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Old 25 March 2012, 03:10   #1
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Country: Canada
Town: Yellowknife CANADA
Make: Zodiac MkI & Aerotec
Length: 4m +
Engine: OMC 2hp/15hp/60hp
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55hp on a 1979 Zodiac MkII GT?

I have a 1979 Zodiac MkII GT in excellent condition. It was just checked out by the local inflatable boat shop and few minor repairs made but is in good health. I currently use a 1993 Johnson 30hp 2 stroke (approx 120lbs) on it and it goes quite well, WOT is about 37kph. I have an opportunity to buy a 1995 Evinrude 55hp 2 stroke (approx 190lbs) tiller motor with both a Durajet leg and an "out board jets" shallow river type jet leg. The MkII is rated for max 55hp, would running a 55hp motor on it be nuts? Thanks for any input.
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Old 25 March 2012, 05:07   #2
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Country: Canada
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Make: Gemini
Length: 4m +
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I wouldn't say nuts, but you will notice a difference in the handling going from 120 to 190 lbs on the transom in a 4.2m boat. It will not feel as nimble and responsive. I have had a Yamaha 40 hp 2 stroke (weight about 170 lbs) on my Mark II grand raid. It was faster than with the 25 hp 2 stroke I normally had on it, but not nearly as much as I had expected it to be.

I haven't used either a durajet, or a jet leg, but have read that (compared to a propellor) the durajet should provide respectable proplulsion (with some loss at the top end) whereas with the the jet outboard, there will be significantly less propulsion.

Are you looking at these two drive types because you are planning to use the boat in some sort of rescue application? That is where I can see those drives having the most practical application. I believe the main reason the military uses the durajet 55s (currently 55hp ETECS that weigh 240 lbs) with their FC-470s is for the safety of their personel who are regularly extracted from the water, often at some speed.

If your application is more for running up rapids & going through shallow water, a regular prop with a prop & skeg guard is probably more practical. It's easier to carry an extra prop or two than try to repair a specialize propulsion system in the field.

The durajet looks interesting, I've looked into them, but have shied away, because I was leery about downtime and costs if it required parts and repairs.
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Old 03 April 2012, 04:04   #3
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Country: USA
Town: Ellenton, FL
Boat name: FC-470
Make: Zodiac
Length: 5m +
Engine: 55h Johnson Enforcer
MMSI: 338118943
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I have an IMARS (improved marine amphibious recbonnasaince system) or AML-35D with a pump jet. I use it on my FC-470. I can attest incredible hole shot, getting on to plane, and awesome maneuverability at all speeds. But you definitely lose out on WOT. While it runs like a top it is more of a workhorse designed to get heavy loads on plane. I average around 22-24 mph w/ 1-4 people in it. Pictures attached:
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"The FC-470 can be used for over-the-horizon transportation, inserting lightly armed raiding parties or reconnaissance teams onto beaches, piers, offshore facilities and larger vessels."
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