The Care and Maintenance of Swing Keels

Article by Paul Esterle

Recently, a reader wrote to ask for advice on maintaining his swing keel, prompting this article. Before we start, let’s get something sorted out—the difference between a swing keel and a centerboard. Both swing up to allow for shoal draft and helping sail trim. Both swing down to provide more resistance to leeway. Both pivot on some sort of pin in the bottom of the boat.

A centerboard is usually a plate or a thin foil. It is ballasted enough to allow it to sink, especially in the case of a wooden centerboard. It doesn’t significantly provide much in the way of ballast. The centerboard case or trunk is usually a significant feature in the cabin.

A swing keel also pivots but it is significantly heavier than a centerboard, to the point it is a major contributor to the boat’s ballast. Even for a small boat, a 400-pound swing keel is not uncommon. On larger boats, say 24’ or so, keel weights can be in the region of 1,500 to 1,800 pounds. Most swing keels are housed in a stub keel so that the keel box doesn’t intrude into the cabin.

The important parts of a swing keel are the keel itself, the pivot pin, a hoisting cable and the hoisting winch.

Safety Note! - In almost all cases, the boat will have to be lifted to work on the swing keel. In some cases, fairly high. Provide adequate blocking and support for the boat. If you are not sure, have a professional in a boatyard do it for you. The only time I had Ternabout off her trailer, I had the boatyard lift her and place her on secure jack stands. A boat falling on your head could ruin your whole day!

Swing Keel Components

Hoisting Cable

Arguably the most critical item, and most prone to failure is the hoisting cable. In most cases, it is a braided stainless-steel cable. When the keel is lowered and the cable exposed it may “thrum” at speed. That sound is the cable vibrating in the water flow and may contribute to broken cable strands at the lower swages and may work-harden the cable itself. The keel end of the cable is most likely an eye formed around a metal thimble and secured by one or more swages. A shackle then attaches the cable to the swing keel. Inspect this shackle for wear and tightness. Less often is a fork swaged to the cable itself. Inspect the cable for wear, chafe or broken strands. I have to laugh at some maintenance tips that suggest you inspect for broken strands by running your hand over the cable. Those broken strands are called “meat hooks” for good reason. Run a rag over the cable and let the rag snag the strands. If the cable is the least bit suspect, replace it.

Keel Winch

The keel winch may look like a trailer winch but it has one important difference. It has a clutch to allow you to release the cable, thus lowering the keel, under your control. Make sure that clutch operates freely and properly. A loose or improperly adjusted clutch may let the keel drop violently, possible breaking the cable or even damaging the hull. Do not try to adjust the clutch. The hoisting cable should wind on the winch drum evenly. Avoid any unnecessary cable-over wraps, they can damage the cable and make lowering and raising difficult. Make sure the winch mounting bolts are tight and secure. Inspect the winch mount for cracks or damage and repair.

Turning Blocks and Cable Tube

The hoisting cable runs down from the winch through some sort of tube. The tube is open to the bottom of the boat and extends well above the water line, otherwise water would flood the boat. To control the geometry of the cable as it leaves the winch on top and the cable tube on the bottom, turning blocks are needed. Inspect these for free turning and lack of wear. Replace as necessary.

Pivot Pin

The swing keel turns on some sort of pivot pin. Inspect the pin where it passes through the swing keel for wear or looseness. Inspect the pivot pin mounting for wear and any indication of leaks or looseness.

Swing Keel

In most cases, the swing keel is an inert lump of cast iron. The things to check on the keel are the keel attachment to the hoisting cable and the pivot pin area. If it is severely rusted, sandblast and immediately coat with a primer or rust converter. Then apply an appropriate (for your area) bottom paint.

Routine Maintenance

1. Inspect winch and lubricate per the manufacturer’s suggestions. Ensure the clutch is working properly.

2. Inspect the cable as you raise and lower the keel. Check for broken cable strands and proper wrapping on the winch drum.

3. Check for leaks around the cable tube and pivot pin areas.

4. Make sure the keel raises and lowers smoothly without binding. Investigate if it doesn’t!

Problem Solving

If the keel is stuck up, it is usually due to one of two causes. The first is, if you grounded, the keel is jammed in its case with gravel and sand. You’ll have to dive under the boat and scrape it out or lift the boat off the trailer so you can free it.

The other cause is marine growth on the keel and in the keel housing. Again, you will have to scrape away the growth to free the board.

On some boats, you can actually let out too much cable. The keel may swing forward enough that the cable is simply pulling up on the board, not raising it. A worse-case scenario is a cable break or winch failure. In this case, the keel may swing down with enough force to crack the forward end of the keel housing. This may result in a leak or catastrophic failure leading to sinking.

Assuming the boat is still afloat, you will need to retract the keel. If the cable is still attached but over extended, you can carefully approach the shore and carefully bump the keel on the bottom until you can raise it. If the cable is broken or you don’t want to risk the shore approach, there is another method. Take a long dock line or a sheet and loop it over the bow. Bring the loop back along the bottom until you reach the keel. Slowly pull the ends of the loop up, raising the keel. Don’t go too far aft or you will risk the loop sliding off the back end of the keel, allowing it to slam down. Get the boat out of the water so you can fix the problem.

Finally

Swing keels are not to be feared. Regular maintenance and inspections will give you years of trouble-free operation and good sailing. •SCA•

First appeared in issue #116