34 Trawler stern thruster

[LindaFlorida]

Good morning, we own a 2009 34 Mainship. We are thinking about adding a stern thruster, because of a tight slip where we need to pull bow in.

We contacted an installer. He asked the size of the existing bow thruster. It’s the Side Power/Sleipner SE100/185T (12 volt). The installer recommended the SidePower SE100/185T-24V-IP.

I was hoping that someone could tell me the size of their 34 Mainship stern thruster.

Thank you,
Linda

 

[Bacchus]

Linda
My 2008 MS 34HT has Sidepower SP95 bow & stern thrusters.
I am very happy with the performance of the pair. I use both for backing into our slip and tend to alternate B & S instead of using either one or the other. They really provide a similar rotation to the boat so either one will provide the rotation. Where having both comes in handy is when doing "fine tuning" you can choose to use either one depending on which end needs tyhe primary correction.

I am happy with both being 12V as mine are both wired to the same thruster 8D bank roughly midship. It is the Mainship OEM location but I have switched to all AGMs aboard. I have recently switch my single eng start from the previous combo house / Start bank of 2 8Ds to my thruster bank 8D. That leaves me with a pure house bank.

I also added a Balmar batty monitor to monitor my house V & SOC as well as thruster bank V.
I would think using one 12V and one 24V would add unnecessary complexity to the batty & charging system. If you have a dedicated bow thruster batty located under the bed then duplicating it in the stern would allow an easier set up but you still need to then have a separate 24V charger.
If your bow thruster batty is MS OEM Im guessing it is located port side near aft end of engine (that's where mine is) and simply adding cable, switch & fusing is all that's req'd to power a second thruster for the stern.

I'll attach a few pics of my thruster wiring that includes alt charging capability.
Details of the Charging System Mods can be found on my Bacchus website - Projects Pg 4 https://dkloeber.wixsite.com/bacchus/project-pg-4

FYI - My stern thruster is mounted off center on port side and includes the tunnel "lids" that helps direct the flow.

Hope that helps - any questions ask away.

 

[LindaFlorida]

Thank you Don,

Our existing bow thruster has a dedicated 12 volt battery charger with two dedicated batteries under the bed in the state room. You make a great point… to connect the stern thruster to a 12 volt system. Why complicate things.

The installer recommended an “ignition protected” stern thruster. After looking at the cost difference on Defender Marine. The price difference between an IP and without is $1,600.
I do not believe that the stern area gets that wet. Also we do not have a gas engine, if he is worried about fumes or water? The bow thruster is not IP protected, in a dry area.

If possible would you happen to have photos of the stern thruster, located on the inside of the engine room? It might help with the install. Another installer did not think that a stern thruster would fit in that area. I told him that many Mainships had them in that location installed by the manufacturer.

Thank you for the exterior photo of the stern thruster.

Linda

 

[Pete Meisinger]

Gosh, with a 34 foot boat with a single engine and a bow thruster why bother with the stern thruster? I can't believe you really need it.

Practice a bit. With your rudder turned as far as it will go in either direction and the boat traveling dead slow in reverse (or at a standstill), You can apply a "burst" of forward thrust with the engine to nearly 2,000 RPM for as long as 10 seconds without really causing your boat to move forward. It will kick the stern over about 3 feet and cause you to travel forward less than that.

pete

 

[Bacchus]

Linda
First question is whether you are single or twin? I'm single and what I'll describe. Twin stringer / tunnel / real estate my be very different... I've never been in the ER of a 34T/HT that has twins.

I see little / no need to go to the IP version with diesel. Apparently MS felt the same when installing the stern thruster option.

I dont have any pics of the stern thruster install and boat is now in for a long winter's nap.
The location is fairly simple to describe.
It is port side in the area to port of the prop tunnel and to stbd / center of the port side shelf that holds the isolation xfrmrs and water heater. Also under the shelf across the strrn for the steering gear.
It is the mirror image of that same area to stbd of the tunnel where the AC pump is located and easier to view, access to check dimensions as a first rough check.
It is fairly snug but room is sufficient for that size thruster

I have had some water in that chamber but it has limber holes that prevent it from building up much depth. Mine also has a small bilge pump there that would only get powered if I was underway and bow high forcing the water aft with no escape. My water infiltration is from rub rail leaks and my website has a write-up of what I have done to fix that... if I get any it is minor now vs before the fix and I do check and recall the exterior top side of the rubrail occasionally.

The tougher issue might be where to locate the battys for the stern thruster?
There is not a lot of available real estate in the aft port side. My thruster bank is port side just fwd of the bulkhead separating ER from Gen / lazaret. If you use that area ( where I thought MS located battys for even the bow thruster) it makes cable runs a little longer but provides the option to use that bank to provide eng start, (that's what I have now... B & S thruster plus eng start) that leaves the stbd side battys as pure house. I have combined my stbd side battys to form a single large bank so I could add a Balmar monitor (Balmar requires connection directly to batty and not through a 1-2-all selector sw).
If that is of interest I can elaborate more on why and how I accomplished that. BTW I am very pleased with moving start and have fairly extensive monitoring of the start/thruster bank V via the new house bank monitor.

 

[LindaFlorida]

Hi Pete, we find that when backing into a slip, we do not need a stern thruster in most cases. But unfortunately the slip that we love, because of the view. We need to pull bow in… our beam measures 14’-3” and our slip is very tight 15’-6”

When factoring in strong currents and winds, especially with a flybridge. The stern thruster is needed. If the current and winds are not a factor. We can pull bow in with a little help from the bow thruster.

The beam measures 14’-3” and our slip is

 

[LindaFlorida]

Don, we have a single Yanmar 370. Your description makes sense. We will look at the location next time we visit the boat.

Thank you very much. Hopefully I can find photos of another owner with the same boat/model with a stern thruster.

 

[LindaFlorida]

Pete, the model name is a 34. But the overall length is 38’-8”.

 

[Pete Meisinger]

Curious that a 38 footer would be called a 34, just one more thing about boats that I don't understand. It's a long list.

But..a 38 footer should be more maneuverable with the "prop burst" than a 34. More mass and weight should allow the stern to "kick" over more and actually change boat forward direction less. I could be wrong but on my 36 I get a lot of stern movement with a burst.

pete

 

[Bacchus]

Pete
Also one of the (few) negatives of most Mainships is the small rudder. Works fine at higher speeds but not great for slow speed maneuvering
To add to that the prop tunnel negates any prop wash that might help.
The LOA is actually 39 ft +/-. These were built with bolt on swim platforms and MS didn't count the anchor platform although they were std equip.

 

[Comodave]

If you want a stern thruster then get one. I put one on our last boat and loved it. As we get older having all the help we can get is worth it. We put both a bow and stern thruster on our current boat and absolutely love having them. My wife will not go up on the bow of our Formula so I put the thrusters in. We leave permanent bow lines on the bow cleat on each side. They run to the after spring cleat and get tied off there when we are underway. When we dock she stands on the swim platform and gets off the stern, ties the stern up and then walks forward and unties the bow line and secures it to the dock. Works very well.

 

[Jeff F]

The pics you provided of your boat last year show a stern thruster. Is there a problem with the existing unit?

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[Cold Duck]

Who knows why builders label their boats something. My MS350 became the MS390 and both, identical, are more than 39ft. Small rudder, rudder placement, windage etc makes the "burst of power" method of turning just not practical in close quarter docking. I have watched Mexican shrimp boat captains turn their 90fters 180 degrees almost within their own length with that burst of power method. It is awesome to see. Me, I'd love to have a stern thruster to help my MS350. Pretty much I can't use the rudder at all trying to get in berth. Just set up with rudder then use bow thruster to fine tune approach. Using the rudder ends up turning almost block to block before you get any movement. Other boats I've had can control w/o thruster and are very responsive to the helm. The MS350 is one of the worse handling boats I have ever used. Once you realize it's limitations, it is OK.BTW, I still love the boat. Fits my other needs to a "T". It's just aggravating to have to deal with its short comings in the slow speed docking mode.

 

[Comodave]

The pics you provided of your boat last year show a stern thruster. Is there a problem with the existing unit?View attachment 133499

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That is a SideShift thruster in the photo. We put them on our boat last winter because we didn’t have room for traditional thrusters. Ours work great. My wife and I installed the bow thruster in 1.5 days and my neighbor and I did the stern thruster in a day. Ours are 24 volt so I have 2 Optima start batteries fore and aft on their own 24 volt chargers.

 

[Cold Duck]

I know this started with the stern thruster for the 34, but I am interested in anyone with a good stern thruster installation on the MS350/390. Another FYI, most thrusters are controlled by two relays to change polarity on the motor. One side died on my bow thruster when anchored out. Thruster so necessary to docking in current/wind that I took dingy and got a relay at Napa auto parts. Relay is similar to old Ford starter relay. This worked to get home then order correct encapsulated relay from mfgr and kept the Ford starter relay as an emergency spare. Had to peel encapsulation off to find vendor as thruster mfgr no longer supports a 1997 thruster. Getting old is not fun for boats and owners.

 

[Pete Meisinger]

Makes me love my Albin and it's "barn door" rudder all the more.

pete

 

[North Baltic sea]

Hi,

my NT 37 is this. It's ok in most cases, but too ineffective in high winds. together the propeller power and side power is sufficient. keep this to the smallest and more efficient you'll be fine for sure.

Side-Power SE40/125S 12V and 2*battery is same my main engines.

NBs

 

[backinblue]

FYI - My stern thruster is mounted off center on port side and includes the tunnel "lids" that helps direct the flow.

Hope that helps - any questions ask away.

Hi Don, I have similar bow and stern thrusters, possibly a newer model and/or slightly smaller than yours. Bow is SE60 and stern is SE40 on startboard side. One question about the stern thruster. I read somewhere that the downward deflectors/lids on the stern thruster decrease thrust (~20%??). Seeing that they are sufficiently below the water line I decided to remove the deflectors to increase thrust. Seems to work fine, never any cavitation or anything like that. I wonder if they just come standard that way so nobody normally thinks to remove them. Pretty simple, just some screws holding them on. Ever try it or think about it?

 

[Comodave]

The scoops are optional. But they probably thought they would cavatate so they installed them. If it works without them then go with it.

 

[backinblue]

If I compare the bow and stern thrusters with the boat at rest, they are probably both at a very similar depth so I saw no reason not to remove them especially if it increases thrust and also less underwater appratus/drag perhaps. Regardless I have seen no downside to removing them. I imagine they are useful if the thruster is very close to the surface of the water.

 

[Moonfish]

Our friends own this company and they have a wireless, DIY smart thruster:

https://www.dockstarthrusters.com/

If you look under "Gallery" you'll see a CHB 34 in our marina named "Maxine" that has one installed.

 

[Bacchus]

Bob
I have had the lids off only for servicing when on the hard. I hsve no way to measure or confirm but my stern thrstr seems more effective than the bow. It may be just quieter. I dont see why the lids would interfere with oper or effectiveness as they are really not in wsy of the flow... just above it??

 

[backinblue]

Bob
I have had the lids off only for servicing when on the hard. I hsve no way to measure or confirm but my stern thrstr seems more effective than the bow. It may be just quieter. I dont see why the lids would interfere with oper or effectiveness as they are really not in wsy of the flow... just above it??

Thanks Don. I believe they partially are in the flow otherwise not sure they would do anything. They direct some of the sideways thrust downward, so it makes sense to me that you get less than full thrust with them. I didn't remove them because I didn't have enough thrust or any other issue, but I did read somewhere that the thrust is decreased with them. Like yours, mine is probably a foot below the surface so I figured they were not needed vs. an installation where it may be just barely under the surface. I have no real before/after data or even a feel of whether it's different, but knowing I am not impeding the thrust in any way makes me happy! Besides, it's fun to modify and try things. Might be worth an email to Sleipner.

 

[mickand]

I have a Sidepower 100 12v externally mounted stern thruster. It's been in heavy use for over 7 years. Easy install and 100% reliable so far.

 

[Arc]

A stern thruster really enhances the thrust of a bow thruster when used together. In addition it’s great for line handling and getting off a leeward dock. I added one to my boat thinking it would be a good toy. Now I would never be without one.

 

[Arc]

https://youtu.be/QACDnB2AkpI

 

[LindaFlorida]

Thank you everyone. Was hoping that someone had a photo of the thruster motor installation (interior) location.

 

[Comodave]

Here are some photos of the one I put in. Took me and a friend about a day and a half to install it. The photos uploaded out of order but you can see the process of installing the thruster. The photo of the stern shows the tunnel that has to be installed. You either use a tunnel like this for a stern thruster or a tube if you are installing a bow thruster.

 

[backinblue]

Thanks Dave. I assume you also didn't need to install the downward deflectors as I referenced in an earlier post? Mine seems fine w/o them and should have a little more thrust w/o them as long as the thruster is sufficiently submerged.

 

[Comodave]

No, I didn’t install them. Never found the need since the thruster moved the stern quite well. I was going to try it first and if it didn’t do well then add them. I don’t remember how far it was below the surface but it was within the specs.