When we purchased our first catamaran, I thought performance was important because at some point we might want to race, and going fast is more fun than going slow. We bought a Catana 471 because it was regarded as a performance cruising boat that was well designed and fast. Well, as they say in the military – “No plan survives contact with the enemy!” and when we started making offshore passages in our “performance” catamaran. I learned two things:
- Sailing offshore is often uncomfortable and stressful
- How fast we were going was much less important than being comfortable and relaxed
Our so-called performance catamaran was a beast to manage in 25+ knots and large waves, and took over 12 knots of wind before we could sail at a reasonable speed. We had to run the motors when winds were light, and got beat up sailing when it was windy. I quickly realized I knew nothing about the design characteristics of a boat that can handle real world conditions in comfort and safety.
Now we’re buying our third catamaran, and we have more sea miles and experience behind us. After owning an Outremer 5X for our 2nd boat, I have a better understanding of what’s important when choosing a catamaran and configuring it for offshore sailing, and there’s no question in my mind, high performance is the answer!
Because we’re cruising sailors and not racers, it’s not obvious why performance is important, and trying to understand performance by discussing it with a naval engineer can be very unsatisfying, because they live in a world of complex details and tradeoffs, where there is no single or simple answer to any question. I did a lot of research and read a bunch of theory, but I didn’t really understand which performance characteristics are truly important to cruising sailors until I experienced them for myself. Wildling was a great learning experience and now we are applying what we learned to the design of Puffin.
In this post I will go over the performance characteristics that I think matter the most for offshore cruising, and some of the innovations that we are building into Puffin to achieve our goals of comfortable, low stress offshore sailing. It turns out we are building Puffin at the perfect time, because Outremer has figured out how to take resin infusion optimization to the next level. They are able to build lighter boats without having to add more expensive carbon fiber. It’s an important breakthrough, and I think we’re looking at the future of affordable, high performance, series production catamaran construction.
Performance is not all about going fast
It’s easy to think high performance just means going fast, and for racing sailors that may be true. But cruising sailors have different objectives. First and foremost we want to keep our family, friends and crew safe and comfortable. We want to be able to handle a wide range of conditions without a lot of effort and stress, and we want to get to our destination quickly and efficiently.
It turns out that in many cases going faster is actually not what we want. When at sea on a passage, as the wind builds so do the waves. Going fast in developed offshore conditions is uncomfortable, stressful and it’s not any fun. Robin and I prefer to sail between 9 and 12 knots on passage upwind and slower when conditions get rough, so we slow the boat down by reducing sail as the wind builds. This protects the boat and allows us to relax, rest properly and maintain a two person watch schedule. It also gives us a safety margin when we get hit by unexpected gusts.
In light winds, we want to be able to sail rather than motor. The old adage: “There is either too much wind or too little” is unfortunately true! When the wind is light, the sea is calm, and things are really pleasant, but it’s no longer pleasant when you have to run the engines. My ideal scenario is to be able to turn off the engines when the wind reaches 5 knots. That way we can sail more and motor less, and we can be sailing when other boats are stuck at the dock waiting for a weather window.
High performance boats are easily driven in light winds. They spend more time sailing and less time waiting for wind or motoring. They log more miles in relaxing, light wind conditions, and they have higher daily averages over time because they can maintain a more constant speed range in changing weather conditions. In higher winds, they use less sail area for the same speed. Smaller sails are easier to handle and generate less force. Less force means less stress on the rig, lines, winches, fittings and crew and fewer breakages.
The most important features
So, performance for us is all about driving the boat at reasonable speeds without engines in light winds and being able to easily and significantly reduce sail area as the wind builds, while maintaining a high average speed and keeping a comfortable motion.
In my experience there are four important design elements that a boat needs to have to meet these cruising performance goals. The more of these that are present and done well, the more comfortable, safe and fun the boat will be offshore.
- Hull length and shape: long, narrow hulls require less power to drive than short, fat hulls, they also slide more easily through waves. But too narrow and there’s not enough room to live comfortably aboard. It’s important to have the right balance.
- Weight distribution: keeping heavy items (like engines, bunks and systems) away from the ends of the boat and keeping the boom low and the mast and rig small and light all reduce the amount of fore and aft pitching. More pitching means less comfort and a big speed reduction as the boat is diving further in and out of waves instead of driving forward
- Weight: lighter is faster and greatly reduces motion in a developed sea
- Sail area: more sail area is faster, but harder to handle and manage as conditions develop. The goal is to have the minimum necessary to drive the boat at the speeds we need.
If a boat manufacturer does a good job with the first 3 items, the boat can have a shorter mast and smaller sails. A heavy, wide hulled boat that pitches a lot will need to put up a lot of sail just to get moving, and will have to carry comparatively more sail in higher winds. This places higher stress on the boat and requires more work and vigilance for the crew. I had to hand steer in developed conditions on our Catana because the boat became very unbalanced due to the amount of sail area we had to carry to make reasonable speeds. With our 5X, we went plenty fast with deeply reefed sails and used the autopilot instead. A completely different experience!
You can see what I’m talking about by comparing a heavy slow boat like the Lagoon or Bali with a Schionning or Outremer. The Bali boats are focused on comfort at the dock and are more oriented to motor sailing in light to moderate winds. They have wide hulls to accommodate their big cabins and living spaces, they have cabins in the bows, and engines far back in the stern, they weigh more than twice as much as performance boats of the same length and they have double the engine size and triple the fuel tank capacity because they spend so much time motoring instead of sailing. Nothing wrong with that, as long as your goal is not long distance offshore cruising.
It’s also interesting to watch different catamarans at anchor. You can see the fat, heavy boats are rocking and pitching, while the performance boats hardly move. Performance is the gift that keeps on giving, it’s even an advantage when you’re stopped!
Our design goals for Puffin
I’ve talked about general characteristics, but here I will be more specific about what we are trying to accomplish with Puffin:
- We want to maximize the amount of sailing we can do in light winds. It’s super annoying to be sailing at speeds less than we can comfortably motor. For us, that’s about 5-6 knots on a single engine. I’m sure everyone is different, but I’ll sail all day at 4-5 knots, rather than turn on an engine. So if our goal is to sail in winds at 5 and above, we have to be able to sail at or very close to the wind speed.
- We need the best motion at sea possible to maintain our speed and comfort aboard. Staying high in the water and minimizing pitching is important, so we need narrow hulls, light weight and good weight distribution.
- We want to be able to easily reduce sail as the wind builds, and have some margin for error so even if we get caught with too much sail up, the rig is not so large, or the boat so light that we risk damage or flipping.
- We want to live aboard in comfort with well designed spaces for entertaining guests, relaxing and sleeping. We need enough space for storage and comfortable cabins.
Armed with our design goals, I needed to find boats that could meet them. This is not so easy to do because manufacturer’s published data is notoriously inconsistent and inaccurate, so I looked at boats that met our light wind performance criteria and then used them as a benchmark to compare boats that have a similar design. I hoped this would help me find the boat with the best blend of performance and comfort.
An excellent example of high performance catamaran designs are the Schionning boats, for example the Spirited 480 and G-Force. There are a few of these in and around Australia so I have some real world data to do a reality check on their published specs.
I know that a minimally loaded Schionning can sail at or slightly above the true wind speed in 5-12 knot winds. They have fine hulls and excellent weight distribution with cabins and engines located towards the center of the boat. This makes them a great reference point for performance criteria. I believe Schionning’s published specs are pretty accurate, so I took the light displacement weight and sail area of the Schionning boats to calculate a performance ratio. Not a completely scientific approach, but it gave me a starting point for further comparison.
Here are the results of my simple performance ratio calculation using Schionning data
|Boat Model||Length (feet)||Light Displacement (kg)||Sail Area – Mainsail + working headsail (m2)||Performance ratio|
|Schionning Spirited 480||48||8,000||125||15.6|
|Schionning G-Force 1500C||49||8,000||128||16.0|
So why go to the trouble of calculating a performance number? Why not just buy a Schionning and be done with it? Well the reason is that I like the performance of Schionning boats, but I don’t love their interior design and cockpit layout. It’s not bad at all, just my personal preference. I’ve been sailing French catamarans for a long time, and there are many design elements that I really like about them. I also like that they are built in a production series with a global after sales support network, rather than the one-off kit based approach used by Schionning, so I wanted to see if it was possible to get a production boat with similar performance to a Schionning. And for that I needed a way to compare different boats.
Using the same methodology as above, I looked at a range of performance series production catamarans:
|Boat Model||Length (feet)||Light Displacement (kg)||Sail Area – Mainsail + working headsail (m2)||Performance ratio|
This approach is only valid when comparing boats that have very similar length, hull shape and weight distribution characteristics. The Balance 526 is a bit of an outlier here, because it has lower performance geometry and weight distribution than the Outremer and Schionning boats, but I was curious to see how it stacked up just the same.
The numbers for the 4X are not too far off the Spirited 480, the difference being due to the 4X being heavier and having a bit less sail area. As a reality check, our 5X would reliably get within 0.5 knots of true wind speed upwind in light winds. We sailed against a 4X in France and they were always a bit faster upwind than Wildling, so that indicates that for boats around 48-50 feet with these hull shapes and weight distribution, a performance number around 15.5 should be a good goal for a true wind speed capable boat.
As a quick aside, I think it’s important to understand why the 4X is heavier than the Spririted 480 and G-Force. Even with the use of carbon fiber on the 4X the other two boats are still lighter, and I believe the reasons for this come down to two differences in manufacturing.
Schionning boats are built using prefabricated Duflex foam cored panels. They don’t use fiberglass matt layup in molds with resin infusion. Constructing a boat out of Duflex panels is a very labor-intensive process, but it works well for Schionning because most of their boats are home built from pre-cut kits, so material costs are more important than labor costs. The Duflex panels create a lighter structure because there is no wasted resin penetrating the core, so for a given surface area, a Schionning will be lighter than a typical resin infused molded boat.
In addition, Outremer does not use a foam core below the waterline. Instead they use a solid fiberglass structure. It’s heavier, but it is also stronger, and it’s an important safety feature on Outremer boats, because it gives them high impact resistance. This has been put to the test multiple times by Outremer owners surviving groundings and collisions with floating objects with no loss of integrity or safety to the boat.
Pushing the 4X envelope
In the meetings regarding our 4X design with Matthieu at Outremer, I asked him what could be done to boost the performance a bit more on the 4X?
He explained that the 4X design is a collaboration with Loïck Peyron to create a version of the Outremer 45 that was more oriented to occasional racing without compromising comfort and seaworthiness. They extended the Outremer 45 hulls by 3 feet, reduced the weight by 500 kg using carbon fiber in various places, and they replaced the self tacking jib with a larger genoa to increase the working headsail area. The option of adding a taller mast with more mainsail area was also considered. Loïck basically said “don’t do it!” He felt that adding more mainsail would only add stress and fatigue to the crew, because reefing would require more vigilance and more effort. Better to be stress free, knowing the boat can handle a wide range of conditions in safety!
This design philosophy demonstrates Outremer’s uncompromising focus on performance cruising versus racing and makes a lot of sense to me, so no changes to the rig, but what about the weight? This is where an unexpected twist of fate led to a breakthrough that would give us the solution I was looking for!
The Rhum test
The 2018 single-handed race across the Atlantic Ocean, the Route du Rhum, was unique in that for the first time, production cruising catamarans were entered in the Rhum Multi class. Longtime Outremer employee and offshore sailing instructor Jean-Pierre (JP) Balmès entered the race sailing a 4X. They encountered 3 major storm systems that decimated the fleet with winds over 60 knots and 6-8 meter seas. Jean-Pierre and his 4X came through unscathed and took 5th place! He beat all the other production multis by a huge margin, and was only beaten by some racing trimarans, and unlike them, he had a toilet that flushed, and could take a shower without using a bucket! A truly remarkable performance.
JP’s 4X was a stock boat, with some of the bedding removed to keep it light and no changes to the sailplan. But, he made an important change to the hull construction to reduce the weight by 300 kg! We were all curious to see how his 4X was handling the extreme conditions. His feedback was the boat was fine, very strong, but didn’t need to be any lighter!
With JP’s design modification, his light displacement was reduced to 7,900 kg, giving his 4X a performance ratio of 15.4, which is right on the performance number I was looking for. Not only that, JP had just tested the boat in the worst conditions imaginable and had no issues at all.
Help from Gunboat
So what did Outremer do to JP’s 4X to drop the weight by 300 kg, without using extra carbon fiber or compromising strength or safety? The answer comes from an unexpected collaboration. In 2016, Grand Large Yachting, the company that owns Outremer, acquired Gunboat and moved their manufacturing to a site next door to the Outremer factory in France. Gunboat are high performance, all carbon fiber, luxury cruising catamarans. And while the majority of their light weight comes from the use of carbon, they also use a different process for doing foam core resin infusion that saves a lot of weight.
The typical method of resin infused layup with foam core uses sheets of foam with narrow grooves cut into them in a cross hatch, creating 1 cm squares over the entire sheet. This allows the foam to conform to the curves of the hull surface and maintain an even core thickness. When the resin is pumped into the molds under vacuum during the infusion process, all of these little grooves act to channel the resin so it flows evenly over the entire surface, but they also remain filled with resin, and over a large area this constitutes a significant amount of weight that has no structural benefit.
Gunboat takes a different approach. They use solid foam sheets with no grooves, and they cut and shape multiple sections to fit together and form curves around the mold surface, with very little space at the joins. They make tiny holes in a grid over the surface of the foam core to allow the resin to fully penetrate and flow between the inner and outer layers of the fiberglass layup during infusion. This process is more labor intensive, but it yields the lightest possible weight for resin infused fiberglass sandwich hulls. The result is an infusion process that approaches the efficiency of the Duflex panels used by Schionning!
Outremer took the Gunboat approach and applied it to the hull sections of JP’s 4X, and achieved a 300 kg weight reduction.
Innovations on Puffin
Matthieu proposed we use the same approach on Puffin as JP’s 4X, and in addition to the hulls they would also apply it to the molded deck section on Puffin, for even more weight savings. Since this hasn’t been done before, we don’t know yet the total weight reduction, but it’s estimated to be over 350 kg.
I wanted to get as close as I could to the 7,900 kg light displacement of JP’s 4X, but since I am adding about 150 kg of additional weight to Puffin that is not on JP’s boat, I needed to find a way to reduce Puffin’s weight even further to compensate. Here’s the estimated installed weight of the extra items we are adding to Puffin:
- 3 x electric winch motors and wiring @23 kg each = 70 kg
- Extra bunk bed in the port forward cabin = 29 kg
- Extra freezer in the galley = 25 kg
- Extra solar panels on the bimini roof and wiring = 26 kg
TOTAL = 150 kg
When we apply the 350 kg weight savings from the light foam core option, then add back the extra weight of our options, we get a light displacement for Puffin of 8,000 kg. Not bad, but can we do better?
On our 5X we had the salon roof constructed out of carbon fiber, which was a good weight savings but this wasn’t an available option for the 4X as Outremer had never done it. I asked them if we could add it, and after some engineering study they added this to Puffin for an extra 50 kg savings.
That brings Puffin’s theoretical light displacement down to 7,950 kg and gives us a performance ratio of 15.3, pretty close to JP’s Rhum 4X. We now have the great Outremer design layout that we love, the safety of solid fiberglass below the waterline, the extra systems and features we want for comfort and sail handling, and we hit our target performance ratio. Mission accomplished!
Of course we will have to be careful not to load Puffin up with a lot of extra weight when we go cruising, but even if we do, we know that we always have the potential to configure her as a fast, safe and comfortable, light wind sailing machine, and who knows maybe we can even mix it up with those Schionnings in next year’s Brisbane to Gladstone race!