In skin-on-frame boat building, mainly polyester and polyamide are used as skin materials. Here we will compare the advantages and disadvantages of the two materials.
Polyamide (PA) "Nylon"
Also known as "nylon." Is the most robust fabric commonly used in skin-on-frame canoe construction. It is extremely strong against tears and impacts due to its stretchability and is therefore also used in bullet-proof vests, for example. A skin-on-frame boat with nylon covering can also be paddled on rivers. Only very pointy or sharp objects in combination with sufficient pressure would puncture the material.
Nylon absorbs water and expands up to 15% in the process. You often see boats covered with nylon fabric when wet, as the skin subsequently dries and stretches even tighter around the hull. What at first glance seems like an advantage, however, is more of a disadvantage, as the coating of the polyamide fabric unfortunately does not prevent the characteristic of water absorption. This means that in damp weather, cold or longer paddling trips, the boat can get a limp skin that forms slight waves. This has little effect on the boats handling characteristics, but it does not look very appealing. This can only be prevented by extremely stretching the damp skin around the canoe frame. Unlike polyester, nylon cannot be shrunk with an iron or a hot air dryer.
For normal use, a fabric with a basis weight between 200-300g/m² is sufficient. For light constructions a lighter fabric can be used. For tours with wilder water, heavier fabrics are also suitable, whereby the weight of the canoe naturally also increases due to the higher paint absorption of the nylon fabric.
Only uncoated polyamide fabrics are suitable for use in skin-on-frame boat construction, as coated fabrics cannot be varnished. Fabrics sold as "waterproof" are also not suitable for skin-on-frame boats, as the water head would not be sufficient for a boat hull and the seams would also not be waterproof. A commonly used polyamide fabric is "Ballistic Nylon" with 310g/m², but other fabrics with e.g. 230g/m² are also commercially available.
Polyester (PES)
Polyester is less robust than polyamide with the same weight, but has the following advantages:
When skinning your boat, it is not necessary to stretch the fabric as extremely as nylon, because it can be shrunk afterwards with an iron. The tension that the fabric receives from shrinking remains permanently intact. Also, unlike nylon, polyester fabric does not absorb water, so it does not become limp and wavy in damp weather or during longer paddling trips. The disadvantage of less robustness can be compensated by using a heavier fabric. If you are more likely to be paddling on lakes or the sea anyway, where the risk of ground contact is rather low, you should give polyester a run!
As with nylon fabric, when using polyester fabric for skin-on-frame canoe construction, it is important to use an uncoated fabric, otherwise the varnish will not adhere. Unfortunately, uncoated polyester fabrics are hard to come by in Europe, as almost all fabrics are sold coated.
In the USA, fabrics are often sold with weights of 6oz/m² (approx.170g/m²) and 9oz/m² (approx. 255g/m²). We would advise you to order at least a 9oz (255g) fabric for the robustness of your boat. If you want to build a very light canoe for still waters, you can also use the 6oz fabric, but this will be quite susceptible to damage.