: Hi All, I hope someone can educate me, from time to time I read on
: this forum about a low volume kayaks and would like to know
: what makes a low or high volume kayak, and is my Night Heron low or
: high volume kayak (just trying to understand the pro lingo)
: as always thanks for your help Nick R.

Displacement is the amount of water (measured usually by the *weight* of the water) which the boat, cargo and paddler push aside (displace). if you add weight to the inside of a boat it will sink lower and displace more of the water it floats in.

If you were to fill a boat completely with water (or oil, or some other fluid) then you could determine the total capapcity of the boat in terms of volume: liters, cubic feet, gallons--by simply pumping out the boat and measuring everything as it came out. Of course if you have a fancy computer it can do the calculus and figure this out without getting things wet.

If you know the volume of a boat, figure out the weight of the same volume of fresh water, or sea water--whatever it is that you are paddling in--and you will know exactly how much weight it takes to capsize the boat. Obviously you do not want to put that much weight into a boat, unless you want it to go underwater. Submarines worry about this, and so do some of the very small rough-water kayaks. If the boat is small enough (relative to your weight) you can force it to go underwater, then paddle it back to the surface.

The volume of a boat should always be greater than the displacement. You may need to translate volumes to weights to check this. Higher volume boats have more room inside for storing camping gear. There is no reason why you can't make two boats with identical hull shape below the water, but one has higher sides and thus a higher volume, while the second has shorter sides and lower volume. Some companies do this, and home builders make such changes all the time. Paddlers with big feet modify the decks to add foot room, which means adding volume.

Hope this helps

PGJ