POWER-CRUISING CATAMARANS
There are three basic hull designs among power-only, twin-hulled cruising yachts: displacement, semi-displacement, and planing designs.
With each of these design styles (compared to power monohulls), their shared twin-hull configuration provides their owners many of the same benefits as sailors enjoy with sailing cats.
- Beachability
- Ballast-free, lightweight construction /li>
- More living room (interior and exterior) per linear foot
- Widely spaced twin diesels for the optimum in maneuverability, safety, and redundancy
But the three primary reasons that power cats are superior to singlehull powerboats are these:
More comfort< br/>
Power cats experience less "rock 'n roll" underway or at anchor because twin hulls are more stable floating upon a fluid than is a single-hulled craft. Also, when proceeding in a seaway the cushioning effect of air-and-spray between the hulls makes for a more comfortable ride (and even improves with added speed), whether you’re heading into the waves, at an angle to them, or away from them. By comparison, monohulls invariably must be slowed as the seas increase in size. And at anchor the catamaran configuration generally is much more comfortable than the sometimes “roll-your-guts-out” singlehull design.
Better fuel economy
The benefit here is truly striking. At lower speeds, say 6 to 11 or so knots, the power cat will use anywhere from 10% to 20% less fuel while traveling at the same speed as her monohull counterpart. At speeds of 15 to 25 knots, the cat will offer as much as 40% to 70% better fuel economy than with a monohull. (Eg. The Maryland 37 cat uses 8 GPH at 16 knots, while a same-size monohull uses about 13 GPH at that speed.) This can mean literally hundreds of dollars in savings per DAY! (Ex. The BearCat 46 uses 13 GPH at 18 knots, while the less roomy Nordic Tug 52 uses 45 GHP at 18 knots. In an 8-hour run that amounts to $200 fuel for the BearCat, and $720 for the Nordic – a single-day’s savings of more than $500!!).
Faster cruising
In the monohull world, displacement power yachts – often termed “trawler yachts” (as compared to planing models) – have long been popular for their sea-kindliness and fuel economy. The inescapable downside to such yachts is that their slow speeds give new meaning to the phrase interminable.) Typically, a 40 or 45-foot displacement monohull has a maximum cruising speed of about 10 knots. But the slimmer, sleeker hulls of displacement type power cats offer as much as twice that — from 15 to 20 knots. Better yet, the latter enjoy the aforementioned low fuel usage. Semi-displacement cats offer you another 25% in speed, typically to 24 or 25 knots. Plus, the flat-bottomed sections of the aft halves of their hulls give noticeably more interior room than the more V-shaped displacement-style hulls. Planing cats (with even more pronounced flat sections) can be powered from 25 to 40 knots (or more), but their hulls do not offer great handling or comfort in the 10-to-18-knot range, whereas semi-displacement and displacement models offer good handling and comfort throughout their respective speed ranges.
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