What you have to remember is that Dave brewed with the ingredients to hand, and while a grain bill of 3Kg for 23L might appear to be 'short' what are the other ingredients also what was the OG that the beer was brewing to?
The water issue is a bit odd, as he only included water for Mashing . . .then you sparged to collect the preboil volume but that wasn't mentioned . . . although if you look at the instructions for brewing the AG Guinness it does cover it.
As a brewing book goes its not perfect, (but a damn site better than those that came before it) as a recipe book actually it's not bad, I've brewed several from it and they do come out pretty close.
The water issue is a bit odd, as he only included water for Mashing . . .then you sparged to collect the preboil volume but that wasn't mentioned . . . although if you look at the instructions for brewing the AG Guinness it does cover it.
As a brewing book goes its not perfect, (but a damn site better than those that came before it) as a recipe book actually it's not bad, I've brewed several from it and they do come out pretty close.