How do you think this vessel sails offshore? - SailNet Community

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Go Back   SailNet Community > General Interest > General Discussion (sailing related)
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  #1  
Old 10-19-2006
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How do you think this vessel sails offshore?

Norwegian-built, traditional Colin Archer design- wooden, gaff-rigged...

LOA: 39.5ft
LWL: 36.5ft
BEAM: 13.7 ft
DRAFT: 6.5 ft
DISPLACEMENT: 24 tons
BALLAST: 3.3 tons
SAIL AREA: Approx. 1200 sq ft

(From gosail.com)
Sail area to displacement (SAD): 15
Displacement to length: 444
Length to beam: 2.9
Theoretical hull speed: 8.09 knots
Capsize ratio: 1.49
Ballast to displacement: 14%

I know she's going to be slowww in light airs, but when I look at the ballast to displacement ratio I wonder how this affects stability, as I've always thought a ratio of 35-40% represents excellent stability for offshore sailing.

Any thoughts?

Warren

Last edited by wfraser; 10-22-2006 at 10:50 PM.
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Old 10-20-2006
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Stable as a brick, just about as fast. Given that the Archer was not much more than a converted life boat then their sailing performance can be guessed at. They are as slow as a wet weekend except on a reach where that gaff main gives you a near perfect reaching sail (other than spinnakers and the like of course). They need to be bloody stable cos when everyone else is safe and snugged up in some protected little anchorage you'll still be out at sea trying to make some headway to windward. While it's fair to say that some of the modern plastic fantastics are taking lightness to unacceptable extremes there really isn't any case for slow, inefficent, heavy, undercanvassed barges in this day and age.
On the other hand....jesus they look nice and if all your sailing is going to be done in the North Sea or you can cope with a lot of motor sailing then they would make some sense. Last week we shared a bay with a traditional double ended gaffer and I'm sure she was more picturesque than our old dear indeed it was a pleasure to have her around.
tdw
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Old 10-21-2006
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TDW- thanks for your input.

I personally am very rarely in a rush to get somewhere unless conditions dictate, so overall speed of the vessel is not that big an issue for me. What I'd like to know is whether the 24 ton displacement and only 3.3 ton ballast renders the vessel inherently unstable in the worst of it.

If caught in a real blow and she gets knocked down, will she right herself.

Warren
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Old 10-22-2006
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I'm not the one to discuss the ratio with cos I'd be talking through by backside if I tried to pretend I new anything about it specifically but Archers are not known for being unstable. However 14% does seem a tad low doesn't it ? I'm also not obsessed with outright speed but I do think it's important for a sailing vessel to be relatively close winded. I know it's said that gentlemen do not sail to windward but it's not always avoidable. One final point, for every Archer built to the original plans there would be a plethora of dodgey old tubs going falsley under the Archer name. I don't know the figures but it would be interesting to know the B/D ratio of a genuine Redningsselskapet. Great name isn't it ?
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Old 10-22-2006
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Doesn't the ballast/displacement ratio simply tell you how much of the boat's weight is devoted to ballast? IMHO, a high ballast/displacement ratio indicates a stiff boat because the ballast overrides the overall weight of the boat, and we assume the ballast is down low. Without knowing how deep down the ballast is, however, this might be a false assumption. The length of the lever arm of the ballast factors in. Consider a hull shaped like a long tube, with concrete filling in the lower half. The ballast/displacement ratio would be high, but the thing would still roll like crazy. Designs with more moderate ballast/displacement ratios tend to be more "seakindlly". They roll more slowly and regularly and are therefore less tiring for the crew on long hauls. Long-distance cruising boats are often purposely built with lower ballast/displacement ratios than their racing cousins because of this. To compensate for the lower ballast/displacement ratio, cruising designs may rely on other things - like hull shape and reduced sail area - to maintain stability. Every boat is a compromise of a lot of factors, each of which plays off the others.
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Old 10-23-2006
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Boats of this kind should not be judged by their ballast/displacement ratios. Their stiffness results rather from the hull shape. The amount and form of wetted hull (under the waterline) dictates their sailing perfomance and they don't really need any extra ballast like modern, slim yachts. Nineteenth century windjammers took only some water ballast, after all!

Last edited by chrondi; 10-23-2006 at 06:13 AM.
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Old 10-24-2006
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Quote:
Originally Posted by chrondi
Nineteenth century windjammers took only some water ballast, after all!
Is that correct ? I was under the impression that the old timers often loaded rocks and stone as ballast , the amount depending on the weight of their cargo.
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