Keeled Over

Beautiful bottoms – boat bottoms that is. While shopping again for a new Fayaway I’ve been snapping a few pics to help explain what we’re looking for in a boat, with specific emphasis on where the sun doesn’t shine. And so here’s my simplistic take for describing how common sailboats look and perform under the water. Firstly, some explanations in layman’s terms. True, I’m a engineer, but certainly not in a nautical sense. So please relax as I try to keep things simple, only in the context of what’s under water.

Fayaway rests on a day-only park mooring at a quiet bay on the north side of Anguilla, while we snorkeled around the coral.

To me, a keel has two purposes:

1. Lateral force opposition. It is a go-between of forces of wind (sails) and water by pressing sideways (parallel) to the water’s surface. Imagine pinching a small pumpkin seed between your slippery thumb and index finger. What happens if you squeeze enough (think: wind and water)? Perhaps also while annoying your wife, the seed will shoot out (propels forward). Also note that the vertical axis of a keel’s central forces is typically centered with the mast centerline. Intuition tells me a good keel should also allow the boat to rotate and turn on this axis. Foremost, an efficient keel should have minimal drag when moving forward, so to slice neatly through the water (less wetted surface means less drag) but still provide enough lateral resistance.

Sailboat forces explained on Wikipedia .
Many forces acting on a sailboat: Thanks to the author of this Wikipedia page from which this diagram was borrowed. Click the pic to decipher its thorough explanation of sailboat forces.

2. Ballast is simply there to add weight low to offset the howling wind and keep the mast pointing toward the sky. More ballast, especially below the water helps with stability, and comfort in rougher seas. Hence the following view:

Adding this up, perhaps a really strong, but thin (less wetted area), deeper (ballast heavy and low) keel would give a good compromise? What is a good compromise between maneuverability, stability and speed? What else is important?

As mentioned earlier, less wetted surface (area below water) means less drag. So it makes sense that flatter hulls sitting higher above water would be faster. Also for another reason, a longer waterline lets us also go faster. Therefore a more shallow but long waterline would be really good right? Well, yes, but if you intend to head offshore and… enjoy a bit more comfort, then there’s more to it. Maybe that sexy Beneteau is good for speed and serving boat drinks to friends, but not so good for comfort. Think of that go-fast boat hitting some big offshore waves. Since most of the boat forward of the keel is very shallow, it will tend to rise and bounce over waves, and pounding back down with enormous forces, shaking the rig. Your seasick occupants will groan every time the thin-hulled bow passes over a trough and into the next wave.

Definition of fast and nimble: J/80 Squibnocket has an ultra-low drag, flat hull, deep fin keel. She turns on a dime, but will rattle your teeth like riding on a jet ski when going to windward in heavy seas.

Somewhere is a balance between speed and comfort. That’s where the tapered forefoot comes in. I’m referring to a gradual drop from the bow back to the keel.

Notice the nice taper between the bow and the leading edge of the keel. Not sure, but I think this is a Passport 40.

How about rudders – in essence an extension of the keel that bends. As the boat glides along through the water, hopefully being propelled by the wind, and as crudely described by my pumpkin seed metaphor, it wants to go straight. That would be ok, except when we really want to avoid a big rock up ahead.

Yours truly, steering away from rocks as we depart St Maarten.

A rudder deflects water to one side or the other, pushing the stern of the boat in the opposite direction. Imagine a small sailboat, with a pencil-sized mast. From above you could twist that mast between your thumb and finger to roll the pencil as though to spin the little boat on it’s vertical (a la pencil) axis, essentially turning away from those rocks up ahead. We can adjust sails, creating a wind imbalance (like twisting the pencil), or change something in the water, or both. A rudder deflects water sideways, pushing the stern to starboard or port, which combined with forward motion, turns us toward safer water. But a full keel (directly connected to the rudder) can inhibit turning nimbly.

Cabo Rico 45 with heavy deep full keel. Imagine trying to turn this thing around in a tight u-shaped dock space? But she rides nicely in a rough sea!

So what rudder qualities do I think are important? Perhaps I’ve read too many books, and heard too many first-hand stories about disabled boats due to a broken rudder. Therefore I give them huge importance. I want one that is fully supported at top and bottom by something called a skeg. It must be able to withstand a large floating log or breaking wave, and yet be positioned far aft away from the keel so to also provide ease of maneuvering and good steering balance.

A beautiful Cheoy Lee – has a deeper full keel with steep forward hull. Plows through waves and has a solid rudder, but maybe too far forward which also changes steering characteristics.

So let’s add things up again. Take for example, a nice solid Island Packet or Cabo Rico. They both have a tapered hull forward to deflect waves, lots of ballast to hold them down, a full keel to slither straight ahead, and a heavy, solidly built rudder to provide ultimate security. Pretty good huh? However, all that safety and security comes at a cost of speed and maneuverability. Recall that a full keel means larger wetted area which means drag, which means slow. A longer full keel also acts like a huge straight rudder, making it difficult to turn. Ugh. What more can we do?

Properly masked, Kelly says these skeg-hung rudders are ok!

Somewhere there needs to be a balance between speed, comfort and safety. What’s yours? Our compromise is a boat with a heavy deeper fin keel, and a really strong skeg-hung rudder. I give you the lovely Fayaway:

Fayaway’s beautiful bottom. All the goodness of a narrow fin keel and giant skeg-hung rudder well-aft allows stability, comfort, speed and nimble turning.
Outbound 44: Another nearly ideal design, for more reasons than the bottom – too bad this one was sold before we were ready, and most others are beyond our budget.

We need to find a larger Fayaway. Examples of this (and there are plenty) are Brewer 44, Caliber 40, Oyster 43, or Valiant 42, or Hylas 44. Now if we could only find the rare affordable one for sale, while also in good condition. Of course, there are many variations even among these specific models. Know of any we’d like?

Valiant contains most of the desirable features.

To summarize our criteria for where the sun doesn’t shine:

  • 40-45 feet long
  • Tapered forefoot
  • Fin or modified fin keel; heavy shoal/bulb ok too
  • Draft not more than 6 feet.
  • Skeg-hung, heavy rudder well-aft
  • Durably built
Another good compromise: Pacific Seacraft has a mild cutaway between keel and very strong skeg/rudder. This hull is called a “modified” keel design.

At the point of this writing we’ve visited many such boats to meet our criteria. However, for some other reason they wouldn’t be ours. And COVID-19 makes this task more daunting. I’ll touch on some details for a few of those visits in an upcoming post.

3 thoughts on “Keeled Over

  1. Don’t forget to consider the draft. In the Bahamas in particular, having a shallow draft is a must. A partial keel with a centerboard is a nice combination. On my Tartan 37, I sail with the board up except when close-hauled. For those times when I fall off the wind, but forget to pull up the centerboard, I’ve found the speed difference slightly more than negligible. Despite the lack of a deep fin keel, she seems to be faster than most of her similarly-sized peers. Maybe a Tartan 40 would suit you?

    Liked by 1 person

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