Which Bow Thruster?

In preparation for doing a repower in a couple of months, I am also doing research and collecting the other components for several upgrades while the boat is in the yard. The boat currently does not have a bow thruster, so I am looking for opinions of which brands to consider. The boat will not be equipped with a hydraulic pump, so the thruster will be electric and my first thought is to keep it simple at 12V. The boat is 40’ (34’ 7” LWL) by 13’ 8”, 30,000 pounds, 4’ draft. My current short list is the Side Power SE 80/185 T or the Vetus BOW7512D.

Thanks.

Bob

Bob

The brand is less important than the quality of the install IMHO. I have a Lewmar and it has been flawless, but most are. BYW, I prefer electric below 15HP

Why stick with 12V, 24 V offers a smaller motor for same HP and easier cabling. Peter on Twistedtree is an expert on this stuff, you may want to talk with him as well as us amateurs.

I installed a Sidepower about 8yrs ago, it also has been flawless. I put a battery right at the unit instead of running heavy cable to the engine room. Works well, have a charge link using light gauge leads back to house panel. There is no provision for AC based charging, except by piggy backing on the house batt, but everything is 12v.

Above a certain size, 24v is definitely better. Put a batt bank up there and then you have to figure out charging. If you routinely have AC power available, just put a 24v charger there and have no other connection to your 12v DC system. Just know that to top up batts, you need AC at least occasionally. The total amp-hours used by the thruster is usually quite low due to short run times, so this should work fine.

Go with the Side Power and consider going one size up. When you really need a thruster you won't regret it.

As others have mentioned mount the batteries as close to the thruster as you can.

I agree with Capt Bill about upsizing. We had a 24V Sidepower installed on our boat about 5 years ago when we bought her.


The charts all spec'd a thruster with an 8" tube with (IIRC) ~250 ft lbs of thrust. The yard doing the install suggested we go up a size to one with ~300 ft lbs. He looked around and couldn't find one anywhere so we went with a 10" tube and around 375 ft lbs of thrust.


It's like horsepower. I've never heard anyone wish they had less horsepower. We live in a windy area and when I use the thruster it's often when the wind is blowing. When I use it I'm always glad we upsized.

The battery box on this boat is built into the engine room liner and is right up against the forward bulkhead. I believe the thruster would only be 5' away. I am going to the boat this afternoon to get some measurements for the thruster tube and other stuff I'm planning on doing, so I'll measure for tentative cable length as well.

I have considered tying into the windless cables for the thruster. The current windless cables are heavy, 2/0, maybe even 3/0. I'll know later today. The cables run right by where the thruster head will be and it would be a matter of cutting the cables and crimping on new ends. The thruster would still have it's own fuse which is lower amps than the windless breaker. I would re-label the windless switch to include Bow Thruster. Just a thought. I don't violate any USCG or ABYC standards.

Agree with 24 volt dedicated bank and going "one up", and will put in a big vote for Vetus based on my experience with their great customer over the phone technical service many years after any warranty expired on a long discontinued model, with parts (I didn't have to get, based on their help) still available. Tells you something about a company's character, and that of their distributor, Florida Bow Thruster.

Rather than piggybacking the thruster on the windlass power cable, how about putting a pair of batteries for both windlass and thruster, and use the existing cables to recharge the battery bank. One thing about electric thrusters is if you need it, you'll likely need it a lot. That day, you'll want a bank close to the thruster, so you won't have a major drop in capacity from the back.

We sort of went through what you are going through a year ago. In our case we had an old anemic Wesmar 12V 5HP bow thruster in an 8" tube. We wanted to significantly improve the bow thruster performance and as an aside add a stern thruster.

In our deliberations it quickly became apparent that we would pretty much need to upgrade from 12V to 24V if we didn't want to enlarge the bow tunnel. So the shared 12V battery in the bow became a dedicated windlass battery and we installed a separate 24V bank for the bow thruster.

We went back and forth between Wesmar and Sidepower; it was a bit of a challenge to compare apples to apples as one (Wesmar) rates in HP while the other (Sidepower) rates in foot pounds. In the end we felt that each had slight advantages over the other but either would be a sound choice.

We went with 13 HP Wesmar thrusters because their control pad fit on our helm panel whereas the Sidepower pad was too big. There was a slight price premium on the Wesmar but not significant.

Blue Sky is 42' and 35,000 pounds.

stubones99 said:

rather than piggybacking the thruster on the windlass power cable, how about putting a pair of batteries for both windlass and thruster, and use the existing cables to recharge the battery bank.
stu, that's what we did. I have four batteries right next to the thruster that are for the thruster and the windlass.

one thing about electric thrusters is if you need it, you'll likely need it a lot. That day, you'll want a bank close to the thruster, so you won't have a major drop in capacity from the back.
i'm not sure i agree with this statement about needing it a lot. The times when i use mine i'm using it for a few seconds at a time, spaced out by several seconds of down time. One big advantage of going with a lot of extra thruster power is that you don't have to use it a lot.
....

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gfc

My boat is an OA 42' and weighs about 33,100lbs. The thruster is a SidePower, 24v, 10hp which has 4 grp31 AGMs snuggled right up close to the unit. When I hit the joy stick on the bridge, the bow almost jumps to the selected side. I can't say enough about the value of having a thruster that is big enough to really muscle the bow. Like others have posted, just really short bursts does the job.

Thruster Batts

24-volt thruster (click on the photo):



No dedicated battery. Sufficient energy hasn't been an issue.

George has had a good experience dealing with Vetus. As a dealer, I have a less than wonderful time dealing with them.

Imtra Corporation, who sells Sidepower, is one of my favorite companies to deal with. Excellent service and a good inventory.

I really can't comment on the thrusters quality. I don't sell a lot of thrusters but I think both brands are pretty well made.

Our experience is with ABT (Trax) and with Side-power/Sleipner. We've had no problems with either. ABT seems to focus more on larger boats and Side-power more on boats in the size ranges most owned by people here. Side-power also does a lot of innovative work from Stabilizers to control systems. For anyone who is wanting thrusters but really doesn't have the space for mounting a tunnel thruster, Side-power also offers a pod thruster. I have no knowledge of it, other than it being offered.

BandB said:

Our experience is with ABT (Trax) and with Side-power/Sleipner. We've had no problems with either. ABT seems to focus more on larger boats and Side-power more on boats in the size ranges most owned by people here. Side-power also does a lot of innovative work from Stabilizers to control systems. For anyone who is wanting thrusters but really doesn't have the space for mounting a tunnel thruster, Side-power also offers a pod thruster. I have no knowledge of it, other than it being offered.

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I just installed the Exturn (Sleipner/Sidepower) external thruster mentioned above. Install was a straightforward bolt-in, and it's been working wonderfully.

Pau Hana said:

I just installed the Exturn (Sleipner/Sidepower) external thruster mentioned above. Install was a straightforward bolt-in, and it's been working wonderfully.

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More information would be good, I`m considering installing an Exturn next haul out.
Any photos of it installed? Was it difficult to attach, does it require fiberglass work to create a base for it? Did you need to add any battery(I`m hoping to use the windlass power supply)? What wattage does it draw? Any discernible effect on performance/speed? Anything else you can pass on from the experience?

My boat came with a Sidepower 12 volt thruster that suffered from short cycle time do to low voltage drop from the cable runs. These were 4/0 cables and the thruster was pulling 400 amps. Had the motor converted to 24 volt and moved the batteries to the thruster compartment with their own charger. The higher voltage units have longer duty cycles, draw less amps, use smaller size cables and can run with normal automotive sealed batteries.

There are some pics of the installation in my refit thread.

Ted

Before purchasing ANY thruster find out the allowed ON time and the required OFF time ..

On time is frequently in seconds , Off time in minuets.

Folks pay the extra for HYD for a reason.

HopCar said:

George has had a good experience dealing with Vetus. As a dealer, I have a less than wonderful time dealing with them.

Imtra Corporation, who sells Sidepower, is one of my favorite companies to deal with. Excellent service and a good inventory.

I really can't comment on the thrusters quality. I don't sell a lot of thrusters but I think both brands are pretty well made.

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As a lifelong retailer, I can understand the difference between a brand's relationship with its dealers, and with end consumers. Some of the most-loved brands with great consumer friendliness were the biggest pains to deal with. Apple (always) and Sony (back in the day) come to mind. Vetus always seemed to me to be more OEM and boatyard oriented than a "retail" brand.

George, I think you've described my situation exactly.

I have run many different boats over the years and have run too may with underpowered thrusters. Since the normal crew on our TF boats are a husband and wife, happiness while docking is worth a few extra bucks for the right power unit.
I have to give credit to someone here on TF who posted this picture a few years ago.

now thats a bow thruster. LOL

FF said:

Before purchasing ANY thruster find out the allowed ON time and the required OFF time ..

On time is frequently in seconds , Off time in minuets.

Folks pay the extra for HYD for a reason.

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hyd and 120VAC

On a properly sized thruster 5 seconds seems like a long time, 10 an eternity. Count it off sometime...

I ran my boat a few years with no thruster. Best learning experience ever. Since installing it, I have never run it for more than maybe 10 sec as I already made my plans to do the maneuver without it. Never had it thermal out, not sure how long the run time is.

remwines said:

In preparation for doing a repower in a couple of months, I am also doing research and collecting the other components for several upgrades while the boat is in the yard. The boat currently does not have a bow thruster, so I am looking for opinions of which brands to consider. The boat will not be equipped with a hydraulic pump, so the thruster will be electric and my first thought is to keep it simple at 12V. The boat is 40’ (34’ 7” LWL) by 13’ 8”, 30,000 pounds, 4’ draft. My current short list is the Side Power SE 80/185 T or the Vetus BOW7512D.

Thanks.

Bob

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I would go with the 100 SE Sidepower on a 24v batt with a separate charger. It's not much more money than the 80 and it's way stronger--think wind and current. We put one on our 36 Sabre and have not regretted it.

Back from the boat. Thanks for responses. Lots of good info to study!

I took lots of measurements and thought it through. I am going to step it up to 24V as recommended and will likely step it up to the Sidepower 100 rather than the 80. I found a place against the forward ER bulkhead to expand the battery bank. That puts the thruster 5' from the batteries. Real-estate is a premium in this ER. And there is just not enough room where I hope to put the thruster and also have reasonable access to batteries (see picture). I am going to see if the yard can install the thruster under that forward cabin floor hatch which is only 13 1/2" by 18 1/2". It is 30" to the bottom of the bilge. They will need a thin youngster to get into that spot. If installed there, it would put the tube about 4' back from the bow at the waterline. The other option is to cut about 2' out of the bottom of a deep storage compartment under the V-birth. It's 41" deep and is where I store the downriggers and crab pot puller, so I don't want to cut it unless I have to. The last picture is from a boat like mine and they cut the bottom out of the compartment to install a thruster. In that boat, it looks like you would have to dive head first into a rabbit hole to work on the thruster. I don't think I could do it. If installed under that floor hatch, I could lay on the head and cabin floor to reach it. Either way, it looks like it's going to be a difficult job.

Bob

yachtbrokerguy said:

I have to give credit to someone here on TF who posted this picture a few years ago.

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Now that's funny! Love that picture.

Consider the possible advantages of using AGM batteries, which can be mounted at a variety of angles and don't need easy access for maintenance. A couple of Group 31's will likely do the trick (though I haven't looked at the specs for the thruster you contemplate).

Remwines,

The thruster needs to be well underwater, or it will cavitate especially if it's a bigger one. Once it cavitates, you are blowing air, not water and your effectiveness drops. Not to mention that cavitation can damage the prop on the thruster.

I would opt for the bottom of the storage compartment.

Stu