rear runner still on the ice might become so big that it bends the blade if no stiffeners are used. 

I'm using a bolt joint to fasten the stiffeners. Here I'm making M5 threads in one of the stiffeners and the other side will have counter sunk bolt head.

Like this!

Assembled.

The rear runners are now ready for sharpening. That will however be explained in a separate post later on! 

Summer is over!

Summer is over and I'm trying to pick up the ice boat project were it was left in spring. Next on the agenda is runners and chocks. Have to admit that the metal work required here is a bit out of my comfort zone. I have been thinking back and forth how to build the runners,fittings and chocks.

For the rear runners I'm thinking there are basically two ways to go. One is to follow Bernd Stymers design explained in the building instructions of the Isabellakiss 2012. Or to build as pictures of earlier Isabella iceboats shown on the internet have.

Animations below showing old design of chocks and runners versus new design of chocks and runners.(Animations are cutouts from the building instructions).

 


Pros and cons of the alternatives.

Alternative one, according to building instruction in Isabellakiss 2012:

+  I like the new design as it seems smart!

+ No need to weld anything.

+ The fact that the runners would be made of L profile bar would remove the need for building stiffeners to runners and at the same time provide full height of the blade. As stiffeners usually tent  make the runners thicker and thus making it harder for the runner to cut true snow on the ice witch slows the boat down.

-  Manufacturing of some of the parts for chocks would need to be outsourced.

- Dimensional drawings for the manufactured parts would need to be made as the  building instructions have little detail when it comes to dimensions.

- Weight is a concern even if I'm not sure the design is actually heavier than the alternative.

-  There seems to be no experience of the new design shared on the iceboat forums.

- I have been to scrap yards twice now to find some material for the chocks and runners but without success. If I buy the material needed from a hard ware store I have to buy big quantities so I should build  several boats at once.

Alternative two. "Old" design runners and chocks.

+ I built an ice boat ~15 years ago were similar chock and runners were used. With the experience from that boat I believe I should be able to build functioning chocks and runners. At least for the rear runners. (I had some problems on the front runner chock on the earlier boat and it was reinforced and modified  at least twice before it worked properly).

+ The chocks and runners can be built out of material one is able to get hold of.

- Result becomes more uncertain as one improvises based on what material one is able to find.

Below some pictures of the first ice boat I built.

The two pictures below are taken before the first time the boat was ever sailed. The first version of runners and chocks can be seen. At this point the runners where sharpened over the whole length and did not have any radius.  Runners where sharpened in 90 degrees angle. There are no stiffeners installed on runners yet!
 

Ready for first shake down test! Witch resulted in a broken support mast :)

This is what the boat looked like before it was sold. Rear chocks were not modified but runners have gotten stiffeners. Front runner chock has been modified. The runners where only sharp and straight on a 10 cm long area below the bolt rest of the runner was made round and with a radius. Also the sail hauling system was completely rebuilt compared to first version.