By Stephen Jensen:

The swing keel on the San Juan 21 is one of the reasons these big little boats can do what they do. A performance fin keel that retracts fully into the hull allows easy launching and retrieving in shallow waters.

The keels are Fiberglass shells with either lead shot or lead bars inserted, then encapsulated with fiberglass resin. They are airfoil shaped, an innovation for swing keels in 1969 when they were designed, and weigh 400 to 420 lbs. The lifting mechanism is inside the keel trunk so there are no cables dragging in the water like other swing keel boats.

This is what the keel looks like outside of the hull.

You can see the “Horn” that the sheave is mounted to that pulls the head of the keel forward to swing it into the trunk.

Occasionally this horn can be ripped off. This was the Case on Charmed Juan. When I purchased the boat, the horn was no longer there.

I tried to install an eye bolt to replace the missing chunk but the bolt just bent as soon as I tried to lift the keel.

I removed the keel by lifting the trailer onto blocks, removing the Axel to gain clearance and dropping the keel onto a dolly

After the repair, the keel looked like this

Another innovation for 1969 when these boats were designed is the keel gasket. This reduces the drag from an open slot under the boat.

Replacing the keel gasket is something that should be done every year or so. More often if you want maximum performance for racing.

As you can see in this pic, the keel gasket has deformed enough that it is now causing more drag than having no gasket at all.

Unfortunately, replacing them is somewhat of a difficult chore. The Mylar gasket material is stiff and getting it to form around the keel is difficult.

There is a Keel Fairing available for the front end of the keel that is class legal and makes a huge difference in just the maintenance. Despite the photos here, it has been ruled illegal to fair the gasket to the hull. It must be screwed on or glued on but no smoothing of the edges to the hull.

The keel fairing makes the task of replacing the Mylar gasket much easier as the gasket only needs to be installed from the aft edge of the keel to the aft end of the keel slot.
A metal keel gasket is also approved for use. It replaces the Mylar gasket completely and is maintenance free. There doesn’t seem to be any evidence that boats with these items are faster or win more races.

Both of these items are available from

Blair's Wind and Wood Boats
400 Diagonal Street
Clarkston Washington 99403
Phone: 509 758 6436 work
Phone: 509 758 0636 home

If you do install the Keel Fairing and or the Metal Keel Gasket, the old gasket retainers must still be installed from the aft edge of the fairing to the aft edge of the slot. This keeps the undersides of the boats equal for our one design class.

Another item some owners have installed on their boats is a window in the keel trunk inspection plate. This allows you to see where your keel is as you raise or lower it.

One problem I was having was I would start to raise the keel before I removed the lock down bolt. This causes stress to the lifting horn on the keel and could be the reason some of the horns have broken off. It also stresses the cable. To remind me not to do this, I have attached a lanyard to the lock down bolt and attach it to the keel winch handle. Now it’s impossible to crank the winch without removing the lanyard, this reminds me to remove the bolt.

The Keel cable is a source of many problems. I know of one boat that still has it's original cable. Others seem to need a new one every couple of years. Over stressing the cable is one cause of failure, the other is a seized sheave on the post and/or horn. It's easy to check the cable, but possibly painful. Run your fingers lightly over the cable. If you get poked by wire hairs sticking out, it's time to replace the cable. When the cable gets overstressed, individual wires break then stick out.

The last and probably most important item to be aware of is the keel winch. In the original owners manual there is a caution about not letting go of the keel winch handle, or letting them freewheel. Severe injury can occur if your hand gets in the way of the handle if it starts freewheeling. There is a Winch available that is much safer than the original. These winches have a little clutch/brake that won’t let the winch free wheel. These are a crank up, and crank down winch. You don’t want the handle swinging around or the keel itself crashing down aganst the stop. If you don’t have this style of winch, seriously consider getting one. They cost around $50.00 to $80.00
Northern Tool