What size Kicker?

[Mr. Osprey]

What size kicker would you out on an 80's 170? My reason for asking is my grandfather has a 1999 2 hp Johnson, a 1970's 4hp Johnson, and a 1993 4hp Mariner (but will likely go on his 9ft Boston Whaler). I'm thinking about asking him if I can borrow a motor in case the Merc goes on the water I don't want to be stuck. Would these be big enough or do I need a 5 or 6 to get anywhere?

[Radioshop]

I don't know the answer to your question, but here's a little insight, a 9.9 moved a 22.2.

[John Jones]

4 maybe.  I don't think the 2 would handle it, especially if there is wind or current.

[JimCt]

My 170 with it's 6hp Evinrude kicker.

Pushes us at about 4-5 mph generally, slower in a head wind or chop.   Much less hp and you'd have simply a noisemaker. Can troll 2 wires at about 3 mph.  You'll need a long shaft motor to get the prop down and away from the stern turbulence.

Consider the kicker a safety device; it'll get you home when the main engine quits.  It's economy for trolling is gravy in the deal.  I've plumbed mine into the main fuel supply and  carry a 3g reserve tank in the bow locker in event there's a fuel contamination situation.