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Old 12 August 2008, 12:50   #1
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Cat B seaworthyness?

Hey Guys,

Super quick Q for the more experienced among you...

What exactly do the different Category classes relate to? I know Cat B relates to "upto force 8 seas with waves of up to 4m in height"... but what do the others give indication of in relation to how seaworthy they are?

Cheers,
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Old 12 August 2008, 18:41   #2
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I only have experience of Cat C & B boats, and I have reached the conclusion the CE marking is a sales aid only for distribution of boats in Europe. It is not a code for the quality, or integrity of construction of the hull.

I was lead to believe that a cat B hull would, by its rating, be stronger, harder, extra layup, stronger internals etc and more seaworthy than a C, and to some extent they are, in that it is a bigger boat,.. but that is where it ends.

If its a poorly constructed bigger boat as I found to my cost with an 8.5 Northcraft cat "B", you can forget placing any credence on its cat rating. To be fair, part of this crafts problem was that the manufacturer plated the transom to carry horsepower it couldnt handle.

But also, and this is important ..because of the weight distribution and layout of that boat, it was far too bow light, and to be honest taking a sea head on in a big six or seven was a challenge, so .. as to your question of seaworthyness, even supposing it was a top spec boat coded for B, if it aint balanced, or fitted in such a way as maintain good seakeeping, you can forget the cat system as having any real importance.

Ah just seen your other thread and posts
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Old 13 August 2008, 17:21   #3
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A = Ocean, force >8, waves >4 m.
B = Sea, force <8, waves 2-4 m.
C = Coastal waters, force 4-6, waves 2 m.
D = Inshore waters, force 4, waves 0,5 m.
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Old 13 August 2008, 18:35   #4
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Brilliant, Thanks gents.
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Old 13 August 2008, 21:20   #5
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I agree the ratings are a joke. Some makers will be over optimistic and others will err on the side of caution so you can have a 9m RIB with the same C rating as a 3.1m dinghy!!!
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Old 14 August 2008, 08:08   #6
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I agree - 100% - with bigmuz statements.

Now, Cat B requires more than 6m in length, that's all - and you could find several italian ribs with this category - and in the 4 to 4.5metre range - because italian had a different definition of distance off the shore, as their C category was limited to 4 miles.

No rough sea testing is required, unless a handling test at max speed on flat sea to check the ability to turn left and right in a short define distance.

Concerning the hull ability to sustain waves, it is the manufacturer responsibility to build strong enough
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