Article Update by Tom Holtey:
The plastic welding links and videos below are applicable to all brands of kayaks made of high density liner polyethylene:
The plastic welding video below is the ONLY one on YouTube that Tom has identified as showing proper, or nearly proper, welding technique for cracks.
The links below will shed some light on the subject of a “hole” and “drag damage” repairs, but are not necessarily good technique:
How to plastic weld a Polyethylene kayak
Repair of Agricultural Sprayer Tank
ALL other YouTube plastic kayak welding videos can be considered suspect, too difficult or are plain just wrong!
Holes from dragging a kayak may 1st appear as a crack, but they are not, and will require a patch.
Do not expect colors to match! There will be an ugly scar anyway. You cannot make the kayak look “new”.
We also sell Plastic Welding Rod, 10 Pack, with enough weld sticks to do 50 inches or more (about 5 feet) of crack or about 100 hundred screw holes.
Filling drilled holes is very similar to welding a crack, but you do not have to scrape out a valley. Do however make sure that all foreign matter, sealant and such, is removed for the hull. A scrapper or knife blade is useful for that. Heal weld rod very hot to make slightly soft. Heat kayak at same time, but not a hot, just hot enough to be shinny. Insert into hole. Use a swirling motion, like stirring a cup of tea. Fill hole and clip of rod with wire cutters. Tamp down with a cool metal spoon.
A hot air gun is the best possible tool use. It is versatile, easy to use and get as well as affordable. A hot air gun with reduction nozzle and adjustable temperature, such as the Milwaukee in the Liquid Logic video, is best. (Just be sure the hot air gun and the reduction nozzle match!) The Wagner Paint stripper Kit is a good hot air gun kit to get. The cost is affordable, about $50, and it come with the scrapping tool in the Liquid Logic video. Use Amazon Link below:
How to determine the proper methods & materials for repairing polyethylene plastic, fiberglass, Kevlar, and carbon fiber kayaks. (For mounting hardware or design modifications see our Kayak Repair & Customization Section)
If you have a damaged kayak, your first step should be to make sure you know exactly what material your kayak is made from. Kayaks are generally made from either composite materials or plastic.
Composite kayaks are made from either fiberglass, Kevlar or carbon fiber. Some are also made of a combination of these materials (for example a layer of Kevlar then a layer of fiberglass), or a hybrid combination of these (for example carbon fiber weaved with Kevlar).
What composite kayaks have in common is their basic construction method. In a nutshell, the kayak manufacturer combines the composite material in it's dry "fabric" form with "resin", which acts as a strong glue. The material is then shaped in a mold and allowed to set. Once it is dry it becomes the kayak you know and love. (right: Current Designs "The Zone" - A look inside the hatch of a fiberglass kayak reveals the fabric construction materials)
The other thing that most composite kayaks have in common is the "gelcoat" layer. Gelcoat is the smooth layer of material on the outside of a composite kayak. It is a layer of a special type of resin. It can be white, colored, or sometimes clear and is there to provide protection for the composite material. It also is there for aesthetics.
If you don't know what type of material your kayak is made from you can contact your boat's manufacturer or ask at a boating or kayaking store for information.
Most very old composite kayaks are made from fiberglass since Kevlar and carbon fiber are newer innovations. If you have an old composite kayak and thus can't contact the manufacturer, it is quite likely that you have a fiberglass kayak. (right: The Zone fiberglass construction)
If you have a damaged composite kayak, once you know the construction material, your next step should be to assess the damage to decide whether you need to repair it, and, if so, what sort of repair to do. (Skip down to Deciding On Composite Kayak Repairs.)
Deciding Which Type of Composite Kayak Repair To Do
Assess the damage to determine whether you need to repair it, and, if so, to decide what sort of repair is required. Below is a guide:
|Deciding on Composite Kayak Repair||Nature of damage What needs to be done|
|Scratch or chip in gelcoat that does not reach the composite material underneath||Nothing needs to be done. This is a superficial scratch and structural integrity is still intact. You can repair for aesthetics, however. Search term: Gelcoat Repair.|
|Scratch or chip in gelcoat that does reach the composite material underneath, however does not damage the composite material||Structural integrity is still intact so you don't need to repair any composite material, however you should repair the damaged gelcoat to minimize the risk of future composite material damage. Search term: Gelcoat Repair.|
|Deep scratch that goes through gelcoat and damages the composite material underneath.||Structural integrity is no longer intact since the composite material has been damaged. You should do a composite material repair using the material your kayak is made from. See step 2 below for further details. Once you have done the composite repair you can do a Gelcoat Repair for aesthetics.|
|Crushed hull, hole in hull or any other type of damage that seriously deforms the kayak or stops it being watertight.||Structural integrity and hull integrity are no longer intact. You should do a composite material repair using the material your kayak is made from. See below for further details. Once you have done the composite repair you can do a Gelcoat Repair for aesthetics.|
|Kayak broken in half!||You can repair a composite kayak that has broken in half. The specific process for this type of repair is not covered on this website, however information in composite repair (for more details see below) and using the search term Gelcoat Repair should provide some valuable help.|
Plastic kayaks are made from polyethylene, which is a very strong, durable plastic that is so common that you probably come into contact with it many times a day. Polyethylene is used in a massive range of products including shopping bags, water bottles, shampoo bottles and children's toys. (right: Perception Illusion rotomolded plastic)
It should be fairly obvious if your kayak is plastic. It will have similar properties and appearance to other polyethylene products that you are probably familiar with. If you are unsure whether your kayak is plastic you can contact your manufacturer for details or ask at a boating or kayaking store. (left: A thermoformed plastic kayak, like this Hurricane Phoenix, can mimic a composite boat with its two-toned combined halves construction)
If you have a damaged polyethylene plastic kayak your next step should be to assess the damage to decide whether you need to repair it and, if so, decide what type of repair to do. (Skip down to Deciding On Plastic Kayak Repairs)
Deciding Which Type of Plastic Repair To Do
Step 1: - Assess the damage to determine whether you need to repair it, and, if so, what sort of repair is required. See the table below:
|Nature of damage||What needs to be done|
|Kayak hull is deformed or bent out of shape.||Reshape the deformed area. See Reshaping Deformed Plastic Kayak.|
|Shallow scratches that do not penetrate the kayak hull.||Nothing needs to be done. There is no way to repair shallow scratches on plastic kayaks. There is also no need to repair them. Plastic kayaks are incredibly tough.|
|Deep scratch that does not actually penetrate the kayak hull but leaves only a very thin layer of plastic.||You can do nothing and repair the damage if it eventually does penetrate right through the hull or you can use scissors or a Stanley knife to finish penetrating the hull and then perform a Plastic Kayak Repair.|
|Scratch or crack that goes right through the hull, making the kayak no longer watertight.||Perform a Plastic Kayak Repair to restore hull and structural integrity.|
Callum Boase is from Australia and has been kayaking for several years. He has a keen interest in repairing all types of kayak and so in 2009 created Kayak-Repair-Central.com, a website that gives kayakers around the world a centralized source of information on this topic.
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