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Old 09-07-2010, 18:12   #1
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What Is the Difference in the Type of Weight on a Cat ?

Here's a question for folks who design and or own a catamaran. I am curious why a cat of say 25ft, can take 6 people plus the captain out for a sail and not be overloaded. Yet if one was to be out alone on the cat with the weight of those 6 people (let's say 150lbs per person = 900lbs) in additional 'stores' to what is normally considered 'cruising gear' on a cat this size, say 1,500lbs, totaling 2,400lbs, many might consider the boat overloaded for it's size
So what's the difference if it's people weight or stores? Best I can tell the boat should sail muc better with the weight down in the hulls as opposed to up on deck/tramps whatever
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Old 09-07-2010, 18:49   #2
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In general, weight is weight. If a cat is designed to be able to carry a 1000 lb payload, you can make that 1000 lbs of people and stores of any combination. If you carry 1500 lbs, you are seriously overweight.

Clearly carrying the weight lower and in the center is better than higher and at the ends.

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Old 10-07-2010, 05:46   #3
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I know of no 25ft cat that is designed for 6 people
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Old 10-07-2010, 07:50   #4
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Cats are different from monohulls, that should be obvious. A monohull with up to 40% of its weight in its lead keel isn't affected so much by load.

A cat however has no keel and most of its performance advantage is due to its light weight. Load them down and they don't sail as well.

I have a very heavy 35' Island Packet Cat. It sails about as well as an equivalent length monohull, but with much more interior room.

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Old 10-07-2010, 13:08   #5
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Just one dead giveaway that a cat is overloaded (or at least too heavy in the stern), is the bottom step at the stern while at anchor. If it is frequently awash/underwater, the cat is overloaded.

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Old 11-07-2010, 18:04   #6
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I know of no 25ft cat that is designed for 6 people
I was under the impression that smaller Wharrams like the Tiki 25(?), and Woods designed Strider 25ft or so; have carried 6 or more people on day sailing trips

Thanks for all the insight I have the answer; in that the designed 'loaded weight' is minus the dry hull weight, for the remaining stores/passengers aboard.
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Old 11-07-2010, 19:17   #7
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Quote:
Originally Posted by CastOff View Post
Here's a question for folks who design and or own a catamaran. I am curious why a cat of say 25ft, can take 6 people plus the captain out for a sail and not be overloaded. Yet if one was to be out alone on the cat with the weight of those 6 people (let's say 150lbs per person = 900lbs) in additional 'stores' to what is normally considered 'cruising gear' on a cat this size, say 1,500lbs, totaling 2,400lbs, many might consider the boat overloaded for it's size
So what's the difference if it's people weight or stores? Best I can tell the boat should sail muc better with the weight down in the hulls as opposed to up on deck/tramps whatever
You are talking two different weights.

900 in just people vs. 900 + 1500 stores

For a given wind speed each boat will sail best at a given weight. Competitive race boats will select crew based on prevailing winds for the regatta. Heavier winds = heavier crew. One design boats always specify minimum and maximum crew weights + max and min total weight. Most regattas won't allow changing crew on a daily basis but it is not unheard of.

If you are loading the boat to 1500 lbs it makes little difference whether it is crew or ballast. However, generally you can move the crew easier for the point of sail so crew weight is better than boat weight.

It make a big difference on any boat loading it with 900 vs. 2400.
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Old 11-07-2010, 21:41   #8
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Weight is weight, no matter what the source. Weight distribution is extremely important - you don't want much weight in the bows.

I never minded having weight low down in the hulls. Although it slowed down our cruising catamaran, it also decreased the capsize risk.
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