Water eviction

G

Graham_Wright

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www.mastaclimba.com
I've found that I have water in my encapsulated keels. (Before you chide me over correct sealing, read the experts comments and confirm that you have checked yours (that's vulnerable sensibility speaking!)).

As long as air is excluded, I see no problem with rust expansion of the steel shot ballast. I would like to fill them with oil but my lubrication oil supplier does not know of one with an SG higher than that of water.

Can anyone advise please?
 
The question is how did the water get in there?
If it came in from the bilge then perhaps the best bet is to try to dry the water out with warmth and of course no water in the bilge.
If it came in via damage to the skin ie at the bottom of the keels then your best bet is to grind away the skin where it is damaged. This should allow the water to run or seep out. Dry it as thoroughly as possible then lay up replacement fibreglass.
It sounds like you have a plan to soak it all in oil from the top which is proably a good idea. I am no0t sure you could hope to avoid rust (and expansion) by excluding air.
Perhapos for a proper fix dig ou the steel and replace with lead.
good luck olewill
 
I had a problem on a previous boat with encapsulated bilge keels ballasted with mild steel stampings set in pitch. The bottoms of the keels were quite badly worn and cracked following some years on a hard sand drying mooring. What surprised me was how little corrosion of the steel there actually was: any exposed surfaces rusted extravagently, but the body of the material was effectively inert. Excluding air is clearly the main priority, and I would suggest that this is mainly governed by how free of voids the non-weighty filling material is. If you do have voids, then pouring in molten lead sounds like a basically attractive idea, but I can't recall offhand whether Pb's melting point (c. 250 degC) is above that which will upset GRP. No doubt someone here will know. If that is a problem then a runny epoxy resin might be a safer bet.
 
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... pouring in molten lead sounds like a basically attractive idea...

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Pouring molten lead into anything which is not dry is very dangerous.
 
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Pouring molten lead into anything which is not dry is very dangerous.

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Absolutely!! /forums/images/graemlins/shocked.gif

You only get to do it twice:
The first time and the last time. /forums/images/graemlins/frown.gif
 
A neighbouring boat in our yard had unselaed steel stampings in his bilge keels. Water got in, they had rusted and were blowing the keels apart. It was an appaling job to break up the rusted mass and dig it all out.

Steel should be Ok if sealed in with pitch or some other waterproofing compound, but I think molten lead would just go straight through the mouldings, and probably set the rest on fire! Also do not try concrete - another small GRP boat came in with concrete ballast poured in the bilges. Chemicals in the concrete had interacted with the resins and the whole contact area with the concrete was so brittle it could be broken up by hand! I have heard there are grades of concrete that CAN be used with GRP.
 
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The question is how did the water get in there?

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I was trying to avoid that because it is irrelevant. The boat is on dry land.

After filling the keels with a mixture of lead and steel shot, capping them and building up a tank around the void for fuel stowage, personal circumstances forced me to abandon the build for several years. During that time, rainwater ingress built up to overflow into these tanks. When I recommenced the build, I pumped our and remedied any damage and (amongst the rest of the jobs) continued with the tanks. It was then I discovered that water had penetrated through the capping to the keels. Drilling a hole near the bottom allowed a considerable amount of water to egress. This water was clear with not a trace of rust. My surveyor sugessted displacing any residual water with a mineral oil. Unfortunately, all the oils I have found are lighter than water so will not displace it above the still-existing drain hole. This is probably above the lead ingots and lead shot that filled the base of the keel and is probably well sealed with resin.

Although the capping at the top of the keel was several layers thick, it allowed water ingress. I am told by the professionals that raw GRP without gelcoat is permeable although only to a slight degree. (I am sure there are those that know better than the professionals and will take issue with this but for my situation, it is irrelevant). The keel tops and the surrounding tank walls have now been sealed with Thistlebond (see previous posts). During this protracted process, the tanks were pressure tested and it was incredible how many minute pinholes showed up.

Once the drain holes are sealed any seepage into the keels will be diesel which will not cause rust. However, any water that remains (and any subsequent ingress which contains water) could, in the presence of remaining air, cause the steel shot constituent of the ballast to rust which might be disastrous.

Hence my desire to fill any voids with an inert liquid. The access will be by a hole drilled through the capping and subsequently sealed.

So;- any suggestions please? I have already discounted syrup!
 
As a matter of interest, I cast the lead ingots, inserted them in the bottom of the keel and filled the surrounding voids with lead shot. (This was followed by the top-up weight of steel balls). During the casting, I managed to splash some molten lead on my neck. Surprisingly, although it hurt, there was no blistering. Out of curiosity, I poured a small amount of molten lead into a GRP receptacle. Once cold, I added more and so on to simulate the building up of ballast. There were no voids left in consequence of this technique. The more lead that eixsted before the additions, the more was the thermal capacity to cool down the additions and the temperature rise was reduced although the agreegate took longer to cool.

Bouncing the idea off the forum, the (sensible informed) observations were that it would not be possible to establish if any weakening of the GRP had resulted and I chickened out.
 
I have a simular problem on my steel yacht where the keel is filled with steel shot covered in pitch then capped with a steel plate which has a void between the steel palte and the top of the pitch. I intend to pressure inject LV epoxy into this void and into any gaps in the pitch / keel side join. I intend to fill empty sikaflex type cartriges with epoxy and inject using an air corking tool and air compressor
 
For steel to rust it requires both water and oxygen. If the residual water in the keels has formed a certain amount of rust on the surface of the steel balls it is probably now de-oxygenated. If you have sealed the top with non-permeable sealant the only way that oxygen or fresh oxygenated water can get in is through gaps in the sealant or by permeating through the GRP. The latter can be solved by coating the GRP if you haven't already done it but the former sounds more difficult if regular access to check its condition is prevented by the tank.
 
I cast a 800kg lead keel using a home made furnace, and found that even with the lead flowing through a section of scaffold pipe the lead still cooled so quickly that it layered...I have to say I was pretty suprised about this.

Had to do it all over again and dump it in even faster and also insulated the cast better.

BTW whilst I was reaseaching this ( long job in pre internet days) I heard that it was possible to put your hand into molten lead without it burning!! Provided that the skin is perfectly dry...... Needless to say I didnt try it

Im entirly sure that moltenlead into GRP would destroy it.

Regds Nick
 
Given that you have this problem and without fairly major destruction you are stuck with rusting steel in your keel, i would cut a few holes in the best place at the lowest point in the keel to drain off the water then use your engine oil idea until that also comes out...leave that 'till its stopped draining then try to find a good way of cleaning and sealing the holes.

This at least gets around yr problem of the oil sitting on top of the water...finally top it up with oil again.

Regds Nick
 
Just a different approach, have you considered "cutting/drilling" oil? This forms an emulsion with water which is non corrosive. Ask oil expert about the long term effects of this. And the effects it has on GRP
Or consider using cooling fluid, mixes with water and is non corrosive.
Never tried it myself......
Best regards,
Theo.
 
Yes, both have just occurred to me as we use cutting fluid in my business. I am wary as one supplier declined to give an assurance their product would not attack my machine slides. It became known in the trade as (word deleted).

Car engine coolant contains an anti-corrosion agent and that seems a better bet.

Glycerine has an SG of 1.26 and sounds pretty benign.

I suppose I could use mercury;- help the ballast ratio!
 
why not contact Comma Oils, dont know there address but should be on web.They make a product called "wax seal" which I use on my steel boat it is excellent for keeping rust at bay,this comes in an aerosol but I am sure you can buy it in containers,unlike "wax oil" another makers product, it is more liquid but the liquid evaporates and leaves wax.You may have to put in smallish amounts but at least it will bond with the previous.Comma should be able to tell you if is ok to use altho.I cant imagine it will attack GRP.
 
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