In 2008, we gave up the search for a second-hand metal sailboat that was powerful enough to take us into high latitudes, be handled by a couple, make 200 mile-days under sail or power, and sneak into shallow harbors. We particularly wanted the flexibility of being able to beach our boat and not have to depend on boat yards for every bottom cleaning or fouled prop. A few years before, we sailed on an Antarctic 65, built from thick plate using the Strongall building method, and we were very impressed with the sailing performance. At the same time, we struggled with the idea of building a 65-ft vessel ourselves without having a full boatyard capability and crew; available finances also excluded the possibility of just ordering a hull.
Strongall was a great solution for us. Strongall is a self-supporting aluminum hull building method based on thick plate scantlings with very little framing. It is perfect for cruising yachts because it provides greater hull strength than steel with approximately 30% weight savings. Until a few years ago, a French yard was holding the patent on it. Using this method, hull plates are precut to finish size and shape and are tacked together using a temporary jig. Another advantage of this method is the speed with which a hull can be created. Amazingly, our hull was together in 8 weeks—like magic! (But then the work started!) Being accustomed to building vessels to USL standards (I worked on a commercial boatyard in Australia), I decided to take the best of the Strongall system and combine it with standards of a commercial vessel. The design for a standard Strongall 65 is for a pleasure craft, but would not pass survey for a commercial vessel. Calculations for our 65 footer,
showed us the scantlings of the vessel had to be improved. Hence, we proceeded forward to build a Strongal-plus design.
Adding extra strength through water-tight bulkheads, extra framing, etc., added a little extra work, but added an enormous amount of safetor high latitude passage-making. I also redesigned the original swing keel to be hydraulic rather than manual. Six thousand pounds of keel is a lot to handle manually. Using hydraulics had the added advantage of stopping the keel from swinging back into its housing if the boat ever should capsize.
Moving the 65 foot plates was quite a handful. As we had no overhead crane, we had to help ourselves with an A-frame and a forklift with a long loading boom. After
all hull plates were prepared, the assembly started with setting the base plate to the correct shape. We set the jig(a set of blocks below the vessel) to form the baseplate into the right shape. One by one we added the chine and
topside plates stitching them with tack welds and small braces. It was quite amazing how easily things came together. At this stage, it was a large advantage had time to arrange correct weld angles on the entire length of the plate butts. Where a boatyard is always driven to consider profits, for us, the accuracy and the quality of weld joints was our highest priority.
The construction of Thor drew upon my lifetime of experience building and maintaining metal boats. I chose my crew because of their youthful energy and experience working metal. It was a pleasure to see the energy they brought to the project and how they inhaled the additional knowledge I could pass on.
After the 5 hull plates were tacked, water-tight bulkheads, floors, keel, and centerboard case were added. To the original design, I added 3 water tight bulkheads plus a large water-tight engine room. From the engine room forward, the vessel has underfloor tanks holding 1200 gallons of diesel and 22,000 pounds of lead ballast in separate ballast compartments. We separated the ballast from the aluminum with 3/8" fiberglass laminate. After all, I had made a lot of money repairing corrosion problem areas on other aluminum boats and did not want to fall into the same trap.
For the superstructure, my wife insisted on a pilothouse. We both had admired Dashew’s Beowulf deck set-up so we fashioned our deck after his including using the pilothouse as an extension of the cockpit. My wife insisted on having a cozy pilothouse for high latitude sailing so we I added a sliding door to protect us in cold weather situations. This would prove to be one of the best design features!
We customized the fit-out to our needs. Our boat has only 6 bunks including a huge owner’s cabin forward and a guest quarters aft. We created a very large owners cabin with private bath/head that could easily be reconfigured back to the original four bunk design forward if there is need. Our guest quarters is designed with a two single bunk crew quarter and a second master suite with separate bath/head aft.
Building a nice teak fit out, took as long as creating the aluminum hull. Watching the weight of the fit-out, we chose to use Nida Core for all non-structural bulkheads and fit out. This made the vessel interior look like the interior of a fiberglass hull under construction. As I wanted to keep the quality of the fit-out high, we wanted to have all trims and framings in solid teak. We were contacted by a retiring builder who had a truck load of old reject Burma teak doors up to 2 3/4" thick. We are especially proud of being able to reuse this resource without adding the destruction of forests.
Building and fitting out Thor was a huge undertaking. The hardest part was finding the right crew. With Gerd's experience in boat building, he always had gift of putting together a team with the right skills and experience. The end result, Thor, has all the qualities of a southern ocean adventurer and specific details we could not find with any other design.
Our final major step in the hull construction stepping the mast. Our deep thanks goes to Buzz Ballenger from Ballenger Spars for all his support.
It is truly impossible to describe the beauty of the park.
Constructing the hydraulic lift keel with 4000 pounds of lead ballast took an enormous effort. Any boat yard would fill the hollow keel with lead and rely on the fact that there never will be any water intrusion to create electrolysis pathways. I wanted a keel that would never create problems for me or owners to come so I separate all ingots with a high density plastic. After filling the keel with 2 tons + of lead, I welded the base plate and vacuumed filled the entire void with fiberglass resin.
We took time to engineer the boat for short-handed sailing. We chose a 1013 Deutz Diesel with 250hp. It is the only engine of this size left on the US market that met Tier 2 and has no electronics. The Deutz 1013 is mainly used on commercial vessels and has a 100% duty cycle 24 hrs a day. The engine lives in a large water-tight engine room, with standing headroom.
We added a bow thruster for ease of handling in close quarters. Three hydraulic winches have made sail handling painless in any weather condition. The big sail and storage compartment, adjacent to the anchor locker was more important to us than an extra few bunks.
We constructed the boat 5 miles from the water. As launch day approached a large truck, an even larger crane, and a police escort was needed. This was the big day when everything came together. Of course, a big celebration followed with all friends and helpers.
One by one we added the chine and topside plates stitching them with tack welds and small braces. It was very important at this stage to check the correct angles to the lower plate and beam at several stations. Working with two full-time helpers, it was 8 weeks from the day the aluminum arrived until we had all 5 plates stitched together into the hull shape.
The most practical tool for cutting the plates was a 7 ½” worm-drive circular saw with Tenryu aluminum cutting blades. Lubricant extended the blade lifetime so we only used about 9 blades to cut the 5 plates to size. We ended up with an extremely clean and accurate cut. After cutting, we pre shaped the plate edges using a standard hand planar with tool steel blades to get a 110 degree welding gap. This was rather difficult as you always had to watch the cutting amount otherwise the planar would grab and destroy the blades in a split second. Using this method, we ended up with a clean weld surface. For welding the heavy plate, we used a 350 amp Lincoln with a water cooled Cobramatic. A 250 amp Miller air cooled welder was used for tacking and later for detail work.
Sailing to the Ends of the Earth
Thor is built from 22,000 pounds of 5086 aluminum. The bottom plate is 5/8” and ¾” making it strong enough to be beached. The rest of the hull plating is ½." The deck and the pilothouse is ¼.” We cut and welded the plates together on a 65 foot long welding table. At this point high accuracy required keeping the plate butts perfectly aligned. This was also the first test for our welding machine set up and the certified welder who was doing all the hull welding during Thor's construction. Several destructive and ultrasound tests were performed; we were very happy about machine and man after the perfect outcome of all the tests.
Three 20 foot sheets were welded together to form the bottom plate. After lofting the shape onto the plate, we cut the plate. As we had only one table, we built one plate after another, strategically placing them aside ready for assembly.