Stern thruster that swivels and lowers?

[Seevee]

The other day I heard reference to a stern thruster that lowers and swivels that can propel the boat forward, and can be used incase of an engine failure.

Anyone heard of such a thing?

 

[RT Firefly]

Greetings,
Azipod drive?

 

[Seevee]

Greetings,
Azipod drive?

Looks neat, but seems like it's for ships and big stuff.

 

[wwestman]

Get a BIG electric trolling motor and put it on your swim platform?

 

[jleonard]

I have a Dickson hydraulic stern thruster but the hyd pump is run by the main engine.

 

[FF]

A 6+ hp outboard would do the trick , and still be of use on the dink.

 

[North Baltic sea]

Greetings,
Azipod drive?

Hi Mr RTF

Yes Azipod, Prepare a buck in the far north the company ABB Ltd. And this little ship sailing somewhere in there like you Allure- and Oasis of the Seas.

 

[psneeld]

There was one thruster manufacturer that made a swiveling thruster...

See if I can find it later.

 

[MurrayM]

There was one thruster manufacturer that made a swiveling thruster...

See if I can find it later.

Here's a 100hp azimuth drive...don't know about it's relevance to our kind of boating, but are used in hard working log boom dozer boats on the west coast: 360 Propulsion - Olympic Drives manufactures Marine Azimuth Drives.

 

[HopCar]

I've been trying to imagine how a thruster could work to power a boat if the main engine was inoperable.

A battery powered thruster wouldn't get you very far. I guess you could power it with a generator and really big battery charger. Hydraulic power from the generator?

I think it would need to be significantly larger than a thruster sized to just push the stern around.

I think there are better ways to use your generator as auxiliary propulsion.

 

[psneeld]

Probably why every thruster manufacturer doesn't have one.

Mote trick than treat...but does have some limited uses.

 

[GreenGoose]

Dickson Hydraulic stern thruster/get-home

The other day I heard reference to a stern thruster that lowers and swivels that can propel the boat forward, and can be used incase of an engine failure.

Anyone heard of such a thing?

Yes, Dickson Stern Thruster makes a hydraulic stern thruster that can be used as a get-home by swiveling 90 degrees and lowering. Dickson Thruster - Stern Thrusters

This article gives an extensive overview of numerous get-home systems including the Dickson system The Get-Home System: Do You Need One And What Are The Options? | | PassageMaker


Many of the Monk 36 boats have these installed either as just stern thrusters or combo thruster/get-home. They don't mention the get-home option on their website, but if you contact them they'll give you any info you need on it. It's basically the same except you need to order the special brackets that rotate and lower which are at time of this writing $650. You use a long rod that connects to the bracket in order to rotate and lower it. It can be done from the aft deck on most boats so that you don't have to climb down onto the swim step to deploy.

You can have either a single motor/prop or double for greater thrust. They show pix of both on their website.

To use it as a get home you need to run it off of another engine than your main. Typically a genset, although you could install a small Yanmar, Volvo Penta, etc just to operate the hydraulic system. Typically it is run off of the genset which also means that you would have to run the genset when docking if you want to use it in stern thruster mode.

The tricky part is determine how fast your genset will push your boat. You can first find the horsepower by consulting the specs for your genset. According to the article above the hydraulic system will transmit 80-90% of the power of the genset to the prop(s).

Then you need to find a calculator that will convert HP into speed for your boat. I used this one by Volvo Penta Find the Best Boat Engine for Your Needs: Volvo Penta Engines. It proved to be pretty accurate and the final install pushed the boat just 1/2 kt less than this calculator predicted. The only downside is that it only uses HP's that correspond to the size of the various engines that they sell. Other calculators are available that work for all HP inputs, but I have no experience with them.

 

[ranger58sb]

Yes, Dickson Stern Thruster makes a hydraulic stern thruster that can be used as a get-home by swiveling 90 degrees and lowering. Dickson Thruster - Stern Thrusters

Woof! Nice first post!

-Chris

 

[HopCar]

GreenGoose, Welcome aboard! Thanks for that post. I think you're going to be handy to have on this forum.

 

[RT Firefly]

Greetings,
Welcome aboard.

 

[heygreg]

The other day I heard reference to a stern thruster that lowers and swivels that can propel the boat forward, and can be used in case of an engine failure.

Anyone heard of such a thing?

If your still out there SeeVee.............YES. The Dickson Thruster is the way to go. However, it will take customization. It's the best solution for a Get-Me-Home scenario. However, you do need a hydraulic power source. Large gensets have a power take off feature (PTO) than can adapt a hydraulic pump. The Dickson Thruster will provide you 6hp each. You will need two thrusters to push your monster boat 4.5 - 5 knots. You can push the Dickson Thruster to 7.5 hp with increased pressure (4000 psi). As for a mechanism to lower the thruster and turn it 90 degrees, this will be a custom made tube in tube configuration. All in all, the set up will cost you $7500.00 when you're done. It will be the BEST investment you've ever made should you become dead in the water and currents or wind become you nemesis.

Here some basic calculations. Hydraulics are 80-85% efficient. Diesels can be loaded to 80%. Thus, you need 20 hp of PTO power to do the job. At 80%, you have 16hp of power to play with, then deduct 20% fluid power loss and you now have 13 hp to feed your Dickson Thruster. Your alternator and water pump on the genset will consume about 1 to 2 hp, so keep that in mind. The minimum genset to do the job is 20 kw.

I will be building the same for my boat. However, I will not utilize an AC style genset. Instead, I will utilize my Aux Diesel engine to push three components. The 1st is to drive a 30,000 btu clutch driven Sanden scroll compressor. This is found in mobile applications. The system will chill water to 38F, then be circulated to 3 evaporator coils designed for 50% humidity & 50% temperature. AKA Sensible / Latent heat ratio. With the AC running, I will also run a clutch driven 160 amp alternator. This will provide power to the evaporator fans that push 400 cfm's each (12 volt). The aux engine will be variable speed that correlates to water temperature. 50F water = full engine speed, usually 3200 rpm's. 40F water temperature or below equates to 1800 rpm's engine speed. If and when I need auxiliary power, the AC and alternator are turned off and the hydraulic pump engages to make fluid power to drive the Dickson Thrusters. If you have a 40 foot monster (or bigger) you'll really need 3 thrusters. Why? Because your boat is a kite and you need to overcome current and winds. Thus, you need to push your trawler 8 mph minimum. In all reality, a 40 footer really needs two thrusters just for docking maneuvers on windy days.

This set up is designed to not have anything AC electrical on the boat and to use your Aux engine as efficiently as possible. AC is stupid in my opinion, but this is how the industry is driven.

You are not out in left field with your idea. Hyd. driven Dickson thrusters made to drop 1 foot and rotate is the ultimate solution.

The absolute BEST engine for your needs is the Universal M25-XPB. It provides 26hp at 3000 rpms. This gives you 20 net hp to use up. Perfect to run 2 dickson thrusters at 4500 psi.

As for the Sanden compressor, the TRSE09 requires 6 hp (4.5 KW) to deliver 30,000 btu's (2.5 tons). The compressor would spin at 3500 rpm's, full load. You need to understand that this type of air conditioning is to run the boat (or flybridge) temperature below 70F on hot summer days in the south. This is what "she" requires. Not everybody needs their boat to be a blast freezer when it's 92F outside.

To run three evaporator blowers (fans), you'll consume 16 amps each (400 CFM), totaling 48 amps. A chilled water circulation pump will draw 6-10 amps.

This means the clutch driven secondary alternator will need to be in the 150 amp @ 3600 rpm's range (Balmar). Count on 4-5 hp off your engine to run your alternator.

Another thing to consider is the engine configuration. Toss the stupid transmission and go with a "bearing supported stub shaft". This provides you the means to side load off the shaft. Your side loads are your belts to run your stuff. You stuff engages and disengages by clutch pully. Hayes Manufacturing up there in Fife Michigan makes this kind of stuff. Here's a link:
https://www.hayescouplings.com/products/bearing-supports/

There you have it. Now get busy .

BTW, I am a test engineer with a refrigeration / air conditioning engineering background. I will build this set up in my warehouse before I install it on the boat. it will be built to be reliable and simple.

Also understand that the AC set up will be much like that used in your car, which is not the same as what is used in your house or office.

BTW.........your in St Pete, I'm in Largo Florida. If your still out there and care to elaborate, let me know. I know a ton of fabricators to do the thruster rotation rigging. I also know a really good machines named Joel Foster who has done some really good "one off" work for me over the years. Joel Foster is in Pinellas Park, FL.

 

[heygreg]

https://www.westerbeke.com/advanced%20specs/universal%20m-25xpb%20(2012).pdf

 

[Comodave]

GreenGoose,

Welcome aboard. Good post, you beat me to it. Glad to have you aboard.

 

[South of Heaven]

Maybe GreenGoose's last name is Dickson??

 

[GFC]

So what if it is? That was a great post and a nice way to start a TF membership.

 

[rsn48]

And the cost of the Dickson thruster?

 

[Giggitoni]

It’s been 2 1/2 years since GreenGoose posted in his thread. I don’t know if he or she is still around.

 

[Comodave]

Good point, I didn’t notice the date of the post...