Wednesday, February 03, 2010

Designing and building the ARGIA

In mid-1985 I designed the Schooner ARGIA, and had her bare hull built over the winter. We went down to the Virginia yard May 1, installed the engine, motored back, and fitted her out and rigged her at Steamboat Wharf in Mystic. On July 3 we left Mystic at sunset, reaching NY City at daybreak on July 4, 1986. We carried our first paying passengers in the Tall Ship Parade that day. There are many stories here, the biggest is that none of the above would have been possible without the help of many talented, hard-working and committed employees and crew, willing to work at "schooner wages".

I recently received some questions on the vessel. Have not done much with this blog for a while, it was a good excuse to post my feedback here. I don't have time to polish my writing, so I will be cleaning it up and expanding it as time goes on.

The questions were: Why does the Argia leaves hardly any wake? What led me to that design? Was it the ease of construction, turning radius, history, or something along those lines?

Disclaimer: I am not a professional naval architect. I have only designed 4 boats. I took an 8-session small boat design class at Mystic Seaport (design 1), where we started out by pouring our own lead ducks. Then I started the Westlawn boat design course (desing 2), but after a third of the way through I felt I knew enough to design and build my first schooner, and dropped out, I was not planning on being a naval architect. Before this, I had taught sailing for 5 summers on Blue Jays, sailed on the Mystic Whaler for 2 years as deckhand and mate, captained Clearwater for 2 years, and worked in the Mystic Seaport shipyard for 2 years. So, while my theoretical background was not strong, I had some real experience under my belt. I then designed and had built the 96 foot schooner VOYAGER (design 3), which is another story. This is about ARGIA, my 4th design, but only the second to have built.

What let me to that design were the parameters I wanted. You can't design a boat to do everything well. The narrower the design criteria, the better the vessel will perform in that range. Naturally, this leads to a lack of flexibility, so most vessels have to be compromises. A boat design just does not happen, you start with rough hull sketches (3 views), sail plans, engine location, and interiors, they influence each other, and you push things around until they come together. Then there is a lot of math that has to work out. There are many of iterations of this process, ARGIA probably went through at least 6 before her final design.

My criteria were:

1. Requirement: A day sailer that was as small as possible, still look good, and carry 49 passengers. Over that number the USCG regs get stricter. The 49 matches well to the number of passengers that a bus can charter bus=one boat.

Result: I settled on a hull that was 56' on deck, with a beam of 18'. Though beamy for that length, there is considerable flare forward and aft. This increases available deck area, without sacrificing appearance and underwater volume, or displacement, too much. Without a cabin house amidships, but a clear deck, considerable seating was accommodated. This also gave us a lot of seating flexibility. With a very beamy stern and large quarterdeck, we were able to accommodate 20 passengers on a large aft cabin.

Small as possible: because the bigger the boat the more it costs to build, maintain and crew, and the longer the boat, the more it costs to dock and haul out.

2. Requirement: A boat that was as inexpensive as possible to build and maintain, but would last at least 20 years without any significant problems.

Result: Hard chine hulls cost at least 30% less than round bottom boats to build, so the choice was made for me. Looking at the nicest looking hard chine workboats, I settled on the ones in Chesapeake Bay. So the hull was inspired by those Skipjacks and hard-chine schooners. I also kept the angle of the bottom to the keel the same from amidships to the transom. Having just one angle to worry about make construction a lot easier. Not compromising materials, we used white oak for all structural timbers (keel, keelson, frames), Honduras mahogany for side planking (strip planked), hard pine for the bottom (cross-planked). Now I forgot if we use fir or hard clear pine for the shelf, clamp and deck beams...have to look this up. The hull was fastened with stainless ring nails. Exterior and interior ballast was lead. A cross-planked hull is very easy to build, once you get past the bow section. There is no bevel, caulking or glue between the planks. They are just clamped together, and nailed to the frames. When the boat is launched it leaks a lot, but it's tight as a drum after a few days. The deck was solid-core exterior plywood with two layers of fiberglass, and was built in a week.

With strip-planked sides, cross-planked bottom, and a solid deck, you have a unibody hull, except for the one caulked seam where the bottom planks meet the keel's rabbet.

3. Requirement: A boat that maneuvered well, could turn 180 degrees in twice its length, with ease of handling. We had to turn in the Mystic river to dock in a space not much longer than twice ARGIA's extreme length, 81 feet.

Result: Most sailing vessels don't need a full-length keel, a third-WL-length one is more than enough, so that's what ARGIA has. A vessel with a shorter keel will be more maneuverable than one with a long one. By also separating the skeg and rudder from the keel, I created a pivot point to spin around, which would not be possible with the conventional full-keel schooner. A large rudder and propeller help with maneuverability. The hull is more like a centerboard vessel with a fixed keel in place of the centerboard.

I always thought visibility to the helmsman is important, I don't want to depend on a bow watch in the daytime. So the quarterdeck was made as high as possible without sacrificing appearance. This also increased headroom below, and created a higher and safer freeboard aft.

4. Requirement: A boat that carried on the traditions of the last century of commercial sail. This included some of the most beautiful vessels ever designed. The link to the past is also a good marketing point. Finally, I wanted to help continue Mystic's illustrious history with commercial sail, ongoing for several centuries.

Result: Here again, I was attracted to the hard chine vessels of Chesapeake Bay. ARGIA, however, is not just a large skipjack. The round bottom pungy schooners also inspired her hull shape. Finally, her sail plan is an almost exact copy of representative schooners of that period, with the exception below. What I liked was one large jib, instead of a separate jib and staysail. This makes the vessel a lot easier to rig, maintain, and tack.

I also studied a lot of Hereshoff hull designs, these comprise some of the most beautiful in the world. No-one would think ARGIA resembles a Hereshoff, but some of the lines I saw in those translated in her spirit. She was also inspired a bit by the hard-chine Blue Jays that I sailed as a youngster.

The standing rigging was made by Dean Seder, head rigger at the Seaport, using traditional techniques. The ironwork by the Seaport blacksmith, Clint Wright. Deadeyes and lanyards instead of turnbuckles. Several other Seaport shipwrights (Roger Hambidge, Brian Mogel, Gary Adair) crafted the interior, skylights, companionways, in the style of the past century. I was extremely lucky to have the assistance of these craftsmen, some of whose names I cannot recall at this moment.

5. Requirement: A boat that sailed well during the major sailing season: Long Island Sound in the summer. Air is light during this time.

Result: Here is where we departed a bit from an "exact" copy of Chesapeake schooner rigs. I increased the sail area about 10% above these, to account for our lighter air. This enables ARGIA to move along a little better in our typical summer weather. With reef points on all three sails, and the flexibility of a schooner rig, we can still go out in fairly heavy winds.

ARGIA has a relatively light displacement for a schooner her size. This allows her to go faster. Stability was addressed by having 30-50% of her lead ballast in the lower portion of her external keel.

6. Make the Math Work: There are many ratios, displacement calculations, stability calculations, areas, etc. that have to meet specific requirements or ranges.

Result: These were all painstakingly learned, computed, changed, recomputed, etc. The explanation is beyond this post!

Finally, why does ARGIA leave so little wake? The one thing to know about boat design is that, discounting wave action, the way the water leaves the hull is more important than the way it enters it. When two cones are dragged underwater, one pointy end first, and one round flat end first, the one with the round flat end first has less drag! I though a lot about how water was going to leave the ARGIA. It has to do with laminar flow, or the smooth travel of the water over the hull. This needs to be maintained, and not disturbed, for as long as possible. This was done several ways:
1. Keeping the angle of the bottom planking to the keel the same from midships to the stern. Thus the water flow never had to "twist".
2. Aligning the leeward chine to the water flow directions, as much as possible in a typical angle of heel, about 10-15 degrees.
3. Letting the windward chine come completely out at 10 degree heel. This also reduced wetted surface, the largest factor holding you back at slow speeds. (note-have to check above angles). And once the chine comes out, the vessel gets considerably stiffer.

Of course, there are almost always waves, so the entry and first half of a hull is also extremely important. I made the cutwater as sharp as possible, but smooth over the first half of the hull. There is no chine at the bow section, it starts a bit aft, so no angle for the water to hit.

I will be adding to this, and revising it, as time goes by. I can't remember all the details right now. At last count, ARGIA has taken over 100,000 people sailing, I hope she takes at least that many more.

1 comment:

Bryan Hammond said...

That was a great, delightfully more than I had expected. I haven't used any of it in my writings thus far but I did take some time to discuss some of your talking points in class the other day. I showed a video of Argia steaming down the river with hardly a ripple to show for it. Surprised a few people. Another hot topic was the, relative to our modern standards, speed of the build from inception to tall ships parade. Certainly a noteworthy achievement considering the high quality of the finished product and of course it's longevity. Thank you again for all the information - Bryan