Ballast Tank Inspection Hatches

I put inspection hatches in the top of the ballast tanks so that I could get at the pivot bolt for the centreboard. This seemed like a good idea at the time because it would avoid cutting holes at some future time if I needed to get at the bolt. Now I am not so sure and, if I were doing it again, I would have made the tank tops solid.

I used these hatches made by Nairn. The lid screws in and is transparent. It was quite interesting to watch the tanks fill up when the boat was launched.

The transparent lid is strong but the white plastic ring isn't. I stepped on one of the hatches, fortunately while the boat was on the trailer, and the lid broke the threaded part of the ring away from the surround with the screw holes. If the boat had been in the water I would have had a big problem!

I removed both the hatches and cut the remains of the broken ring so that I could see how it had failed. Here are a couple of photos. First photo shows what is left of the outer part of the hatch.

The next photo shows a cross section of the outer part of the hatch. You might need to enlarge the photo to see the crack across the narrow corner. The plastic at that point is only about 1.5 mm wide and is certainly not strong enough to stand on, at least not when it is poor quality plastic.

 

I went looking for a better type of hatch to put in the existing holes. Needless to say, the metal hatches were too small! I now have two new hatches but I had to enlarge the holes slightly.

 

 

These hatches are made by Armstrong, click here for more info. They cost about 4 times the original Nairn hatches but they are more than strong enough to stand on!