Posted: Thu May 19, 2016 3:12pm

I have a stainless steel tank, that requires insulation. What is the best product and method. Access is best from Aft, wooden, into accommodation. I remove 11/2 buckets of water in the spring from the bilge. It is a Reeves Hull.

Posted: Thu May 19, 2016 5:08pm

I am afraid that I do not fully understand what you want to do or why you want to do it. Domestic bulk water tanks are not normally insulated. The hot water calorifiers usually are but the insulation is applied at the factory. I also do not understand where the 1.5 buckets of water come into tank insulation. Of course you might be talking about a stainless steel toilet pump out tank. Domestic water tanks are normally located right at the front of a narrowboat while calorifiers tend top be towards the rear. The access hatch for the cabin bilge is also at the rear of the cabin. Do you mean that you access the water tank in question from the front of the accommodation by reaching forward under the well deck? Please try to explain what you want to do, why and exactly where this tank is. Also please explain how the water relates to the insulation. Many thanks, Tony Brooks

Posted: Fri May 20, 2016 9:04pm

An interesting comment about not insulating the pot water tank. I have viewed the tank there is a void space of about 6 inches around the tank. The spray foam is thin and poorly applied. When the air is warm and the pot water is cold the tank sweats. This causes leather to turn green mould in the adjacent cupboards. I rotate a dehumidifier and the rooms are well ventilated. I would like to stop the tank from sweating.

Posted: Sat May 21, 2016 7:24am

There are two approaches to this, insulate is as you say or remove the moisture laden air. Both have difficulties. I think the easiest method of insulation would be to make templates for each flat surface of the tank from cardboard and use this to cut polystyrene sheets (say 25mm thick) that could be glued to a dry tank with suitable adhesive. make sure the top sheet or the side sheets are sufficiently oversize so they side of one sheet butts up against the edge of another. Then tape the joints with aluminium tape to complete the vapour barrier. If the tank is triangular you might be able to use a long baton to push the front of the side sheets into position but you are unlikely to be able to tape the front joint. Unless you take the tank out you will not be able to insulate the bottom of the tank. The other way is to try to avoid warm cabin air getting into the bilge area. A simple way may be to seal the aperture behind the lining and furniture that give access to the tank using polystyrene sheet and a polyethylene vapour barrier, again taped at the edges to form a vapour barrier. Ideally when the boat was built arrangements would have been made to ensure there is a constant draft of air through the whole bilge area but retrofitting it will be very difficult. However having insulated and vapour sealed the aperture as above it may be possible to cut outside vents in the cabin front bulkhead and remove a strip of insulation from between the bulkhead and lining to allow some air exchange to the tank area. Unless you are a live-aboard I would advise that you leave your cabin bilge trap open throughout the winter.The bilge water could just as easily be from leaking windows or condensation on any uninsulated areas of the hull, including the base plate.

Posted: Sat May 21, 2016 11:22am

Yes I am a live aboard, I have 2 fans from the bilge supplying fridge and freezer. An extraction fan over the shower. The windows are Channel Glaze deluxe anodised double glazed. The frames get dripping wet but they have drain holes. I was hoping you to say fill it up with rock wool, this is to fill up the air space to stop an air change cycle.

Posted: Sat May 21, 2016 12:07pm

There is no way I would advise that because such products can and do absorb water. However if you can get some large polythene bags, fill the with rock wool, seal them, and pack the void with them it would go some way to keeping the amp air away from the tank and the bags would prevent the Rockwool absorbing water. the bag would also act as a local vapour barrier. If you can find a way of allowing external air into the void and put a vapour barrier behind the wooden lining you may well find your existing fans would keep that are fairly damp free. That would be my first approach.