Saturday, October 31, 2020
Text Size

Fixing up your boat

Control Systems: Centerboard

This was written in response to Bruce Smith's question,
"What is the most effective way to run the board up and down on a 505? I have #7202 and it looks like the way it is run now is all wrong and does not work. Any ideas will be helpful. thank you."

There are many different ways to rig the CB up and down controls. The standard Waterat system is described herein.
Centerboard Up Control
The uphaul usually runs on the starboard side and is deadended to an eyestrap that "shares" the bolt holding the two cheek blocks to the CB horn. The line is deadended on the port side, runs through the port side of a double block shackled to the mast step, through the starboard side horn cheek block, through the starboard side of the double block on the mast step, and then aft to another bullet block on the starboard aft end of the trunk so that the helmsman can pull it from the side tank. The line has a knot in it such that it just stops the board from going any lower, as the two cheek blocks on the horn are about to hit the CB cap. I actually touch the cap for CB max. down/forward in light/medium air. This knot fetches up against the aft bullet block.
Centerboard Down Control
The downhaul usually runs on the port side starting near the back end of the trunk where it is also made fast to the centerboard cap at a point about 6-8 inches forward of a through-deck turning block. No becket block is used here, rather it goes through a hole through the cap (port side), and has a stopper knot underneath the cap. The line then goes through the portside block on the centerboard horn and then goes back to the through-deck turning block taking it down through the centerboard cap to a cheek block on the side of the trunk just above the floor. Coming out of the cheek block it terminates where it is bent to a length of shock cord. Make the line long enough that you can pull on it a little without pulling the rope-to-shockcord splice into the cheek block - you need at least 2 or 3 inches of line through the block when the CB is in the full up position. The shock-cord is stretched and led to a small Harken block shackled to one of the eye straps sharing bolts with the lower transom pintle, and from there goes forward all the way along the floor and the bottom of the centerboard trunk to the diagonal bulkhead (starboard side) where it is made fast. My shockcord simply goes through a small hole drilled in the bulkhead at the bottom near the center, and has a stopper knot on the forward side of the bulkhead. The shock-cord keeps the slack out of the system and helps keep the board from drifting up in light air and during tacks.
Why It is Rigged This Way
The CB up control is on the starboard (windward) side of the CB cap, a few inches in front of the mainsheet jammer, so the skipper can reach in and grab it to pull the board up for the first reach (on starboard). Since it comes out of a bullet block on an eye strap, it can be pulled from either tank (though it is slightly closer to the starboard tank)

The CB down control (with shockcord takeup) is on the port side of the CB trunk, so the skipper or crew can get the board down just before rounding the leeward mark. One of the skipper or crew are usually in the boat and able to reach this control.

Peter Mignerey
Ali Meller

Member Login