Wait... I.. can't let that go. This mangaka thinks the gang plank (made of wooden 2x4s) is strong enough to not only support the weight of the fenrir when the boat can't but also to sheer the boat nearly in half (also made of wooden 2x4s). If he had that kind of weight it'd just snap the gang plank, they'd say "well crap now we have to smell wet dog all day" and then they just hop on, jumping the short gap. There's no way the gang plank would do more damage to a boat than a cannon ball!
Yes, and this is also the first time we've seen any indication that Feru even has weight. In just the previous chapter Feru ran around in the mansion just fine without destroying any stairs, slept on a couch that would have been designed for humans without a hint of a problem, didn't break any floorboards....
Not to mention all of the other times that Feru has walked into random shops and inns and guild halls and not a single one ever had any problem with Feru's weight.
With the power of Feru's blessings that protect it from disease and poisons and other status conditions, it wouldn't be unreasonable for Feru to have immunity to being obese in some capacity (not sure if it would prevent the negative health effects of being obese, or prevent getting obese in the first place...).