Dutchman Boom Brake Install

Posted on Tuesday 20 June 2006

The Dutchman Boom Brake Installation on the Pretty Gee.I am almost done with the boom brake install. The final step of the install is mounting a Spinlock Powercleat on the cabintop, just outboard of the port genoa sheet winch, which should be done tomorrow.

Here are the details of the installation.

Hardware:

  • 1 x Dutchman Boom Brake BB500
  • 1 x Wichard 1/4″ extra-long shackle with captive pin, for starboard chainplate
  • 2 x Wichard 1/4″ shackles with captive pin, for the boom and port chainplate
  • 2 x Schaefer Padeye backing plates, for use as boom brake straps
  • 1 x Harken Ratchet Block, for port chainplate
  • 1 x Spinlock PX PowerCleat, for the cabin top
  • 1 x Samson Trophy Color Braid 3/8″ line, for use as the brake line.

Preparation

First, I drilled out the one of the holes on the padeye backing plates to fit the large clevis pin on the Telstar chain plates. I then drilled the other hole on the padeye backing plates to fit the 1/4″ shackle threaded post.

Starboard Chain Plate

Starboard Chainplate Detail.I removed the cotter pin on the starboard chain plate and pulled the chain plate clevis pin and added the boom brake strap to the clevis pin, so that they are outside the the chain plates. I then replaced the clevis pin and put the cotter pin back in. I bent the boom brake strap slightly to allow the shackles to lead more fairly. I put the extra long shackle on the starboard boom brake strap, and then tied the bitter end of the 3/8″ brake line to the shackle.

Boom

The Dutchman Boom Brake Boom Detail.I unscrewed the padeye for the aft lazy jacks, and moved it just aft of the forward padeye for the lazy jacks. I moved one of the spare padeyes up to where the aft lazy jacks are supposed to be, and screwed it in place.

I used a centerpunch to mark the two holes I will need to drill for the boom brake padeye, but haven’t drilled or tapped the holes yet. It really isn’t necessary, as the forward lazy jacks padeye prevents the boom brake padeye from moving forward at all. If I decide it is necessary to have the padeye screwed in place, I will have the holes drilled and tapped tomorrow.

I used a 1/4″ shackle to attach the boom brake to the boom. I threaded the brake line through the boom brake, and ran it to the port chain plate.

Port Chain Plate

Port Chainplate and Ratchet Block Detail.I followed the same procedure for the port boom brake strap that I used on the starboard one. The only difference is I used a 1/4″ shackle to attach the Harken ratchet block to the boom brake strap. I ran the brake line through the ratchet block and back, along the port side of the cabin top, to the cockpit.

Cockpit

I placed the Spinlock PowerCleat on the cabin top, a few inches outboard of the port genoa sheet winch. I marked the holes for the PowerCleat and then drilled out the holes. The holes are oversized and go through the plywood backing plate that is used for the genoa sheet winch. I then taped over the bottom of the holes, after cutting a small slit in the cabin head liner. I then started to fill the holes with thickened epoxy.

The holes took quite a bit of epoxy, and I found out why a few minutes later. After topping off the holes several times, I decided to check to see if the duct tape had pulled away from the plywood block. It hadn’t—but I discovered that there was some epoxy leaking out over the outboard edge of the plywood backing block Apparently, there was a small gap between the backing block and the fiberglass above it, and the epoxy was now filling the space between the two.

The leakage is the reason I am still waiting to mount the PowerCleat. I have to finish filling the holes and then re-drill them for the mounting bolts for the PowerCleat. I couldn’t finish filling the holes yesterday as the weather decided to not cooperate—it’s been raining off and on since last night—when it poured.

I am using the port genoa cleat for the brake line, until I finish mounting the Powercleat. I’ll be testing the boom brake this weekend.

Finishing the Installation

I should have the Powercleat mounted tomorrow. I also have to seize the shackle pins with Monel wiring, to prevent them from working loose.

Installation Notes:

The boom brake is a bit oversized for the mainsail on the Telstar. It is designed for main sails up to 500 sq. ft. in size. The manufacturer recommends going up a size if you are planning on going off-shore and are near the maximum size for the brake unit. The smaller BB250 unit is designed for main sails up to 250 sq. ft. in size. As the Telstar main sail is 242 sq. ft., I decided to go up a size.

I used Lanocote on all the screws, to help prevent galvanic corrosion between the stainless steel screws and the aluminum boom. I also used Lanocote on the shackles, to prevent them from galling and seizing.

I filled the holes through the cabin top with thickened epoxy, to prevent water from penetrating the balsa core in the case of any water leaks, and to provide a strong surface for the compression loads of the mounting bolts.

The ratchet block makes it much easier to tension the brake line, and adds to the holding power of the PowerCleat. I don’t see a need for a winch or block-and-tackle for the brake line, but if I find one is needed—I can attach a block to the cockpit rail and use it to lead the brake line back to the genoa sheet winch.

If you have any questions about the details of this installation, please drop me an e-mail.


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