Which Bow Thruster?

I have a 41ft Cheer Men with Twin FL120's. I know many will say if you have twins why do you need a thruster but with a keel starting amidships and a hole Sh#t load of windage forward they are not much help when you've got to dock in a tight slip with a 20 knot wind on the beam, it just blows the bow off.

Anyway, the captain has decreed (and I concur #1) that I buy a bow thruster but I want to get opinions on size, makes, etc.

We're in the same boat, so to speak, and have pretty much decided on the a&e turn Yachtthruster. I understand the pros and cons of external vs internal; despite the internet horror stories, I haven't heard of 1 real world example of an external thruster causing damage to a boat due to a log strike.

Plus, I like the DIY approach, and the lack of 2 4" holes in the hull ...

Pau Hana said:

We're in the same boat, so to speak, and have pretty much decided on the a&e turn Yachtthruster. I understand the pros and cons of external vs internal; despite the internet horror stories, I haven't heard of 1 real world example of an external thruster causing damage to a boat due to a log strike.

Plus, I like the DIY approach, and the lack of 2 4" holes in the hull ...

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I was looking at that one as well and I like the simplicity (and relative cost savings) of the install but at 1.8kw, I wonder if it's strong enough to handle my windage.

According to a couple of charts I've seen they seem to recommend 3-4Kw as a mimimum.

Here's a link to Lewmars chart.Lewmars chart

While I don't believe you really need one, if you get one, be sure you get one that is not sized to small just to save a few bucks. Having one that is to weak when you really need it is worse than not having one at all.

While I much prefer hydraulic thrusters, in your case it is more than likely battery operated units you will be looking at.

Vetus, IMTRA, Sidepower, Lewmar, etc all make good units worth looking at. You choice may end up having more to do with who in your area installs thrusters .

Capt.Bill11 said:

While I don't believe you really need one, if you get one, be sure you get one that is not sized to small just to save a few bucks. Having one that is to weak when you really need it is worse than not having one at all.

While I much prefer hydraulic thrusters, in your case it is more than likely battery operated units you will be looking at.

Vetus, IMTRA, Sidepower, Lewmar, etc all make good units worth looking at. You choice may end up having more to do with who in your area installs thrusters .

Click to expand...

I was wondering about hydraulic now that you mention it, no batteries to recharge, etc. How are these normally powered? Off the main engine or the genny? Is there a lot involved in installing these compared to an electric?

Rduval said:

I was looking at that one as well and I like the simplicity (and relative cost savings) of the install but at 1.8kw, I wonder if it's strong enough to handle my windage.

According to a couple of charts I've seen they seem to recommend 3-4Kw as a mimimum.

Here's a link to Lewmars chart.Lewmars chart

Click to expand...

We're looking at the duplex unit:

Yacht Thruster - Bow and Stern Thrusters Models / Technical

Pau Hana said:

We're looking at the duplex unit:

Yacht Thruster - Bow and Stern Thrusters Models / Technical

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Oh yeah, didn't see that one.... That might be an option. I don't think the slim profile would affect boat speed hardly at all.

I just wonder on a trawler with a very pointed entry how that will mount, the flange isn't V shaped from what I've seen.

How much are the duplex units?

About 6 grand +/-.

When I checked out the units, the "V" was enough to mate up the hull with little concern.

Capt.Bill11 said:

While I don't believe you really need one, if you get one, be sure you get one that is not sized to small just to save a few bucks. Having one that is to weak when you really need it is worse than not having one at all.

While I much prefer hydraulic thrusters, in your case it is more than likely battery operated units you will be looking at.

Vetus, IMTRA, Sidepower, Lewmar, etc all make good units worth looking at. You choice may end up having more to do with who in your area installs thrusters .

Click to expand...

I wholeheartedly agree with his first sentence. When we put our thruster in the bow, I checked the charts and found the one they recommended. The boat yard that did the install recommended upsizing to the next size up. (Both would have had an 8" tube). When he tried to buy that size he couldn't find it so he, on his dollar and with my permission, put in the NEXT size up that uses a 10" tube.

I've never regretted going bigger. When the wind is blowing it's nice to have that extra oomph to move the bow.

Rduval said:

I was wondering about hydraulic now that you mention it, no batteries to recharge, etc. How are these normally powered? Off the main engine or the genny? Is there a lot involved in installing these compared to an electric?

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You can run them off a hydraulic pump mounted either to a main engine or your Genset. Or you could use a hydraulic power pack setup where the pump is AC powered and the pack is mounted near the thruster perhaps.

The nice thing about hydraulic thrusters is you can run them for as long as you like without worrying about them timing out due to the motor over heating. And the inherent reliability of hydraulics.

But on a smaller boat a battery operated system where the batteries are located near the thruster may be cheaper and easier to install.

Capt.Bill11 said:

You can run them off a hydraulic pump mounted either to a main engine or your Genset. Or you could use a hydraulic power pack setup where the pump is AC powered and the pack is mounted near the thruster perhaps.

The nice thing about hydraulic thrusters is you can run them for as long as you like without worrying about them timing out due to the motor over heating. And the inherent reliability of hydraulics.

But on a smaller boat a battery operated system where the batteries are located near the thruster may be cheaper and easier to install.

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GFC: I agree, better to have too much than not enough.

Capt Bill: The AC powered hydraulic power pack sounds interesting. We have our queen bed in the forward stateroom right over the thruster and there is a ton of room in there. Getting AC to a hydraulic power pack under there would be a breeze. Plus she does sit a little bow high at the moment and a bit of weight up there would certainly help things.

Has anybody used an AC hydraulic pack? Can you recommend brands?

Wow, a quick online check seems to show that hydraulics are WAY more expensive than the electric DC systems. On the order of 3 to 4 times more expensive!

Instead of an AC hydraulic pack, you might be better off with a PTO mounted pump on your generator. Either way you will be running the generator, adn direct PTO power eliminates the losses associated with generating and then consuming electricity.

You will need to run the numbers for hydraulic capacity to see what you need. A big advantage to a pump on the generator is that it runs at 1800 RPM. In contrast, a pump on the main engine running at idle will produce far less flow per CC of pump size.

I've got pumps on both the main and generator, and either can power one thruster up to full power, but it takes both pumps to power both thrusters at full tilt. The main engine pump is huge, and even then only drives one thruster at idle. The bottom line is that they take a lot of power, and it needs to come from somewhere.

Our bow thruster is anemic at best; good only for a very slow push away from the dock under low/no wind conditions; to use it with any conviction during typical docking manoeuvres would provide standing room only entertainment for the dock crowd.
If we do decide to upgrade, the big question - aside from manufacturer - will be to determine whether we go 12v or 24V. Both approaches have their pros & cons from what I can tell.
Since it hasn't been mentioned in this thread, I wonder what the thoughts might be?

Conrad said:

Our bow thruster is anemic at best; good only for a very slow push away from the dock under low/no wind conditions; to use it with any conviction during typical docking manoeuvres would provide standing room only entertainment for the dock crowd.
If we do decide to upgrade, the big question - aside from manufacturer - will be to determine whether we go 12v or 24V. Both approaches have their pros & cons from what I can tell.
Since it hasn't been mentioned in this thread, I wonder what the thoughts might be?

Click to expand...

with 24V more power is possible, smaller cables are required, and you will have smaller resistive power losses. High power devices like a thruster is where 24V can really make a difference. The down side is that you will need some sort of dedicated charger

We have had 2 trawlers, both single with bow thrusters, the first a Camano with Sidepower, and the current Monk 36 with Vetus. I have not had problems with either. In both cases the bank of batteries ran the house, windlass, thruster, and started the main engine.

I went with the largest Lewmar in 12V, 8HP. Usually its enough, and a lot of the time I don't even need to use it at all. But for the times when it isn't enough I really regret not going for a larger 24V unit. For the OP, that 8HP unit might well be enough. I would just say that if you are going to the trouble of installing one, don't scrimp, go large.

Power for mine is 4x12V AGM's up in the bow next to the thruster. It would have been easy enough to have a 24V charger dedicated to keeping them charged, no need for an elaborate 24V system addition.

I was reading another thread earlier where they said they used an "echo charger" that ran off their 12v bank to charge their 24v bank.

Is it true that AGM batteries are safe to put in unventilated enclosures (like under my bed)?

I went with the extern, it works really well. You should go at least one size larger than they recommend. The yard that did the install had to fabricate a pad for it to mount to because the V on the keel was too sharp for the adapter they make. Be careful with the paint the yard uses, it has to be safe for aluminum. Mine was painted with the wrong paint and it caused electrolysis so all the paint has blistered off and I'll need to have it hauled and re-painted.

Sorry didn't get the picture in the last post. Alex at yachtthruster is great to work with by the way. There are more pictures of my install on thier web page. I did a stern thruster too just for fun. I can do 360s in the fairway no problem. ?

twistedtree said:

with 24V more power is possible, smaller cables are required, and you will have smaller resistive power losses. High power devices like a thruster is where 24V can really make a difference. The down side is that you will need some sort of dedicated charger

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The 24-volt bow thruster on the Coot has plenty of power. Fortunately, the boat's electrical system is based on 24 volts. Also, it helps not having excessive superstructure catching high winds.

What did that bow thruster cost excluding the batteries, charging system just the bow thruster?
Thanks,
Bill

Rduval said:

Wow, a quick online check seems to show that hydraulics are WAY more expensive than the electric DC systems. On the order of 3 to 4 times more expensive!

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Never said they were cheap.

twistedtree said:

with 24V more power is possible, smaller cables are required, and you will have smaller resistive power losses. High power devices like a thruster is where 24V can really make a difference. The down side is that you will need some sort of dedicated charger

Click to expand...

+1

Billylll said:

What did that bow thruster cost excluding the batteries, charging system just the bow thruster?
Thanks,
Bill

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$5,500 installed when boat was built. It has no dedicated battery. Works off the house batteries.

markpierce said:

$5,500 installed when boat was built. It has no dedicated battery. Works off the house batteries.

Click to expand...

Thank you,
Bill

markpierce said:

$5,500 installed when boat was built. It has no dedicated battery. Works off the house batteries.

Click to expand...

Do you feel you compromise your battery life overall from use of the bow thruster?

Do you spend a lot of time on the hook? I'm wondering how long it takes you to recharge the batteries after using the thruster and do you do it from the Genny or shore power most of the time?

I have seen solenoid setups that allow a batterry placed in the bow to be charged with the normal 12V system.

A solenoid setup connects the battery in series to the 12V system when you turn on a 24V thruster or windlass..

It allows for a more powerful windlass/thruster with smaller sized cables running forward and without a 24V charger.

Can't find a link to one right now...will look some more.

(here's one suggested way to do it....but not my favorite 24 Volts from 12)

Here's Vetus's solution but way too pricey...have seen homemade versions with a couple solenoids and switches..more complicated than Yandina's but still worthy of consideration. http://www.vetus-shop.com/vetus-ser...olt-thruster-with-12-volt-charging-p-941.html

After a few debacles at the dock with my thruster quitting on me, I have decided the wiring must change. Sunday, I came in to 10 to 15 knot gusts, bow thruster ready but did all the maneuvering without it and didn't even reach for it! Short quick bursts of throttle, rudder hard to port, kicking the stern over, more bursts in reverse stopping forward momentum and I backed right in like a pro. I need a resource that shows a good wiring diagram and battery set up for my thruster and windlass. The setup I currently have just isn't working for me. Can anyone point me in the right direction? I'm a little tired of hauling up the anchor over the top of the shiny new windlass. I just don't want to wire it twice, I want to do it right the first time. Sorry for the thread hijack...

slowandsteady said:

After a few debacles at the dock with my thruster quitting on me, I have decided the wiring must change. Sunday, I came in to 10 to 15 knot gusts, bow thruster ready but did all the maneuvering without it and didn't even reach for it! Short quick bursts of throttle, rudder hard to port, kicking the stern over, more bursts in reverse stopping forward momentum and I backed right in like a pro.

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That sounds promising, in any case. Is your slip to starboard as you enter your fairway?

Our home slip was to port, and I could take maximum advantage of prop walk. Almost never had to use the rudder, there...

-Chris