# Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Thought this might be useful to people.

I've just been wondering how my metric fibreglass cloth compared to imperial measures. Google helps out here if you just type: "175 grams per square meter in ounces per square yard" in the search box (without the speech marks).

You can also use it for calculations such as working out a rough measure of the weight of the fibreglass inside and out on the black pearl kayak I'm building. Assuming 3 square meters surface area (just guessing this number), 175 grams per square meter fibreglass and an equal weight of epoxy, and applying the fibreglass/epoxy inside and out then I can do something like this:

"(2 * 175 grams) per square meter * (2* 3 meters squared)" = 2.1 kg

Just thought I'd check on http://www.wolframalpha.com and, yes, the exact same syntax works.

In fact wolframalpha lets me go a step further and I can combine unit conversions with calculations eg to add in the weight of the paulownia wood strips assuming the web link I found quoted an accurate density of 20lbs per cubic foot. It's nice the way it shows you in detail how it interprets what you've written:

(2 * 175 grams) per square meter * (2*3 meters squared) + ((20 pounds per cubic foot in kilograms per cubic meter) * 3 square meters * 5 millimeters)

= 6906 grams (and plainly my epoxy/fibreglass ratio must be appalling :)