Issuma Centerboard

Centerboard, labeled, ashore for painting

Unlike most sailboats, all ballast in Issuma is in the centerboard--there is no internal ballast, nor a ballasted keel--just the ballasted centerboard.

The ballasted centerboard is great for an expedition boat--it allows motoring (not sailing) into shallow areas, and, if stuck in ice, raising the centerboard leaves less for the ice to grab the boat with, making it more likely to pop up rather than be crushed. But one absolutely must always remember to put the centerboard all the way down and the locking pin in before setting sail. Otherwise, there is the danger of a gust of wind heeling the boat far enough over that the centerboard pivots up and the boat capsizes.

The centerboard trunk goes all the way to the deck (it is covered by a piece of plywood when the keel is down)

It is just possible to squeeze into the centerboard trunk

The centerboard has 4.5 tons of ballast and also serves as a 700 litre fuel tank. So it has hoses for fill, vent and supply coming from it.

Looking down into the centerboard trunk with hold-down brackets removed:

On either side, hold-down brackets hold the centerboard pivot pin down (this is to hold the centerboard in the trunk). Four 3/4" stainless steel bolts hold down a small bracket on top of the hold-down bracket. The hold-down bracket is prevented from twisting out of place by one 3/4" stainless steel bolt. The channels in the centerboard trunk that the brackets slide down also prevent the brackets from twisting out.

The threaded rod in the picture is for adjsting how tight the hold-down bracket is (unless there is a lot of wear, one would only adjust this when first installing the board).

Inside the boat

Before sailing, the centerboard must be locked down. There are four (reinforced) holes in the centerboard trunk for the locking pin. I know the lowest pin hole is the position that is safe for sailing. I do not know specifically what each of the other positions are for--I use them for motoring, or when at anchor in shallow water.

Inside the boat, besides the four holes for the pins, there are horizontal pads, two per side. The horizontal pads are screwed (there is a special tool for this) in when the centerboard is down and locked. They prevent the back of the centerboard from slopping around in the centerboard trunk in waves. Properly adjusted, the centerboard does not make any noises in waves.

Not shown in the pictures, but to make it as plain as possible to know that the centerboard pin is in or out, when out, it is stored in front of a white-painted area, in plain view of the cockpit.

Removing/Installing the centerboard

I've removed the centerboard once (so far) for inspection (it was fine, no signs of wear). Issuma was tied between two barges when the centerboard was removed. I did it this way to ensure no winds could heel her over when her centerboard (and therefore all ballast) was removed.

More about inspecting the centerboard at this blog entry,Inspecting the Centerboard


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