Fun with Spinnakers

When we purchased Wildling, I didn’t order a spinnaker because I wasn’t sure if we would need one, and if we did, what type and size we should get. I’m glad I waited, because now that we have sailed our boat for a year, I have a better idea of what I want a spinnaker to do for us. So this month I went through the process of selecting our spinnaker.


Although Robin and I have sailed many miles with a spinnaker on our Catana 471, I really enjoyed learning more about spinnaker design during this process, and I thought I would share some of that information in this post. I would like to thank Jean-Pierre at Outremer (designer, test pilot, and catamaran guru), Nick at Doyle Sails UK, and Volker (who’s 5X is now under construction and will be launched later this year) for sharing their experience and advice.

First a bit of theory: When sailing to a downwind destination in a catamaran, particularly a fast one, we really want to sail on a reach (90-130 degrees AWA), because it’s much faster than sailing deep downwind. Once the angle starts to get more than 130, things begin to slow down to a point where at 150-160, a reaching sail isn’t much use. On a performance boat, as we sail higher (further towards the wind), the boat accelerates and the apparent wind angle moves further forward, which makes sailing a reach very effective, and even though it might be at an angle to the destination, requiring us to travel further by gybing back and forth to stay on course, the extra speed means it’s still the fastest way to get there.


Reaching under Code-D. Notice the luff of the code-D is quite straight, which makes it good for reaching but limits it’s abilities deep downwind. The straight luff also makes it easy to furl.

On a technical note: this technique of creating apparent wind is what allows true performance catamarans to move the apparent wind forward of the beam and create speeds well in excess of the true wind speed. take a look at the Americas Cup multihulls that sail at boat speeds close to 40 knots for a demonstration of this.

So every boat should have a downwind reaching sail, which for us, is our Delta Voiles, Code-D gennaker, and you would think that since reaching is the fastest way to get downwind, then that’s the only downwind power sail you need! Well, perhaps… if you’re a racing sailor, then yes, reaching is the way to go. But it takes a lot more work and attention from the crew. You have to trim the angles just right, compensate for wind shifts and watch things carefully. But when cruising, our objectives are different to a racing sailor. What we want is low-stress, comfortable, and fast enough.

So what’s fast enough? I’m sure this is different for everybody, but on Wildling, our target speed range is 9-12 knots. If we’re under 9, I’m working to get us more speed, either by sailing different angles, changing sails, or dialing in the trim. If we’re over 12, then I’m going to start reducing sail to slow us down. There’s no extra benefit to us from sailing a reach and doing a bunch of gybing if we could go fast enough, and more comfortably, on a direct course.

We’re going to be sailing Wildling back home to Australia, a voyage that involves may thousands of miles downwind in the tradewinds, that are often blowing at 15 to 25 knots. It would be ideal if we could turn the boat downwind, set our sails for our “fast enough” speed and not have to constantly mess with the sail trim. That’s where the spinnaker comes in. With a spinnaker, we can sail deeper downwind angles than the limit of our Code-D. But which type of spinnaker should we buy?


There are two types of spinnaker: asymmetric and symmetric, with the asymmetric being the most common spinnaker on a cruising catamaran. Asymmetrics are more like a gennaker, in that they have a different length luff, and leech, but they have a lot more curve in the luff than a gennaker, which allows the luff to twist around to windward and generate power at a deeper angle. They are good for deep reaching, usually up to about 150 degrees, and they can get deeper still if the tack is moved to the windward hull. They’re good because they are versatile, and if you don’t have a gennaker, and want only one downwind power sail, then the asymmetric is the way to go. There are a couple of problems with running deep angles on an asymmetric though. Running deep is not their optimum power zone, and in order to gybe, you have to first douse the sail, move the tack to the other bow, gybe the boat and then rehoist the sail. Some folks rig a system of lines to move the position of the tack between the bows, which saves some of the work when gybing, but depending on the amount of wind, it’s usually safest to douse the sail and rehoist.

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Doyle asymmetric spinnaker

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Doyle symmetric spinnaker










Assymetric spinnaker reaching downwind. Notice the much more curved luff than the code-D allowing it to twis more to windward and generate more power at deeper angles.

Asymmetric spinnaker reaching downwind. Notice the much more curved luff than a reaching gennaker (e.g. code-D) allowing it to twist to windward and generate more power at deeper angles.

Since we have a Code-D, we’re looking for our spinnaker to fill in the 140 to 180 degree angle range, and that is the domain of the symmetric spinnaker. Symmetrics are made to run deep, and gybing is essentially automatic, because they just float around the front of the boat onto the new point of sail, with a few tweaks on the control lines. No need to douse and rehoist.

We decided to get a symmetric spinnaker for Wildling, so the next step was to figure out the size, cut and type of sailcloth for the sail. For our tradewind ocean sailing we want to be able to handle situations where the wind builds more quickly than we expected, and we don’t want the spinnaker to tear if it gets hit by a 25 knot gust. We also don’t want it so big that we can’t get it down in a breeze.

There are many excellent sailmakers that can make a great spinnaker. We chose Doyle sails, mainly because I’ve used their sails before and know they are well made, and Doyle was willing to listen and understand our needs and design a specific sail that will work for our boat and our cruising plans. They are making us a symmetric spinnaker with a fairly wide and deep cut in the top section of the sail which will allow it to lift and fly out in front of our mainsail. We sized the spinnaker to be 30% smaller than our sail plan specifies with a heavier 1.5oz fabric that will handle 25+ knots of breeze. This should give us a strong sail that will hold it’s shape well and be fairly easy to control and douse with a spinnaker sock.


Deep running with a symmetric spinnaker

It’s also worth mentioning that there is another symmetric sail that is becoming more common, and that’s the Parasailor. It’s essentially a symmetric spinnaker with a parafoil wing in the center. The wing provides some lift and also can spill the power from gusts. It’s a great idea, but we decided against this sail for two reasons: It’s more difficult to get the sock down over the parafoil wing in stronger winds; and we know of another 5X that tried the sail and found it didn’t work very well. The 5X has a lot of acceleration and it tended to collapse the sail too much when they sped up on waves (although it seems that could be solved by experimenting with the size of the sail).

Parasailor spinnaker

Parasailor spinnaker

We don’t have the all the deck fittings and control lines needed to fly a symmetric spinnaker on Wildling, so now that the sail is ordered, the next project is to prepare the boat to be able to use it.

Lessons from racing – how much is too much?

We raced Wildling in the Outremer Cup regatta last weekend, and while we were careful about our sails and rig loads and didn’t break anything, we did push the boat a bit, and there was one point when we decided we should furl the Code-D because it was getting overpowered, and right when we were furling, the gennaker on the boat next to us literally exploded in a wind gust, creating a vertical tear from head to tack!

It was a scary reminder of the need to pay careful attention to rig loads on a catamaran, and it got me thinking, how much is too much, and how do you know when you’re pushing too hard?

When I learned to sail on monohulls, we were taught the two golden rules for managing an overpowered boat.

Rule #1: When the boat heels too much, depower. Usually first by letting the traveller down and then by reefing. Since Rule #1 varies based on experience and sea state, i.e. 20 degrees of heel feels OK to me, but is too much for Robin, we have golden Rule #2.

Rule #2: It’s time to take a reef when you first think about it. Or in our case, it’s time to take a reef when Robin tells me to stop leaning us over so far, damnit! Gusty conditions on a monohull are not a big deal either, just reef to give a comfortable heel most of the time, and let the boat heel further every now and then to spill the power from the gusts.

So how do we apply these two golden rules to a catamaran? It turns out, not very easily. It becomes less of a feel thing, (at least until you get to know your boat) and more of a numbers game. Catamarans don’t heel, so they can’t spill the power of the wind, all the power has to be absorbed by the rig. In gusty conditions, this becomes dangerous, as rig loads can become unsafe very quickly, so the golden rule for catamaran reefing is to reef for the gusts. But since the gusts are occasional, how do we know when and how much to reef, and what happens if we carry too much sail? We’re not going to capsize in 25 knots of wind, so no big deal right? Since stories of rig failure, broken masts and exploding blocks seem more common on catamarans than monohulls, I think it might be a bigger deal than I realized.

Our catamaran came with a reefing plan from Outremer. The plan tells us at what wind speeds we need to reef, or change headsails to avoid overloading the rig or capsizing. Here’s the reefing plan for Wildling:

Reefing Plan Outremer 5X

Reefing Plan – Outremer 5X

We were above this plan at times during the Outremer Cup, and nothing broke, we even flew our Code-D in 20 knots, so we have proven that Wildling can handle more load than this plan dictates, so is the plan just a conservative suggestion from the manufacturer, designed to make sure no boat ever gets damaged, or is it a prime directive to be broken only at great risk? After our racing experience, the answer wasn’t as clear to me, so I did some calculations to try and find out.

Before I go into the calculations, I want to give a plug to the Attainable Adventure Cruising website. John, the author, has published a large amount of excellent information on offshore cruising and I have learned a lot from him. I was reading his article on rigging a “proper” jibe preventer (because after our autopilot went crazy last year and jibed us without warning, I need to rig a system to protect the boom when it happens again). In the article he talks about mainsheet loading at different wind velocities and how to calculate the forces the preventer needs to be able to withstand. I started calculating the loads on our mainsheet using the Harken formula in John’s article, and the results were pretty interesting, so I ended up building a spreadsheet to determine Widling’s mainsheet loads at different wind velocities and different reefing points.

Here are my calculation results:

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Mainsheet load in kilograms

What’s impressive to see in these results is how much the rig load increases from a gust. For example, with a full main at 20 knots, a gust of just 10 knots higher, more than doubles the rig load! My calculations are probably not that accurate, so the actual numbers are not very useful, but what is interesting is to see the relative changes in load as wind increases, and as we add or remove reefs.

I wondered how much load we were putting on our boat when we exceeded the reefing plan. The hardest we have ever pushed Wildling was during our delivery test sail, when we had full main and jib in 30 knots on a beam reach in flat water. Our boat speed was 19.7 knots! Sailing at these conditions gives a calculated load of about 3,750kg, which is about 10% higher than the maximum load in the reefing plan at 3 reefs and 50 knots. So I’m going to use this as the maximum safe limit for our boat.

If we plot the loads on a chart, and define a safe zone below the Outremer reefing plan, and a danger zone above our maximum load, and then put a racing zone in between, it looks like this:

wildling_rig load chart

This chart helps to put everything into context. The Outremer reefing plan might look conservative in steady conditions, but it becomes much more realistic when you take into account the loads from gusts. For example, with no reefs at 25 knots steady, we’re under the danger zone, but we now have only a 5 knot gust margin. That might be OK in a race when you’re watching things very carefully, but for cruising, it’s just not enough. Taking Outremer’s advice and reefing at 20 knots, gives us the margin we need to handle changing conditions.

So what?

So what are the conclusions from all this? For me there are two important conclusions:

  1. BEWARE OF GUSTS! – The rig loads they generate are extreme and they happen very quickly. Reef early when sailing in gusty or building conditions. Reef deeper if sailing around squalls.
  2. Follow the plan! – This exercise has given me greater respect for the Outremer 5X reefing plan. It is well designed and has a good balance between performance and realistic gust tolerance

We know from experience that we have a strong boat that can go beyond the reefing plan, and that’s great because it gives us a safety margin, but it’s important not to confuse occasional race conditions with long distance offshore cruising conditions, and the need to sail conservatively. The nice thing about a performance cruising catamaran, is that you don’t have to push it in order to sail fast and be safe.

Back to the future

If you’ve been following this blog, you are no doubt getting the picture that I’m passionate about combining the feelings of sailing fast in a boat that responds well, with the comfort and safety of exploring remote anchorages and long distance cruising. As I’ve come to find out, this is not at all easy to achieve, and finding a boat that can serve both purposes is in fact a tall order.

I’ve met a lot of sailors, racers and cruisers over the years, and we all seem to fall in different places on the < speed – sensation – safety – comfort > spectrum.

There are those that are perfectly happy tooling around in a catamaran loaded up with all the comforts of home. For them, the need to sail fast, or even spend a lot of time worrying about sail trim, is not that important. They realize that cruising boats spend 95% of their time at anchor, so worrying too much about features that optimize the other 5%, doesn’t make much sense.

Built for comfort

Built for comfort

There are the racing folks that focus on performance, with cruising a secondary consideration. They are looking for light weight, lots of sail area and narrow hulls. This leads to a great sailing boat, that is cramped to live in and has to be watched closely so the high powered rig doesn’t break or flip the boat over.

Built for speed

Built for speed

There are others that consider cruising catamarans as a charter holiday contrivance, that at best, don’t sail very well, and at worst, don’t behave anything like a real sailboat should! These folks are committed to the traditional sailing sensations and classic beauty of a cruising monohull. They find the claims made by catamaran owners that they can sail all day without spilling wine from a glass left on the salon table, to be irrelevant, especially if that comes at the expense of needing to start the engines in order to push the bows through a tack!


Classic beauty!

Over the years, the range of boat models available on the commercial market have organized themselves more or less into one of these three camps, with the vast majority of catamarans falling into the 95% at anchor / charter market segment. For a long time, I just accepted this segmentation of boats and boaters as being a logical manifestation of the physical realities of boat design and function. It made sense, and most of the people out sailing, myself included, seemed to be happy with the available options, and willing to live with the associated compromises. That’s life right?

But what if we could enjoy the sensations of really sailing, and even sailing fast, in a boat that is also comfortable and safe to live in? During our voyage from Australia to Singapore, I was introduced to a boat that I have come to view as the game changer, that for the first time was able to successfully marry the two seemingly incompatible aspects of boat design (performance and comfort). That boat is the Aikane 56, and it has been fascinating to learn how much an influence this boat, that was designed and built in the early 2000s, has had on the latest generation of performance cruising catamarans.

Aikane 56 - ahead of it's time!

Aikane 56 – November 2000, and well ahead of it’s time!

The Aikane 56, is a beautiful boat. She is light and fast, yet very comfortable, with plenty of room for full time cruising. She can sail faster than the true wind speed and is perfect for entertaining at anchor. We spent 3 months buddy boating (cruising together) with Eric and Tamara aboard their Aikane 56, Sea Child and I came to firmly appreciate what an exceptional boat she is.

When it came time to sell our Catana 471, and look toward our next boat, I was sure I wanted an Aikane 56, but the problem is there were only 3 of them ever made back in the early 2000s, and finding a used one that was fitted out the way we wanted was pretty much impossible, so we continued the search for a boat that was similar to the Aikane.

The interesting intersection of fate here, is that while Xavier Desmarest, the now owner and President of Outremer Yachting was pursuing his long time career as a monohull builder, he was introduced to the Aikane 56 by a colleague and friend, and for the first time he realized the possibility of building catamarans that could be comfortable, safe and also sail really well!


Xavier Desmarest – President of Outremer Yachting and “catamaran renaissance man”

Like many in the classic boat-building industry, Xavier was witnessing the increasing trend towards catamarans, but was also lamenting the fact that the current crop of catamarans were not the kind of boats he wanted to sail, much less build and sell. When he found the Aikane, he began to develop a vision for a catamaran of the future. His move over to run Outremer began with the concept of updating the existing range of boats that were well proven, safe, and high performance, but tended to be a bit cramped and sparse in terms of comfort, and bring them closer to the configuration of the Aikane 56.

Since purchasing the molds for the Aikane proved to be too complicated, he did the next best thing, and went to VPLP, the architects that designed the Aikane to see if they would be willing to design him a new boat, that would fulfill his vision. Marc Van Peteghem agreed and the result is the Outremer 5X!

Take a look at these two pictures, the Aikane 56 above, and the Outremer 5X below. See if you can spot the signature VPLP lines of the two boats.

Aikane 56 from the mast top

Aikane 56 from the mast top


5X from the mast top

Xavier had a lot of doubters when he started down this path. Because there are no other series production builders making catamarans like the 5X, the trade media all wondered if it would be a success. Were there enough sailors that wanted to buy a catamaran that deviated so markedly from the industry standard? After releasing the 5X, the boat has won the European boat of the year and US Boat of the year awards and they have had a steady stream of orders. He is also using the design concepts from the 5X to renew the other models in the Outremer line, the Outremer 51 and the new Outremer 45.

I love it when people with a vision have the courage and fortitude to go against the trends and show us new possibilities, and sometimes even, remind us of possibilities we had forgotten. It seems that with the new model lineup from Outremer and Xavier’s guidance, it’s a case of “if you build, it they will come!”