Mar 26, 2013

Design: SurfSki MV605wp

My brother builds kayaks & Hawaiian style racing canoes (pic below). He asked me to design for him a Surfski, for a change not one available here so I started checking current designs, and they all look 'antique' beyond performance. Only the Point 65 Bourbon Orca look somehow updated, but after some research it didn´t had that much success, at least on the info I've found in the web.

After reading and researching current designs, I reach the point where I thought 6,40mts was too long for the average racers, those Surfskis are designed for some Olympic champions in mind, weighting 90kgs.

Lighter paddlers might have too much boat to handle, although being a displacement hull, lenght was key on speed, but you also had drag,  an intermediate solution was possible aiming for the average paddler. Then I found a really good technical lenght optimization paper by William Baker, supporting my initial thoughts.

The other key variable was transportation and I decided to go for a 605cm hull. Some other builders also offer the 640m and a shorter model.

Then my local sailmaker told me about the raids he usually makes with his kayaking friends, and how upwind chop was killing their speed and making a tough ride, he thought on current F18s designs... I told him I was just designing what he needed.

Surfskis are used in many different conditions: open waters & lakes,  flat or choppy,  even surf launches plus shorebreak actual surfing back to the beach to end a race depending location. They also use them for fun, training & most of the time downwind races.

With all this feedback I went for a wp bow volume distribution plus good initial stability using some extra width aft to take advantage also on the downwind runs.
Racing or paddling downwind you can experience some deep bow submerging too (check pic left, image by, the Epics and other top brands have some good reserve volume with a 'V' cross section shape as the majority of other standard kayaks,  but to have a stable ride both downwind-upwind  the modern wp volume distribution I though was a really good solution together with a little more rocker.

I also draw current industry standard, the Epic V10/12/14 Series with the 6,40m standard lenght, and asked Ralph Moolenaar from Marine CFD to make some comparative speed/drag tests between both models. Ralph is part of the F18 Open Project, and he is been working hard lately so he was my first choice for these new tests.

We entered some realistic values on weight for an full carbon 6,40mt Epic V12 with a 90kg Pro, against a standard coremat built construction of the 605mts WP with a lighter paddler.

Results were within expected range. And additional features must be taken into account, as current design go for slim , fast and unstable rides, trying to emulate the K1 speeds, the problem with this is that you paddle your Surfski in open waters, and having more stability may translate in more effective rowing.

Quite an interesting project, looking forward to paddle soon as it is going to be a nice and cool ride, lets see if I remember how to paddle, as a kid I trained in K1/K2, hulls with almos zero stability for newbies. I've paddling the super stable 'proa' like canoe (my bro pic above) and it was lot of fun.

I hope to be sending this to the router on our off season (June/July). Next project I'm working on is a Racing SUP--

The F18 Open Project continues in good shape and I already have some excellent quotes on model/molds and even hull/foils builds in Europe. It is more practical/cheaper to make the model/mold/2 hull combo than to make 2 oneoff hulls. More info soon.

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