Our step by step guide is designed as an introduction to the boat shrink wrap process. Boat shrink wrapping may involve working at height and the use of a propane gas heat tool and in doubt you should always ensure that you have the correct training and equipment.
The perimeter band is what the bottom edge of the shrink wrap film will be fixed to. It provides a tidy, finished edge to the cover and also anchors the shrink wrap down so that when you finally heat shrink the cover, the cover pulls tightly around the boat. Without a perimeter band, during heat shrinking, the shrink wrap would have a tendency to pull up and the finished cover would be too slack. On very small boats it may be possible to tape the shrink wrap sheeting around the hull of the boat but in our experience we have found a perimeter band to be the most robust solution. A perimeter band us typically made from rope or a woven strapping.
As mentioned, the perimeter band is generally positioned at the level of the waterline of the boat. This is because most people do not feel it necessary to provide weather protection to the underside of a hull but also because it can be very difficult welding and shrinking the cover deep underneath the hull.
You may find it necessary to drop some loops of rope or strapping from cleats or stanchions down to the waterline every 2-3m to hold the perimeter band in the right place. The perimeter band is then tightened. There are products specifically designed for tightening woven strapping around pallets that can be used for tightening the perimeter band but most boat shrink wrappers tighten the strapping by hand.
For boats up to 20 metres (60’) in length we always try and use a roll of shrink wrap that will completely cover the boat (both lengthways and across the beam) without joins. Although it is quite possible to overlap and heat weld two sections of shrink wrap together, this can be time consuming and with respect to shrink wrap boat covers in particular, may adversely affect the finished appearance.
Typically, a shrink wrap cover for a boat will finish at or around the waterline where the perimeter band has been installed. Measure over the highest part of the boat and 30 cm below the perimeter band / waterline to determine the maximum width of shrink wrap film that you require. (Because of the shape of most boats, you will always have an excess of film at the bow that must be trimmed.)
Shrink wrap film is available in widths of up to 16 metres. So, if you are shrink wrapping a large boat that requires a film wider than 16 metres, you must then use the film across the boat, rather down the length and it will be necessary to make a weld or join between two sheets of film or weld a skirt around the lower edge.
Shrink wrap film, once heat shrunk ‘drum tight’ will tightly mould around the boat and fittings. However, any particularly sharp edges should be padded to avoid creating a hole during the heat shrink process. Shrink wrap sheeting can be cut around ‘protrusions’ such as masts and aerials and then heat welded & taped together but it is very difficult to make a guaranteed watertight seal. If possible, avoid protrusions and lower and masts or aerials before you start the shrink wrap process.
Place the roll of shrink wrap on a stand so that it can be turned and unwound easily. Using a stand also keeps the shrink wrap film off the ground and so keeps it clean and free from damage from small stones etc which may cause small punctures in the shrink wrap. For boats that can be covered in a shrink wrap roll up to 16m, the stand is placed at the stern and the shrink wrap pulled along the centre line of the boat to the bow. For boats that are wider than 16m, the stand will be placed at the side of the boat and the shrink wrap pulled over the boat from side to side in strips (number of strips depending on the length of the boat).
Place the film on the stand so that as you unroll it, the folds of the film are facing upwards. This will help to stop it snagging when you unfold it.
In step 4, the shrink wrap film was pulled from the roll over the boat to the bow. Ensure you have enough shrink wrap film over the bow, so it is 40-50cm below the level of the deck. Bear in mind that because of the shape of the bow you do not need to take the film over the bow and down to the waterline as you will have to trim a huge amount of film away.
Cut the film from the roll. Unfold the film. A shrink wrap film designed for shrink wrapping large items like a boat or industrial product should be centre folded. This means that when you unfold the film, it remains centred on the boat. If this is not the case, don’t worry, it will just need a bit of readjustment to make sure everything is level and equal.
Starting from the widest point of the boat, tuck the shrink wrap film around the perimeter band and up the inside of the cover. If the perimeter band has been tightened sufficiently it should hold the tucked film in place enabling you to use the heat gun to create a weld between the two pieces of shrink wrap film. The weld should be approximately 30cm deep and any wrinkles and air bubbles should be minimised. As you work forward towards the bow, tucking the film around the perimeter band and heat welding it to itself, you will inevitably find that the film is hanging further and further below the perimeter band and you will need to trim some of the shrink wrap away to maintain a neat 30cm, overlap and heat weld around the perimeter band. Once completed, the rope or woven strapping should now be pocketed in the shrink wrap weld.
Because a boat is a complex shape, there will be parts of the shrink wrap cover where it must be trimmed and heat sealed.
At this stage, it can be useful to install woven strapping that pass underneath the hull which will prevent the perimeter band being pulled up as the boat cover is heat shrunk drum tight. This will result in a much tighter finished cover.
Finally, you can now begin shrinking the cover to get the drum tight finish you are looking for. Using a propane gas hot air gun, start at the perimeter band and shrink upwards, using a technique similar to spray painting as you heat the cover and chase any wrinkles and creases away from you.
Always use the heat gun sparingly directly around the perimeter band area where the cover has already been welded. Shrink wrap film, once heat shrunk, will have a tendency to make a hole when you go back again to finally shrink the cover. Although these small holes can be fixed using shrink wrap repair tape, lots of repairs will affect the finished appearance of the job.
To get the best results you should try and heat shrink 100% of the surface are of the cover. However, the shape of boats can make shrinking over the top of the boat very awkward, particularly on large yachts and motor boats. In addition to selecting the right type of access equipment fot your needs you should consider using an extent
A zipped access door can be installed to allow access to the boat. Although a door can be installed at any location, they are generally installed to allow access into the cockpit. The most common type of door features a ‘U’ shaped heavy duty zipper which is sewn into a rectangle of polythene. When the shrink wrap sheeting has been fully installed and heat shrunk ‘drum tight’ the door is taped into the required position using shrink wrap tape. Finally, the door is unzipped and the shrink wrap cut away to create an opening.
Where a boat is to be shrink wrapped for storage it is advisable to make provisions for ventilating the cover. Specialised self adhesive air vents can be used or a hole can be cut into the shrink wrap sheeting.