New Siskiwit SOF Kayak Hits the Water

Tibor Berki from Sweden, the person behind RUGD clothing, completed an unique build of a Siskiwit SOF kayak. He used fiberglass-reinforced foam for the frames, added sealed bulkheads, used an ocean cockpit instead of a whitewater-style cockpit, and he added hatches. His builder’s log is detailed and fun to read.

His build ended up at 13kg (28.6 pounds) with all the extras. He is debating on adding a skeg. In his building log, he mentions that he had problems with the dye he used, but I think it looks fantastic! I don’t own a SOF kayak anymore, but now I want one again because his looks so good.

Check out his builder’s log. It’s worth it!

His main feedback about the design is “Wish you all the best and thank you for a great design!” and “A big Thank You to Bryan Hansel at PaddlingLight.com who made the drawings for this stable, fun and agile kayak!”

Cockpit Placement in a Yost-Style Kayak

In his builder’s log, he points out something that I thought about when designing the Siskiwit SOF kayak. The cockpit placement is locked in by the rear frame. That placement will work for many paddlers but not all. The reason is that a paddler’s center of mass will vary based on the paddler’s build and weight distribution. I have three rules of thumb for kayak cockpit placement:

• Rule of Thumb One = The aft of the cockpit opening should be positioned 3.5 to 4 inches from the back of the paddler when the paddler’s Center of Mass and the kayaks Center of Buoyancy are aligned. Or for most paddler’s 14 to 16 inches behind the Cb.
• Rule of Thumb Two = For a good kayak cockpit placement put the coaming of the cockpit 15 inches behind the longitudinal center of buoyancy.
• Rule of Thumb Three = Have 55% of the cockpit behind the Cb and 45% in front assuming a standard keyhole-style cockpit.

All three of these came about from studying many of the kayaks reviewed by Sea Kayaker Magazine. My favorite one is rule number one because it is the most accurate. With plywood boats and cedar boats, the paddler can move the cockpit around to nail the position. But with a Yost-style frame, you get it where the designer put it.

The longitudinal center of buoyancy for the Siskiwit SOF is at 7.877 feet. If we subtract 14 inches with get about 6.7 feet for the back of the cockpit. The rear cockpit frame is at 6.67 feet, so it’s right where it needs to be for me.

Tibor is six feet tall and the paddlers that prototyped this version of the Siskiwit are shorter. The original was designed for me and I’m 5’10”, so it makes sense that there is this variation. He gives the following feedback:

• Move the 6′ 8″ – 1″ back for easier rolling and CG a bit more aft. I lowered that cross member by 1″ in the middle but would like it even lower.
• CG to CB seems a bit off for a Skin-On-Frame without a skeg. My CG needs to move back a little (more).
• Because of the above, if you want this kayak for surfing I would recommend installing a skeg.

Your Thoughts?

To address this, I could include multiple placements for the cockpit design. I’m not sure I can make that happen anytime soon. It is easy for me to output custom stations for people, but they wouldn’t include all the cutout locations for the stringers. Those would be easy-ish for a builder to add. Or I could move the entire cockpit back by two inches to give more leeway for paddlers in seat placement. I’d be curious in hearing the thoughts of other builders or potential builders.

Thoughts?