I/O trolling question

[mechdawg]

Hi all,
I have a 21' Sea Ray Sorrento with I/O its our family fun toy. My wife and I love to fish and are trying to get into trolling with it. We learned two problems pretty fast with it. 1 even at idle it goes way to fast. 2 At idle for any real lenght of time (10 minutes or more) the temp starts to get up there. I assume the later is due to less water intake at such a slow speed from the outdrive. I am thinking about getting a happy troller plate as a cheaper solution to a trolling motor for the time being. I am just wondering how well those work on a setup like this and do you think I may still have a problem with higher engine temps?

Thanks

 

[lnnnsxt]

Adding the trolling plate would help with your speed, but worsen the overheating. If you are overheating now, then when you add the increased drag of the plate and slower speed for the water pump pickup, there will be less flow to the motor. First issue to work on is overheating, that motor should be able to run for hours at idle without overheating. You need to verify that the water pump is not sucking too much air, or the impeller is damaged preventing good draw up to the motor.
The addition of a bow or transom mounted electric trolling motor is more logical to control speed, but obviously cost more.

 

[mechdawg]

Thanks for the reply that is kinda what I was thinking. I will look more into why the motor is doing what it is doing.

 

[SuperD]

Weak impeller!

 

[skookum9]

Once you fix the overheating problem then a trolling plate will help. A sea anchor will also do a lot to help control your speed as well and will also be a big help if you are wanting to do some still fishing and not drift like crazy because of the wind. But if you are wanting to troll, I just don't think that these fixes will be as good as having an 8 or 10hp kicker motor on board to troll with.

 

[SuperD]

I just don't think that these fixes will be as good as having an 8 or 10hp kicker motor on board to troll with.

laugh hyst laugh hyst If they were, there would be a lot of kicker motors sitting on the rack, couple hundered dollars versus a couple thousand dollars.

Ways to slow down from cheapest to most expensive:
5 Gallon buckets
Sea Anchor
Trolling plate
Electric trolling motor
Kicker motor

 

[lowe1648mt]

If the impeller does not fix the overhearting problem, have a look at the exhaust manifold. If the boat was used in salt water, it could be partialy pluged. It can also happen in fresh water, just takes longer.

 

[KOKANEE]

My boat last year was doing the same thing. Changed out the impeller and still ran on the warm side, so I then changed the thermostat runs like a champ now. Might want to check the thermostat it was only like $25.00

 

[SuperD]

My boat last year was doing the same thing. Changed out the impeller and still ran on the warm side, so I then changed the thermostat runs like a champ now. Might want to check the thermostat it was only like $25.00

Boats that run a lot in alkyline water or salt are subject to sticky thermostats. Not that others won't too but if that fits your case, it would be a good chance that your thermostat might be stuck partially open.

 

[mechdawg]

I saw a post on another forum about the check balls on top of the manifold. So I pulled the hoses off cleaned them up a bit and put more tension on the springs that hold them closed at idle. It seems to have worked we went out today and had no problem idling even if we were still going to fast to be trolling.

 

[Bduck]

I have the Alpha One Mercriuser I/O. I keep it at the top of its game when I'm out on any body of water. Both the I/O & my kicker have year old impellers. If you don't change those every so often, you may end up changing something that could dig deep into your pocket. One thing that is bad on impellers is dry running your outdrive systems without water circulation. That is the lubricant for the impeller. I'm always seeing dry running operations going on in peoples driveways or at the launch ramps or campsites. Also wouldn't hurt to change you main engine thermostat. If your getting a overheat condition, these are the main culprits you want to tackle. About $40 dollars in parts is better than a $4000 bill later. 4moremney

 

[jacksonlaker]

I have an I/O in my Crestliner. I have a trolling plate and I use 1 or 2 sea anchors, depending on how fast I want to troll. I have doing this for years with no problems. 2 bags gets me down to 1.5, 1 bag about 1.8. No bags I troll around 2 to 2.2. I have never had an overheating problem, but if I troll for a long time, my plugs will load up and I have to clear them. The bad part about the I/O is having to drain it when it gets cold here early in the season.

 

[Bduck]

I had a troll-matic plate on my I/O. It was great up to the point where one of the springs broke loose into my prop. Needless to say it cost me a new prop. As mentioned by jacksonlaker the sea anchor is a favorite of alot. But its not mine although it works very well.

 

[mechdawg]

Thanks for the ideas all. I will have to do some research on replacing the impeller I am pretty mechanically inclined and would like to do it myself I have just never worked on a boat before. It is a Mercruiser Alpha 1. As far as I can tell the impeller has not been replaced in many years. As for the trolling plate I read somewhere that even in the up position it lowers your top speed and increases fuel consumption by approx 3%. I am leaning more towards the sea anchor idea for the near term solution. I really appriciate all the help and comments from everyone.

 

[Bduck]

Once you get the lower unit seperated, check the water ports for debris. Sometimes a impeller will come apart and chunks of rubber will lodge in these ports blocking passage. The Alpha one as in most Merc lower units, be sure to shift to fwd gear before separating unit. it must be in fwd gear position when going back together. Easy to work on.

 

[S.S. Fireball]

+1 on everything above.

Your mercruiser should idle almost indefinitely without overheating. So as noted, tackle that first. I had a similar problem and after trouble shooting I discovered the root of the problem was clogged water passages in the manifolds which restricted flow enough to create an overheating issue. Not even a hint of a problem since they were replaced.

It is typical to replace an outdrive impeller once a season for preventative maintenance. I would recommend doing it now and at least keeping track of the interval from here on out. I don't have a mercruiser, but I have the info from the manual on my OMC as far as how much volume it should be pumping. I check it at the beginning of each season - just remove the intake hose at the inlet to my heat exchanger (I have a closed cooling system on my engine block) & pump into a bucket while timing it. Simple calculation will tell you if you're within spec.

For me, trolling is always done with a 10hp four stroke kicker. I had the nice one that came with my boat from the previous owner stolen, so I scoured craigslist and found a 1980's honda for just a few hundred dollars, disassembled & cleaned the carburetor. I have not had a single problem with it in over 5 years. The gas savings over that time alone have probably paid off by now. I can troll all day for several days on my small outboard tank that holds maybe 3 gallons. Plus it saves wear and tear on my main motor.

The kicker also serves as a reserve to get me home if there are ever any problems with my main motor, too. It happened once - there was an electrical problem & I was dead on the water. It took a long time but I got back to the dock on the kicker power alone. Just food for thought it could also save an expensive tow into the marina.

It all depends on what species you are targeting, how much time you realistically plan on trolling, and what your budget is.

Good luck with the overheat problem. Tight lines.

 

[mechdawg]

Thanks again to everyone it has helped us alot in our choices. The fix I did to the bypass check valves has helped alot so far the boat idles just fine now. I do plane on replacing the impeller soon as well. As for the trolling we have bit the bullet and decided to go with a Minn Kota trolling motor. I think in the long run it will be the best choice. Cant wait to get out there with our new gear and possibly catch something....

 

[Ken Jones]

I had at one time a 22 foot Sea Ray. I had a happy Troller on it and caught a lot of fish. You can't go wrong buying a Happy troller. Make sure its the large size troller.

 

[thejolley1]

Hi Ken
I have a friend he has 18ft lund with 150 horse merc. with trolling plate works just fine. Before I got my trolling motor I drug a 5 gal. bucket with hole drilled in the bottom that work great for me for many yrs.

 

[Ken Jones]

Jolly one I also have used the 5 gallon bucket, it worked great. There cheap.