Do I Really Need Stern Thusters

[Alaskan Sea-Duction]

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?

 

[rslifkin]

I'd add a bow thruster, but skip the stern. I've definitely had times where being able to push sideways on the bow would have let me do something I otherwise couldn't (or would make it easier). I can't think of a time I couldn't move the stern where I wanted with just the engines though.

 

[E-Sea Going]

I had a Stern Thruster installed on my 2007 Mainship Pilot 430. It is an absolute luxury versus a necessity, but it allows me to move the boat parallel into and out of my dock which is very tight. Ours is an electric Side power unit and has been very reliable for the past 10 years. Now that I have it, I would never get another boat without one.

 

[Comodave]

Do you need them, maybe not. Do you want them, if so then do it. As we get older we aren’t as strong or as quick so docking is more difficult. If a thruster helps us stay boating longer than without, what is that worth?

 

[koliver]

Tom

1 No
But, there was a time recently when I thought I might be able to use thrusters if I had any. This was when I was alone on the boat and needed to get off a dock with a significant cross wind blowing me off, but with little room beside me and over 100 ft to go before the end of that narrow passage. Before releasing the lines, I thought that with thrusters, those would hold me against the dock till the lines were all released and I was back at the wheel. Instead, I had to single up bow and stern, remove the springs, then quickly haul in both bow and stern lines and get back to the wheel, then use more speed than I otherwise would need, just to have enough steerage to get out.
In that situation I likely wouldn't have used the thrusters other than to hold against the dock.

2 hydraulic, no overheat, no shortage of operating time available.

This advice is from someone who has never had thrusters, so it is worth all of what it cost you and no more.

 

[O C Diver]

I don't think you need a stern thruster based on your cruising experience. That said, if you're not a total newbie, take electric over hydraulic (IMO). Generally, if you're timing out your thruster, it's either undersized or you don't understand what a rudder (on single engine boats) or jockeying engines (on twins) is supposed to accomplish. I would much rather clean up the electrons from a broken battery cable than the hydraulic oil from a broken hose. Have a friend who has probably removed 20 gallons of hydraulic oil from his bilge over 4 or 5 incidents of failed hoses, orings, and leaking fittings.

Ted

 

[Lepke]

For most yachties, a bow thruster helps. What I have against them is most are high maintenance. In salt water the seals usually fail before the owner gets around to maintenance. If it's electric driven, it usually means a new motor. Hydraulic will leak and leave a sheen before the motor is hurt. Make sure the shaft is a good grade of stainless or better yet, monel.

I learned boat and ship handling a long time ago and have a prejudice against unnecessary expensive equipment. I dock the old fashioned way with engines, rudder and lines. The only times I've had thrusters available, I was docked before I remembered they were there. So I have no practical experience on the help thrusters offer. I think if most yacht owners would spend a couple days practicing their landings, most would rarely need a thruster.
I've never seen a thruster on a sailboat and they're single screw. How do they dock?

 

[SteveK]

Do you need them, maybe not. Do you want them, if so then do it. As we get older we aren’t as strong or as quick so docking is more difficult. If a thruster helps us stay boating longer than without, what is that worth?

Dave best answer.

That said I did internet search and 74% agreed that Tom needs all the help he can get.

 

[Retriever]

What I have against them is most are high maintenance.

My old boat had a bow thruster, the current one has bow and stern. Neither have required much maintenance other than zinc changes. Some thrusters ask for every-other-year fluid changes. Mine have basically been maintenance free until seal replacement time...ABT says every 6 years and it only takes a few hours when the boat is out of the water. I've spent way less time and money on thruster maintenance than I have on main engines, generators, stabilizers, black water systems, hot water systems, diesel furnaces, air conditioning, windlass, or any number of other systems aboard.

I've never seen a thruster on a sailboat and they're single screw. How do they dock?

The Beneteau 46 sailboat in front of me has a bow thruster and I've seen a lot of sailboats in that size range with bow thrusters. Stern thrusters, not so much.

There's often a lot of talk about how commercial boats get by without thrusters. I've seen the Alaskan fishing fleet maneuvering, and while it's usually impressive, it requires a lot of power from the helmsperson and agile crew jumping to the dock with lines. And look at the boats! They're not polished like a yacht. I've watched commercial fish boats shatter pilings and put V-shaped indentations in docks when they pinned the bow in a slip, then drove forward to get the stern over. Not something I want to try with my boat.

Thrusters make maneuvering so much easier, safer, less stressful, and more predictable, especially for the average cruiser who's likely to be older than a fishing boat crew and with fewer deckhands than a commercial boat.

I've only had electric thrusters on my own boats and they work fine. Never timed out or had a failure. I've worked on plenty of boats with hydraulic thrusters and they're a joy...variable speed, often higher output, can run continuously. Hydraulics are more work to install if you don't already have hydraulics on the boat...you need a sufficiently large PTO, hydraulic cooling, a reservoir, etc. Failure modes between electric and hydraulic are different, but both are well understood and good design, installation, and regular visual inspections can mitigate most failures.

 

[tiltrider1]

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?

Yes you need stern thrusters. With out them you will never really reach the peak of superiority that I know you can achieve. We all know anyone drinking Henry Whinehart’s Private Reserve on a boat with no stern thruster is just a pretender.

 

[BruceK]

Yes you need stern thrusters. With out them you will never really reach the peak of superiority that I know you can achieve. We all know anyone drinking Henry Whinehart’s Private Reserve on a boat with no stern thruster is just a pretender.

Hmmm...https://www.google.com/search?client=firefox-b-d&q=henry+whinehardt

 

[markpierce]

Consider a single propeller and rudder my stern thruster. Use the bow thruster if needed or to exercise.

 

[backinblue]

I've never seen a thruster on a sailboat and they're single screw. How do they dock?

Sailboats generally have larger rudders that will move the stern when in reverse. My boat has a comparatively small rudder and the prop is in a tunnel and there is no prop walk. Trying to dock stern-in against a strong current would be next to impossible without a bow thruster at least. Stern thruster helps too, but I could manage w/o it.

There are many modern conveniences on boats that make it easier and more enjoyable. Many of them are not absolutely necessary to go boating, but why not use them if you want to? You can navigate w/o a gps, but few do.

 

[Hippocampus]

Have owned and cruised many sailboats. All over 36’ had bow thrusters. None were effective at or over 15-20k.

 

[Shrew]

I have a single with a bow thruster. I managed to live without the bow thruster for a season when it died (Typical issues booking someone to do service in late June). While I learned to live without it, that didn't mean I didn't want it back.

When I finally got it back, my newly honed skills made it so I relied on it significantly less, but that doesn't mean I don't use or wouldn't want it. I don't have a stern thruster, but would love one.

If you had one, you would use it and love it.

 

[wkearney99]

I have both bow and stern thrusters on my EB47, and make use of them. Could I get by without them? Probably not without the bow thruster.

I have had the stern thruster act up in the past and have successfully used the twin engines to mostly accomplish what the stern thruster could provide. But it wasn't as smooth an operation. It's possible to use the twin engines to shift the boat from side to side but that does tend to also move the boat forward/backward a bit in the process and that can be jarring to guests on board if they're not expecting it.

With the stern thruster it's trivially simple to bump the stern to port/starboard without any change to forward/reverse momentum. We have a hydraulic swim platform and can't use that as a nudge/pivot point when in tight quarters. The thruster makes it easy to keep the platform out of harms way.

With sufficient batteries electric is fine. If you're grinding the thruster excessively you're doing it wrong. Use the engines to make the large moves, and then the thruster to fine tune it.

I'd also point out that many hydraulic systems are engine-powered, typically one engine or the other. If you have any issues with that engine then you're losing thrusters too.

If I changed one thing I'd make the stern thruster in ours more powerful. As it stands, if I apply both of them the bow thruster moves the bow much more than the stern thruster moves the stern. Our has to use cowlings on it in order to direct the flow away from the swim platform supports. I'm guessing this causes some loss of directional thrust.

I don't know that I'd change to variable control as the use of thrusters seems most typically an on/off sort of application. Though I'm sure being able to apply the power gradually could have it's benefits. Especially if integrated with a joystick system that also included the engines. If I were building new or doing a refit, sure, I'd probably go for variable. But on/off is fine for now.

 

[Choices]

Thrusters are very convenient. They accomplish many things.

Give a novice and chance to learn and save himself in a jam.

Saves wear and tear on transmissions and drive trains.

A workboat is way different than a pleasure boat. Shafts are bigger, maintenance quicker and watched closer, dings and scraps are ignored.

I ran a crew boat to pay for college, the things we did to them were hard to believe. No way a yacht could survive that.

Even if the thruster fails, and few do, you will make it back. May not be the prettiest landing though.

With twins there really is no need for a thruster at all. But it still is nice.

 

[wkearney99]

I'd cast doubt on the 'wear and tear' angle for the drive train. They're designed to handle the sort of things necessary for docking.

Thrusters DO fail. Either from broken blades or electric source. I've had both happen.

The novice angle... better get the popcorn out for THAT debate.

 

[jgwinks]

For most yachties, a bow thruster helps. What I have against them is most are high maintenance. In salt water the seals usually fail before the owner gets around to maintenance. If it's electric driven, it usually means a new motor. Hydraulic will leak and leave a sheen before the motor is hurt. Make sure the shaft is a good grade of stainless or better yet, monel.

I learned boat and ship handling a long time ago and have a prejudice against unnecessary expensive equipment. I dock the old fashioned way with engines, rudder and lines. The only times I've had thrusters available, I was docked before I remembered they were there. So I have no practical experience on the help thrusters offer. I think if most yacht owners would spend a couple days practicing their landings, most would rarely need a thruster.
I've never seen a thruster on a sailboat and they're single screw. How do they dock?

Lots of sailboats have now thrusters, at least around here. A friend has an Islander Freeport 41, long keel and singles screw. His slip is pretty tight and would be very difficult without the thruster. I don't see the need for a stem thruster on a twin screw boat, the engines fill that need.
One of the commercial boats I ran was 45', single screw with no thrusters. I never had a problem docking that one, it just sometimes took a little more advance planning than a twin or one with thrusters would.

 

[jgwinks]

I'll correct my last, lots of cruising sailboats have thrusters. Racers don't, they add drag and slow you down. The trophy shelf is the only priority for those guys.

 

[4fun1]

I have both bow and stern with twin engines. They come in handy alot. My wife is not that great at line handling. It makes it much easier to get off a gace dock with boats for and aft. I can just push straight off the dock. Also our home slip is narrow with aboout a foot on each side has has a lot of current. Add in the wind and wakes where we are makes it so much easier to stern into our slip. Usually just need to kick the stern one way or the othe without losing momentum. I use the engines to control the boat most times.

Some people say it's cheating, I say I am just using all the tools in the toolbox.

 

[Alaskan Sea-Duction]

I have both bow and stern with twin engines. They come in handy alot. My wife is not that great at line handling. It makes it much easier to get off a gace dock with boats for and aft. I can just push straight off the dock. Also our home slip is narrow with aboout a foot on each side has has a lot of current. Add in the wind and wakes where we are makes it so much easier to stern into our slip. Usually just need to kick the stern one way or the othe without losing momentum. I use the engines to control the boat most times.

Some people say it's cheating, I say I am just using all the tools in the toolbox.

Thanks for the post. Are you electric or hydraulic? Pros and cons?

 

[Comodave]

I have both bow and stern thrusters on my EB47, and make use of them. Could I get by without them? Probably not without the bow thruster.

I have had the stern thruster act up in the past and have successfully used the twin engines to mostly accomplish what the stern thruster could provide. But it wasn't as smooth an operation. It's possible to use the twin engines to shift the boat from side to side but that does tend to also move the boat forward/backward a bit in the process and that can be jarring to guests on board if they're not expecting it.

With the stern thruster it's trivially simple to bump the stern to port/starboard without any change to forward/reverse momentum. We have a hydraulic swim platform and can't use that as a nudge/pivot point when in tight quarters. The thruster makes it easy to keep the platform out of harms way.

With sufficient batteries electric is fine. If you're grinding the thruster excessively you're doing it wrong. Use the engines to make the large moves, and then the thruster to fine tune it.

I'd also point out that many hydraulic systems are engine-powered, typically one engine or the other. If you have any issues with that engine then you're losing thrusters too.

If I changed one thing I'd make the stern thruster in ours more powerful. As it stands, if I apply both of them the bow thruster moves the bow much more than the stern thruster moves the stern. Our has to use cowlings on it in order to direct the flow away from the swim platform supports. I'm guessing this causes some loss of directional thrust.

I don't know that I'd change to variable control as the use of thrusters seems most typically an on/off sort of application. Though I'm sure being able to apply the power gradually could have it's benefits. Especially if integrated with a joystick system that also included the engines. If I were building new or doing a refit, sure, I'd probably go for variable. But on/off is fine for now.

Too small is a typical complaint about thrusters. I always go bigger than the manufacturer recommends. It is one time cost and the benefits last for the life of the boat. On our last boat I put one on the stern since I ran the boat from the flybridge and by the time I got down the stern usually had blown off the dock. It would push the stern up wind in 25 mph winds since it was oversized. I never have heard of anyone complaining about the thruster being too big, but have heard lots of complaints about it being too small. The bow thruster works better because there is usually less windage, less depth of boat in the water and less weight forward.

 

[4fun1]

Thanks for the post. Are you electric or hydraulic? Pros and cons?

Mine are electric. They each have their own set of two batteries located next to the thrusters.

Plenty of power, never ran out of juice.

 

[Comodave]

My thrusters are 24 volt so I have 2 AGMs fore and aft. Plenty of power.

 

[GFC]

Tom, you saw how effective my bow thruster was when we took Beachcomber to Seattle. It made going through the locks a breeze and made docking in "strange" situations much easier than it might otherwise have been.
,
Think back to our docking at The Dalles. That was definitely one of the most difficult dockings we did on that trip and, thanks to the bow thruster it was a piece of cake.

I've always felt that when a boat has two engines/props you don't need a stern thruster. But that's just me.

 

[jimdavi]

I have both a bow and stern thruster of appropriate size on a single trawler. They take the Stress out of high wind docking, help hold against the wind and are a big help if/when needed. Love ‘em, although I try to not use them if able.

 

[Hippocampus]

I’m curious why you don’t see more retractable thrusters? Would think beyond decreasing drag when underway it would also decrease growth and maintenance. Also note on sailboat hulls you often see a conical depression aft of he bow thruster in an attempt to preserve laminar flow along the boundary layer. See this less frequently in power. Why? Finally given swim platforms are nearly ubiquitous why isn’t the stern thruster integral to them? Platform could be immersed and continue the rocker of the canoe body thereby increasing effective lwl and decrease turbulence. Also thruster would be in “clean” water if retractable.

 

[mvweebles]

Hydraulic over electric. Proportional thrust versus binary on/off switched thtust. Either/both can add expense to the install so it's a tradeoff.

Thrusters do require maintenance. Not just zincs, but not unusual for a mullosk shell to get wedged and break a blade.

Do you need a stern thruster? Probably not, but all docking situations are different. Will you like it once installed? Unquestionably yes. I'd be stunned if you said to yourself "sheesh, that was a mistake. I'll uninstall it at next haul.".

The most expensive boat to own is one that doesn't get used. If having a stern thruster will let you use your boat more and/or make the use more enjoyable and stress free, it's a good investment.

Finally, if you have a mate who is intimidated by docking, s/he may be more comfortable driving the boat if it has full bow/stern thruster. Docking is a lot of fun and a sense of pride when done well. Sharing that sense of accplishment with your mate is a good thing

Good luck.

Peter

 

[hobbystuff]

I just installed a stern thruster on our single engine trawler after 10 years of ownership. I do just fine without it but there have been a few times over the years that it would have come in handy: Backing in a straight line and moving the stern off the dock when departing (I usually back off, using the prop walk to move my stern out - often using a line and a push forwards to start things off).

I have had the thruster installed for less than a month now and here is my experience:

(1) Leaving the haulout. Launched boat from annual haulout which included the thruster install. Haulout area was crowded with boats waiting, and the wind was up. No room to turn around, I was able to back up 300' in a straight line using the thruster, squeezing between all the boats. No zig zag, blast of forward, reverse, blast of forward, reverse. There probably wasn't even room to do that.

(2) Returning to my slip. I have a lovely slip at our yacht club that requires a relatively tight starboard turn into the fairway, and then another relatively tight starboard turn into my slip. It often takes all the rudder I have to achieve that last turn, and we often have prevailing winds or light current running perpendicular to us. I have made that turn for years, but it requires a balance of throttle and rudder to get lined up for the slip. What often happens, however, is that the momentum built up as the stern swings becomes very hard to stop. Our finger is a port tie, so occasionally I have had an issue where we only have the bow in the slip and the stern keeps going port. It takes a fast full port rudder and a blast of throttle to stop it, but that doesn't always work. It also means some extra forward momentum that then needs to be managed. With the thruster, I can tighten up the initial turn into my slip, and easily stop the stern when needed. Two quick blips is all it takes.

(3) Leaving the gas dock. We took on fuel on a busy weekend that saw the typical fuel dock crammed with boats and only a couple feet between fore and aft. The wind was blowing quite hard from basically directly astern of us. When departing, we did what we would usually do but didn't use a bow line, fat fender and forward gear to rotate the stern out. Instead, we untied and I used the thruster to pivot out the stern on the fat fender placed forward and then just backed out in a straight line.

I find it easiest in windy conditions to back into the wind as a way to control the bow (since we have no bow thruster), so backing into the wind in a straight line is nice. The stern thruster does give me more confidence in quickly moving the stern to keep the bow in control when pointed into the wind however. A bow thruster would be better for that, I believe.

Ultimately I like our stern thruster. Did I need it. No. Does it take some of the stress out of things? Yes. One big plus is that my wife doesn't need to do quite as many gymnastics when we arrive or depart. If nothing else, that helps as we are not getting any younger!