: It does makes a difference, just not a HUGE one. See below.

: Per high school science class, taken at sea level and 77F, the
: specific gravity of pure water is 1.000. Fresh water is close
: enough to pure so we'll keep that 1.0. For salt water it's
: around 1.025 (depending on where you're paddling and the current
: temperature. The North Atlantic is higher than the South
: Atlantic and much of the Pacific. Anyway...). That change will
: throw off a 250# displacement by a massive 6.25 pounds (ish).
: Now let's take Nick's "Night Heron" as an example. He
: graciously lists the sinkage as 84 lb/in. So that big 6.25 pound
: change amounts to a grand total of a 1/16"! Not sure how
: many paddlers could tell the difference...

: I know of very few kayak designers that will tell you if the design
: displacement is for fresh or salt water. I would assume fresh
: and back-calculate if it's a life or death concern.

: It probably doesn't really matter but when I'm designing a kayak I
: look where it's going to be paddled. For an 18' sea kayak: I use
: SG for salt water. A 13' solo canoe: fresh. It's a simple
: project option on the design software I use. If in doubt just
: ask.

Hi Dan,

For big boats anyway, displacement is normally stated for salt water. No idea for paddle boats, though as you've stated it really doesn't make much of a difference anyway. Well unless you paddle on the Great Salt Lake in Utah :)

Bill H.