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Old 26-10-2010, 17:20   #1
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Wide Beam vs Narrow Beam

Old style boats have a proportionally narrow beam to length with a high ballast ratio; whereas nearly all modern mass-production boats have a relatively wide beam and low ballast ratio and depend upon form stability (ie width) to support their sail area. Unless one is proposing to sail in the South Atlantic or similar, does it really matter?
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Old 26-10-2010, 17:29   #2
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Define "does it matter".
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Old 26-10-2010, 17:45   #3
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Are you looking at it from a comfort standpoint, a speed standpoint, a safety standpoint?
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Old 26-10-2010, 17:47   #4
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Originally Posted by Srah 1953 View Post
Old style boats have a proportionally narrow beam to length with a high ballast ratio; whereas nearly all modern mass-production boats have a relatively wide beam and low ballast ratio and depend upon form stability (ie width) to support their sail area. Unless one is proposing to sail in the South Atlantic or similar, does it really matter?
I would somewhat question the premises. Modern boat do not exactly "depend" on form stability (other than cats, of course). The still have keels and ballast. Form does not play the major role, AFAIK.

"Modern boats" i also a pretty broad term -- they are sometimes different one from the other, aren't they?
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Old 26-10-2010, 18:21   #5
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Among others I have owned two boats that represent the bookends of this question- a 35' Jeanneau (broad beam light displacement, low sail area) and a Saga 43 (narrow beam, lighter displacement, high sail area).

The Jeanneau was easy to sail, forgiving and slow. The Saga was tender and fast. Some of the fast was due to its sail area certainly, but much of it was due to its narrow beam. The Saga would heel over and sail!

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Old 26-10-2010, 18:47   #6
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Depends what you are after.

Some sweeping generalisations:

If you want to go fast - it matters - wide & flat (like a boat designed within the most "Open" box rules) are likely to be much faster off the wind

If you want comfort - it matters - the narrow beam of the older designs are likely to be more comfortable in a sea.

If you are concerned about stability - it doesn't matter - The modern boat will be built to ISO 12217, Category A. Which requires an AVS in excess of 128 deg. (compared to say 130ish for an Irwin).
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Old 26-10-2010, 18:53   #7
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Old style boats have a proportionally narrow beam to length with a high ballast ratio; whereas nearly all modern mass-production boats have a relatively wide beam
You must have a narrow beam boat or you will all die.

Mine is so norrow its like a string in certain underware.

Any boat designed in the last 40 years was designed by weirdos... I think the 1960's acid trips finally reached home.
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Old 26-10-2010, 18:57   #8
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beam and ballast

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Define "does it matter".
Yes coastal floating condo or blue water cruiser
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Old 26-10-2010, 18:58   #9
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More beam equals:

- more space per each ft of LOA,

- more initial / shape stability.

We often end up with a more spacious (!), stiffer (!!) boat.

I think, extreme weather aside, the beamier - the merrier (!!!)

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Old 26-10-2010, 19:04   #10
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I heartly concur. When I was living aboard people often asked how can you live on a boat. I'd say, think waterfront condo and you get the picture, well, except for the floppy white things above the roof ...

I like the beam for space.
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Old 27-10-2010, 02:11   #11
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Are you looking at it from a comfort standpoint, a speed standpoint, a safety standpoint?

My reading of books on heavy weather suggests that a relatively narrow beam is an important safety factor. But there are trade-offs, as noted by replies in terms of space; although possibly not in comfort except in harbour. I certainly spend far more time messing about on the boat attached to a pontoon than I actually do sailing.
I'm probably unlikely to end up in “survival” conditions (I'm unlikely ever to be a blue water cruiser) so is the trade-off worth it? I ask because I was pondering changing to a 40ft (12m) boat and was considering a new Jeanneau or Beneteau with a 4m beam to 12m length against a second-hand deck saloon with a 3.5m beam to 12m length
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Old 27-10-2010, 02:42   #12
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Originally Posted by MarkJ View Post
You must have a narrow beam boat or you will all die.

Mine is so norrow its like a string in certain underware.

Any boat designed in the last 40 years was designed by weirdos... I think the 1960's acid trips finally reached home.

likewise.

and agree.....
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Old 27-10-2010, 04:08   #13
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It all depends on the architect: if he is good, the boat is good.
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Old 27-10-2010, 04:57   #14
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My reading of books on heavy weather
Have a look at when the book was first published.
The 'bible' is Allard Coles Heavy Weather Sailing and like ALL those books they came from more than a generation ago. That one being written in the 1960's.
Similarly Lin and Larry Pardy - love them - but theirs written from the perspective of very old design boats.

In fact I do not know of any book written on the subject by someone in a modern designed purpose built cruiser thats authoritive on the subject.

So all your reading may not help you as everything available has not taken into account 40 years of development that has totally and utterly changed our life at sea.


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Old 27-10-2010, 09:11   #15
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my boat is 1976 built--- designed in what, 1960's?? by wm garden--my beam is 12 ft, depth 6'6"........is very heavy and sits in water like a brick and cuts thru seas like a charging lion. is awesome to see. but , yes, IS designed 40 yrs ago. ALL our old standby heavy displacement cruisers are 40 yrs old or older in design.
so what IS the new replacement for these heavy full keel cruisers? these -- by these i mean the heavy displacement cruiser in general, certain in specific, as westsail-- have proven them selves worthy of facing big seas and surviving. what is our new design to replace these?? will it meet the perfect storm test?? what will be designed, or has it already been designed-- to replace these heavy ladies (mine is a big momma)???
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