The building of Sleipnir.

We’re building a 33′ Viking Ship in Vista, California!

For many years I’ve been fascinated by Viking ships, from the time in 2001 when I joined the BC Viking Ship Project in Vancouver BC and we built Munin, a 42-foot version of the famous Gokstad Ship.

Munin was built by two Norwegian master shipwrights, Arne Frostad and Chris Frostad, with a group of about 40 volunteers who helped make it happen. I was in charge of the sail and rigging, and became her captain during her first season. She was a lovely ship, a delight to sail, and from that experience I had a wish to build my own ship.

My life changed and I moved to California, first to Santa Barbara and then to San Marcos, with my wife Pia, and when I retired in 2018 I got serious about making my dream come true.

The first thing I had to do was find a place to build my ship, and that was not easy! Then I came across the Viking Festival at the Sons Of Norway in Vista, and I met one of the directors, James Jerpseth, and told him about my dream of building a ship. To my surprise and delight he said the Sons Of Norway would be glad to let me build my ship on their property!

The Sons Of Norway have been wonderfully supportive, and I thank them every day for having given me the opportunity to make my dream come true!

I was extremely fortunate that I met another Swede who shared my interest, and became my trusted companion and help mate in this endeavor. Ivar is a semi-retired engineer who lives in San Juan Capistrano and comes down to Vista two days a week to help me. Ivar has done most of the riveting on Sleipnir, and has helped me in many other ways, especially when a second pair of hands or eyes are so helpful! We often discuss design aspects, particularly where there are questions about how best to do something. Without Ivar I doubt I would have got as far as I have and I will always be grateful to him for his faith in what I was doing, and for his patience with me during the hard times. He is truly a good friend!

So I started collecting my tools, bought materials, and started to work.

I had a copy of the plans used to build Munin, and first I had to make full-size patterns of the frames. I did that by taking a picture of the plans and projecting the lines onto a big sheet of cardboard, from which I could transfer the lines to plywood sheets that I cut to the right shape.

Viking ships are built right-side-up, so the first thing I had to do was build the keel. The keel is made from 2″ by 10″ oak boards, joined with “scarf” joints in which the pieces are cut at an angle on the width, about 8″ long and then matched up, glued and finally copper-riveted together.

The vertical ends are called “stems” and required several pieces to be cut and joined with big stainless steel bolts, the same way that Munin’s keel had been built.

Once the keel was built and set up level at the shipyard I installed the temporary frames: what an amazing experience that was! I could finally see what the ship would look like!

Next came the biggest job: planking! I had bought a full sling of 2″x6″ 12-foot boards from JW Lumber, a local yard, and first I cut them into 3/4″ slabs and planed those down to 5/8″ for the planks.

Viking ships are built with “lapstrake” planking, where the planks overlap each other by 1″ and are riveted together with copper rivets. The Vikings used iron rivets, but those are not available to us, and copper is a fine, durable and easy-to-work material. Rivets are a very strong way to hold planks together. The process is as follows:

• we place the new board into position, overlapping the one that’s already in place
• we mark the location of each rivet, 1/2″ from the edge so the rivet is within the 1″ overlap of the planks
• holes are then drilled for each rivet, after which we remove the new plank and apply PL caulking to the joints (especially the scarf joints!)
• the new plank is then placed back onto the previous one, and we carefully align them to be sure the overlap is maintained
• clamps are then put onto the planks to hold them in place
• rivets are in two parts: a nail and a “rove” or washer, which is cup-shaped and has a hole a bit smaller than the diameter of the nail
• we first drive the nails through the holes, then, holding a heavy metal block that has a hole drilled into it (which the nail goes into) against the rove (which is on the inside of the ship), we drive the nail onto the rove, until it is tight against the wood
• finally, we cut the nail just a bit past the rove and then hold the metal block on the outside (against the head of the nail) and with a small hammer carefully hit the cut-off nail so it rounds over the rove, making the rivet.
• once finished, the rivets are very strong, as there are two “heads” which securely hold the joint together. Plus, when the wood gets wet it swells, making the joint even tighter!

I’m not sure whether the Vikings invented this type of construction, but they certainly used it to great effect: their ships are both strong and light-weight, because the planks are thin but the overlapping joints are actually like small beams, double the thickness of a plank, and give the hull rigidity.

The alternative, used later by many countries, involved very heavy structures and thick planks that were laid on-edge to each other in a method called “carvel”. These planks have to have caulking inserted between them (a process called “paying”), which is prone to leaking. The strength of this type of hull is mostly in the very heavy frames. There is an interesting expression from when old-times sailors were hoisted overboard to “pay the devil” (the plank at the waterline), a double meaning if ever there was one!

While we’re discussing aspects of Viking ship design, there is one that is quite amazing: the shape of the hull is not just round but gullwing-shaped, so it curves up from the keel and then down again so there is an up to 2″ hollow about halfway out from the keel toward the sides. This has the effect of moving the center of buoyancy of the hull outward, where it is more effective in keeping the hull stable: a round hull is more prone to tipping than one shaped as an inverted “W”, and that makes for a very good sailing ship, as I have experienced: many modern sailboats heel over as the wind pushes the sail, because the hulls are round. We’ve all seen sailboats do this, a lovely sight, but not the most efficient! Viking ships stand straight up, because of their shape: the sail is more effective this way as it “sees” more of the air moving over it. The “square” shape is also important for two reasons: the center of effort of the sail is low so the ship isn’t pushed over so much by the wind, and a rectangular sail is a better airfoil than a triangle. Actually, modern high-tech racing sailboats are now cutting off the top of their sails for this very reason!

Viking ships are double-enders: this design also has big advantages. Not only are they very beautiful (!!) but they are inherently fast because they do not generate a stern wave. There is a physical limitation to other hull types, that they cannot exceed a speed in knots that is the square root of their waterline length multiplied by 1.34. So a boat that has a waterline length of 25 feet has a maximum “hull speed” of 6.7 knots. There have been documented cases of Viking ships sailing in excess of 17 knots! When I sailed Munin we recorded a speed of 7 knots in only 12 knots of wind, fast indeed!

From the first time I sailed the 42′ Munin in Vancouver I have been so impressed with Viking ships: 1200 years ago, the Norse really knew how to build a very good sailing ship! And that is one of the main reasons I decided to build Sleipnir.