Bilge Water and Encapsulated Keel

[anjolain]

When cleaning the bilge last autumn, I noticed a suspicious spot on the back corner of my deep bilge. I have had the boat for two years, and this was the first time that I removed the floorboards to get access to clean the bilge thoroughly. In the back corner of the bilge I found a spot which was not covered by the topcoat. See the attached picture.

The spot may have been there since new, or it may be a result of frozen bilge water. Nevertheless, it is on the place which is often wet, because it is very difficult to dry the bilge completely. Even the drain plug does not drain the back corner of the bilge, not the mention the bilge pump. I am little bit concerned about the moisture, that may have seeped into the keel. Furthermore, I believe, that the previous owner of the boat was not too interested in drying the back corner of the bilge.

My boat has an encapsulated cast iron ballast. However, I believe that there is some other filler material used under the bilge, since it sounds different (when tapped with a hammer) compared to the iron in front of the bilge.

Just to reinforce my fears, I noticed that some spots on the keel (and under the bilge) remained wet, as a result of condensation, when temperature was close to zero. I believe that there are some cavities on the keel that maybe filled with water.

My repair plan for the next winter lay-up period is following:

1. To drill some holes in the wet spots on the keel, see what comes out, dry out and inject epoxy into the holes.

2. I am also doing a bottom repair (slurry blasting, new epoxy coatings etc.) next winter. The yard that I am using has a HotVac -equipment available, so I am planning to have the gelcoat peeled off the keel, and use the HotVac to dry the water out from the keel cavities. Any ideas, how efficient HotVac could be on this kind of situation?

3. With the bilge, the most important thing is to have it watertight. As water with some diesel and oil has been standing there pretty long, it may be difficult to have epoxy to stick with the laminate. I have been sanding the bilge quite a lot, but there are still some darker spots in the laminate. If I now seal it with epoxy, is this going to make matters worse, since I am sealing the moisture in? One option that I have heard of, would be to drill some holes into the bilge and pour some acetone.

I would appreciate your thoughts especially on HotVac, and bilge coating.

[zeehag]

what make boat is it?

[barnakiel]

When the boat is on dry drill a hole through the laminate to completely dry the keel. You will know then how much water found its way into the ballast section.

In either case there is not much that can be done - dry the thing and patch the hole very, very well.

From the inside, I would clean the bilge with hot water and strong cleaning agent to get rid of any traces of oily substances. Then I would re-seal the top epoxy/glass/epoxy. If access is very bad, I would just pour epoxy/hardener mix and let it settle in the lowest point of the bilge to seal it completely off.

Most interesting post and a great picture too.

b.

[atoll]

i would be a bit wary of drilling holes in the bottom of the keel,as they can be very difficult to seal again,water trapped in the encapsulated keel can take years to drip out,plus the oily nature of bilge water and positive pressure will work its way past the epoxy before it has a chance to cure.

tenting the keel over winter and keeping it heated will evaporate water trapped in the keel.

after that pouring liquid resin and filler mix should seal the bilge from further problems.

cast iron needs air to rust,so the better it is sealed the less chance of expansion from rust.

[barnakiel]

Originally Posted by atoll

i would be a bit wary of drilling holes in the bottom of the keel,as they can be very difficult to seal again,water trapped in the encapsulated keel can take years to drip out,plus the oily nature of bilge water and positive pressure will work its way past the epoxy before it has a chance to cure.

tenting the keel over winter and keeping it heated will evaporate water trapped in the keel.

after that pouring liquid resin and filler mix should seal the bilge from further problems.

cast iron needs air to rust,so the better it is sealed the less chance of expansion from rust.

Yep.

Should any holes be drilled in the bilge to let the moist air out?

BTW this take is probably best in warm climes - I guess cost of keeping the boat in a heated space over the boreal winter could be prohibitive.

b.

[Fiberglass1Inc]

Hot vacs hve been very effective for drying certain laminates in certain conditions. However, it comes with a caveat. Have you ever tried to dry a shirt that went over the side into salt water? Then you know that you will never get it truly dry until all the salt has been removed. The glass fiber in your hull is really no different than the cotton fiber in the shirt and must be fresh water rinsed many times before it can completely dry and the hot vac, if applied too soon will remove 95% of the moisture but not the salt. As soon as the vac is removed the remaining salt will pull the moisture right out of the air and onto the laminate surface. Another equally important benefit of the frequent fresh water rinse is that glycol compounds, which are the chemical result of broken down polyester, will blush to the surface along with the salt. Once these have arrived on the surface they become tacky and very difficult to thouroughly remove. The fresh rinse every other day will remove the blush before it has a chance to dry. Nothing sticks to glycols.

[cburger]

Have you moisture metered the suspect areas to confirm you actually have a problem?

[atoll]

Originally Posted by barnakiel

Yep.

Should any holes be drilled in the bilge to let the moist air out?

BTW this take is probably best in warm climes - I guess cost of keeping the boat in a heated space over the boreal winter could be prohibitive.

b.

water trapped in voids is not a big deal if the bilge floor is sealed up properly,iron needs air to rust.

there are some very good water soluable epoxy products that may be better for this type of repair that can be poured into the bilge rather than coventional amine resins.

http://www.antel-uk.co.uk/tds/waterb...y-coating.html

[anjolain]

First of all, great forum! Thanks to you all for contributing.

"what make boat is it?"

The boat is an older Hallberg-Rassy.

"Have you moisture metered the suspect areas to confirm you actually have a problem?"

I do not think, that moisture meter is totally reliable with the keel if there is some filler material inside. The hull was quickly checked with a moisture meter a couple of days ago, and at least the hull seems to be relatively dry for a 20 years old boat.

It is also promising to hear that HotVac is efficient in drying the laminate. I do not think that salt is going to be much of a issue, since the boat has spent the last +10 years in the Baltic Sea, which has a low level of salinity. Secondly, I believe that it was mostly fresh water (together with some diesel/oil), that has been lying in the bilge. The keel looks ok from the outside, so there is no signs of blistering. I believe that the laminate in the keel is very thick and it is most probably the strongest part of the boat. So I do not think that some moisture in the keel would significantly weaken the boat structurally. However, as she is going to have the bottom renovated and going to spent the next winter indoors, I think that it is reasonable to deal with this issue before it turns into a major problem.

I hope that the iron ballast is intact, so the problem is limited to the area under the bilge. I am not sure however, what filler material is down there...

[atoll]

Originally Posted by anjolain

First of all, great forum! Thanks to you all for contributing.

"what make boat is it?"

The boat is an older Hallberg-Rassy.

"Have you moisture metered the suspect areas to confirm you actually have a problem?"

I do not think, that moisture meter is totally reliable with the keel if there is some filler material inside. The hull was quickly checked with a moisture meter a couple of days ago, and at least the hull seems to be relatively dry for a 20 years old boat.

It is also promising to hear that HotVac is efficient in drying the laminate. I do not think that salt is going to be much of a issue, since the boat has spent the last +10 years in the Baltic Sea, which has a low level of salinity. Secondly, I believe that it was mostly fresh water (together with some diesel/oil), that has been lying in the bilge. The keel looks ok from the outside, so there is no signs of blistering. I believe that the laminate in the keel is very thick and it is most probably the strongest part of the boat. So I do not think that some moisture in the keel would significantly weaken the boat structurally. However, as she is going to have the bottom renovated and going to spent the next winter indoors, I think that it is reasonable to deal with this issue before it turns into a major problem.

I hope that the iron ballast is intact, so the problem is limited to the area under the bilge. I am not sure however, what filler material is down there...

on a 20 year old europeon boat,most probably a polyester resin with a mix of microballoon's(armospheres) would have been used to fill voids,and set keel in place

[cburger]

[QUOTE=anjolain;950767]

I do not think, that moisture meter is totally reliable with the keel if there is some filler material inside. The hull was quickly checked with a moisture meter a couple of days ago, and at least the hull seems to be relatively dry for a 20 years old boat.


If I was contemplating a project of the scope you are discussing I would want to be absolutely sure I was not chasing a ghost. If you are contemplating drilling holes into the keel to drain water I think I would get that moisture meter around the areas of the keel that are suspect and not make any assumptions.

My boat has a deep bilge at the back of a full keel with an encapsulated lead slug. Boat has been up on the hard for many years. I decided to put another layer of glass with polyester resin on the bilge bottom, then coat with barrier
coat for good measure.

[barnakiel]

If you contact HR they will most likely tell you how the boat was laid up and what components were used.

b.

[anjolain]

Originally Posted by atoll

water trapped in voids is not a big deal if the bilge floor is sealed up properly,iron needs air to rust.

there are some very good water soluable epoxy products that may be better for this type of repair that can be poured into the bilge rather than coventional amine resins.

Epoxy Paint - Waterbased Epoxy Coating

Thanks for the hint, it seems like a perfect coating for the bilge.


"drilling holes into the keel to drain water I think I would get that moisture meter around the areas of the keel that are suspect and not make any assumptions."

Yes, hull and keel will be carefully checked with moisture meter after the slurry blasting next autumn. We will be paying special attention to those susceptible spots. Couple of days ago the guy at the yard, who is probably doing the repair, just quickly checked the area with moisture meter. So it is difficult to say too much based on that quick check.

"If you contact HR they will most likely tell you how the boat was laid up and what components were used."

I already contacted HR, and got following answer from them: "The steel keel is put into a keel pocket of GRP. Then a mixture of polyester and talc is poured on to fill out the gap between the steel keel and the GRP outer skin. It is not unusual that there may be some air pockets left, but that is not a big deal"

However, their response did not quite answer my question about the material under the bilge. As I mentioned, it sounds quite different compared to the iron ballast in front of the bilge, so either the iron ballast it is totally delaminated under the bilge, which I do not think is very probable, or there is something else.

[atoll]

Originally Posted by anjolain

Thanks for the hint, it seems like a perfect coating for the bilge.


"drilling holes into the keel to drain water I think I would get that moisture meter around the areas of the keel that are suspect and not make any assumptions."

Yes, hull and keel will be carefully checked with moisture meter after the slurry blasting next autumn. We will be paying special attention to those susceptible spots. Couple of days ago the guy at the yard, who is probably doing the repair, just quickly checked the area with moisture meter. So it is difficult to say too much based on that quick check.

"If you contact HR they will most likely tell you how the boat was laid up and what components were used."

I already contacted HR, and got following answer from them: "The steel keel is put into a keel pocket of GRP. Then a mixture of polyester and talc is poured on to fill out the gap between the steel keel and the GRP outer skin. It is not unusual that there may be some air pockets left, but that is not a big deal"

However, their response did not quite answer my question about the material under the bilge. As I mentioned, it sounds quite different compared to the iron ballast in front of the bilge, so either the iron ballast it is totally delaminated under the bilge, which I do not think is very probable, or there is something else.

industrial talk and polyester mix is quite a lot heavier than a microballoon mix,it is also a lot more viscous,so the chances are if only a couple of applications were used,most of the material migrated to the lowest point of the bilge leaving only a thin layer of polyester on the higher parts of the ballast casting.

i reccomend using a water based epoxy mixed with a good amount of micro fibers to decrease the viscosity,also use a rubber cake spatula to form a nice fillet against the vertical surfaces,this may work best by doing multiple applications after the ballast part is covered initially.

[Fiberglass1Inc]

I may have misunderstood your problem. If there is water inside the void at the aft end of the keel it is unlikely that the hvac is going to pull any moisture through multiple layers of laminate, typically pretty thick in way of the keel. From the photo it looks like a void in the last inside layer of glass. If that's the case just make a clay doughnut slightly larger than the hose of a wet-dry shop vac, plce the hose and doughnut above the void and let it run. Do that off and on for a couple of days and you will remove the moisture. I thought you were trying to remove moisture from the hull in order to do a blister job.