Operating In Heavy Current

[rcwass]

I run my boat in the Piscataqua River, Between Maine and New Hampshire, all of the time. This river has a very high current. I have a 1990 22 foot C-Dory Cruiser. My boat was equiped with a 1990 70 HP Johnson with the original prop. All purchased as a package in 1990. This current bounces you all over because the C-Dory is so light. When I run against the current the 70 HP motor cavitates. The 70 HP motor is running at the proper depth and I've checked the trim several times. This 70 HP motor has overheated and I've had to shut down twice in this heavy current, NO FUN.
I have since repowered to a 2009 Evinrude ETEC 90 HP and haven't had as much trouble in the river but not many hours yet. I haven't run against the tide when the current is the heaviest either. Has anyone had any problems in high current? Or, does anyone have any suggestions.

[tpbrady]

I've run all kinds of boats in rivers with high currents as well as run my 22 through some narrow openings with a fairly high tidal current flow. Other than being a little squirrely in the eddys your hit, the motor really shouldn't notice any difference. Running an outboard in current is like running an airplane in the air. It's the water speed that the boat and motor see. The water speed is high but the speed over ground (SOG) would be less.

[matt_unique]

What Tom said...the Piscataqua has claimed many a faltering engine. The boat will move all over but should not affect the engine unless you are literally in white water.

[Smuttynose]

The Piscataqua is indeed a challenge. It is my understanding that the tugboat captains have to have a special license to operate this river. My 22 with a 90 Honda is in Sagamore Creek and several times a week I am 'white knuckling' the narrow channel bridge by the Wentworth that the locals refer to as the WaterSlide. When necessary I will use the trim-tabs to raise the bow and sink as much weight into the stern as needed. I also completely ignore all of the Go Slow, No Wake signs. I can not imagine losing power at this point!

See you out at the Shoals,
David

[Byrdman]

Tom and other are target on. Looking at your post, if your motor is far enough into the water, ...keep in mind that your e-tec is about 50 pounds lighter....way back there on the transom.... than other 4-stroke motors. While at the dock, take a 50 pound object (coolers loaded work)...and place it in the motor well area... and, now just how much did the transom "sink" into the water? That little bit of extra depth may stop the "air-ride" if you are cavitating.

That lighter is better is in your favor....unless you are getting air rather than water, that may be caused by the boat actions...or re-actions to the current...and lifting towards the surface.... and taking in air while working hard to keep you going.

If you "always" boat in that water area, it may be worth looking at weight in the bow vs weight in the stern....or, lower your motor a bit.

We all know our CDs are not about blazing speed, but, rather good, dry, safe enjoyable times on the waters. Air in prop is not fun.

Byrdman

[Rich]

I run the Piscataqua also and know how bad things can get with an engine down. Blew a cylinder on my old whaler once over by the power plants luckily a good samaratin towed me out. The river current is very strong at certain times in the tide cycle. I have a 90 suzuki on my 22 cruiser and when running with the tide(during peak current) my tach is at 1800-2000rpm doing 6knots when running against it I'm doing 4000rpm to maintain 6knots. I'd like a little more power but have never had a problem. Depending on winds and boat traffic it can be a little gnarly but I'm sure you know the worst spots and once in the harbour things get better. The inland waters are not as bad as the track to Portsmouth. You should be fine with the Etec but I know the feeling of wanting more power.