COMPARING MONOHULLS TO THE HORIZON PC58 CATAMARAN

An 80 ft x 21 ft monohull  is  about the equivalent to our Horizon PC58 cat, since they have about the same spaces (approximately700 sq/ft) in salon, galley, cockpit, and the same on the flybridge (approximately 390 sq/ft), with 3 cabins, note that the master cabin is similarly large. Such a monohull in GRP would draw about 1.8m and weigh about 65 tons lightship, 78 tons loaded, compared to our Horizon PC58 which weighs about 33 tons lightship and 37 tons loaded..  Consequently, to get 24 knots in the monohull you would need about 1800 Kw (2400 HP), which is fully 60% more HP and fuel required than our cat at the same speed.

Our 58ft catamaran in a typical 1.2m chop with 25-knot headwind would be equally comfortable to the 80 ft monohull.  This is because the slim hulls of a cat offer far less resistance, penetrate waves better, have a lower water plane than a monohull, and are therefore less reactive to wave induced motions.   Now the real final comparison is to compare the price of the PC58 with a typical 80 ft mono-hull capable of 24 knots and finished to the same high quality.  Typically they are around  $4.5 – 5 million.  The Horizon PC58 is unbeatable value at half that price!

Here are a few other features to consider:

The Horizon Yachts PC58 (in average half load condition) has a displacement length ratio of 270 (136 for the demi hulls). This is relatively as heavy as a monohull of the same length, however  in a cat each hulls’ wave pattern that is generated  separately and is according to the D/L of the demi hull,  with the resulting  reduced wave heights. A D/L of 136 would be equivalent to a very light cruising monohull .

The slimmer the hulls (and of course the lighter they are) the less “interference” drag is generated in the tunnel.  This can be alleviated by increasing the hull to hull clearance and by increased  wingdeck height. In this case we have a hull to hull clearance/bwl ratio which is a 30% increase over the minimum value I have successfully used in the past.  Wingdeck height is physically 12% higher than my minimum on this length.

A deep spray knuckle is incorporated. This is essential in producing a dry boat. With the fairly vertical lines of cat hull sides the spray root tends not to be directed outward, and a fairly low knuckle (kept low so that there is less chance of it being wind driven) this can be deflected outwards.

The hulls feature a horizontal “flat” at the back. This acts like planning wedges to reduce stern trim at speed.

We are particularly proud of having brought all our years of catamaran design experience to ensure the Horizon Yachts PC58 is in a class of her own and look forward to welcoming you aboard at the Fort Lauderdale International Boat Show, October 2011.

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