Looks like an Adze but

[john k]

was thinking Hand Adze  but has a large hole and reworked axe handle in there,  I think the adjustable wrench gives you an idea as to size.  Must of been a favorite tool of someones due to the repeated welding repairs to it.  Specialty adze?

[crankshaftdan II]

Maybe a adze used for hollowing out boats/canoes and had a shorter handle originally???   Just my two cents worth???