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Old 11-23-2016, 02:13 PM   #1
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Putting Ballast into a hollow keel

I have a 1983 30' (29'7") Atlantic/Prairie trawler which is 12,000 lbs.displacement. I just switched from a 43' 32,000 lb. deep keeled sailboat to this boat and the difference is considerable. I was wondering if anyone has placed additional ballast into the hollow keel of this boat? I have a flying bridge & the dink is carried high up to the bridge deck level and I think some additional ballast would make the boat steadier & smoother without hindering performance. Any thoughts?
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Old 11-23-2016, 03:14 PM   #2
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About the same situation here: my last "big" boat was a 41' sailboat and I just bought a Prairie 29.
I knew what to expect: trawlers will never be as stable as a sailboat and the Prairie 29 is a small boat. Small waterplane: look at how the hull flares open a few inches above the waterline.
That small waterplane is almost certainly why she moves so easily, burns so little fuel but it also reduces initial stablility. Add a high VCG and you have a boat that rolls
easily. It is more the result of the hull shape than ballast ratio. Ballast will only work at pronounced angles of heel.
I accept the boat as she is: I did not expect a big boat or sail boat stability and I am certain that it is not unsafe.

In my designs, to add ballast in a box keel, I specify lead ingots with the space between them filled with lead shot and epoxy poured over.
It is practically irreversible.
If you want try with just a couple tons of ingots 1st.
It will bring the DWL down. She will still roll but the heave will be reduced. Fuel consumption will increase and resistance too. I hope you have enough HP to compensate.

I would not do it.
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Old 11-25-2016, 07:06 AM   #3
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I can share the downsides of such installation. My prairie was afterfitted with concrete ballast from the fwd engine room bulkhead all the way aft to the stuffing box. To do this the stuffing box was removed, about a 5' long bronze tube was fitted to the shaft log extending about 15" from the reduction gear and a DSS fitted there. So I have approximately a 5' unsupported shaft which is susceptible to whipping and flex. The boat does have a very quick 'snap roll' as to what similar hulls of this size I have been on have. Part of my usage is to keep the fuel tanks very low. She holds 200 gl fuel. And I think since I took delivery and got her home I haven't had more than 75 gl aboard at any time. I like to keep the fuel turning around with high filtration.

The downside to the cement is: 1. Inaccessible shaft log. 2. Missing intermediate pillow bearing (as is on plywood bulkhead in your boat). 3. No way to put boat on blocks in Freezing weather to drain bilge (unless you block boat bow down and have a drain hole forward) ((as I do)).

I wish whoever did this installation has put a PVC pipe in the bottom all the way aft so I could drill a hole in aft end of keel for winter drainage. I would concur with lead. You can find lead in approx 2'x 3" ingots that can be slid down, stacked up and still allow drainage. They are removable and can be slid around the shaft to fill up the area down low.

The boat is tender. The PO added a sticker to the ladder to FB. LIMIT 5 Persons on FB. For a sensible reason.
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Old 11-25-2016, 08:05 AM   #4
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Please, please do not let Art see this post. He will bonkers!


Sailor: Art started a post about this topic. There is some good info on that post so have a look.


I would say give it a try to see how it goes. You can always remove it.

Best of luck and happy cruising too you.

Cheers
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Old 11-25-2016, 08:38 AM   #5
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I had a Jarvis Newman that had concrete in the keel. I also owned another lobster type boat that had a water balasted keel. Both worked well.
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Old 11-25-2016, 09:01 AM   #6
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Quote:
Originally Posted by hfoster View Post
Please, please do not let Art see this post. He will bonkers!


Sailor: Art started a post about this topic. There is some good info on that post so have a look.


I would say give it a try to see how it goes. You can always remove it.

Best of luck and happy cruising too you.

Cheers
H. Foster
Where is that post?
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Old 11-25-2016, 11:25 AM   #7
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Here's one of them. Cement Ballast in keel?
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Old 11-25-2016, 11:25 AM   #8
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Jacquesm:


Here it is. Sorry I should have posted it with my post.


"Added" Ballast - Good or Bad


I hope Art doesn't see it!

Cheers

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Old 11-25-2016, 12:43 PM   #9
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Thanks.
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Old 11-25-2016, 12:53 PM   #10
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No worries Jacquesm.
Cheers
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