In our last feature with Dennis Klaaijsenn we reported on his epic 24 hour windsurfing feat. There he told us about his future plans and one such goal was to cross the North Sea. Well, the time came much quicker than we had anticipated and Dennis has already undertaken the challenge with a huge amount of success. However, as you would expect, windsurfing 192km on one tack is no easy feat. So here's the story on how this mighty challenge panned out.

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North Sea Crossing: The Challenge

After a number of 24 hour windsurf sessions over the last three years I was looking for a new challenge.

In August 2013 I was approached by an old classmate, who now works at Wind Star Cruises. He asked if I was interested in joining a Caribbean cruise with one of their ships, the Windsurf, sailing on my surfboard. The cruise schedule would start in St. Maarten and go via Antigua, Tortola, British Virgin Islands, Saint Barths and return to St. Maarten. The total distance is around 750 kilometres and would be spread out over 7 days. Ribs would accompany me during the day and I would overnight on the Windsurf. The sailing schedule, combined with the north east trade winds, give a perfect sailing angle.

It seemed like a super cool challenge. My wife Louise and myself sailed many years on cruise ships from the Holland America Line, Louise as purser and myself as navigator so we know how much fun it is on cruise ships.

I measured the distance and realized that this really would be a killer week and that I had to go make the necessary training kilometres at sea. As a 7 year old boy I started surfing on the sea at Nieuwvliet Bad (The Netherlands) but for the last 15 years I had surfed mainly on inland waterways.

I gladly accepted the challenge and set up a tight training schedule. As soon as the wind was blowing from a northern direction I went to Domburg or Vrouwepolder in order to be able to make long reaches along the Walcheren coast. With South west winds you can surf from Vlissingen to Westkapelle. It soon felt like the olden days, surfing between the waves of the North Sea.

For organizational reasons, the cruise ship challenge fell through. I had the necessary training hours in the arms and legs and really wanted to put it to good use.

Through a work colleague I got interested in the North Sea crossing, from Lowestoft to Ijmuiden. A distance of 192 kilometres which many yachtsman and surfers have attempted in the past, the aim being to cross the North sea.


The new challenge was born. Organizing a safe crossing from England to the Netherlands over one of the most densely crowded sailing areas of the world, was a big undertaking.

First I checked with my own organization, the Dutch Pilot Association. As a pilot you assist the master of a ship to navigate the Vessels safely, from the pilot station out at sea, through shallow waters to port, and bring the vessel alongside the quayside. The pilot stations are located out in the open sea where you board the vessel via a rope ladder. These climbs can be up to 9 meters high and unfortunately the transfers aren’t always done with flat calm seas. With waves up to 3 meters you sometimes hang on the pilot ladder like a monkey so a physical fit condition is paramount. The Dutch pilotage agreed to sponsor my North sea crossing attempt as they wanted to highlight the importance of having to be physically fit, to do this profession.


Our first option was to use of one of our fast pilot boats as my assistance boat during the attempt. Dispensation was requested and granted so that the pilot boat would be allowed to operate outside the regular sailing area and the last step was arranging the insurance aspect. Another option was to have a collaboration with the Dutch Rescue Service (KNRM)

The Pilotage got in touch with the Dutch rescue service, KNRM, and they saw in this challenge an ideal platform to showcase the cooperation between the two organizations. Also it would be a good endurance training for the crew and equipment. It was important to the KNRM that there would be no financial element for the KNRM. The KNRM relies solely on donations. This was absolutely not an issue for me and all costs were covered by my other sponsors.


Now the boat was arranged, a possible crossing came within sight (Oct 2013). The waiting game started for the right wind and wave conditions. For a crossing with this easterly course you need to have a due north of Southerly breeze. With northerly winds the swell and sea would build too fast which would reduce the speed and consume too much energy. Therefore a northerly wind was never explored as a serious option. A due southerly breeze for the entire crossing and a force of 20 knots, about 5 Beaufort, is ideal. Seafarers know that out at sea the wind is always stronger than at the coast due to the reduced friction of the wind over the sea.

Until the end of October the seawater and the outside air temperature are warm enough to give it a try. Later in the year too much energy is used to keep the body warm and the days are too short in terms of daylight.

It looked like the crossing would take place, just two weeks after the corporation with the Dutch Pilotage and the KNRM was a fact. On Tuesday the 22nd October 2013 the wind looked favourable. I came back from a family holiday in Fuerteventura the Sunday before so it was a tight schedule, but it could work. On Monday came the message of the KNRM that two of their boats were not available due to maintenance, this left them with no spare boats. The crossing can only be done using one of the spare boats of the KNRM so the attempt was called off for that Tuesday.

Jealously, I followed the crossing of Dutch windsurfer Ron Kleverlaan, wishing it was me. He had the organization for the Tuesday in check, and around 11 am he departed from Lowestoft. Winds were favourable and reached force 7 at the beginning of the attempt but subsided at the end which meant a record-time was no longer an option. After 8 hours and 23 minutes Ron came ashore in Egmond aan Zee. He used a 5.6 and 6.2 square meter sails during the crossing. I had only planned to use a 7.0-7.8 and 8.6 square meters for that Tuesday. Had I been able to get everything in place, the crossing would have been mega heavy with 7.0 as my smallest sail. I updated my log book for the attempt and added my 6.4 to the equipment list of sails to take with me.

By the end of November 2013 due to the sea temperatures it was obvious that a crossing in 2013 would no longer be possible, I scheduled a training with the KNRM department in Neeltje Jans which is located in the south west of Holland.


The day before the training, a storm force wind had blown from the north so a big swell was running. On the day itself there was a wind force 5 to 6 from the north, no conditions for a crossing but perfect for a heavy duty training session. I had three sets sails rigged and secured in the gunwale so we could also practice a sail change. Via a waterproof VHF set attached to my crash jacket I had contact with the boat at all times.


The communication worked well and in terms of speed the KNRM boat and myself were evenly matched. The sail exchange was heavy and not without dangers. Due to the high waves it was difficult to get the sail back on deck, especially when you keep in mind that you are in the water only a few meters from propulsion jets of the boat. When the sail was back on deck we decided not to go with another sail into water. For a record attempt it would be possible but for a training we estimate the risk of damage too high.

During the winter months, luckily one of the warmest winters in recording, the work outs in the gym and running were keeping me in shape for the next season. I picked up Yoga during the summer months and that gave a big improvement in my core stability.

In April of this year I went to Hyeres, South of France with my German training buddy Denis Standhardt. The intention was to get used to the new Tabou boards and NeilPryde racing sailing provided by my sponsor Vertigo sports. The wind wasn’t as strong as we had hoped for and all 5 sessions I surfed were with an 8.6 m2 sail. Nevertheless, it was a successful trip with a combination of slalom and endurance training.


The summer wasn’t very windy. Lots of light winds and not many heavy surf conditions. Luckily we had northerly wind regularly so the sea trainings could still take place.

After a successful 24 hour distance record attempt on 10th August 2014 and with 728 km on the GPS at the end, my hands and body had to heal for a couple of weeks as a result of the physical abuse. At the beginning of September my body was once again ready for action.

The second week of October a southern flow settled over our region. Many times a day I looked at the predictions on different websites. The fact that meteorology is a class I had to follow during my studies at the Maritime Academy, has helped a lot in assessing the weather models and interpreting the various wind and pressure maps with their corresponding wave systems around them.

The 6th, 7th and 8th of October all seemed to have favourable wind conditions , but as the dates approached the wind became too Southwesterly, Southeasterly, or blew it too hard. With 30 knots, gale force 7, a successful crossing is unlikely.

On Oct 12th all weather maps and weather reports predicted a very stable southern flow for Saturday, 18th of October. "Would this be the day I had waited for ?" As the week progressed the predictions remained practically unchanged. The stress level went up and my sleep was regularly interrupted by the thought that it could really happen this time.

On Thursday, 16th I visited the KNRM headquarters in Ijmuiden to discuss the final details. Two boats were out of service for maintenance once again. I thought "Would this be a déjà vu from last year"?


On Friday morning the 17th the liberating phone call came in. "The boat is available, YES!!!!". Screaming with joy it dawned on me, it's going to happen. I had my good friends and surf buddies Lars Tattje and Sjoerd Saaman joining me on the trip to England as "wing commanders". Tickets were booked for the evening ferry from Hook of Holland to Harwich on Friday so we would drive from Harwich to Lowestoft at 07.00 Saturday morning, a trip of two hours.

In Lowestoft, we were able to use the facilities of the RNLI, the English counterpart of the KNRM. I had spoken to the skipper of station Lowestoft already and he was excited to help with this attempt. At 09.00, we arrived at the docks in Lowestoft and it blew 20-24 knots, wind force 5 to 6. The boat, the KNRM's Koos van Messel was just coming in and we decided to rig four sets; of which three would be secured in the gunwale. Along with four boards, the necessary spare fins, masts and booms were put on board.

I would start with the 7.0 RS Racing EVO 6 and Tabou Manta 66 wide and 36 Z fin. We lashed the 6.4 – 7.8 and 8.6 with the boards the manta 59 – 71 and 81 wide. The wind would be veering 5 degrees during the crossing and decrease a few knots so we anticipated on switching to larger material if necessary.

I had a GT 31 GPS on both my arms where the bearing and distance and heading were displayed. Around my wrist I had a GPS where I could read the speed, average speed, distance and time.

On my back I wore a camel bag filled with three litres of energy drinks and with energy bars and gels in the side pockets so I could drink and eat during the crossing. A VHF and AIS Sart in case of emergencies were attached to my crash vest. Sjoerd joined in the Rescue boat and Lars had the long journey back to Holland, with the car and trailer, ahead of him.

Just outside the Lowestoft breakwaters I went in the water. A short stretch was sailed to make sure the equipment was rigged and tuned to perfection for the journey. The RNLI joined us for the practice run and to make some footage for the local news station.

Just after 11 a.m. local time we reset the clocks and told Lowestoft port control we were off; GO TO THE START, READY, GO!


The first few kilometres you pass shallow water with sand banks which generate confused and steep waves. The wind force was good and the rescue boat followed me, steering a direct course to Ijmuiden.

The waves were steep but because the current and the wind went in the same direction the wave period became longer and the tops of the waves didn’t crash over themselves. The wind increased and I had to tighten the outhaul of the sail. It was a real bumpy road and you could not take your eyes of the water for a moment. Every few seconds I went into the air and the landings were not all equally soft. After having sailed two hours in front on the boat, we had covered 65 kilometres . The significant wave height was 1.5 to 1.8 meters which means the highest waves we encountered were 3.5 meters. From time to time you plummeted into the wave crest a few meters down which caused a lot of strain on my feet. Since you sail the whole crossing starboard tack, your rear leg and foot endure the most pressure. There is only a limited degree of movement but even the smallest change in your posture can already give some temporary relief from the pain. The skin of my hands was thinning quickly. Because the Callus hadn’t built fully yet since the 24 hour session in August, blistering was inevitable.


After bouncing over the waves for two hours, I asked the boat to try and sail in front of me for a while, to see if this would reduce me flying through the air a bit. This worked well and the peaks of the waves would be flattened a bit. Now I could sail a slightly broader course and also the speed went towards the 40 km/hr with peaks just over 50 km/hr. When we came across shipping, the rescue boat and myself communicated how we would pass them. It must have been a strange sight for the navigator on duty of a sea-going vessel to see a windsurfer surfing in the middle of the north sea.

The control over the equipment was good. Despite the harsh conditions and the occasional spin out upon landing, I crashed only once. That was after 130 kilometres when I got out my trapeze line. I fell back and saw the gear flying meters through the air in front of me. A good time to take a few minutes to rest and an extra bottle of power drinking was provided by the boat.

We were then on a schedule of 4 hours and 55 minutes and it looked fine. Physically the wind and waves were taking its toll on my body but with the knowledge that we only had to cover another 60 to 65 kilometers I moved on.


The wind became lighter from here on. I had to release the adjustable outhaul to trim more shape in my sail and it became clear that I would need a larger set in the long run. I agreed wit Sjoerd that I would stay on this set until I could no longer plane. It would take a few minutes to get the lashings of the sails and at 24 kilometers from the coast the 7.8 was thrown overboard. However, the wind then decreased so quickly that I could not plane with the 7.8 so we changed to 8.6 with the 81 wide board and 46 fin. Due to the two sail changes and the light winds, the expected arrival time was now at 5 hours and 25 minutes.


Five kilometres from the Dutch coast, the wind became so light that I could no longer plane. At a speed of 8 km per hour! I floated towards the shore, losing a precious 35 minutes. After 5 hours and 53 minutes, I passed the official timing point of the pier at Ijmuiden, 17 minutes after the current sailboat record time, set by Skipper Bouwe Bekking with the Volvo ocean racer Delta Lloyd.

After 6 hours and two minutes I finally felt sand under my feet at the beach. Fantastic! The sailboat record still stands, the windsurf record of 7 hours 56 minutes, has been improved by two hours.

At the KNRM headquarters in Ijmuiden the previous record holders Tim Klein and Jaap Kriele were awaiting to congratulate me. What a special moment; we animatedly talked about each other’s challenges at sea. My successful attempt came exactly 16 years after they had improved the time from Olympic Windsurf champion Stefan van den Berg (1998). Stefan set the record exactly 16 years earlier in 1982.


KNRM, Dutch pilotage, Vertigo sports, Louise, Lars and Sjoerd, thank you so much for your support and commitment to this marathon session!

Quickly the question arose: "What will be your next challenge?". I think NOT having a challenge will be the biggest challenge of all. Time to embrace surfing the way I started it…