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Done Deal is a 1998 Catalina 380 Sailed on SF Bay

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Dutchman Boom Brake Installation & Use

This device is designed to control the speed of the boom as it crosses the boat, primarily during jibing. It also makes a great preventer. The brake uses three sheaves mounted between two plates in a triangular configuration; a line wraps around these in a serpentine fashion. The two upper sheaves are in a fixed position and do not rotate; the lower sheave either rotates or is fixed depending on the setting of the control knob on the front of the device.  When the line running through the brake is tensioned the device grips the line; the greater the tension the greater the grip.  By adjusting the knob, more or less braking friction is available for any amount of line tension in winds below 10 knots.  For winds above 10 knots, the manufacturer suggests tightening the knob completely, to freeze the lower sheave. 

There are two ways to install the boom brake: (1) using a single line for braking and control,  or (2) using a primary line for braking and secondary line for control. 

On the single line installation ,the line is anchored to a chainplate or  toerail, then runs  through the brake which is attached to the bottom of the boom, and then to a block at the toe rail or chainblock on the other side of the boat, and then back along the side of the boat to the cockpit.  With this method the line can be controlled from the helm, but it is hard to get enough leverage on the line to lock the brake in high winds.  Generally this method requires a winch and line stopper, to make an effective high-wind preventer.

On the two-line installation, the primary line runs from one side of the boat, through the brake to the other side of the boat; this line is anchored on both sides to either a chainplate or toe rail.  The secondary line runs from the top of the brake, through a block attached to the bottom of the boom; then it runs to a block at the foot of the mast and then back to the cabin-top.  By pulling on this line the brake is pulled toward the boom, and puts tension on the primary line.  This allows the option of including a block and tackle between the boom and mast to increase the leverage on the line.  The manufacturer recommends a 4-1 purchase.  With the extra leverage on the secondary line, it is easy to modulate the braking force, and the boat can be jibed using the brake alone.

One day on a friendís C36 we played with jibbing the boat in low winds solely using the Boom Brake, without touching the mainsheet.  This was a single line installation.  It worked great as the boomís low load and slow velocity allowed us time to tension and release the brake as needed.  However, neither of us felt confident using the brake this way in higher winds.  In the lighter winds we could experiment with adjusting the friction knob, but who wants to fail a couple of times on 20 knot jibes? 

I donít rely on it as a brake but just use it as a preventer.  When I want to jibe in higher winds, I release the tension, and jibe controlling the main sheet.  I would be more likely to use the braking feature if I had the 4-1 block and tackle.

 

Link to Single Line Example

Link to Double Line Example