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Old 25-07-2009, 23:03   #1
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Cruising Cat

Hi all,
I am new to catamarans but have sailed mono hulls. I was wondering about sailing performance on cats affected by weight. I reckon including people, gear and food I will load a cat by about 700kg. What do you think the minimum size cat I will need without its performance getting affected by the weight? There is also water and fuel which would mount to close to 400kg. I know the designs vary the amount of load but what would be a rough figure for the minimum length?

Thanks all for your help.


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Old 25-07-2009, 23:27   #2
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Welcome to Cruisers Forum Plukky!

Your answer depends on your performance expectations....which is something only you can answer. Sorry, I wish I could give you a definitive answer.

I am wondering how you got your numbers, because as a boat increases in size, you can carry more fuel, water and other stores without adversely affecting performance.


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Old 25-07-2009, 23:41   #3
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I am wanting fairly good performance so I can achieve 200nm+ per day given ideal conditions.
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Old 26-07-2009, 02:18   #4
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A boat long enough to achieve that should be able to carry that sort of weight.
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Old 26-07-2009, 02:46   #5
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Plucky you will find that most cat owners with a boat large enough to do those ssort of numbers will deliberately slow the boat down anyway when short handed and cruising. about 150-175nm day seems to be a more comfortable number.

Being bounced around is fine for a few hours, but soon gets annoying.
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Old 26-07-2009, 08:18   #6
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I found this excerpt from the owner of a Atlantic 42 on Chris White Designs

"Our trip from Cape Town via St. Helena and Ferndando da Noronha (including dog legs back to Noronha and into the Brazilian coast from Noronha) covered about 5700 miles and lasted about 31 days at sea, for an average of 184 miles per day or 7.7 knots. We spent at least 8 of these days powering at 2200 - 2400 rpm with one engine, giving us about 5.5 - 6 knots (sometime with some assist from the sails). While in the doldrums we also spent a lot of time drifting along at 3-4 knots, thus decreasing our average daily run considerably. Our maximum speed under sail was 19.3 knots, and our maximum sustained speed (for more than an hour) was 11 knots. We frequently surfed at 12-15 knots, and slowed to 8-9 knots on the backsides of the seas.

If you crunch the numbers given in the story (Motor at 6 knots for 8 days = 1152nm. Sailing at 8.24knots for 23 days = 4548nm for a total of 5700nm).
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Old 26-07-2009, 09:04   #7
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Plukky, we've done 200 mile days twice on our St. Francis, but they definitely were "ideal" conditions! Not something that could be sustained over a long passage, simply because conditions don't stay that way. Sea states get to the point where going that fast puts too much stress on the boat and/or the crew gets to the point of mutiny; or, the wind becomes too variable such that the speed drops.

In order to get consistent 200 mile days and high load capacity will require long waterlines and big bucks.

You can certainly get good performance and good load capacity in smaller, less expensive boats.


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