Do I Really Need Stern Thusters

Thanks guys for the good feedback.

I knew there was potential.

One potential problem I thought about was the fact that reverse thrust would start out w a loaded propeller and lots of prop walk. But as speed increased the prop walk would unload .. fall off fairly quickly but you’d probably still have the same thruster push so the “system” would quickly become unbalanced .. and a straight course aft would not be had.

But w me it’s all just theory as I never have operated a thruster. My prop walk problem was mostly while backing down on an unset anchor. The wind is usually on the nose and on my Willard the wind pushed the bow off usually (as I remember) on the stbd side.
The obvious thing to do it would seem is to just let the wind push me sideways but feeding out rode until it was time to make it fast and straighten out and follow up w a little reverse to set.
Mostly I remember the anchor line did’nt feed sideways nicely AT ALL. I always felt foolish in this situation. But we always anchored up successfully.

Another factor in the equation is the windage on your boat. Ours, with the upper helm enclosed, is like a big sail. Consequently, when we put on the bow thruster last season, the boat yard thought a stern thruster would be a good idea. Since stern thrusters are a bit easier to put on then bow (no tunnel, etc.), the cost did not double.

We went for the largest that could physically fit which were 24-volt. The two 12-volts required for each thruster plus the 4 8D's already in place would probably be a bit much for the alternators, so we upgraded the alternators at the same time. (This, being in the category of one thing leads to another....)

Are we glad we put both in. Absolutely, and worth every penny.

Good for you Mike. FYI there are bolt on bow thrusters that don't require a tunnel. However, not the best location if you were to hit something under the water.

Tom, look at it this way. With your savings of 15 boat bucks by not going to AK this year, your stern thruster would be almost free!

My boat is lying in the Med and it is, most of the time, stern to docking and that is with the wind, against the wind, cross wind etc. Against the wind is not so much of a problem, but with the wind with a bit of cross wind it is very nice and comfortable to have thrusters working with you. No matter the wind I can still dock the boat by myself (have a remote on the engines, thrusters and windlass), which is a very comforting idea.

I know in the States you dock mostly sideways, in which case a stern thruster is not really necessary. The bow thruster I would not want to be without though, a Defever 49 is a high boat, catches a lot of wind and that thruster prevents very uncomfortable situations in a marina.

GFC said:

Tom, look at it this way. With your savings of 15 boat bucks by not going to AK this year, your stern thruster would be almost free!

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Lol! This true, but if fuel prices continue at thier present rate, we will only go north evey other year.

Alaskan Sea-Duction said:

Lol! This true, but if fuel prices continue at thier present rate, we will only go north evey other year.

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Ok, put a bunch of solar panels on the boat, then mount the stern thruster fore and aft and use it to propel the boat instead of diesel…. Of course you will have to go easy on the thruster so as not to overheat it.

Comodave said:

Ok, put a bunch of solar panels on the boat, then mount the stern thruster fore and aft and use it to propel the boat instead of diesel…. Of course you will have to go easy on the thruster so as not to overheat it.

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That would be interesting. I think there are a few solar boats that have made it to Alaska.

Back to the OP. So to install a bow thruster a big hole is drilled into the bow. As far as propulsion, it seems hydraulic maybe the most efficient. So the pump is electric activated?

If you already have hydraulics aboard then it might be the way to go. But from scratch electric thrusters are the more cost effective and probably much easier to install. No need to run hydraulic lines from the engine. And with hydraulic thrusters you may need to rev up the engine to get the thrust you need. That makes docking interesting.

+1

Comodave said:

Yes, my wife isn’t the steadiest person out there and the thrusters help when we are docking. Not having to rush about is much safer. She fell about 5 years ago, 5 surgeries and 3 years later she is better but I don’t want her falling again in a hurry to handle dock lines. Thrusters are worth every penny.

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Simple, let her operate the boat and YOU handle the lines. That's what I do and have a remote thruster control in my hand. She has never had a problem doing that, but most of us men are much bigger that our partners and can handle lines much easier.

Nomad Willy said:

Never had thrusters but see a possible advantage w stern thrusters. No prop walk if over time you found out at what rpm in your single screw boat the stern thruster neutralized the prop walk and allowed backing straight. One would need to do it at one speed and it would take time and experience to balance the rpm of the engine backing and the thruster propeller speed to back straight. Would be great to be able to back straight 30’ .. or 100’ straight back.

Has anyone tried this?

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Many times. I currently back out of my slip and have to back up about 300 feet before I can turn around. Slowly works pretty good, occasionally coasting. And both thrusters help with keeping it straight, but don't need them much. Just as easy to use forward to straighten out.

Seevee said:

Simple, let her operate the boat and YOU handle the lines. That's what I do and have a remote thruster control in my hand. She has never had a problem doing that, but most of us men are much bigger that our partners and can handle lines much easier.

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Well, I actually don’t have a lot better balance than she does. She doesn’t like to run the boat, she knows how but she would only do it in an emergency. We have the thrusters so it works well for us.

Comodave said:

Well, I actually don’t have a lot better balance than she does. She doesn’t like to run the boat, she knows how but she would only do it in an emergency. We have the thrusters so it works well for us.

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Good point, but if her safety is in jeopardy, I'd argue to dock single handed and let her do nothing, not worth her safety. I'll often do that when my co captain wants to sleep.

She handles the stern line when we dock. We have a huge swim platform since we put the extension on it. Makes it easier for her to board, the dog too. Our bow lines are always on the bow cleats and run back to the stern spring cleat. She does the stern line and steps onto the dock, undos the bow line from the spring cleat and makes it fast to the dock. Some variation of that is our normal procedure. No one has to climb up onto the bow to handle lines. It wouldn’t work without the thrusters to hold the boat to the dock while she carefully does her line work.

Great thread… just learned that I can convert my side power thrusters to proportional. Might consider that as very helpful holding the boat in high winds/currents. Guessing a few boat bucks.

jimdavi said:

Great thread… just learned that I can convert my side power thrusters to proportional. Might consider that as very helpful holding the boat in high winds/currents. Guessing a few boat bucks.

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Yes, it isn’t cheap but you can run them for a much longer time if needed.

The short answer is NO.
Practice, learn docking with spring lines and 'back and fill'.
Will a stern thruster make life easier for you? That is your decision.

A caution; unless you have hydraulic thrusters, you must have the batteries to support the demands of the thrusters

On my single, the bow thruster reduces transmission abuse. The "barn door" rudder serves as a stern thruster.

Transmission abuse is debatable. Most hydraulic marine transmissions will survive an incredible amount of shifting in and out of gear provided the engine is at idle.

OldDan1943 said:

The short answer is NO.
Practice, learn docking with spring lines and 'back and fill'.
Will a stern thruster make life easier for you? That is your decision.

A caution; unless you have hydraulic thrusters, you must have the batteries to support the demands of the thrusters

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,,,,and the cabling to carry that large of a current.

This discussion gave me a great idea. I am going to get rid of the starter motor and heavy cables and battery in my cars and install hand cranks! That will be less maintenance and increase my mpg. I can probably cancel my gym membership as well. Thanks for the inspiration!

Years ago, there were spring started engines. Hand cranks to put tension on the spring then release tension spinning the engine and hopeful the engine, if it didn't start, "do over".

OldDan1943 said:

Years ago, there were spring started engines. Hand cranks to put tension on the spring then release tension spinning the engine and hopeful the engine, if it didn't start, "do over".

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There was also hydraulic starters with nitrogen accumulators. You would pump up the pressure in the accumulator and let fly into the hydraulic starter motor. Same drill, no start, start pumping again. There were also straight air starters which were favored by gasoline haulers, but you need an air compressor and a fairly large reservoir for that.

backinblue said:

This discussion gave me a great idea. I am going to get rid of the starter motor and heavy cables and battery in my cars and install hand cranks! That will be less maintenance and increase my mpg. I can probably cancel my gym membership as well. Thanks for the inspiration!

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Now who's over thinking? LOL

I have hired an experienced big boat captain and his mate to help speed the docking learning curve on our new to us motor yacht. We jumped from a 46 GB to a 65’ Pacific Mariner. Adding in the swim platform gives us an LOA of 70 feet. She has a hydraulic bow thruster that is really powerful. The captain won’t let me use it until I am proficient at docking without it. He says you never know if and when the thruster will fail. Plus, if you are proficient without it, you will see it as a value added tool rather than a necessity.

Alaskan Sea-Duction said:

To break off the other post regarding cost of stern thrusters, a few side questions.

I do not have thrusters. I have twin engines. Thinking of installing bow thusthruster.

1. Do I need Stern thrusters with twin screws?

2. Hydraulic or Electric?

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Looking back at your original post...

And your TF join date (2012)... I'd have thought you'd know by now if you need a stern thruster or not.



-Chris

Alaskan Sea-Duction said:

To break off the other post regarding cost of stern thrusters, a few side questions.

I do not have thrusters. I have twin engines. Thinking of installing bow thusthruster.

1. Do I need Stern thrusters with twin screws?

2. Hydraulic or Electric?

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As a person who’s had both single and twin engines without thrusters, I definitely have an opinion.

Would be nice, but I’ve never viewed them as essential. I might think differently if I had one, but never grew up with that.