C29 Ballast Configuration

[MrSeaDragon]

Some questions for Mr Compass, or other knowledgeable guru's :

- What would I find if I delved into the keel below the bottom of my bilge ??

My curiosity is piqued by the need to secure "something" (yes its a battery) in the forward half of the bilge. 

- If I drill into the bottom of the bilge, how thick is the glass ??

- Is the ballast a solid cast piece that fills the entire space, or chunks randomly thrown in ??

- Is there air space between the chunks, or around the cast piece, just waiting to be filled up with water ??

- Is the space filled with bog/resin, or something else ??

** Can bilge water, leaking past my battery tiedown fixings, go anywhere and cause a problem ?? 

With hope for answers and kind regards,

Greg

C29 Sea Dragon   

[Phillip of ninoxyacht]

Far easier to grind the f/glass and epoxy some sort of timber bracket to the hull, without penetrating the bilge. 

I've only seen the bilge cavity near the sump and under the (former) diesel. The latter was a water tank. The sump accumulated a lot of dust, debris and had rust in the water. 

Having epoxied plywood to make an outboard well, I'd say that epoxying is far easier than opening a new can of worms. 

Phill 

[Graeme Lock]

Shakti's PO very kindly left a couple of little unfilled holes in her bilge floor, so I can tell you that there is some space above the ballast and that bilge water can accumulate in there. But i don't know how big the void is. 

I can also tell you that if you have some keel impact damage, even minor like mine, it can disturb the sheet of FG that segregates the keel tank from the ballast section, so that a small amount evil-smelling stuff can leak into the keel tank. Which is why I don't use it for drinking water any more.

Cheers, Graeme

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[MrSeaDragon]

Thanks guys for that very interesting info, and yes, I think glassing something in is definitely the best option. I was just hoping that I was past grinding and fiberglassing, but I guess it never ends ! 

I'll put my thinking cap back on.

Kind regards,

Greg.

[Maeling]

Okay! you have a lead ballast casting - however it is shorter than the space by about 220mm.  This spare space (in production) was then filled with Quartz rock - then the whole of the ballast was fibreglassed over.  On Maeling, I used small ingots and stacked them in, filling the voids as I went with lead shot.  I elected to put a fibreglassed in bulkhead at the back of the ballast - giving me a deep well for the bilge pump draw pipe to suck from. at the top of the well I have a 6mm hatch lid to prevent stuff entering the bilge. It has worked well for over 40 years.

AND on the bilge well cover plate I have float switch and auto pump - never used it in anger!

Just to continue this lesson - Don Lees once told me of a yacht he had to fix.  The owner used steel punchings a ballast. At some time he grounded he on a bommie up in the islands and wore a hole into the keel.  The boat started to get tender as the ballast drained overboard.

The things that happen!

Geoff

On Saturday, April 12, 2025 at 7:36:47 AM UTC+10 MrSeaDragon wrote:

[Maeling]

Greg, what problem are you trying to solve? I've missed part of the conversation

Geoff

[Maeling]

In my case, I chose to GRP a wall at the back of the ballast.  I can see down to the moulded bottom of the well, the floor of which is about  200x90mm

G

[MrSeaDragon]

Hi Geoff, 

Other than satisfying my curiosity about the only part of my boat that I don't know intimately ;-),  I am wanting to secure a battery in the forward part of the bilge. One option is to drill into the glass over the ballast, and I'm just wondering on the possible ramifications of doing that (bilge water penetration etc). The ramifications would be dependent on the composition of what lies underneath it. 

I think I've decided not to drill into the glass anyway, and to just glass on some blocks to anchor the battery to. 

So are you saying that on the production boats the ballast was solid cast lead that fitted the moulded keel void fairly well and just needed glassing over ?? So, If I did drill through the glass on either the top or the sides there would be little or no void between the glass and the lead ??

On your details of the aft end of the ballast, on my boat the keel water tank extends forward to level with the start of the dinette seat, and has a very deep forward section 200-300mm long measured fore-aft. I'm guessing this is the same space which on your boat is the deep part of the bilge.

Kind regards,

Greg

C29 - Sea Dragon

[Maeling]

For production reasons, I expect the ballast casting would have been a loose fit not requiring any modification after fitting.  Then being glassed in so it can't accelerate.  The well on Maeling is about 250mm long fore and aft.  The back of the well is the aft water tank.  I did some work on a C28 a long time ago and was disappointed by the oily water sloshing around and smelling.  On Marling, I have a GRP moulded pan sitting below the engine to catch any oily waste.  Luckily the Beta 14 doesn't leak (yet)

Geoff

[Maeling]

It appears Don was looking over my shoulder.  He is not happy with the thought of someone penetrating the membrane enclosing the ballast.  I do know he once had to survey a boat that LOST its ballast!!

Not sure what type of boat but the owner had completed it and for ballast used steel punchings as a densly packed ballast. But - the boat grounded on a coral reef and wore a hole in the keel - the punchings spilled out like a Pokie win.  - Oops!!

Geoff

[MrSeaDragon]

Thanks Geoff, Don & All :-)