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05-05-2012, 21:33
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#1
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Registered User
Join Date: Apr 2012
Location: Maui
Boat: Dreadnought 32
Posts: 5
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Removing Concrete Ballast
does anyone have any advice on changing ballast from concrete to lead. i have a dreadnought 32 full keel boat. i hope it will be more stable.
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05-05-2012, 21:36
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#2
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Registered User
Join Date: May 2009
Posts: 1,379
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Re: removing concrete ballast
Wow, sounds like a nightmare to me. I'm guessing the current ballast is fiberglass encapsulated in a full keel right?
Have you considered consulting a marine architect. You may be able to bolt/glass on a heavy bulb to the existing keel. Or something less destructive than removing the concrete.
Also what types of stability issues are you having?
__________________
Let your heart tell you where to go, but let your brain tell you how to get there.
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05-05-2012, 21:40
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#3
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Registered User
Join Date: Apr 2012
Location: Maui
Boat: Dreadnought 32
Posts: 5
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Re: removing concrete ballast
looks like concrete and steel punchings, basically poured in. i just got the boat and it feels a bit like a rocking horse.
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05-05-2012, 21:42
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#4
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Registered User
Join Date: Apr 2012
Location: Maui
Boat: Dreadnought 32
Posts: 5
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Re: removing concrete ballast
i am worried about leaving the concrete as sooner or later it will rust and expand.
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05-05-2012, 22:07
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#5
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Registered User
Join Date: May 2009
Posts: 1,379
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Re: removing concrete ballast
The concrete and punching really shouldn't rust if they are correctly encapsulated in the keel.
If your boat is rocking badly have you tried adjusting where you are carrying weight? Move some trim ballast around and try to get the boat more comfortable.
__________________
Let your heart tell you where to go, but let your brain tell you how to get there.
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06-05-2012, 10:38
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#6
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Registered User
Join Date: Dec 2008
Location: St. Georges, Bda
Boat: Rhodes Reliant 41ft
Posts: 4,131
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Re: Removing Concrete Ballast
If your rocking is in a fore 'n aft motion, this is largely contributed to by the shape of stem and stern overhang and resulting ends bouyancy.
If you change to lead you have a few considerations to make.
Volume for volume, the lead is much heavier and will change your roll centre height, and the resulting sailing angle (your list).
This then involves the designed sailing lines for your hull shape.
As an example, but going the other way, my class of boat was designed with heavy wooden spars, and 12000lbs of lead.
The pendulum effect of the heavy spars dampened the stability motion speed of the lead.
Some owners changed to aluminum masts and found the lighter weight above no longer balanced the ballast weight equation, and the boats became jerky and not as "smooth thru the water".
There is a lot to consider before possibly ruining (improving ) the boat.
__________________
so many projects--so little time !!
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07-05-2012, 02:34
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#7
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Registered User
Join Date: Apr 2012
Location: ashore in So Calif.
Boat: No more boat (my medical, not the boat's)
Posts: 1,453
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Re: Removing Concrete Ballast
You may wish to do a bit of research. I vaguely recall a post by someone, probably on a forum similar to this, where the person had removed the ballast (steel punchings?) and replaced it with lead.
I also recall another post, which may or may not have been on the same forum, that contained a comment indicating that a mild tendency to "hobby horse" in certain sea conditions was a trait of the otherwise stout and comfortble Dreadnought 32s.
BTW, for what it is worth, it is definitely now the "later" part of "sooner or later," and if no expansion has occurred the ballast material is well encapsulated!
Fair winds.
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07-05-2012, 04:40
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#8
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,515
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Re: Removing Concrete Ballast
Greetings and welcome aboard the CF, buzzstar.
Thanks for contributing.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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07-05-2012, 11:42
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#9
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Registered User
Join Date: Apr 2012
Location: Maui
Boat: Dreadnought 32
Posts: 5
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Re: Removing Concrete Ballast
Thank you for the advice. the boat has wooden spars. you say volume for volume lead is much heavier. my thinking is the same weight of lead would be lower in thbe bildge, making things more stable.
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07-05-2012, 11:53
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#10
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,531
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Re: Removing Concrete Ballast
Your rocking horse may have more to do with hull shape. You are talking a jack hammer and a big mess. "fuggidaboudit".
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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07-05-2012, 12:49
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#11
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CF Adviser
Join Date: Dec 2008
Location: sausalito
Boat: 14 meter sloop
Posts: 7,260
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Re: Removing Concrete Ballast
The Dreadnaught 32 was offered as a kit boat or a completed boat. You could buy an unfinished hull, a hull + deck, or a finished boat. Sounds like yours was a kit, originally, because I understand that the factory boats had lead keels. You may want to get in touch with the owners association to figure out your next step, especially in terms of whether anyone else has made such a conversion.
The big question I'd want to know before proceeding is whether your current ballast weighs less than the original design.
__________________
cruising is entirely about showing up--in boat shoes.
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07-05-2012, 19:03
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#12
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Registered User
Join Date: Aug 2006
Location: Skagit City, WA
Posts: 25,531
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Re: Removing Concrete Ballast
Here's a question for you... will a boat with a heavier ballast roll more than one without? (with no sails up) (ie: will a weighted pendulum swing more times than an unweighted one?) The answer for the pendulum in my old clock is less swings with weight removed.....
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
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07-05-2012, 19:13
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#13
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Registered User
Join Date: Aug 2010
Location: NSW Australia
Boat: Traditional 30
Posts: 1,980
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Re: Removing Concrete Ballast
A simpler solution may just be to put a bomb on the keel. But a lot of motion also has to do with the natural righting moment of the hull shape itself.
If its just rolling at anchor, you could just "wing out some weights" to stiffen her up a bit.
Or a similar idea using buckets. Cheap and effective.
7729--Building a Stabilizer
__________________
Cheers
Oz
...............
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07-05-2012, 22:16
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#14
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Moderator Emeritus
Join Date: May 2007
Location: Ohio
Boat: Now boatless :-(
Posts: 11,580
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Re: Removing Concrete Ballast
Quote:
Originally Posted by dandreadnought
does anyone have any advice on changing ballast from concrete to lead. i have a dreadnought 32 full keel boat. i hope it will be more stable.
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A friend of mine here spent a couple of months jackhammering cement out of his bilge. It is not a job to be undertaken lightly. He basically wanted access to the steel hull and also wanted to reduce total weight of the boat. He has not put anything back in so far.
Are you planning to put the same amount of weight back in? Have you calculated the weight? Do you have a source and a price for this much lead?
As far as your question - "Does anyone have any advice?" - My advice is move weight around the boat first and see if it makes a difference.
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08-05-2012, 12:19
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#15
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Registered User
Join Date: Apr 2012
Location: Maui
Boat: Dreadnought 32
Posts: 5
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Re: Removing Concrete Ballast
sorry for not being clear. i was talking about stability under sail.
a big reason i think it is worth removing the concrete, is we are concerned the steel punching will rust and expand and cause a huge problem.
we just bought the boat and intend to entirely re do everything, and don't want to have to then go back and tear it apart later.
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