Despite having owned and sailed numerous monohulls and currently a
multihull, I do not claim to be unbiased. In my opinion, this debate is futile not only because of the inherent bias in so many (all?) of us, but because we are to some degree comparing apples and oranges. No boat is right for everyone. Certainly, there are no absolute answers.
Issues such as appearance, of course, are almost completely subjective and hence largely irrelevant to any rational debate: some will prefer the space-age, 'Millenium Falcon' look of many modern catamarans, whereas others will find anything other than a traditional monohull with long overhangs and a sweet shear to be ugly.
Even items such as
interior space/layout are not absolutes: some will prefer a tight, dark, cozy and traditional
interior over something larger and more bright. Simply put, bigger is not necessarily better for everyone, particularly since it will often come at the expense of greater
docking fees.
Comparisons of sailing attributes such as the motion at sea involve subjective preferences, but also the need to assess the individual boat: it is decidedly not just a matter of heeling versus not heeling, nor even of pounding versus not pounding (and indeed, many modern monohulls with flat sections aft will pound mercilessly when sailing upwind in heavy seas). The real question is, what motion do
you prefer and how does the individual boat you are considering deliver in that regard?
'Performance' on the whole varies dramatically from boat, but let us just say:
most modern monohulls will point higher than
most modern multihulls, whereas
most modern multihulls will be more stable/comfortable downwind, and faster on a reach than
most modern monohulls. Again, the preference is largely subjective and should be geared towards the type of sailing that you are most apt to do.
Dual engines of course provide redundancy and assist in maneuverability under
power, especially in reverse - but they also add to cost and the time required for
maintenance. What matters most to you?
Although this area leads to polarization, perhaps more than any other in the multi versus mono debate, IMO
safety is another area which requires an individual assessment of priorities. Here is my best effort at some
unweighted pros and cons on the issue of safety. Of particular importance is the fact that they are unweighted; to some, the fact that a capsized mulithull stays capsized would outweight all other considerations. To others, the ability to avoid sinking would do the same.
1.
Most multihulls are unsinkable, providing an additional margin of safety if holed and taking on
water;
most monohulls are not.
2.
Most monohulls point higher than
most multihulls, providing an additional margin of safety if required to
claw your way off a lee shore in bad conditions.
3.
Most multihulls are more stable downwind, having less of a tendancy to roll and/or broach when running before a storm than
most monohulls.
4.
Most monohulls will self-right if capsized, whereas multihulls will not; on the other hand,
most multihulls are more resistant to knockdowns/capsize than
most monohulls.
5.
Most multihulls provide a more stable platform in heavy conditions from which to reef, inspect/repair
rigging, deploy sea-anchors/drogues than
most monohulls.
6.
Most mulithulls have shallower
draft than
most monohulls and hence are better able to avoid groundings.
7.
Most multihulls (at least catamarans) have the redundancy of twin engines and hence are better able to deal with the failure of an
engine, loss of/damage to a prop, than
most monohulls.
8. It is easier/safer to carry gear/tools etc. from the interior of
most multihulls out into the
cockpit, than it is to climb the
companionway stairs while carrying the same in
most monohulls.
This is, of course, not a comprehensive list and I am sure that even these propositions, as stated, will spark some debate/disagreement. They are not intended to be definitive, but rather to be illustrative of the fact that even on the singular issue of safety, there are no absolute answers as to which type of vessel is to be preferred.
Brad