Spray after ballast and batons and ducting and sub flooring. Mask flooring, around windows etc carefully. Time and care at this stage will save a lot of work and effort in the future. Cover batons with parcel tape before application of foam. This can be peeled off after the foam has cured leaving a smooth surface ready to receive the lining sheets. Over-spray on floor bearers can be easily removed with a spade.
If removing windows, place cut ply forms that are slightly larger than the aperture on the inside of the shell and hold in place with a dob of silicon or MS polymer. After spraying these forms can be removed, leaving the shell insulated close around the window aperture.
If windows cannot be removed, they can be masked. The last thing you want is pu overspray on the glass. Any areas of the shell skin that are not insulated can be infill insulated at a later date with aerosol spray can foam.
After you have laid the sub-floor you can remove high spots of PU sprayed foam insulation off the walls and ceiling. It’s safer and easier to tidy up the insulation after the floor is down and you won’t be continually picking bits of foam out of the bilges and from between the ballast.
Lay some dust sheets over the floor to catch the mess, use a straight edge across all the batons that will support the interior lining and remove insulation high spots. This can be easily done with a pad saw and a sharp blade. As we mentioned above, remove all overspray from any areas that need to be exposed to support panels. This is one of the most physical jobs after the ballasting that you will have to do so take your time and don’t cut corners. Care taken here will ensure a good surface for the panels to be mounted on. You can make a curved form for the roof to ensure there are no high spots between the batons that will hold the roof panels, especially if the panels are curved to the shape of the steel.
It’s worth noting here that even timber batons can cause a thermal break in the insulation if they are exposed. Often manifested as stripes across the boat roof or sides on frosty mornings, the way to prevent this is to apply further insulation over the sprayed PU foam and between the batons and timber cladding panels. In this instance metallised plastic insulation can be sandwiched between the exposed batons and the linings.
Information on types of insulation available can be found in the Integral Parts
section of the website.