Most of you who have followed our journey for some time are familiar with our somewhat infamous centerboard issue, where we ran aground in the Illinois river in 8′ of water when our boat should only draw 4′. This was the most dramatic and expensive example of the issues we’ve had with the centerboard thus far, but that’s not to say it’s been the only trouble our centerboard has caused us.
In this week’s video, This Little Thing could SINK our Boat, we’re highlighting another pain point and some of the additional maintenance that comes along with having a pivoting centerboard. We’d like to take this opportunity to talk a little bit about the pros and cons of the centerboard system and shed some light on how we’ve been using it with real life examples.
Sailors love to talk shop. It seems everyone has an opinion when it comes to boats, and if you’re not too careful, it can lead lead to hours upon hours of enjoyable and sometimes educational discussion. Invariably anytime we get beyond the general pleasantries of “She’s a beaut!” or “What’s the length?” we know with more and more certainty that we’re talking with a sailor. As the questions get more specific e.g. “How much fuel do you carry?” or “How tall is the mast?” we will eventually hit this question: “What’s the draft?”
Up until this point, it’s only a Q&A session, but as soon as we divulge the boat has a centerboard — and that with the board up we draw between 4-4.5′ but when it’s down closer to 8′ — the discussion will turn one of three ways:
- The questioner wasn’t quite prepared for that answer and is dumbstruck because they didn’t know as much about boats as they thought they did, and were unaware of the centerboard concept or are unaware a boat of our size could have a centerboard.
- The questioner’s face lights up with a twinkle in their eye and responds with something like: “A perfect Bahamas boat, nice!”
- The questioner’s face scrunches up with terror in their eyes: “Why on god’s green earth would you want to maintain a system like that!”
And after three years of owning, maintaining and traveling aboard a boat with a centerboard, we’ve been in each of these 3 camps at one point or another. Let’s dive in and tackle each point of view.
What is a centerboard on a sailboat?
A centerboard is a retractable appendage that pivots in and out of a slot (centerboard trunk) in the hull/keel of a sailboat. Having the ability to raise and lower the centerboard allows the the boat to operate in shallow waters when lifted, while maintaining good upwind sailing characteristics with the centerboard down. Similarly, lifting the centerboard reduces the wetted surface area, resulting in lower drag while sailing downwind. This combination of characteristics makes it possible to build a safe, seaworthy boat, capable of easily sailing upwind off a lee shore, while still allowing the boat to tuck way up into shallow anchorages when necessary.
When first looking for our sailboat, weren’t specifically looking for a boat with a centerboard. It wasn’t on any “avoid ” list of ours either; it just wasn’t on our radar. So when we first saw the boat online and noticed it had a centerboard, we were pretty ambivalent about it.
Is that like a Swing Keel?
Many people have incorrectly referred to our boat as having a swing keel, and for good reason as they are quite similar on the surface. Before finding our boat, we were aware of other boats with swing keels (specifically Southerly Yachts popularized by “Distant Shores“) and some of their unique benefits. While the swing keel is similar on the surface, it’s an entirely different animal from our centerboard. They both feature large underwater wing-shaped appendages that pivot from underneath the boat to provide additional wetted surface area to reduce leeway and increase lift for sailing upwind. The main difference is that in a swing keel boat the pivoting appendage is actually the keel. In cruising boats, swing keels weigh several thousand pounds, while centerboards weigh a couple hundred. Thus, a swing keel also contains a large part of the boat’s ballast, so the position of the keel can have a substantial effect on the stability and motion of the boat. Additionally, when retracted all the way up into the hull, the boat can be left to dry out while sitting upright in the sand — pretty cool.
Distant Shores II, a Southerly 480
The flip side is this: In the fully retracted position, the keel needs somewhere to go — which takes up interior volume of the boat. Additionally, moving an extremely large and heavily ballasted keel up and down requires some serious mechanical gear, and unless the swing keel is lowered to some extent, there is nothing counteracting the force of the sails to prevent leeway and the boat will not sail to windward.
Whereas with our boat, in addition to the centerboard, we have a shoal draft keel (which actually doubles as a housing for the centerboard). Even without the centerboard down the boat will still sail to windward. Dropping the centerboard only serves to increase the pointing ability and windward performance. The centerboard does not contribute meaningfully to the ballast of the boat (as it weighs about 200lbs), so its effects on stability in the up or down position are muted. It is designed primarily as a hydrofoil to prevent leeway when sailing upwind and is significantly lighter than its swing keel cousin. Lastly, by retracting into the keel instead of all the way into the hull it does not have any negative effect on the interior volume of the boat.
What are the benefits of having a centerboard on a sailboat?
Besides increased upwind sailing performance, the major benefit of a boat with a centerboard is a shallow draft. For our needs navigating the inland river system, sailing the notoriously shallow Gulf of Mexico, and cruising Bahamaian waters, these are fantastic qualities to have in a boat.
The inland river system has a controlled depth of no less than 9′ in the channel from Chicago to Mobile, Alabama, but most of the channel is significantly deeper than that. However, searching for marinas and anchorages for the night where you have to exit the channel means the depths start changing quickly. With our shoal draft keel we were able to sneak into a number of marinas with sub 5′ depth at their entrance or at the dock that would’ve been impossible in many other sailboats of our size. Even in Mobile we ran aground twice while moving through the marina to get to our dock.
In the Bahamas we find ourselves anchoring way up towards shore with the catamarans instead of much further out near the monohulls. Yet when it comes time to sail to windward, we’re able to drop the board and point much higher than we otherwise would’ve been able to with the shoal draft keel alone. This can shave miles off long passages and minimizes the number of tacks required in a tight channel.
Additionally, dropping the centerboard just a little bit can give us much better handling in tight quarters, as it prevents the bow from falling off downwind when trying to dock in strong crosswinds.
This all sounds pretty good, right? Why would you not want a boat with a centerboard?
What are the issues with centerboards?
With all the apparent benefits, you’d think the centerboard would be a no-brainer. And if you’re purely concerned with performance, then absolutely, it is. However, the centerboard represents an added layer of complexity that just isn’t absolutely necessary for the operation of the boat. Along with this added complexity comes additional maintenance to ensure the system continues operating normally, and even then, when everything is operating correctly, the maintenance itself can create some stressful situations. Below are a few of the negatives of having a centerboard we’ve discovered so far:
Our centerboard is raised and lowered via a control line, or centerboard pennant. The line is always underwater inside the centerboard trunk, and is incredibly difficult to inspect. The line exits the boat below the waterline meaning we have an unprotected thru-hull without a seacock to close, should there be a leak. The through-hull is connected to a hose and the hose connects to a conduit in the mast that rises well above the waterline.
The centerboard line runs through this conduit and then exits the mast through a sheave at the deck level. It then runs through a turning block and clutch/winch to lock it off. Each of these items require some level of maintenance and/or at least inspection on a regular basis. These are all fairly simple parts, and the system is quite well-designed. However you can probably already imagine some of the issues…
Stepping & unstepping the mast is more difficult
Because the line runs through the mast, stepping and unstepping the mast requires a few more steps to ensure everything goes smoothly. When unstepping our mast, we need to temporarily slacken the centerboard pennant to allow the mast to be raised out of the boat. To ensure we can run the line back through the mast we need to run a messenger line in the mast to be able to retrieve it again when re-stepping.
When re-stepping the mast, extra care needs to be taken to ensure the mast doesn’t get hung up on the centerboard pennant or the conduit it runs through. We’ve heard of other boats stepping their mast only to realize later that they pinched their centerboard control line.
Naturally (or accidentally) slackening the centerboard pennant allows the centerboard to drop, increasing our draft to 8′, unless it’s secured in some other way. We did this at the start of our river trip by securing a line athwartship from each of the midship cleats to act as a set of suspenders to keep the centerboard pinned up inside the trunk. Unfortunately this wasn’t tight enough and slipped off the centerboard allowing it to drop into the fully-down position. This set us back a few days as we fabricated a much stronger system to secure the centerboard line using an exit sheave at the mast partners.
The centerboard trunk is difficult to clean & paint
While our boat was hauled out, we repainted the bottom with CopperCoat. However we were unable to paint the centerboard or the trunk with the same. Had we known better, we would’ve pulled the centerboard immediately after hoisting the boat out of the water with the travel lift. But since it was our first time hauling the boat for storage, we didn’t realize that once we were moved to the hydraulic trailer which the yard used to position boats, we would not be able to get enough height to drop the board and remove it.
We did hang in the slings over the weekend prior to splashing, which gave us time to get underneath the boat with the board down to clean the centerboard trunk and repaint the board and trunk with ablative bottom paint. But we couldn’t repaint with CopperCoat because of how long it needs to dry before being splashed.
The centerboard pivot point is difficult to inspect
The centerboard pivots on a large stainless steel hinge. This plate is bolted into the keel of the boat and has a large pin that runs through the centerboard allowing it to pivot around this point. There is also a heavy duty stainless eye on the backside of the centerboard that the pennant line connects to. Both of which are always submerged in water, and while they are stainless, stainless corrodes in environments lacking oxygen. So these parts need to be inspected on a regular basis, and this means removal of the entire board, which is easier said than done.
The centerboard can get stuck in the up or down position
The centerboard is designed to pivot up and down in the trunk with fairly small tolerances on either side. Any more space than what is needed to get the board out, and it will interfere with the flow of water over the hull, increasing water resistance and drag. Any extra space will also allow sea life to make its way up into the trunk. Thankfully it’s very dark up in there, there isn’t much water flow carrying nutrients into that space, and we have been diligent about keeping it clean. While we haven’t run into this particular issue yet, we’ve heard of some boats that have had so much growth in the trunk that they can’t get the board to move.
While, we haven’t had our board stuck in the up position, but we have had the board stuck down. The centerboard is a hydrofoil, so the leading edge is a bit wider than the trailing edge, much like an airplane wing. And whereas dagger board trunks (where the board drops in vertically) can be contoured to follow the shape of the board almost exactly, our centerboard trunk is rectangular, as it needs to accomodate the width of the leading edge moving all the way through it. This means the trailing edge of the board (which is on the top when in the retracted position) leaves a lot of extra space between it and the trunk, creating a wedge shape… Maybe you can see where I’m going with this…
A perfect storm scenario can brew under just the right conditions. Imagine for a moment you are loosening the centerboard pennant line to drop the board down, but for one reason or another, the sideways pressure of the water against the board when sailing upwind, growth in the centerboard trunk, stops or slows the dropping motion of board — perhaps it even gets pushed back up slightly as the boat pitches forward and backward in a large wave. You, as the unsuspecting crewman, continue to slacken the line thinking the board is dropping, but in reality what is happening is the line comes to rest on the top of the board, and because of the wedge-shaped trailing edge, the line slips down ever so slightly between the board and the trunk, and gets trapped. Once there it wedges in between the board and the trunk making it extremely difficult to move.
This has happened to us twice. The first was an easy fix, which occurred during a daysail after purchasing the boat. We could’ve easily addressed it without getting into the water, but it was hot, the water was clear, and despite being warned about this particular scenario, I didn’t have a good visualization of what was happening and wanted to see it for myself.
There is actually a built-in mediator of this problem which saved us considerable effort: A short section of exhaust hose with a diameter that almost exactly matches the width of the centerboard trunk serves as a conduit for the last 18″ of line of the centerboard. This prevents the slacked line from getting wedged in too tightly and allowed us to break it free with a tiny bit of force.
The second time however, was much worse, and is covered in detail in Episode 24. We were in the Illinois Sanitary & Ship Canal, in incredibly disgusting water with no visibility, and because we hadn’t secured the centerboard line properly, the board unbeknownst to us dropped all the way down, and under zero tension actually hung forward of its pivot point. In this position, the geometry for pulling it back up is all out of whack. With the protective hose completely out of the trunk, pulling the control line, only wedging it further in between the trunk and the centerboard.
So is a centerboard actually worth it?
While we’ve been both super happy we have a centerboard and a shallow draft, we have also been exasperated by the extra maintenance, sometimes wishing we had a “normal keel.” But at this point we’ve circled back around to mostly ambivalent. The maintenance while sometimes stressful is all part of owning a boat and the benefit of having a shallow draft when needed are immeasurable.
In reality, we probably only use the centerboard 15-20% of the time we’re actually sailing. If you think about the benefits discussed above, it’s really only necessary in moderate upwind scenarios, which we often avoid anyway. It’s just way more comfortable sailing downwind! We’ve also found in light wind conditions the extra drag created by the centerboard outweighs the pointing ability it generates, so we leave the board up. To top it all off, when we’re not actually sailing (which is most of the time when the boat is at the dock, at anchor, or hauled out for storage) the centerboard is always in the retracted position. For the actual lifespan of the boat, the centerboard is in the down position much less than 10% of the time.
On more than one occasion I’ve thought that I’d rather have a keel full of lead where the centerboard trunk exists now. It would give us added stability 100% of the time, we’d have no additional maintenance, and we’d only miss out on the benefits 10% of the time. However that 10% of the time could potentially make all the difference if we really needed to get off a lee shore. Whenever we are using the board — i.e. upwind especially in a narrow channel or maneuvering under power in tight quarters — we’re often saying to each other “Thank goodness for the centerboard!”
In the end, as with everything on a boat, it’s a trade-off. There’ll always be pros and cons of every design decision. There isn’t one right design for every boat or every boat owner. Overall, we’re happy with our Tartan37c and would not pretend to know more than the S&S design team who dedicated their lives to designing these spectacular boats.
Let us know what you think!
Do you have any experience with a centerboard? Did we miss anything? We’d love your feedback.