This weekend I will be fishing for three days in the LCI fishing derby. Never trolled in a boat this size. Any concerns other than keeping a close eye on oil pressure and my temperature gauge when trolling with a 350 mag B3? Maybe a good question for
@MarkB
Comments
It's pretty normal for big boats to troll in the great lakes at idle ... many, many +30 footers that go to one engine and idle to get down to a preferred 2.5 mph for salmon fishing.
I've never really had any issues trolling for extended hours on the boat. Some say the alternator doesn't really kick in until 1500 rpm, but I've found my batteries hold voltage (13.7V), and I'm going 600 rpm, so I'm pretty sure the alternator is working.
Temps don't seem to be an issue, and neither is oil pressure.
I really don't think you have to worry about anything, there's thousands of hours being put on engines in this mode every weekend. I'm sure an hour at 600 RPM is much less wear and tear than an hour at 4000 rpm.
What lake is the fishing derby on, and what fish species are you going after? The thing you'll have to worry about is getting down to appropriate trolling speed, with most going to fast at idle, especially with a tail wind.
Boat Name: King Kong
"Boat + Water = Fun"
I agree with Mark, no harm to the engines. If you want to go slower you can buy attachments that do on your drive but I hate those. Instead if you can not get down to the trolling speed you want because of your idle setting you can purchase a drogues (different sizes)which area canvas bag that goes into the water and drags on a line behind your boat....that will drop your speed. I have seen guys rig a plastic pail with a float and some holes in it that worked perfectly.
You might get a kick out of this. Rinker will rig the EC 360 as a killer fishing machine with bait and fish lockers and prep stations. I did not order that model but my 2014 EC 360 with twin 502 Magnums came with a variable TROLL setting. Can you imagine that..... twin 502s at TROLL....too cool eh?
Yes MT is correct. Most guys will put trolling bags (1 or more) in the water, on the side of their boat. The bags are normally a few feet up from the stern so as not to get in the way of your fishing lines. They are cone shaped, about 36" in diameter at the throat, and go to a point at the tail. They tie off on the front rub rail and the tail also has a rope attached (need this for retreaving it, as you can't pull it via the front, too much drag). Amish bags makes some good bags.
As MT says, a lot of guys do the same by simply using a 5 gallon pail and tying this off to the rail or cleat.
Some put on a drag plate on their drive. It has a plate that folds down behind the prop, to stall the force. I don't like those for many reasons ... 1) you lose steering without prop thrust, 2) you have to attach them through your drives and have stainless to aluminum touching, and that introduces galvanic corrosion, 3) if you forget the plate in the down position and hit the gas to go back to shore, you'll damage everything! Plus they'll be about impossible to reach with an I/O to drop and lift that stall plate.
I'm willing to bet you'll get down to around 3 mph at idle, and no less, so this will likely be an issue. 2.5 mph is what you need for salmon and trout. 1.5 mph is what you need for Walleye/Pickerel.
You may want to consider the bucket, unless ... can you control troll speed? Do you have smart craft or similar? My smart craft has a troll control mode, and allows me to set the rpm down to 500 RPM and increase in increments of 10 rpm. This is like speed control, but going down to 500 rpm, I can get my speed down to 2.2 mph.
Boat Name: King Kong
"Boat + Water = Fun"
I have also adjusted the idle speed up from stock settings as well, it idles at 800rpm now. The stock Idle seemed to low and would stall out after a few hours. The stock idle was at 700 or so based on the RPM gauge.
Its easy to adjust, pop open the engine cover take a screw driver and adjust the idle screw. I had to play with it a few times to get the correct idle for trolling MPH, and so that it was not too fast for engaging the gears. And not to slow so that it would stall out.
That being said on any EFI engine you can still adjust the idle with the idle screw if the engine has a throttle plate design. All it does is press on the throttle plate just like your throttle would, there are no issues with doing this. All our race car LS6 v8s which are vastly more advanced than the boat engines can be adjusted for idle manually. With no ill effects to the EFI control system.
Adjusting your idle on EFI engines that have a throttle plate with manual adjust will not mess anything up. Your not adjusting mixture its a mechanical adjustment that slightly adjusts the throttle. Some newer EFI systems have a digital stepper motor design that cannot be manually adjusted, so with these systems you are SOL. AKA drive by wire engines.
I think you are over cautious and promoting some false Ideas with engines.
depending on the EFI either MAP or MAF design, they all compensate for engine control regardless of what the idle is at. If you wanted you could set the idle at 2000rpm if you so desire. The engine would run as it should at the 2000rpm level, with correct fuel as being metered by the MAF, or pressure in the case of MAP.
Adjusting the idle is a VERY easy way to get the correct troll speed, if you cant compensate with your trim tabs. And without having to deploy water brakes.
Now IF you have to adjust your idle LOWER..then you will run into issues if you lower it to the point the engine is stalling out. In my case however I had to raise the RPM to get the desired troll speed for my boat.
Boat Name: King Kong
"Boat + Water = Fun"