Keel Types and What They Say about Sailors

"Let's talk about keels.  That is always a sure way to get someone's knickers in a twist." 
- Bob Perry, Sailboat Designer

A discussion about keel types is always fun among a group of cruising sailors, particularly in a cockpit while sharing sundowners.  Everyone has a preference and most keel types have a unique forte. I'm not going to dig too deep into design and technical aspects of keels since Bob Perry already covered that thoroughly in the guest post he did for me awhile back (Keel Design According to Perry).  What I am going to do here is briefly talk about each of the keel types I'm aware of for cruising sailboats and hit on some pluses and minuses as well as provide an example or two of specific boats for each keel type.

But first, what does your keel say about you?

The full keel calmly and confidently says "I like the journey more than the destination and am in no hurry to get there".

"I feel the need for speed!" remarked the 10-foot fin keel with bravado.

"I can adapt to just about any situation and scenario." said the lifting keel in a sophisticated tone.

The elusive twin keel comments that "I'm perfectly content to wait out this low tide right her on the mud flat".

Full keel (and modified full keels): There was a day when full keels were the bread and butter of a good bluewater cruiser.  A full keel can provide good tracking and decent downwind performance for milk run cruising.  They also provide protection for the propeller and rudder and may be less prone to a catastrophic event like an open ocean keel separation due to a collision with an object floating just beneath the surface (think an errant shipping container).  I'm also a fan of encapsulated ballast, which is more common a full keel boats.  However, these designs tend to be found on heavy boats which can exhibit a hobby-horsing motion in certain seas.  While some salty cruisers will argue about the speed of a full keel boat until they are blue in the face, most would argue that many of today's other keel options will out perform a full keel on just about every point of sail. 

Pros: Good downwind performance and tracking. Rudder and prop protection.
Cons: Tend to be slower and have a lot of wetted area/drag. Often don't point well. Difficult to back-up under power.
Examples: Westsail 32, Baba 30

I'm not sure the make of this full keeler, but I spotted it
a few years back in Sturgeon Bay on Lake Michigan.

Fin Keel (and variants like bulb keels and wing keels): Fin keels are far and away the most common keel type on today's modern cruising sailboats.  I suspect this is because they generally offer good sailing performance and can be had in enough variations to fit many needs.  Maybe there's also a cost and/or production factor in there too?  In any case, fin keels tend to have good sailing performance to windward and can even make for a sporty ride, hence many racing boats use a type of fin keel (often a modified bulb or T-bulb).  Some fin keels are deep and narrow and offer very little drag.  Of course the trade off here is draft.  Deeper fin keels can offer greater performance, stability and in some cases better tracking, but you'll need to mind your depth finder and charts and may be very limited in shallow cruising grounds like the Bahamas.  Shoal draft fin keels and wing keels are compromises that attempts to offer some of the standard fin keel performance while reducing draft.

Checked your keel bolts lately?

There are also a variety of fin keel variants such as bulb keels, T-keels, and wing keels.  Bulbs put ballast low at the bottom of the keel for better balance and righting.  Wing keels are often seen in shoal draft versions of deeper draft fin keel boats.  The wing-shape keel allows for a shallow draft and more ballast in the keel while also sometimes providing additional lift from the keel wings.  While I know catastrophic keel bolt failures are rare, keel bolt maintenance and inspections are something important to keep current.  There are also a few fin keel designs that have encapsulated ballast and thus no keel bolts - the S2 11.0 comes time mind, but these designs are the exception.

Pros: The most effective keel for driving a boat to weather with minimal drag off the wind. Wide variety of types for many needs.
Cons: Vulnerable to groundings. Rudder/prop is unprotected. Some deep draft versions limit sailing locations. Keel bolts require inspection/maintenance.
Examples: Hylas 44, Pacific Seacraft 37

Lifting Keel: I've always found lifting keels on cruising boats interesting, probably because they're basically like a large mechanically operated centerboard that many people used when learning to sail on dinghies such as a Sunfish.  The advantages of a lifting keel are many, not the least of which is being able to greatly reduce both draft and drag by retracting the keel up into the hull.  Reducing draft has the obvious benefit of increased access to shallow gunkholes and harbors, but less obvious is the benefit of raising the keel when sailing downwind to reduce drag and increase speed.  I have some personal experience with both benefits having owned (My first boat!) a Helms 25 swing keel.  I could literally feel the boat accelerate downwind when I cranked the keel up.  Additionally, the boat's balance and center of resistance can be adjusted through the movement of keel.

The Southerly 49 draws less than 3 feet with the keel up and can sit down on a beach.
With the keel down, she draws more than most 4 footers (10 feet!) and sails very well.
Photos is courtesy of Paul and Sheryl Shard at Distant Shores.

One really cool aspect allowed by some lifting keel designs is the ability to beach the boat or let it dry out during a low tide with the keel retracted.  If you aren't familiar with this, check out the video Distant Shores did recently about beaching their Southerly 480 overnight in the Bahamas.  So what's the downside of a lifting keel?  The first thing that comes to mind for me is the added mechanical gear needed to raise the keel, such as a manual winch or a hydraulic pump.  Both of those require maintenance and could fail at in inopportune time...like the middle of the Pacific.  Another downside that I see, and this may just be me overthinking things, is the relatively large hole/s in the bottom of the hull need for the lifting gear and/or pivot bolt.  The less holes in the hull the better I feel.

Pros: Ability to adjust drag, draft, balance, etc.  Ability to beach the boat.
Cons: Additional mechanical gear to maintain.
Examples: Alubat Ovni 455, Southerly 42RST

Bilge/Twin Keel: This is the keel type I know the least about and have zero experience with, so bear with me.  According to YachtingMonthly, "There have been many design variations that come broadly under the term bilge keels. Strictly speaking, bilge keels are in addition to a long central keel, fitted near the bilge, where the hull turns from the bottom to the side of the boat.  Traditionally, these were non-structural, shallow and long, largely intended to reduce rolling. Twin keels, in contrast, replace the central keel entirely and the boat is structurally adapted to make these the main ballast-bearing hull appendages."

The Sirius 35DS sitting pretty at low tide.

While twin keel designs have never really been popular here in the U.S., French and British sailors and builders still find them appealing.  The main appeal is clearly the ability to let the boat stand on it's keels and dry out in areas with a large tidal range.  This can be advantageous for underside inspections and working on props, anodes, bottom paint, cleaning the hull, etc.  However, my common sense tells me twin keelers trade speed and windward ability for this privilege.  Research says this might not always be the case.  In November 2015 Sailing Magazine tested the Sirius 40 DS in the fixed keel version (5.6') and the twin keel version (4.75'). The verdict? “Despite the extra weight and only 1.45m draft, we could not find any difference in the sailing performance and the height in the wind compared to the well-sailing fixed keel version”.

Another consideration for would-be twin keel sailors is the rudder configuration.  Some twin keel sailboats have a single rudder on centerline that is left exposed to potentially hazardous flotsam and jetsam.  Others have twin rudders inline with the keels that would seem to be a bit more protected.

Pros: Can dry out during low tide for easy maintenance and inspections.  Generally have a shallow draft that's good for gunkholing.
Cons: May exhibit rolling motion.  Slower and with less windward sailing ability than other designs.
Examples: Sirius 32DS, Westerly Centaur

So what does it all mean?  It means we as cruising sailors have a ton of considerations when thinking about our ideal keel.  Are gunkholing and easy, affordable maintenance a priority for you?  Perhaps consider a twin keel.  Do you want the best performance possible and the most miles-per-day on passage?  Better look for a modern deep fin keel.  Favor a thick, heavy hull with no worries about keel bolts or how quickly you move from place to place?  A full keel double-ender might be your ticket.  No matter your choice, someone in the yard is likely to strike up a conversation about your keel during haulout.

Have a keel preference or experience you'd like to share?  Write it in the comments below or share it with me via email.

>>  For more sailboat design writing and thoughts, visit my Sailboat Reviews page.  <<

1 comment:

  1. 57 Degrees NorthMay 16, 2020 at 2:41 PM

    I tend to think that keel type is only one variable, the others being hull form and rig. Bob Perry says don't try and defend the full keel on its performance merits... Fair enough, but how do you define performance?

    I wonder if a lot of the grumbling about fin keels hasn't more to do with the fact that so many modern designs are inherently compromised in the quest for speed and luxury accommodations. Sadly, a lot of modern design is a reflection of society at large, where people simply don't have any time...

    As you alluded to, it depends on what your priorities are. Does "sailing" mean racing around the cans with evening cocktails and wife swapping in the marina, or bluewater passage-making?

    I will say that when you're 200 miles out in the Gulf of Alaska, and it's sketchy enough that the kids are scared silent, and the wife is giving you "that look", the ability to point a couple degrees higher and wring another knot out of a reach suddenly takes a backseat.

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