Character build advice - dwarven unarmed werecrab

[terramex]

looking for some advice on building a character for a high seas/ lots of aquatic adventures.
Trip Fisk Swordsbane, at high tide he turns into a werecrab (snip fisk), a bit of a fun gimick character to play with my little brother based on a comedy anti sword character on youtube.

Preferably looking for a way to play him as an unarmed grappler/natural weapons and have some utility outside combat. I like the idea of main or offhand claw being a sword breaker.

Would it be better going a homebrew monk design, or bloodhunter with custom lycan stats and tweaks? or something else completely? Not too concerned with an Op character but I want to be able to play him to later levels and be useful.

Thanks for any help in advance.

[Mork]

I would take at the path of the beast barbarian. You can get claws and underwater breathing from that. reflavour unarmoured defense as carapace.

IF you want to grapple, try to get expertise from somewhere. Either a 1 lvl dip in rogue (out of combat utility, and the crab is an ambush predator), or with the skill feat for athletics. That way you have advantage from rage, and a real high modifier. Nothing will ever escape your grasp. "shove" them to the ground, and they can't get up again either and you and melee fighters have advantage while the poor creature has disadvantage.

Swordbreaking.. is not really easy to get in 5e. I think the closest you well get is it the battlemasters "disarm" maneuver. If you go the grappling route you can drag your opponent away from the weapon it just dropped so it can't pick it up again either.
Either you take 3+ levels in battlemaster or take the Martial Adept feat. So you can do it 1 time each short rest.

Problem with this approach is that you get all your werecrab abilities by.. level 10 or so??

You can also take symic hybrid as a race: http://dnd5e.wikidot.com/simic-hybrid
That will give you water breathing, grappling claws (and you now have 6 limbs, more.. crablike?) - combine with the classes from above, but exchange the beast barbarian for another barbarian or leave out.
I don't think going monk to get bigger dice on your unarmed attacks is really worth it. You start with d6's already, so it's level 11 before you even get a higher die. Monks don't get much grappling bonusses. You do get more bonus action attacks, but as a symic hybrid you already can bonus action grapple.

[terramex]

Thanks heaps, that was such a great and fast response!