Test Sailing a Pacific Proa

[JohnRPollard]

I recently had the opportunity to help a friend test-sail his newly launched Pacific Proa. It was very fun, interesting, and FAST.

Proas are a variety of multihull with two hulls, but they are not catamarans. They are double-enders in the truest sense of the word, meaning their bows and sterns are reversible. In a Pacific Proa, the outrigger hull (the "ama") is always kept on the windward side of the boat.

What makes them interesting is their method of tacking, called "shunting," a maneuver that is very different from what most sailors are accustomed to, and which allows the ama to remain to windward at all times. Also, they do not ever jibe, they only shunt.

Shunting is a fairly straightforward maneuver, but it does take a little while to wrap your head around the notion as certain aspects of the maneuver are counter-intuitive (e.g., bearing away when it comes time to "tack").

My friend posted up a short video on UTube that I thought some might enjoy.

Test Sailing a Pacific Proa

I will try to post some additional explanations and observations later. In the meanwhile, feel free to post comments or questions and I will respond as time permits.

[peterchech]

Wow 12 knots on the first sail? Pretty frigging badass. Russ brown really figured out the modern pros, getting ideas from dick newick. It looks like john harris is really gonna follow in his footsteps and hopefully improve on browns proas a bit. Best of all, you can buy plans for this one! Looks like a real blast... I love the little sit in cockpit, gives some protection from the elements.

Any pics of the interior? Did u feel the ama lift as speed picked up?

[Faster]

Very cool.... did you lose the jib on a port tack 'just because' or is it main only going that way?

[JohnRPollard]

Originally Posted by peterchech

Wow 12 knots on the first sail? ...
Did u feel the ama lift as speed picked up?

It may have been only 12 knots while videotaping, but we actually hit 15+ knots on that test sail. I did not notice the ama lift, but the design calls for water ballast at higher wind speeds and we had none for this test. So it may have come up a tiny bit, briefly - I was too giddy to notice. Also, one of us was usually sitting or standing outboard, providing some ballast.

Originally Posted by peterchech

Any pics of the interior?

I haven't spooled this one, but it may show some interior features: Walking Tour of Proa Madness

[JohnRPollard]

Originally Posted by Faster

Very cool.... did you lose the jib on a port tack 'just because' or is it main only going that way?

Hi Ron,

This was a first test-sail, and the breeze was moderate and puffy, so we went conservative for the most part. We started out sailing with a single reefed mainsail. Later, we hoisted a jib but kept the mainsail reefed. This is when we hit 15+ knots in a puff of about the same speed, I'd say. You may have noticed in the video that I had both the jib and main sheets almost in hand, but made no effort to trim as we gained speed and the apparent wind moved forward (which certainly would have helped).

After we shunted to head home, we had some difficulty with a jib halyard and decided to douse it. We then shook the reef out of the main and sailed like that for the remainder.

Before shunting, the jib -- which is set on the fly -- gets doused. After shunting, it gets hoisted again at the opposite end of the boat, i.e. the new bow. The final configuration calls for two jibs on furlers which will simplify the process.

[Faster]

Rudders have to be 'switched' too, presumably.. looks like they retract at the 'bow'... Another thing... intuitively I'd have thought the proa went to leeward to resist heeling like an ama on a tri. But I gather with it to windward there's less drag?

[JohnRPollard]

Originally Posted by Faster

Rudders have to be 'switched' too, presumably.. looks like they retract at the 'bow'... Another thing... intuitively I'd have thought the proa went to leeward to resist heeling like an ama on a tri. But I gather with it to windward there's less drag?

Yes, two rudders that move up and down much like daggerboards. During the "stalled" part of the shunt, the rudders are swapped.

Again, yes, it is somewhat counter intuitive that the ama remains to windward at all times, at least with a Pacific Proa. Pacific Proas are the traditional version of this design, originating from Polynesia. There is actually another kind of proa, a modern variant called the Atlantic Proa. The AP keeps the ama to leeward.

The big advantage to the PP design with the ama to windward, is it allows the ama to be used as a base for staying the mast. The APs can't do that because their ama is to leeward, so their rig tension or free standing rig must be engineered much more robustly.

The mast is stepped off-center on the main hull. That, along with the righting moment provided by the windward ama, keeps the boat very level. On a PP you're not supposed to fly the hull. If the hull is flying, water ballast or a reduction in sail is called for. They don't worry about the drag, because both hulls are so fine (especially the ama) they are very easily driven.

[CalebD]

Very cool JRP!
I had a hard time imagining how the ama stayed to windward until I realized that the boat never actually tacks in the conventional sense. Instead, during a 'shunt' the stern becomes the bow and the rudder is then deployed in what was the bow while the jib is then deployed on what was the after stay but after 'shunting' is now the fore stay. This explains why the jib needs to be doused in order to 'shunt'.
Very interesting.

Proa - Wikipedia, the free encyclopedia

[JohnRPollard]

Originally Posted by CalebD

Very cool JRP!
I had a hard time imagining how the ama stayed to windward until I realized that the boat never actually tacks in the conventional sense. Instead, during a 'shunt' the stern becomes the bow and the rudder is then deployed in what was the bow while the jib is then deployed on what was the after stay but after 'shunting' is now the fore stay. This explains why the jib needs to be doused in order to 'shunt'.
Very interesting.

Proa - Wikipedia, the free encyclopedia

Thanks Caleb! Yes, it was very cool. I'm a dyed-in-wool monohull sailor, so for me this was quite a different experience.

I am by no means an expert on proas or sailing them. I don't know a whole lot more than what I've recently learned on the test-sail of Madness. But I should have discussed the mechanics of shunting a bit more in the intro post. I'm sure that Wiki link does a good job, but I'll just talk briefly about it here for continuity sake.

In many respects, sailing the proa was no different than a conventional boat, mono- or multi-, with a conventional fore-and-aft rig. As you're sailing along, there's the usual heading up and bearing away, trimming and easing, reacting to shifts and puffs, pinching up as close to the wind as possible, etc.

The way it differs is in what happens when it would normally be time to tack or jibe a conventional rig. It's at this point that the proa instead shunts.

Let's say you're sailing along close hauled, and you can see that you won't make your mark on this "tack". So you realize you'll have to take a leg over on the other "tack" in order to make your upwind mark.

Now, instead of turning the bow up and through the wind and tacking the sails over, the proa eases sails and bears away. As the proa bears away to a beam reach, the main is eased all the way to leeward, so it is just streaming there like a weathervane, producing no drive. Likewise the jib is eased and doused. The boat coasts to a stop. It is completely "stalled."

At this point, the working rudder is raised, and the lazy rudder is dropped. The helmsman shifts to the opposite end, takes the new tiller in hand, then trims the mainsail in again -- pulling the boom back toward the end of the boat that previously was the bow. [The boom has two mainsheets affixed to it -- one leading to each opposite end of the cockpit.] This powers up the main again, and the boat begins moving in the opposite direction. Set the jib, trim in tight, and you're now sailing upwind again on the opposite "tack".

You would do the same thing when it comes time to "jibe", except you'd initially bear up toward the wind to a beam reach from a broad reach. After shunting, you'd bear off again.

Bearing away for a "tack" is hard to get used to. Likewise, the idea of completely stalling the boat during the shunt is strange to read about I'm sure. Most of us do not like to stall our boats, losing all forward weigh and rudder control. But in a proa the shunt is a no-nonsense, no-fuss maneuver. The boat just comes quietly to a stop, and floats there very serenely while the rudders are swapped and the formerly lazy mainsheet is taken in. I was expecting controlled chaos during this process -- reading about it sounds complicated -- but it was actually straightforward and uneventful.

[peterchech]

WOW that is a fast boat... John Harris is the man!

What I really like about the pacific proa concept is the balance of forces.

By keeping the ama to windward, there is always tension in the stay and compression in the crossbeams. That's perfect. Unlike, say a trimaran, where the crossbeams have to be very strong to resist bending forces when an ama is to lee (one ama is always to lee). So theoretically a pacific proa can be built much lighter (and cheaper) than a similar carrying capacity trimaran or catamaran and can use less exotic materials. Also, the ama doesn't need to have much buoyancy because it is usually just skimming the surface. Therefore it can be built similarly light and small. Finally, since you are only building one ama instead of two, there is less work/cost to owning the proa.

These boats were developed by dirt poor islanders for whom building two or three full hulls (like a catamaran or proper trimaran with buoyant amas) was prohibitively expensive and time consuming. Also limitations in materials strength favored the low stress proa theory. A simple shaped log worked as the ama, and coconut fiber rope stayed the mast/sail. These were the fastest boats in the world until fairly recently in history. They were recorded as doing 15 knots or more by Spanish explorers in the 16th century, using woven plant material (pandanus) sails. Pretty impressive.

I built a 24' tacking outrigger canoe last year and sail it regularly. It doesn't shunt like a proa, but next year I'm going to refit it as a shunter to experiment with this a little bit. Here's a little video to show what it feels like ama to lee. Ama to windward is much faster and you feel that the boat is just not straining nearly as much, doesn't have to punch through the waves and swells nearly as much. IMHO a far superior ride.

YouTube - Broadcast Yourself.