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Multichine 31

The Multichine 31 ballast is a cast iron bulbous fin-keel with a flat tip of relatively shallow depth. (The boat’s draught is 1.63m – 5’ 4”). This keel has been adopted in most of our cruising design for its excellent performance for her depth, especially when sailing close-hauled, and also for the fact that she brings down the boat’s centre of gravity with practically no loss in lift. Besides its flat bottom performs like a sledge in case of accidental grounding and also for the bulb not surpassing the keel’s fore or aft tip ends. Being without overhangs it is less prone of tangling with the anchor rode in case the boat swings at her anchorage when tide changes and wind lightens.

Whoever suffered a mishap like this in a cruiser-racer of long bulb fin-keel knows too well what we are meaning. Being made of cast iron, it lasts for a lifetime requiring practically no maintenance and probably will not suffer any damage in case of accidental collision.

A few clients of ours passed by this disagreeable experience with different boats from our designs employing the same type of fin-keel. After colliding with an obstacle, for their surprise, the most they could observe of damage was a scratch in the anti-fouling or a small dent in the leading edge of the fin-keel at most.  The keel bolts employed for its attachment are easy to be obtained drop-forged stainless steel 16mm (5/8”) bolts.

The keel is easily assembled or disassembled anywhere there is a crane or travel-lift. Photo Zilmar Franzen

There is a certain difficulty in some countries to find foundries interested in casting sailboat keels, since the order might be too small to spend a whole batch and not small enough to be made with the left-over of another order. For those who find problems ordering the standard cast iron Multicine 31 bulbous keel, or have preference for another system, we have two other options: a steel case keel with no bulb filled with lead poured in, possessing the same draught and weight as the bulbous one, and a lead, performance oriented, fin-keel with a slightly deeper draught, also with no bulb.

Bulbous keel
Material Weight Height Length (at root) Length (at tip)
Cast Iron 1450 kg 0.950m 1.80 m 1.31 m