Refit project: Water in the keel!

Posted on by sydolphindance

Last December, when blogging about our maintenance schedule for this winter, I wrote that most probably new things will come up, once we start digging deeper.

Unfortunately, this turned out to be too true — we recently found out that there is water inside DD’s keel! However, this unpleasant finding was not totally unexpected, since last spring, I noticed some condensation on certain areas on the keel when the air temperature was close to zero. I noted down those areas, but I did not want to speculate it too much then: further investigation would have involved drilling holes into the keel, since the moisture meter is not reliable in the keel area. As the sailing season was just round the corner, I decided to leave further investigation for this winter.

The reason for the mysterious condensation became more obvious, when I took a closer look of the bilge: the back corner was looking suspicious since it stayed wet, even if I had dried it just a few days earlier. Furthermore, I found out that a part of the topcoat was missing in the back corner of the bilge. I am not sure if this defect has been there since new, but it was really difficult to spot, since the bilge pump hose was blocking the vision. Only when I lifted the hose, I could get a proper view of the whole bilge sump. Over the years, there has probably been some bilge water standing there. This is the negative side of having a very deep bilge: the bottom of the sump is difficult to reach and the pump, or even the drain plug, does not dry the far end of the bilge. The water in the bilge has probably, over a very long period of time, seeped into the keel.

To investigate this issue further, Jarkko Marsh (from Airisto Marine Oy), drilled a few holes in those suspect areas, which I had noted down last spring. The first drill did not reveal anything other than bone dry laminate and filler. Therefore, the second drill was aimed at a bit lower spot, and this time some water was leaking out from the hole. We decided to drill more holes into the keel in order to get all the water out. The good news is that, there is no iron ballast under the bilge sump, but some kind of putty which is used as a filler. If iron would come in contact with water, it would start to rust and expand, which would have probably damaged the fiberglass as well.

At first, Jarkko set up a vet vacuum machine to the holes to get the most of the water out. After this was completed, he set up his HotVac-pads on the keel. To my knowledge, the HotVac Hull Cure is the most advanced method of drying up fiberglass laminate and it is used widely in osmosis repairs for example. The HotVac pad applies controlled, uniform heat and high vacuum to the affected area. This treatment should also get DD’s keel completely dry. After the treatment, the holes will be filled and re-laminated, and the bilge re-coated. I will report about the progress of this repair later in the spring. 

In general, an internal ballast/encapsulated keel structure, used for example in all Enderlein’s HR-designs, is a strong and almost maintenance-free structure — as long as the water stays out. But the fun part begins when water is added into the soup. Most often, this might happen if the keel is poorly repaired after a grounding. However, also the bilge water may over the time leak into the keel, since after all, the topcoat in the bilge is not totally waterproof. Therefore, in my opinion, the bilge should have been initially coated with epoxy and not with topcoat. However, a larger leak would require some sort of damage to the topcoat layer (e.g. cracks, missing topcoat or leaking screwholes etc.). In general, keeping the bilge dry is a good idea for any boat, but I think that it is especially advisable for boats with an encapsulated keel. 
/Antti
Water leaking out from the lower hole
HotVac pad installed to the affected area.
The pad applies controlled heat and high vacuum 

      DD was lifted up a bit and is now supported from the hull, so the keel is hanging free. This makes it possible to apply new barrier coat also to the underside of the keel.