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Old 13-10-2010, 17:59   #1
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Two Questions Regarding Draft and Stability

Alright, I decided that I want a boat that is unshakable- even in a storm. I know that a boat like this would have a good displacement, a full (or NEXT to full) keel, and a wider width. Now, those things add to the draft, and commonly, boats of that nature that are around the 36' to 43' have a draft of 6'+... I find this to be unreasonably deep, atleast for most marinas it is... As said, I want a full keel boat with heavy displacement- a boat that will live through a storm in the Atlantic as I throw the sea anchor windward, batten down the hatches, and watch classical movies. A real, stable, seaworthy boat.

So- here is my first question. Would downsizing from a 42' boat to something smaller (lets say both boats have a full keel, with equally proportioned heavy discplacement) would that reduce my draft?

Also, I have taken a look at centreboard keels, I heard that they have quite reasonable stability, with the ability to turn draft to a number that makes me go "Woah... By golly, thats beachable... Sort of...", but will this centreboard cause me problems? Will it get stuck in a storm and screw me over? Is it REALLY that stable?

Edit : Opps, forgot to mention. Bluewater boat of course.
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Old 13-10-2010, 18:08   #2
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You describe a boat in which you want to hunker down and suffer the hard blows. Not my idea of a good solution. How about the opposite boat: one that can make progress in bad weather, maybe avoid some of the pressure, not drag out the time anchored in the eye of the storm.

Say it's a gale on the California coast. You'd be in full foulies suffering the full pressure of the weather. Passing you would be smiling people in modern boats wearing teeshirts, making great time out of the weather.

Also, wider boats are less stable. Perhaps more initial stability, but not ultimate stability. 6 foot is a reasonable draft. Less is probably unreasonable from any performance standpoint ... but I suppose on a full keel boat it makes no difference.
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Old 13-10-2010, 18:10   #3
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daddle,

Would'nt the boat go broadside-sea if it had the sails up in a storm?
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Old 13-10-2010, 18:13   #4
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In a storm you want your board up... not down if your running before the wind else you'll find that board will act like a pivot if you get smacked by a quartering wave and you may well end up being broached...
However... you'll want it down if your trying to beat off a lee shore...
There's another thread by Dnielo asking the same question... maybe the two of you should converge... save a lot of repetition
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Old 13-10-2010, 18:17   #5
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If you want to learn about stability read up on GZ (the lever arm):

Get your captain's license - Google Books

You're not going to be able to look at a boat on the dock and determine the angles, so take it with a grain of salt but at least the general concepts you can work with and draw some conclusions from.

And while not overly vacillating, there are boats of all stripes that have survived bad conditions. There's as much (if not more) going on with your chafe protection in a storm as your hull design in the version you put out above.

My draft is under six feet, there's a lot of weight in a "fullish" keel, and it heaves to quite nicely. That was one of the things I wanted in a boat and for me it works great. Some people (who are masochists as far as I'm concerned) would rather run before the weather dodging waves every 15 seconds for hours on end because they can't heave their boats to.

A 42' boat can get a lot harder to control than a 32' boat as well. All things being equal the smaller the boat is the less force will be on any line and the less horrible the ramifications of any particular mistake.
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Old 13-10-2010, 18:19   #6
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daddle,

Would'nt the boat go broadside-sea if it had the sails up in a storm?
Not if the rudder is effective. Maybe you should define 'storm'.
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Old 13-10-2010, 18:22   #7
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boatman61,

No, mine is different from Dniello...

You want it the board UP in a storm? Okay, now I'm confused to things I've been told for years, I always thought more keel = more stability indefenitely...

So why would anyone want a full keel if it didnt help them in extreme weather conditions?

I'm still confused as to why you want sails UP and the board UP in extreme wind conditions, isnt that just asking the wind to slap your sails and make you go horizontal (or upsidedown completely) with no keel or board under the boat to stop it from flying around the sea like a top?

rebel heart,

Thats what I thought!

More displacement, keel, and size = more stability... That goes right against what boatman said, but I'm one of those people who dont mind staying in one place during bad conditions instead of trying to make progress...

Please do correct me if I'm wrong though...

daddle,

What type of rudder? Attached-to, or fin?

Storm? Hrmmm... Let me think what a storm means to me... I guess it's just a heavy gale with bad rain, high tide, and indecisive winds...
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Old 13-10-2010, 18:26   #8
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take a look at the pacific seacraft or alajuela 38 or valiant 40. or a rare westsail 43. then there is the hans christian or island packet 38. but have your american express card ready
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Old 13-10-2010, 19:12   #9
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[QUOTE=Elemein;540104]boatman61,

No, mine is different from Dniello...

You want it the board UP in a storm? Okay, now I'm confused to things I've been told for years, I always thought more keel = more stability indefenitely...

So why would anyone want a full keel if it didnt help them in extreme weather conditions?

I'm still confused as to why you want sails UP and the board UP in extreme wind conditions, isnt that just asking the wind to slap your sails and make you go horizontal (or upsidedown completely) with no keel or board under the boat to stop it from flying around the sea like a top?

Ok... I'll try and explain.... eg Beneteau Oceanis Clipper 331 has a shallow draft well ballasted wing keel with a board inside... the wing keel is longer along the length of the boat than the drop keel... draft keel up is 0.90m... down its 2.00m... width is around 0.70m so basiclly you've around 1.30m of light narrow keel hanging under you.
It works great for directional stability going into the wind but once you start moving the wind aft of the beam it becomes a liability..... as for sails up... if your hove too its what keeps you pointed towards the waves... sails down and your lying ahull... beam on to the seas.... sea anchor out and your stern too.
Sailing fast downwind, board down... can cause her to trip/pivot whatever ....
and if your hunkered down below as you put it... believe me that extra draft aint doing nothing for your stability.
If you plan on doing lots of upwind sailing go for it...
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Old 13-10-2010, 19:18   #10
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Okay, so question 2 is answered, but not the first one...

I get it, downwind, you dont want a boad hanging downwards else you trip or pivot, even in a gale, going directly downwind on a run can't really affect you (you're running away from the waves [mostly], away from the possibility of tipping [your going downwind], and away from the possibility of getting hit hard by any waves) but the thing is, if you're going upwind- you want the board UP to remove that possibility of pivoting or swinging over, and you want the sails down (this is UPWIND to remind you) so that you remove the possibility of tipping over.

Am I right? Or am I still missing something? Please correct me, chances are, I got something wrong
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Old 13-10-2010, 19:31   #11
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... wider boats are less stable. Perhaps more initial stability, but not ultimate stability. 6 foot is a reasonable draft. Less is probably unreasonable from any performance standpoint ... but I suppose on a full keel boat it makes no difference.
Last I checked, life rafts have little draft.
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Old 13-10-2010, 19:34   #12
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Last I checked, life rafts have little draft.
Good idea. Never looked into anchoring my boat while dinghy-ing on into the marina...

Uhm. Dumb question. How would I do that? (anchor my boat elsewhere, know nothing will happen to it, row to the marina, check in my boat, and continue?)
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Old 13-10-2010, 19:37   #13
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Dumb question. How would I do that? (anchor my boat elsewhere, know nothing will happen to it, row to the marina, check in my boat, and continue?)
You missed my point. Draft isn't necessarily required for stability.
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Old 13-10-2010, 19:39   #14
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You missed my point. Draft isn't necessarily required for stability.
:O I just realized that.

But I was pointing your point to another point.

6'+ draft in a marina with shallow clearence (not uncommon) kinda is bad for your boat (keel scraping the bottom of the marina at all times? Oh, thats fine... right? [not])
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Old 13-10-2010, 19:45   #15
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I don't wish to sound condescending or dismissive, but it seems like you are planning for the future, which is a good thing, but I get the impression that you haven't done a whole lot of sailing, in which case I'm not sure that you are even asking the "right" questions, nor yet have the capacity to understand the answers. It is my opinion that a boat's ability to survive a storm is predicated more by it's crew than any inherent design feature. Having said that, bigger boats are, as a broad generalisation, safer in storm conditions if only because the likelihood of being rolled depends on the wave height versus the beam of the boat. Personally I wouldn't be too fixated on draft. Shallow draft is good for anchoring in shallow water, for sure, but for me at least, it isn't going to be something that is going to determine what boat I buy. Mine, for example, draws nearly 8', but in almost 5 years of having the boat, it has never yet prevented me from getting into a marina, nor anchoring in a bay.

What I am saying is that there is no teacher like experience, and getting out there and sailing will answer most of your questions (not that asking questions here is a bad thing).
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