I use SoapCalc for every batch and what I do is to totally ignore the 'water as % of oils' box and the 'water:lye ratio' box, and head right for the 'superfat discount' box and 'lye concentration' box instead.
The 'superfat discount' box is for how much oil you want to remain unsaponified in your soap to ensure that your soap is never lye heavy. I usually set it at 5%, which is a good, general amount. You can go with a higher % or a lower % depending on your recipe and what your goal is, but 5% is a good, safe, generic number that many soapers are most happy with as a default %.
The 'lye concentration' box relates to how strong of a lye solution you want to use. The higher the concentration/solution, the less water you use in relation to the lye amount. For example:
25% solution = 75% water/25% lye
33% solution = 66% water/33% lye (water double lye weight)
40% solution = 60% water/40% lye
50% solution = 50% water/50% lye (half and half)
Basically, the higher the lye concentration, the quicker the finished soap will harden, the less the finished bars will warp or shrink due to excess water evaporation, and the quicker things will move in terms of your raw soap coming to trace.
I use a 33% for pretty much all my batches. I've gone as high as 40% before in a Castile soap with a well behaved fragrance and it was wonderful, but I wouldn't try it with a seizing fragrance unless you want soap-on-a-stick.
I started out soaping with a 25% solution 2 years ago, but that's just too much water for my tastes. I really like 33%. It's a good, solid, happy medium for me. My soaps harden up quick, hardly shrink at all, and never warp. It's also very rare that my soaping session ever goes beyond 20 minutes before my soap comes to a trace. Actually 20 minutes would be considered quite unusually long. Five to ten minutes seems to be the norm for me with a 33% lye solution (and a stickblender).
When you set the lye concentration box to whatever % you want to use, and/or the superfat level, SoapCalc automatically sets the 'water as % of oils' for you. I've found that it's not something I ever need to worry about. The lye concentration and superfat % are more important, IMHO.
HTH!
IrishLass
P.S. Hi MikeInPdx! Looks like we're posting to the same threads tonight!