Monoes vs. Multies - below 30'...
Greetings all. I'm planning a short adventure next summer: sail from UK to Iceland (or maybe even Greenland coast if time allows) for a bit of climbing, then sail back again. The idea is that the exercise will be a bit Tilman-esque, but just two of us in a smallish boat, which we'll buy ready-to-go for the purpose. And before we get deluged with warnings, we're pretty experienced sailors who understand what we're taking on.
The reason for starting this thread is that I'd like some comments on whether a mono or cat would be most appropriate for the trip (we're thinking about a 25-28 footer). After reading a lot of literature I've got a leaning towards a cat (e.g. Heavenly Twin-ish) for a number of reasons, but it may be badly misplaced (i.e. over-influenced by Tristan Jones!). It seems to me that multies are starting to get more popular (again) in the larger sizes, but should this influence our thinking on a sub-30-footer?
So, comments please, on the following themes:
1. Safety. If a cat goes over, it stays over (but is less likely to go over?). This is the first and most important consideration?
2. Length-for-length speed and up-wind-ability.
3. Comfort and stowage. A multi seems to have more space for length, but is this an unwise trade-off considering the open-water nature of our objective (back to 'safety'...).
Multi vs mono?
Here's a link to a guy that apparently did extensive cruising with a Heavenly Twin:
If I was going to get a multi I'd probably lean toward a more high performance version. But I guess the thing you have to look at is the weather on your course at that time of year. Sounds like the water would be really cold and so a capsize would be a bitch.
As much as I love multies for that particular "adventure" on a 30' or smaller boat I think I might lean toward a really well built mono....
The main reason for going for a multi is speed.
And that speed is dependent on light weight. After reading a very pro-multi book, I came out with the impression that when sailing a multi, its best to use a gram scale for weighing your provisions. Heavy items such as SCUBA tanks, compressors and other such like best be left ashore. It seems to me that when choosing a vessel, it is best to plan on a multi that is at least 20% longer than a mono that would do the same job.
So if a 20ft mono will comfortably carry your stuff (without sinking below its marks) you will need at least a 24ft multi to do the same job. this, of course, means greater boat costs (not to mention higher docking fees).
It is also interesting to note that your tybical mono is far more tolerant of overloading than your typical multi. The rigging as well as hull (or crossbeam) strains on a multi go up in direct proportion to increases to its weight. This is almost never the case with monos. I have done righting curves of my own designs and have discovered that even doubling the displacement does next to nothing in increasing the initial stability of my mono design.
What I get from this is that a multi is best for speed for size (about 50% faster than a mono of the same length and level of technology) and a mono is best for cargo capacity for size. For your intended purpose, a mono would probably give you more bang for the buck, whereas the multi is perfectly safe if not designed as an all out speed machine (watch out for really tall rigs and super slim hulls), not pushed too hard (the main reason for multi capsizes), and not loaded beyond her design payload (her design displacement minus actual wieght empty).
Reputable multi designers will let you know what that number is.
It is usually 1/3rd the stated displacement, but on higher performance boats it could be considerably less.
So choose carefully.
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