Operating in Strong Current

R

rcwass

New member
I have an all 1990 22 foot Cruiser and I'm now experiencing problems going against the tide or strong current. I've operated the boat in San Pablo Bay California, Sacramento River California and Potomac River Maryland and never had this much current nor problems. Now I'm operating in the Piscataqua River which seperates New Hampshire and Maine. This river has very strong tidal water and twice now when I try to go against the tide at it's strongest my 70HP Johnson cavitates and overheats. Once the alarm goes off I have to shut down and use my kicker to get towards shore.
Now, I've tried changing the trim on the outboard and it either does nothing or makes it worse. I have trim tabs on the boat and they are up. I installed a String Ray Fin on the outboard years ago to stop a stern slide in turns. The Sting Ray solved that problem but I may remove it this season to see if that' the problem here.
Has anyone experienced this problem or does anyone have any suggestions.
This river is narrow in stops and there's a lot of water moving especially on extra high or low tides.
Thank You
 
Can't help with your problem but many thanks for the memories of the Piscataqua.
Does the Troll still "operate" the bridge? He owes me 2 VHF antennae.
Used to moor in Great Bay Marina and enjoy our favorite sport of sitting at the picnic tables with a cold one watching others docking.

Merv & Kathy
 
The correct motor for a 22 Cruiser is a 20" and the 1990 Evinrude 70hp should be a 20".

I would try removing the sting ray. That could be causing turbulence. Is the boat's bottom clean? Have you recently changed or damaged the prop? The most likely size prop is a 15 pitch for a light load or a 13 pitch for a heavy boat. Does the motor overheat in calm water?

Does the boat reach its normal top speed in calm water? The motor rpms should be between 5,000 and 6,000 at wide open throttle. Does the motor overheat in calm water?

If the motor runs as above and the boat speed is normal, then there may be an overheating problem. Be sure that the fuel is fresh, good quality and that you are using a good quality 2-cycle oil, preferably Evinrude (Bombardier) oil. If the waterpump was replaced and the check stream is strong, the next thing to check is the thermostat. Checking the thermostat requires that the thermostat housing be removed and the thermostat inspected and perhaps tested for opening at the correct temp. Salt water and long use can be damaging to a thermostat. Also check the water inlet screens on the lower unit.

Retired Evinrude mechanic.
 
The only thing I would add to Larry's post is when was the impeller changed? I like to change them every 2 to 3 years and every 200 to 300 hours. If the engine was run "dry" at one point--or even with reduced load, it will start the process of detiorrating the impeller. It sounds as if this is compounding the problem.
 
sounds like your gettin good advice posted above , do you have the right prop? is it in good shape? somethings deffenately wrong with your cooling system get it to a repair shop if you can"t repair it your self . it will be a lot cheaper than a re- build if you fry it. i would highly doubt current would have anything to do with cavation or turblence problems, (unless ur running in some white water rapids :lol: )
 
sounds like your gettin good advice posted above , do you have the right prop? is it in good shape? somethings deffenately wrong with your cooling system get it to a repair shop if you can"t repair it your self . it will be a lot cheaper than a re- build if you fry it. i would highly doubt current would have anything to do with cavation or turblence problems, (unless ur running in some white water rapids :lol: )
 
This boat has never run good against this current. The boat is too light and all over the place. To get better control of the boat in this current I went to the local Evinrude Dealer. He asked what my wide open trottle (WOT) RPM was. I never really paid much attension to it so I took the boat out and ran it on a calm day, back and forth up the river where the current isn't strong. My prop was a 3 x 13 1/4 x 17 and the RPM was 5000. The specs for this motor say the WOT operating range should be about 6000 RPM. I purchased a new prop, a 3 x 13 3/4 x 13 which now gives me about 6200 RPM. The control in the river is a little better. I can run against the tide most of the time but when the tide is extra high or low the current is extremely strong and thus my problem. The water pump is new but the thermostat isn't. I'll look into that. I'll also remove that Sting Ray Fin. I think the river water is boiling with an upward motion pushing the underside of the Sting Ray Fin and forcing the stern upward. Thus, the prop is sucking air. I've talked to several from other forums and have had a lot of good help. Not all boat hulls are the same and react the same in currents like this so I'm looking to see if other C-Dory owners have experienced this problem. I think other C-Dory owners in this area are all equiped with newer, heavier 4 strokes with more HP. I appreciate all of your suggestions.
I'd like a new 90HP E-Tec if I can talk my wife into it.
 
MORE HP is always the answere in my book but, not always correct.One thigs for sure you are on the right site for help with your c-dory keep postin the brats will find you an answere.
 
Hi Lorraine J,
Not to speak to your overheating problem, but rather the change/deterioration in performance. Shifting to a smaller prop may have resulted in a change in the P-factor (prop thrust asymmetry) of your OB, and improved steering in flat waters. This leads me to wonder if running against current changes the fore & aft trim of the boat? I can envision that, running upcurrent, your bow might rise, changing the angle of attack of the prop into the water. That would aggrevate the P-factor again. Have you tried trimming-in your OB as you head upcurrent? That should bring the bow down, make water flow more perpendicular into the prop disc, and correct some of the P-factor. On an older motor without power trim this could be a bear to solve, getting into shallow water to change the trim by climbing overboard. Carry a piece of 2X4 lumber a couple of feet long to help out. Don't ask me how I know.
I suppose the change in trim could reduce cavitation at the same time. If the OB cooling has good flow, and the temperature of the check-stream is not excessive, you might have a faulty high-temperature alarm.
All the best.
Rod
 
I have power trim and have played with the trim in this current and it either has no effect on the cavitation or makes it worse. The power trim also makes the bow go down which makes it dig into this strong and erratic current causing the boat to shift from side to side. This current is not a straight line current it's very erratic because the bottom is rocky and full of ledge. There is a lot of upflow in this current. This is why I think I'll remove that Sting Ray Fin on the outboard.
 
I'm not sure. I know it's not like it was when the boat was new. Then I could get 25 - 27 MPH. Speed dropped off to about 20MPH with the old prop. I never knew why. I've never put bottom paint on the boat and I trailer the boat so the bottom is clean. I normally ran at about 4000 RPM, that's when I had the old prop and WOT trottle was 5000 to 5200 RPM. Now, with the new prop, I haven't checked max speed because WOT RPM is about 6200 and I don't want to run this old motor at that RPM for any length of time.
 
I also have a 90 cruiser with the original 70 Johnson. I keep it on a mooring in the North River in Scituate Ma. where the current runs at various levels of ferocity. Running against the current at the posted 6 mph is a constant exercise of working the wheel. While testing my Yamaha 8 4st kicker I found the boat was more steady on course with the kicker and me at the tiller. Maybe its because of the high thrust flat prop on the kicker or maybe its my heavy kester at the transom. Steady but not speedy just about holding headway speed at narrow points in the river. I have the orig teleflex steering and prob the orig cable. I see a 75/90 e tec in my future but I dont know if that will change anything at slow speeds. It hasnt been a big concern my mooring is a mile or less from the mouth and half the time im going with the current. My top speed has been 28 mph traveling liight and alone.
 
Sonethings wrong, i don"t get why if you guys can run at 25 - 30 mph, how you barley can feel a 6 knot rip ? I"d guess , that on plane you would be sailing right over the top of it, what happens when you run with the current ? I don"t get it. hopefully someone else will chime in to help , doesn"t make sense to me , seems kinda hard to figure out without bieng on the boat to see what it is doing , what am i missing brats ? ................. john
 
Bow wander would be more pronounced with a heavy bow of course.

I run a 32', 6 ton, twin outboard engine, flat bottom passenger boat in ripping/bubbling current in the spring. It definitely takes constant attention and corrections at the helm to keep her straight. If the bow is heavy your props lift up just a few inches but it makes a significant difference in thrust and control. In this current you need to 'give it the gas', put the bow up, and make constant corrections to get through. I usually approach the heavy current area relatively slowly then add good rpm to negotiate the pass.

Your first order of business is fixing your engine. After that double check your bow loading. The C-22 is relatively flat so they will not track as well as a deep V in high current BUT they are also less affected when your hull gets angled to the current.
 
Back
Top