Bow Thruster vs Stern Thruster

[rwidman]

My marina is primarily a dry stack operation with about fifty wet slips and fifteen or so of these under an annual lease. Dry stack boaters use the remaining slips if they want a slip for the night or weekend.


There is an adjacent boat dealership dealing in mostly bow riders, deck boats and center consoles. We get a constant flow of brand new boaters.


A couple weeks ago, a guy managed to drive his boat sideways actually over a finger pier and hit a boat in the next slip. Mostly what I see though is people driving too slowly and the current taking them into finger piers or other boats. Often, when they see they are about to hit something, they turn the wheel and hit the throttle, forgetting that unlike a car, a boat steers from the back. This just makes the collision worse.


There is a captain at the marina who gives group and individual training and I try to recommend this when I can without sounding insulting.

 

[psneeld]

As an aside, when I worked for Sea Tow, our franchise was very hesitant to unground these type of drives.

If we did, it was at very low power which made an ungrounding on a falling tide probably a long term grounding, and depending where, it could develop into something worse.

Maybe with more experience with them, policies may change, but would make me think long and hard before buying them.

 

[Fletcher500]

Tight spot. I have a marina I visit with a similar configuration.. I always find it amusing when people feel a need to stand there with their hands on their hips, or yell directions. Often the people speaking are less experienced than the person docking. If someone is helping with lines, great, otherwise go about your biz, and let the person dock.

That is great that you can handle your boat without need of a stern thruster. I can to, as long as I limit where I try to dock. I don't want to limit myself that much however. I am sure that if I was better at handling my boat, I would have no need of a stern, or bow thruster.

Here is a spot I wedged myself into on my last trip. Langley WA. This is roughly the configuration of boats that were there when I went in. The yellow arrow points to the slip that was open. I added the boats to the google image that were there when we arrived and left. I am not good enough to squeeze into that space without bow and stern thrusters. As it was, everyone there on the dock was very, very nervous when it became evident as to where I was headed. BTW, it wasn't my choice, but where the warfinger directed me as it was the only empty slip in the small harbor and I think I was as nervous as any of the onlookers.

 

[MurrayM]

I offered up the Volvo IPS drives because Mark was asking just how complicated steering systems could be. No way I'd go for them...we're having big tides right now and there's everything from sticks to logs floating around.

 

[Capt.Bill11]

NOT like most boats...IPS Has a skeg BEHIND the props... NO PROTECTION FWD

Exactly what protection do most twin inboard boats have in front of their props?

 

[rwidman]

Little to none.

My boat has a keel and skeg to protect the prop and rudder (and of course to help it go where I point it). I've grounded it (in mud) more times than I would like to admit but I have always (knock on wood) been able to back off and continue on my way.

Actually, it's usually my wife who grounds it but not always.

 

[Bruce B]

They drive normal at lo or hi speed...you have to engage the computer & joy stick at lo speed and you then control direction and thrust w the joy stick.
The drives rotate but less than you might guess...I forget the exact # but memory says it's around +\- 30* and they can reverse...pretty cool to run but I don't think I'd invest in them. I can do almost the same maneuvers w single main and 2 thrusters...I just have to be cautious to not over do the thruster use

Exactly the thoughts we had when we decided to look at trawlers.
The reason I asked about the thrust vectoring in the IPS/Zeus is that the boats equipped with those systems have no rudders. I wonder how well they steer with a single pod?
Bruce

 

[rwidman]

Exactly the thoughts we had when we decided to look at trawlers.
The reason I asked about the thrust vectoring in the IPS/Zeus is that the boats equipped with those systems have no rudders. I wonder how well they steer with a single pod?
Bruce

If you were actively looking to purchase one, you could ask for a demonstration. They can't be too bad because a lot of high end manufacturers are beginning to use them.

Many conventional twin screw boats don't do well on just one engine. Others seem to be OK.

 

[Bruce B]

If you were actively looking to purchase one, you could ask for a demonstration. They can't be too bad because a lot of high end manufacturers are beginning to use them.

Many conventional twin screw boats don't do well on just one engine. Others seem to be OK.

More curiosity on my part than anything else.
I like understanding how things work. It never occurred to me that a conventional twin engine drivetrain boat might not steer well with an engine out.
We didn't ask for a demo of the Sabre as we decided that the express design wasn't suited for our needs.
I actually think the pod drives are brilliant! I'm sure the benefits are enticing...
Bruce

 

[alormaria]

I'm holding out until Marine Trader offers "voith schneider cycloidal drive".

That's the ticket. Yeah, that's the ticket...

 

[CPseudonym]

I'm holding out until Marine Trader offers "voith schneider cycloidal drive".

That's the ticket. Yeah, that's the ticket...

Coming soon to a dealer near you...

 

[Ka_sea_ta]

The AL plate builders up here use a lot of Volvo diesel outdrives... Some like Coastal Craft have gone to IPS drives... In order to protect the drives they build a keel or keels in front of the drives (legs) The builders refer to these as log jumpers.. It's impressive to see one hit a log at 30 knots the back of the boat just violently jumps out of the water... I think it would be more impressive to be riding in one....

 

[Bruce B]

The AL plate builders up here use a lot of Volvo diesel outdrives... Some like Coastal Craft have gone to IPS drives... In order to protect the drives they build a keel or keels in front of the drives (legs) The builders refer to these as log jumpers.. It's impressive to see one hit a log at 30 knots the back of the boat just violently jumps out of the water... I think it would be more impressive to be riding in one....

See the things you learn here? I've never heard of Coastal Craft... Kind of cool looking boats. Something new every day.
Bruce

Coastal Craft Yachts - Custom Boat Builders Canada

 

[GFC]

When we bought our boat six years ago we had it shipped from MI to Portland, OR. The yard that was putting her back together installed some equipment for me, one of the things was a bow thruster. The yard was a dealer for Side Power so that made it easy.


The Side Power charts suggested a thruster with (going from here) 225 pounds of thrust and an 8" tube. He suggested going up one size to 275 pounds of thrust, still with an 8" tube. He couldn't find one of those so he put in a thruster with 325 pounds of thrust in a 10" tube.


This thruster moves the bow of our 60,000 pound boat like it is a toy in the bath tub. I don't use it often, but once in awhile when we're backing into the slip I'll use it if the bow is a little out of alignment.


Here's what the install looks like....

 

[Ka_sea_ta]

See the things you learn here? I've never heard of Coastal Craft... Kind of cool looking boats. Something new every day.
Bruce

Coastal Craft Yachts - Custom Boat Builders Canada

I first saw one these in Hoonah AK back in 2003. The sides were so fair I thought it was a glass boat.... I got to know Jeff the owner of CC. He told me they spend as much time fairing the hull as they do welding it. The quality of workmanship is impressive as is the price.

 

[Bruce B]

I first saw one these in Hoonah AK back in 2003. The sides were so fair I thought it was a glass boat.... I got to know Jeff the owner of CC. He told me they spend as much time fairing the hull as they do welding it. The quality of workmanship is impressive as is the price.

They really are interesting looking boats aren't they! Seems like a nice but slightly different take on an express style yacht.
Thanks again for the introduction.
Bruce

 

[BruceK]

Riviera are putting Volvo IPS in several of their boats, eg the 36SY and 445SUV. It appears they move the engines aft, creating more usable space below and a more accommodating boat. That`s a plus, but IPS exposure and the risk of the unit dropping off in an impact, needing salvage or a new one, is a negative. Of course that needs balancing against potential prop/skeg/shaft impact damage with conventional setups. I seem to recall some frightening figures from earlier threads for IPS maintenance and replacement.

 

[Great Laker]

I would like to have both bow and stern thrusters on our 41' boat. I do not have room for an internal bow thruster due to water tanks under the forward cabin deck. I will be putting in a stern thruster since it is so easy to do. For the bow thruster, I am looking at the external pod thrusters that bolt onto the keel below the water. Does anyone have experience with them? Sidepower looks pretty good with their variable speed controller.

I am in the camp that if I could only have one thruster it would be a stern. I can put the nose in against the dock, stop forward momentum, and push the stern over without moving forward or backward. Plus, I can steer the boat with the stern thruster while backing out of a narrow channel with the stern thruster as well. Consider putting in just the stern and trying it that way. You might find you don't need to spend more on a bow thruster.

 

[Jeff F]

They drive normal at lo or hi speed...you have to engage the computer & joy stick at lo speed and you then control direction and thrust w the joy stick.
The drives rotate but less than you might guess...I forget the exact # but memory says it's around +\- 30*

I am guessing here, but based on what little I know I would bet that the computer is always engaged, and that wheel steering is fully 'drive by wire'

 

[dhays]

I am in the camp that if I could only have one thruster it would be a stern. I can put the nose in against the dock, stop forward momentum, and push the stern over without moving forward or backward. Plus, I can steer the boat with the stern thruster while backing out of a narrow channel with the stern thruster as well. Consider putting in just the stern and trying it that way. You might find you don't need to spend more on a bow thruster.

I am the opposite. If I had to choose one, it would be a bow thruster. I can move move the stern sideways a little with throttle and rudder. With a single engine boat I can point the bow, but not move the bow sideways without a thruster.

 

[dhays]

I am in the camp that if I could only have one thruster it would be a stern. I can put the nose in against the dock, stop forward momentum, and push the stern over without moving forward or backward. Plus, I can steer the boat with the stern thruster while backing out of a narrow channel with the stern thruster as well. Consider putting in just the stern and trying it that way. You might find you don't need to spend more on a bow thruster.

I am the opposite. If I had to choose one I would take a bow thruster. With a single engine boat I can move the stern sideways some with rudder and throttle. While I can point the bow, I can't move it sideways without a thruster.

Edit. Sorry about the duplicate. Bad cell connection.

 

[Codger2]

I am the opposite. If I had to choose one, it would be a bow thruster. I can move move the stern sideways a little with throttle and rudder. With a single engine boat I can point the bow, but not move the bow sideways without a thruster.

 

[FF]

"With a single engine boat I can point the bow, but not move the bow sideways without a thruster'

Our launch pivots about 2/3 back from the bow.

So moving the bow does require moving the stern with prop walk , and basically in only one direction.

 

[raymond.goff]

I have a 34 Marine Trader with a bow thruster. There is no way I would ever have a single screw without one. My bought also has a Lehman 120. This picture is before I bought her and started repairs.






Sent from my iPad using Trawler Forum

Raymond Goff
1978 Marine Trader 34

Www.libertytrawler.com

 

[Bruce B]

Interesting thread. I've repaired bow thrusters for friends but I've never used one...
Our current sailboat, due to its fin keel/spade rudder configuration, is so easy to direct both in forward and reverse, that we never even considered the option. Our previous sailboat was a centerboard/full keel with an attached rudder. That was a horse of a different color! In reverse, it would go backwards. Sometimes to port and sometimes to starboard. We eventually learned to control the beast but it was challenging! I remember a friend of mine who is a licensed captain watching me one day and reprimanding me for my technique. He decided that he would take me out for a few lessons...
2 hours later he walked away from the helm and said the boat was possessed!

Anyway, as the American Tug comes equipped with a bow thruster and we are spending all of this money anyway...we have elected to equip her with a stern thruster too. The memories of that sailboat made it an easy decision!
Bruce

 

[dhays]

Interesting thread. I've repaired bow thrusters for friends but I've never used one...
Our current sailboat, due to its fin keel/spade rudder configuration, is so easy to direct both in forward and reverse, that we never even considered the option. Our previous sailboat was a centerboard/full keel with an attached rudder. That was a horse of a different color! In reverse, it would go backwards. Sometimes to port and sometimes to starboard. We eventually learned to control the beast but it was challenging! I remember a friend of mine who is a licensed captain watching me one day and reprimanding me for my technique. He decided that he would take me out for a few lessons...
2 hours later he walked away from the helm and said the boat was possessed!

Anyway, as the American Tug comes equipped with a bow thruster and we are spending all of this money anyway...we have elected to equip her with a stern thruster too. The memories of that sailboat made it an easy decision!
Bruce

You won't be sorry. Your experience with a full keel sailboat will help you I think when you start to drive your new boat. I do miss the way my sailboat would spin in a dime in forward or reverse. As I have gotten more experience, back and fill does work pretty well depending on the wind and current.

 

[danderer]

I do miss the way my sailboat would spin in a dime in forward or reverse.

Ditto. I didn't know how good I had it then. (At least in this particular instance.)

 

[bcam]

Interesting thread. I've repaired bow thrusters for friends but I've never used one...
Our current sailboat, due to its fin keel/spade rudder configuration, is so easy to direct both in forward and reverse, that we never even considered the option. Our previous sailboat was a centerboard/full keel with an attached rudder. That was a horse of a different color! In reverse, it would go backwards. Sometimes to port and sometimes to starboard. We eventually learned to control the beast but it was challenging! I remember a friend of mine who is a licensed captain watching me one day and reprimanding me for my technique. He decided that he would take me out for a few lessons...
2 hours later he walked away from the helm and said the boat was possessed!

Anyway, as the American Tug comes equipped with a bow thruster and we are spending all of this money anyway...we have elected to equip her with a stern thruster too. The memories of that sailboat made it an easy decision!
Bruce

We saw a number of ATs while in the Broughtons this summer. All had both and several had the control station in the cockpit for backing down. Very nice and something we will do when we add the stern thruster.

 

[Bruce B]

We saw a number of ATs while in the Broughtons this summer. All had both and several had the control station in the cockpit for backing down. Very nice and something we will do when we add the stern thruster.

I saw one boat with a cockpit control station and didn't understand why it was there! Now it makes more sense. We will not have that option but I'm guessing that the visibility to the rear is good enough to get by. I have a friend who owned a Nordhavn 40 and that boat had virtually no clear view aft. He needed a camera to see what was happening behind him.
Bruce

 

[Simi 60]

I have a friend who owned a Nordhavn 40 and that boat had virtually no clear view aft. He needed a camera to see what was happening behind him.
Bruce

I have the same
installed these, one in the engine room and one out back
2X 18 IR LED CCD Reverse Camera 7" LCD Monitor CAR Rear View KIT 2X 10M Cable | eBay

Work great, only annoyance is the red yellow green reversing lines.