MapisM
Well-Known Member
OK then, time for some additional thoughts, now that I can call it a working day.
1) Absolutely. I posted my experience in this previous thread, but in a nutshell talking about air entrapment effect on the boats we're talking about - at any speed they can achieve - is plain nonsense.
2) I think that the "railway" effect of the two parallel hulls becomes relevant only above a minimum speed - I'd say 5 or 6kts at least. Below that (and particularly at almost zero speed, as when maneuvering), it's just a matter of where forces are applied, hence the props "at the corners" - so to speak - are more effective.
3) It depends on what you actually mean by 'better': safety or comfort?
I would dare to say that a well built cat is at least as good as an equally well built full D trawler in terms of safety. I'm using this type of monohull for the comparison because that's typically considered the best to deal with really rough stuff.
But in terms of comfort, there are bigger differences. My experience with cats is limited to short cruises on some 40' to 50' diving boats. Occasionally, when diving outside the reef, I saw their behaviour in some 6' to 8' short(ish), irregular waves. No big deal really, the boat handled that perfectly, but everybody onboard had to sit and grab firmly the rails, because the boat movements were very stiff, and she quickly snapped back even from a relatively small roll. I am pretty sure that a similar size stabilyzed monohull would have been more comfy, because her typical behaviour is very different: the roll motion is smooth and gentle, with a longer period.
Maybe this difference would be less relevant in bigger and longer oceanic waves, where a wider surface exposed to the waves movements is less relevant given the size of the wave, but I don't have hands on experience on that.
1) Absolutely. I posted my experience in this previous thread, but in a nutshell talking about air entrapment effect on the boats we're talking about - at any speed they can achieve - is plain nonsense.
2) I think that the "railway" effect of the two parallel hulls becomes relevant only above a minimum speed - I'd say 5 or 6kts at least. Below that (and particularly at almost zero speed, as when maneuvering), it's just a matter of where forces are applied, hence the props "at the corners" - so to speak - are more effective.
3) It depends on what you actually mean by 'better': safety or comfort?
I would dare to say that a well built cat is at least as good as an equally well built full D trawler in terms of safety. I'm using this type of monohull for the comparison because that's typically considered the best to deal with really rough stuff.
But in terms of comfort, there are bigger differences. My experience with cats is limited to short cruises on some 40' to 50' diving boats. Occasionally, when diving outside the reef, I saw their behaviour in some 6' to 8' short(ish), irregular waves. No big deal really, the boat handled that perfectly, but everybody onboard had to sit and grab firmly the rails, because the boat movements were very stiff, and she quickly snapped back even from a relatively small roll. I am pretty sure that a similar size stabilyzed monohull would have been more comfy, because her typical behaviour is very different: the roll motion is smooth and gentle, with a longer period.
Maybe this difference would be less relevant in bigger and longer oceanic waves, where a wider surface exposed to the waves movements is less relevant given the size of the wave, but I don't have hands on experience on that.
