I'm new to baking with weights--but so far these seem off--for the sponge I've used more like 1/8 cup of each flour and 3/4 cup water. I'm not sur...

AJ is correct - the 178 was an unfortunate typo (118 being the correct number) and has been corrected, sorry readers! I've triple checked all of the other measures and they are spot on, so hope you give it a go! The sponge ratios are slightly different from some you might see in other recipes, because of the ratios of the other ingredients later (namely, the star - the yummy beer!). Best of luck on your bread baking journey!

I find the sponge somewhat perplexing, but I've not tried the recipe, so I cannot much in the way of insights. I do know that there is an error in the conversion for water. One half cup of water = about 118 grams, not the 178 in the recipe.
I agree with Amy that sponges are typically 50 - 50, but by weight; in this case, the water would be 56 grams. But again, I haven't made this, so 178 grams might be the right amount of water, in light of the quantities of other ingredients added later.

Also, when making sponges, many of us would use much less yeast and let the sponge sit for a much longer period to develop flavor. With the rye flour, which tends to ferment quickly, and the porter, which no doubt is full of flavor, that might not be necessary.

In any event, may I respectfully suggest that someone on the staff at Food52 might want to take a look at the water conversion and revise the recipe. It is not my intention to berate or belittle anyone at Food52. There seems simply to be an error here, one way or the other. ;o)

Sponges can be different consistencies, but more often than not, they are roughly 50% liquid and 50% flour. That means that this recipe looks right. I'm a pastry chef and I would use what they suggest. I'm curious why you think it's wrong? I converted "1/4 cup" rye into grams and it comes out almost identical to what they suggest.