In 1881 family search.com has the IOM census and there are a few Rushen born married Thomas Crebbins as fishermen on boats:
Stephen Hine: Thomas Crebbin 40
Nellie: Thomas Crebbin 49
Sarah & Ann: Thomas Crebbin 30 (b. Arbory)
XL: Thomas Crebbin 50
Is your Catherine the one with six children (Catherine 15, John 13, Eleanor11, Catherine 9, Margaret 3 & William 2?
On Ancestry UK, I found a couple in the 1861 census:
John Crebbin nephew 29 married Fisherman b Rushen
Catherine wife 22 b. Rushen.
He is the nephew of Willam & Isabella Karran. This Thomas would have been about 49 in 1881 and is probably the son of John Crebbin and Jane Karran, christened April 26 1832.