Originally Posted by AirMedMech
I've heard that multi-hull boats are short on space compared to a mono-hull of comparable length.
I'm interested in the stability aspects of multi-hull boats, but I'm not thrilled with the idea of cruising with my wife in a boat that has us cramped like sardines in a can.
Any insight on this subject? How big of a boat is required for a reasonable amount of comfort for two people? And how much bigger would a multi-hull have to be to provide that same level of comfort?
Just now starting the journey toward the possibility of acquiring a sailing vessel, so I have lots of questions. Thanks in advance for your time and advice
Just to clarify terminology a bit: Multihulls are technically any vessel with more than one hull
. Common sailing multihulls tend to be either catamarans (2 hulls) or tri-marans (3 hulls). The most common type of cruising multihull
sailing vessel is a catamaran
. So, I'm going to assume that's what interests you.
Re Space. I think that most people who have been aboard modern production cruising cats feel the opposite about the space. Loads of accomodation space on most modern cats (an almost absurd amount on some larger cats). A frequently used very rough rule
of thumb is that to get similar accommodation space you would need to look at a mono about 1.5 times the LOA
. And, that does not include the above deck
space -- lots of deck
space on a typical cat.
Re Motion "Stability". It sounds like your question is more about "motion" than technical stuff like "stability curves" so I will answer under that assumption. Simplistically, many people like cats because they don't heel perceptibly. I've run a lot of charters with guests on monos and cats and while I have not crunched the numbers on this, anecdotally, guests do appear less prone to sea sickness
on cats (not immune, just less prone). Heeling really makes some non-sailing guests uncomfortable (scared even) so they obviously prefer cats. Minimal heeling also makes it easier to enjoy all that deck space underway (I remember one of my first cruising cat sails
...walking around the level decks with GPS
in one hand reading 10+ knots...and a beer
in the other...thinking "hey I could get used to this!"), On long crossings, crew fatigue also appears to be significantly less on a cat. I suspect that in really heavy sustained conditions that might not hold true, but in light to moderate conditions definitely appears to be the case. Apparently due to minimal heeling. Assuming no significant wind/current opposition, cats do not
tend to "sail" at anchor
(some monos do...like my H33 -- big time! But depends upon the design of the boat). Cats may do really interesting dances at anchor when wind
are opposed however. Underway cats move "differently" than monos. I think of this as a more "arrhythmic" movement created by the fact that you have two hulls moving through the water
-- quite often each hull
will be at a different point in the wave train causing an irregular motion in the boat. In most circumstances this is no big deal, but can be unpleasant in "beam seas" (seas approaching parallel to the center line of the boat). Beam seas can of course be unpleasant on a mono too, but the effect is more pronounced on a cat. As with the space, it has been my observation that most non-sailing female guests tend to prefer the motion of a cat.
Re "how big". For cruising boats, whether mono or cat, about 40-45 feet seems to be good practical size for cruising. You see fewer cruising boats both above and below this range (have not actually done the math, but my perception anyway). Again, for the same space/comfort level a catamaran
could be smaller than a mono. Case in point, my little Wildcat 35 with 4 cabins, queen sized bunks, two full heads, full galley
, roomy main salon
, loads of cockpit
and deck space is way comfortable as a cruiser and a live aboard. No need for more space at all. And, bumping up a bit in LOA
to lets say a 40-45 foot catamaran does not really give you much more liveable space. What it does give you is more load carrying capacity and more water
line length (thus more boat speed potential). On a smaller catamaran loading has a noticeably bigger effect on performance than on a larger cat. I used to run larger cats in charter
, which we loaded up with many cases of beverages and full-service charter
stuff, guests and all their gear
, and it had minimal effect on performance. On a larger cruising cat I can still rock along at low double digit speeds with these loads in moderate winds...a smaller cat -- not likely.
Did that answer your questions?