SD.....I'm not sure that I can survive on $10.00 a day for food. I eat more than that for breakfast (slight exaggeration) and I don't know about the rest of you but I get damnably hungry and thirsty at sea.
The passage Toronto-NYC-Scotland is some 5,000 nautical miles. Lets say at an average of 5 knots thats a forty day voyage without allowing for stops. That's a lot of vittles.
OTOH.....forty days of four hours on and four off is a pretty hard ask. One would be dog tired by the end of it.
Personally, a trip like this with two up (plus the cook ?) should be on a share food basis yes. The question is what's a fair amount ? I'd have thought around half what is being asked.
"Those who do not observe the impulses of their own mind must of necessity be unhappy." Marcus Aurelius