Back up Outboard Engine

[Seadog]

I have a Quicksilver 5.8 meter boat and was thinking of getting a backup outboard engine, any thoughts to what size would be needed.

and if mounted on a stern bracket what size shaft would it need.

I did  look at Seastart rescue but they only cover up to 3 miles from the coast.

Any help would be appreciated.

[Brian]

A mate used to have a Merry Fisher 580, he had a 5hp Longshaft as an aux. It wouldn't break any records, but it did get him back safely when the main engine failed.

[Maverick Martin]

With a boat that size I would suggest an 8hp would be ok, should push you along at hull speed 6/7 knots