Actually, my original question was
So I need to learn about bow and stern thrusters. Are they on/off or variable thrust? Are there any that you can leave on for longer periods than just for short bursts?
I did not go into my docking methods in any detail because I wasn't asking about that, I was asking specifically about the thrusters themselves.
A lot of well intentioned and mostly very good advice has poured forth and I truly respect and appreciate that everyone is trying to be helpful. But a lot of it is unnecessary. I'm not a novice at docking. I'm not even a novice at docking single-handed. I am a novice at docking a larger boat single handed with thrusters. I wasn't even asking about that, though I appreciate the advice. And some of you have addressed that very directly. Some have just gone beyond what is necessary.
So there are a couple of options:
I'm in the boat, maybe even on the flybridge. I come alongside the dock with a crosswind. I put the engines in neutral and go out to put a line around a cleat - only to find that I've been blown 30 feet from the dock since I neutralled the engines.
OR.
I'm in the boat, I come alongside the dock with a crosswind, I put just enough thrust on the adjustable thrusters (I now know that they do exist) to hold the boat against the dock. I step out of the cabin, or climb down from the flybridge, and put a line across. Maybe a spring line if the cleats are convenient, maybe just a safety line. Then I step off onto the dock, with the thrusters still going, and put a couple of secure lines onto cleats. At that point I can either shut down the thrusters (and the mains) or I can leave them running and use them to help me to setup all of the mooring lines.
Personally, I like the second option better.
And I promise that, even at 70 years old and barely over 100 pounds, she can probably argue more STRONGLY than you can.
Fatbear,
You have a TON of good advise here. And Alfa Mike's offer is most generous and worth while. Now you have an experience boater with thrusters that can show you how they work on a boat the size you want. Can't beat that.
As for the use of thrusters, the are only there to just better position you. It's hard to make them move the boat significantly, but can move it enough to get a line on, help in a turn, bring the bow/stern closer in, etc.
Below is a typical side tie. It will vary with different boats but the concept is the same. As for the thruster, there's only one main time I'd use it and that is diagram A to be absolutely sure I get that first spring line around the piling, even if I loose the stern a bit.
A second time, perhaps is after the boat is up against the dock with one spring line holding it, there's a tendency for the stern to get blown away from the dock, especially in a single. Yes, one can power up a bit, but often very hard to get the stern in. So, leaving the throttle in forward idle, I'd use the thruster to try to help swing the stern in, at least to get a line on, and while I don't like pulling the boat in, with the thruster and some tugs on the line I can get it in. With a twin, it's easy.
I'd never use the thrusters to hold the boat against the dock. They just don't have the strength, and will likely burn up the batteries. The engine with a spring is MUCH more effective, and safer.
Another time thrusters are very useful is backing in. Backing in with the wind pushing off the dock is the most challenging of docking. So is backing into a slip with wind, but one can pivot on a piling if needed.
I'd use the thruster to push the stern over just enough to get a line on, and it would most likely be right at the stern, especially in stronger winds. The thruster is a real help for this. Then spring forward to straighten the boat before reversing to get all the way in, adjusting the line as we go.
Another great time for a thruster is backing into a slip. That final alignment is easy to get by moving the stern sideways to fit. I'll stand on the stern with the remote thruste, and position the boat to back in, and tell my Admiral to give me xxx reverse. We use "thousands"... so if I say give me 3 reverse, she gives me reverse... thousand one, thousand two, thousand three. Works great. Once the stern is in my next duty is get a spring around the upwind, first piling and we can pivot, maneuver from there. And backing in as the wind twists us a bit, I'd use the thruster to straighten the boat up.
Another time thrusters are helpful is when you need more help in a tight turn, like a back and fill with a single against the wind, or in a tight dock area.
Yes, thrusters are very helpful, wouldn't be without.