Borderline Breaks

The things we can learn from board repairs ... for example where you should not put your feet. Let's start with the end:

This is my blue Skate 110 which I bought to replace the white Skate 110 that I wrote about in my previous post. The picture shows the end result of my latest repair attempt. If you click on the image to see the larger picture, you'll notice a slightly different blue in the repaired area, which extents from the back of the pad to the edge of the board at the "F", and extends forward to the "N".

I discovered a soft spot towards the rear of this area last fall. Upon exploring, I discovered that the glass and the PVC foam underneath had a break. I dug out the core foam all the way to the sandwich at the bottom of the board, filled the void with polyurethane (PU) foam, and glassed it over. The PU foam is harder than the original EPS core, forming a hard "plug" that connects the bottom and the top - good enough, I though.

When putting the fiber glass on top, I noticed bubbles forming: the new structure had several little "pinholes". The inside of the board was still under a bit of pressure, and the air coming out pretty much kept the little holes open. I tried to fix this with an extra coat of epoxy while the board was cooling off, hoping this would pull the epoxy in and close the pin hole in the process. However, this did not work as expected, and I saw bubbles forming after a few sessions.

The next repair attempt including removing the glass around the pin holes, and glassing the entire area over again. This repair held for a couple of month, but then I noted a new soft spot right next to the initial repair. I used some Solarez since it was freestyle time, but that barely held for one session. So .. time to try again.

When I opened the board up, I saw that the initial repair was still intact; however, the top glass fiber layers were broken right at the edge of the repair. When I made the initial repair, I did not rebuild the PVC sandwich layer because I had neither divinicell nor the vacuum setup. I figured that having the PU plug extend to the bottom would make it stable enough; but what I had not considered was that I would have a hard plug right next to the somewhat softer, slightly elastic sandwich construction. This create a "Sollbruchstelle", which then indeed created a break.

This time, I tried to do things right. The first step was to open up a relative large area that included the previous repair area, and digging out all the soft EPS foam. I then hooked up the area to a vacuum pump to see if I could draw any moisture. This removed some slight dampness from the top of the EPS foam, but the vacuum trap remained empty after several hours. Fortunately, very little water had gotten into the board.

The next step was rebuilding the foam core with PU foam:

That was followed by sanding the excess foam off, and removing additional foam to allow re-building of the PVC sandwich. After some filling, glassing, and sanding, here's what the repair area looked like:

When you look closely, you'll notice a slightly different color along the top and right side. This is the edge of wood veneer reinforcement. It extends about two thirds of the way to the edge  near the front of the repair area, but not nearly as far at the back. The original soft spot that had developed had definitely not been covered by wood.

Using wood veneer as reinforcement under the rear footstraps makes a lot of sense, since wood has excellent mechanical properties to absorb and distribute the impact after jumps. Extending the wood past the padding makes sense, too: the padding under the foot pads is not very wide, and my size 12 feet need to be quite deep in the foot straps for my heel to be on the padding. Most of the time, however, I sail with just my toes in the foot straps, so my heel rests on the board next to the foot straps. I must say that I find it somewhat peculiar that the wood reinforcement did not extend further back. There are several possible reasons for this, like to much deck curvature, or "interference" by the fin box. Whatever the reasons were, it seems my heels were often positioned right next to the reinforcements, which eventually led to damage. It's no surprise that the damage was on the right side of the board, either: my home spot Kalmus had starboard jumps most of the time. Even when not jumping, just going over the chop there would put a lot of stress on the back heel, which does not even have any padding underneath.

I am quite sure that the reinforcements in my older Skate 110 were quite different. I use the old Skate a lot more often than the new one, and often with bigger fins, which lead to more outboard foot placements and more back foot pressure, but the old Skate never got soft in the back. The old Skate seemed to have a lot of carbon reinforcement, while the new Skate seems to have wood veneer instead (although the areas I repaired on the two Skates are different). But mainly, the old Skate 110 actually had two sets of footstrap positions, including a more outside one that's missing on the new Skate; and the padding on the old Skate extends further to the rails. So placing the back foot more outside on the old Skates was not a problem, but it appears to be a problem on the new Skate, at least when sailing in heavy chop or jumping a lot. Maybe I just need to go to tiny little freestyle fins to enforce a more centered foot placement and less back foot pressure...

Fixing My Favorite Board

In 2010, I got a white Fanatic Skate 110, and it has been my favorite board ever since. But last year, I discovered that the deck near the front foot straps was getting soft. My favorite board repair guy, Donnie in Hatteras, did not want to repair it, so I figured I'd use it to learn board repairs on. The first installment was a big nose job last fall. A while later, bubbles started to come out near the soft area, so it was time to learn new stuff - soft deck and sandwich repair! Most of the things I did are based on the excellent instructions on "The Board Lady" web site.

The first step was to take the padding under the front foot steps of:

That took a while. I started to understand why Donnie did not want to do the repair.

A small exploratory cut was next:

You can see the sandwich construction: a few layers of glass fiber on top, then a thin (~4 mm) layer of high density foam, a single layer of glass, and the EPS foam core. The sandwich looks good, but there's a big air gap that should not be there. It seems the EPS foam got compressed just too many times and eventually tore apart.

I enlarged the cut-out area, but the soft area was quite large, so I decided to treat most of the affected area with expanding polyurethane foam, introduced through many little holes that are covered with blue tape in the next picture:

You can see the foam expanding all the way into the cut-out area. In the cut-out area, I removed some of the damaged EPS foam, so I had to build the area back up, also with marine polyurethane foam:

I just love playing with the pour foam. You mix together a couple of liquids, and then you have about a minute to inject it before it expands about 50-fold. Fun!

After sanding down the PU foam, the next step was to rebuild the sandwich layer. I used one layer of glass and two layers of thin divinycell. To press everything together, a vacuum setup is needed, as shown in the next picture:

Once you have the stuff and know how to use it, this is easy. The PVC foam must be covered with three layers of different plastics: perforated release film, then "breather" material, and finally vacuum bagging film. This was the first time I did this, so I made one small mistake: I put the sticky stuff that connects the vacuum bagging film to the board to close to the treated area. That made it a pain to take off later!

I also had to close all the little holes I had drilled to get the PU foam into the board to fill the air spaces. That required some sanding first, and then some epoxy and lots of small little glass fiber discs:

Once the epoxy had hardened, each of the little holes needed to be sanded again to smooth things out and to get a good feathering connection between the new and the old glass.

The divinycell also needed to be sanded down and glassed over. I used two layers of glass, but no carbon. The original construction appears to have a layer of carbon cloth on top, but it's very thin; you can see in the next image that I accidentally sanded through it at a few spots.

The board came with two sets of foot strap positions, inner and outer. I never used the outer positions, so I simply filled the holes in the outer plugs with some epoxy mixed with low density filler (the brown stuff). The next step will be to add one more layer of glass over the entire center area; some sanding and filling; putting new padding down; and painting over all the little holes (more to protect the epoxy from UV than for cosmetic purposes).

This repair has already taken quite a few hours, and still needs more work. Someone who repairs boards professionally would have to charge at least $400-500 for such a job, and even that assumes he'd be a lot faster than I was, and that he'd charge an hourly rate much lower than what I have to pay a local car repair shop. How long the repair will last is an open question, so I can definitely see why Donnie did not want to do this.

For me, however, this was fun, and a useful learning experience. The Skate in the pictures above is not the "Team Edition" model, but this repair clearly shows that it still contained quite a bit of carbon - it looks like at least one thing layer of carbon cloth over most or all of the top. In contrast, the 2015 Fanatic Skate that I got as a replacement did not seem to have carbon reinforcements, at least not at the places I looked so far; instead, the 5 years newer models appears to use wood for reinforcing (more about that in a future post). I always had the impression that my blue 2015 Skate was not quite as lively as my white 2010 model - but the newer models seemed a bit easier to sail in very choppy conditions. I now think that this is because only the older model has the extra layer of carbon, which gives it a bit more stiffness. So I'll be very glad when I can sail my white Skate again on the lighter wind days!

The Nose Job

A few months ago, my favorite windsurf board needed cosmetic surgery:

I had gotten a bit confused while having fun. I forgot that I was not a wave sailor. I also forgot that I do neither loops nor Grubbies. But when a lovely little wave presented itself, I tried to jump of the lip so that I'd land back on the wave. Which must have looked like a bad Grubby or loop attempt. At least so I think - I got thrown around, and the mast landed on the nosed of the board.

That was not the first (or second or third or ...) time the mast hit the nose. Nor was it the hardest crash. But the damage was much worse than ever before, with a big crack that went from the top to the bottom of the board. The main difference to previous crashes? My poor board was not wearing any protection! For three years before that, it had worn plastic protection where it mattered - on the nose. With double-density foam! That had not kept the nose from being hurt. In fact, I had it repaired twice at Fox in Buxton. The repair guy there stated that all the nose protector  did was making the repair more expensive, since he had to remove it and replace it. So the second time, I told him to leave it off.

Well, wrong he was. With the nose protector, the nose needed two repairs over 5 years. Both times, the damage was not nearly as bad as this time around. I was actually able to temporarily fix the board with ding stick, and keep using it until our next trip to Hatteras. But without the nose protector, the nose lasted only a couple of months, and the damage was much more severe than ever before.

I love my Skate 110 dearly, but it was showing signs of age and heavy use. The area under the foot pads was starting to get soft - damage that, according to the experts, was not worth fixing. So I figured - if the board is almost dead, maybe it is the perfect board to practice board repairs on!

I had never done any board repairs, other than using a bit of ding stick for small holes. This one clearly needed much more serious work, including some new fiberglass. Back when the concept of "pin tails" and "fully retractable daggerboards" was new and exciting, I had built a windsurf board. Not quite on my own - the university that I attended actually offered a course "Build your own windsurf board". A long time ago, but I remembered that working with fiberglass and epoxy was not that hard.

I started asking a few questions on the iWindsurf  forum, and got a number of useful tips. So I went ahead and bought a bunch of supplies:

• West System epoxy resin, slow hardener, metering pumps, and filler from the local West Marine store
• Fiberglass from Fiberglasssupply.com
• Polyurethane pour foam from a couple of different suppliers (since the first one I got did not work)
• Sandpaper, gloves, dust masks, and masking tape from the local hardware stores
• Epoxy mixing sticks from amazon.com
• Cups for mixing the epoxy from the local grocery store
• Spray paint from a local car store

The electric tools I used for the project were:

• A battery-operated Dremel tool (ca. $30 from Amazon)
• An electric sander

I decided to do the fix in two parts, starting from the top of the board. I used the Dremel tool with a disc wheel blade to cut through the fiberglass and the PVC foam underneath, and removed some of the damaged foam underneath:

My original plan had been to fill the hole with polyurethane pour foam, and then glass it over. However, when I mixed some of the foam to get an idea how to work with it, it did not polymerize. The foam I had gotten said the mix had to be 1:1 by weight. I did not have an accurate scale, but I figured that mixing by volume should also work (many other PU pour foams suggest to mix by volume). Maybe that was the problem? I bought a scale with 0.1 g accuracy, and tried again a few days later, but still nothing happened. Obviously, the pour foam was bad (I later got a refund for it).

The local West Marine store had pour foam, but they wanted almost $200 for something that I could get for less than $50 online. I ordered from a different supplier through Amazon (for easy returns), but since the chemicals have to be shipped via ground, waiting for it to arrive would have added another one-week wait to the repair. Since it was the middle of the best surfing time of the year, I developed another plan.

My idea was to use epoxy to fill the hole. To reduce both the weight and the heat produced during polymerization, I added a lot of filler to the epoxy. I also added a lot of styrofoam bubbles that I made from pieces of packing material. I was concerned about things getting to hot, so I first let everything polymerize in a cup. Everything looked good:

So I made another batch and filled up the hole. Everything looked fine at first:

But a few minutes later, bubbles started forming, and I knew I was in trouble:

When I opened up the other side of the board a while later, this is what I saw:

The heat from the polymerization had melted a lot of the styrofoam, and produced a big hole! I had overlooked one thing in my test: in a cup, the heat from the polymerization can easily escape in all directions. But in the board, the epoxy is surrounded at most sides by styrofoam, which traps the heat! That starts a bit of a chain reaction: with no way for the heat to escape, things keep getting hotter, which makes the polymerization go faster, which makes things even hotter... until it's hot enough for the styrofoam to melt, and air bubbles form.

Alas, the pour foam still would not arrive for a few days that I did not want to wait. So I started again with my epoxy-filler-styrofoam ball mix, but with two important modifications: 1. I made it even thicker (to "peanut butter" consistency), and 2. I added only small layers, instead of trying to fill the entire hole in one turn. I carefully watched for any bubbles, but did not see any. After about 4 or 5 layers, I had finally filled in the entire hole.

Sanding things down was pretty easy, since I had used so much filler. I started with the electric sander, but switch to manual sanding pretty quickly, since I had better control that way. On the top, I had to fill in the air bubbles with some epoxy-filler mix, and then sand again. Putting on three layers of glass was pretty easy:

After sanding down the glass, I sealed the region with a layer of epoxy without filler:

At this point, you can actually see a small area from a previous repair. One more careful round of sanding, and the area was ready for painting:

Here's what the bottom looked liked after painting it:

Not bad, I thought! I took the board out for a test session, and it behaved just like it always had. But when I inspected it closely back home, I noticed that there where bubbles coming out! Not in the region that I had fixed, but right next it, in the region that had been repaired before (or close to it). 

So the tools came back out. I cut out another section to make sure that the damage was limited, filled it, and glassed it over again. You can see the second section in this image:

This was a small repair, with much less drama than the first one. Good practice! Here's an image of the top after the final round of painting:

One concern I had about the repair was that the area I had repaired was now harder than the surrounding area. It would probably be more resistant than the original, but a hard hit with the mast could now break out the entire area! But as much fun as the repair was, I had no desire to repeat it any time soon, anyway, so new protection was in order. I bought a Dakine EVA traction pad at the local windsurf store, cut it up, and taped the pieces onto the new nose. The most endangered area is now protected by an inch of EVA. In a hard crash, the EVA will absorb some of the energy by deforming, and distribute the rest of the energy over a much larger area - not too different from an air bag in a car! On the sides of the nose, the EVA is thinner, but both impact angles and leverage are not as bad there. In really bad crashes, the nose may still take damage, but it is now nicely protected from most mast hits and catapults. 

I spent about $250 on all the things I bought for the repair project. I used only a small fraction of most things (like epoxy and fiberglass) for this repair, so I can do many more repairs at no additional cost (I actually did another small repair a couple of months later, when Kiri Thode's board got damaged on his flight from Bonaire). I have used the board more than 30 times since the repair, and it sails just like it did before the damage, so it was definitely worth doing. I thought it was a fun project, too - and I now know that I can easily repair any similar nose damage in the future. With Nina working on Vulcans and Flakas, that might come in handy sooner rather than later!