By Gary Fegan
Following Elaine’s interview with Huub Founder Dean Jackson, I asked Professor Huub Toussaint a few questions around the R&D of wetsuits.
Buccaneer Tri: Where do you start when thinking about designing a wetsuit?
Huub Toussaint: The starting point is somewhere 30 years ago. Back then I was a young PhD student comparing swimmers to triathletes to find out why swimmers swim faster than triathletes, even though the latter are better conditioned. We measured oxygen uptake while swimming and drag for top triathletes and Olympic level swimmers. One of the triathletes was Axel Koenders, at that time a world-class athlete. He brought a wetsuit to the test in the pool and proposed to measure the drag effect of wearing that suit. It was 1987. We found a massive drag reduction (12%) for all athletes (all wearing the same suit!). The paper was published in 1989 in Medicine and Science in Sports and Exercise.
25 years later Dean Jackson asked me to join him building a new triathlon wetsuit company. At that time he brought examples of suits on the market and he explained to me the marketing of each suit. I thought some things contradicted the things I learned in my swimming research career. During that discussion I had ‘flash backs’ of the tests we did with triathletes and swimmers. The drag of triathletes was 30-50% higher than that of equal sized swimmers. Why?
- Triathletes are ‘snakers’. So they have a lot of side-ways movement that creates drag.
- Triathletes have muscular legs that tend to sink creating a less-than-optimal hydrodynamic body posture when swimming.
So it was these 2 issues we tried to address with the Archimedes suit. We use an eXoskeleton around the hip to limit the snaking and provide additional buoyancy to the legs to get them horizontal, thus streamlining the triathlete (the 3:5 design). We then looked at maximal flexibility for the shoulder area and a nice touch was adding the quick release zipper and the calf release. Furthermore we made sure that the 3mm neoprene had strong enough insulation qualities to keep the body warm. Our partners from SwimSmooth suggested we reinforce the trunk section such that ‘overreaching’ during hand entry was limited (for example right hand crossing the midline to enter the water left in front of the head).
BT: What regulations do you need to adhere to with regards to panel design, thickness of suits etc?
HT: Contrary to pool competition swimwear, the rules for triathlon suits are not so strict so as to limit innovation. We have to observe the rules regarding maximal thickness of the material (5 mm) but that leaves a lot of possibilities for designing suits incorporating the science we gathered by evaluating drag in swimmers and triathletes.
BT: What limitations does a suit design need to overcome, such as the material, bonding of seams?
HT: I think the greatest challenge is to create suits that fit the athlete and that goes beyond height and weight parameters. From my work with Olympic swimmers I learned that what is good for one swimmer is not necessarily so for another of similar size. A lot of manufacturers still seem to adhere to a ‘one size fits all’ approach. So you want to design wetsuits that leave some fitting of the suit to the athlete; for example do their legs have a tendency to sink or float? With Huub, you can choose different thickness of materials especially for the legs to create the best ‘trim’ whilst you’re swimming. Dean is the expert in choosing the right materials and selecting those factories that are capable of making wetsuits with durable seams.
BT: How much does body shape influence or change a wetsuit? Are there differences between a small and a XXL suit is it just a matter of scale?
HT: The use of neoprene in the construction of wetsuits is quite ‘forgiving’ for size issues, due to the enormous elastic capacity of the material. That being said, we design suits that are very flexible in parts where that is necessary (such as the shoulder region) but we also use very stiff material to brace other areas, such as the hips. That creates difficulties if an athlete has a body type and size that deviates from the norm. At present we are looking to apply technology to address this sizing issue.
BT: How much do the materials used make a difference and is the most expensive (such as the recent industry favourite Yamamotto rubber) always the best?
HT: Last year we did some simple testing of the buoyancy of wetsuit materials. I can quote the white paper we published: Although common materials were evaluated, as these are applied in different wetsuits, quite large differences in buoyancy effects per unit area were found. The lowest value observed is 28.8 N/m2 while the highest value is 37.3 N/m2, a difference of almost 30%. It should be noted that the lower values are found for the less thick material. However, if the buoyancy is expressed for amount of material used (hence buoyancy per kg material) still large differences are found. Here, the NBR material scores highest for buoyancy with 31.5 N/kg; while the lowest value is 20.4 N/kg [Note – NBR is a laminate of Yamamoto smoothskin and a Life Jacket material named NBR (not provided by Yamamoto)]. A rather large 54% difference in buoyancy effect is thus found. If buoyancy is expressed per unit of material-volume, the differences are much smaller (see Fig. 1): the lowest value is 6.4 N/L and the highest buoyancy is 8.8 N/L for the Huub Composite 2013 White material. This comparison of different materials shows that rather large differences in buoyancy effect exist if the buoyancy is expressed per area of used material. Two factors determine the differences: material thickness and the intrinsic buoyancy of the material itself (i.e. buoyancy/volume). Thus, we found that if patches of equal area and equal thickness are used, the material that will give the highest buoyant force is Huub Composite 2013 White.
Fig. 1: Buoyancy per unit of volume for different materials (N/litre)
BT: Do forearm catch panels actually work?
HT: Most probably not. This may come as a surprise to some, but extensive pressure measurements suggest that the hand is used for propulsion (i.e. a large pressure difference is measured across the surface) and that the forearm functions as a ‘guide’ for water that is transported on both sides to the hand. (lookup ‘pumped-up propulsion in swimming’to get a better understanding). So the forearm with or without catch-panels has no direct propulsive function
BT: What types of testing is undertaken on new wetsuits?
HT: After the design of a new suit, we have the manufacturer make test samples. These are first tested for build quality. Then, after initial improvement rounds, we have samples tested by our test swimmers. Samples are tested for their drag reducing effect using the ‘Measuring Active drag’ –system – an instrumented swim-ladder mounted in the pool. Swimmers ‘swim’ on it by pushing off from push-off pads and push-off forces are recorded. When swimming at constant speed, drag is in balance with the measured push-off force. From that we can evaluate the effectiveness of the design of the suit in terms of their capacity to reduce drag.
MAD – Measuring Active Drag
BT: How long is the cycle from inception, through testing to production of a top of the range wetsuit?
HT: At present it is too long. It takes time to make the drawings, to send those to the factory in China, to explain what you want, to check the quality, the selection of materials, the seams, the finish of the product. And then you have to start testing for usability, durability and evaluate the drag reducing effect. It takes several rounds of sending suits back and forth before we are happy. So we are very busy trying to reduce the time taken for development and testing.
BT: What do you see as future advances in wetsuits, can you reveal what you’re working on now?
HT: We want to optimize the design process by using the results of testing. Not only by looking at the effect of the whole wetsuit on drag reduction, but also by looking at the optimal material that is used. The buoyancy per unit of material is a good example of that. At present we are preparing other tests where relevant design aspects of wetsuit material are measured. We now are very busy to build our own lab enabling in-company testing.
BT: Are newer wetsuits more fragile than their predecessors?
HT: Let me speak for Huub wetsuits – we try to make quality products because we know that happy customers come back, or even better, they promote our suits. So we aspire to bring quality products to market that are durable and create a performance advantage.
BT: Magazine reviews are often quite subjective; how can someone objectively compare wetsuits without being able to find a retailer that will let you try a few in the pool?
HT: The question implies that there is one best suit for all. Trust me, that’s not the case. That being said, magazine reviews do give some overall information for example regarding customer service, usability, the science and experience behind the product, etc. But in the end I guess it is best to try out in the pool if possible.
BT: What buoyancy advantages (if any) are there for a 3:5 user in Swimskins?
HT: The swimskin covers and compresses the torso and thighs and in doing so not only reduces the frontal area of the body to aid streamlining, but also reduces the surface friction of the swimmer. This is added to the benefit of changing the centre of buoyancy through compression and shifting body mass toward the suit’s central core. Also using the X-Skeleton on the suit braces the hip-joint that together with the over-all compression is enhancing the swim performance
BT: Over the course of an Ironman distance swim (3.8Km) for a typical 1 hour swimmer, what would you expect the performance gain to be?
HT: Again, that depends on the swimmer. But some amazing results have been reported if performance in a brief is compared to that in a swimskin. Paul Newsome (SwimSmooth) reported a gain of 4 seconds per 100 m, so for 3800m that would translate into a performance gain of about 2 minutes and 30 seconds.
BT: Do swim skins give any the support and lateral stiffness benefits that wetsuits give or is it just minimising drag?
HT: The support and lateral stiffness benefits are there to minimise the drag! Yes!
BT: Given what you’ve said above, with a swim skin is around £250 and a top of the range wetsuit twice that, do you think this is a fair price?
HT: Great question. It comes down to manufacturing and numbers. A wetsuit really is amazing value considering the cost to time saved and is only bettered by a cheap set tri bars. What the Swimskin delivers is that extra edge and although not low in price, this is down to the athlete numbers being small for these products. The research costs and testing make the small sizes versus costs outlay slightly different from the wetsuit where larger units are sold for the research and testing.
Many thanks to Huub for taking the time to answer these questions if you have further questions you can find him on twitter @Hu2bH2O
Also, check out Jay Prasuhn’s interview at the old testing facility from a couple of years ago…