\Jump aboard for a look at the pros and cons bow thruster technology.
Bow thrusters have been available to coastal boaters since the early 1980s. In recent years, they have become more mainstream, partially because of technological advances in motor construction, and also due to availability in smaller, more affordable models that are gaining gradual acceptance by builders and influencers for both single and multi-engine sportfishing platforms.
With the recent introduction of single outboard engine joystick control and bow thruster integration from Yamaha (Helm Master EX), Mercury (Joystick Piloting for Outboards, a.k.a. JPO) and Honda (using the Ultraflex interface), bow thrusters are sure to get a major boost as a go-to option for new boat owners.
On the other hand, current owners of older, “experienced” fishing boats can also add a bow thruster of choice via aftermarket means from local installers that practice this very specialized combination of art and science.
Bow Thrusters Explained
Bow (and stern) thrusters come in a variety of types, both internal and external, with multiple power sources (electrical, hydraulic, AC, DC, etc.) For this review, we’re going to simplify our coverage and focus on some of the most popular and affordable internal, tunnel-drive bow thrusters that are powered by the typical 12-volt batteries found on most coastal fishing boats.
The majority of recreational vessel bow thrusters are positioned in a fiberglass composite tunnel located under the waterline in the bow section of the boat. A 12-volt DC motor drives a small sideways-facing propeller with a sudden burst of energy that helps push the bow of your boat either to port or starboard, rather than forward or aft.
Thrusters are usually deployed when moving in or out of your slip at the marina or when pulling up to a fuel dock with a wind and current doing its best to wreak havoc with your close quarters navigation plans. Bow thruster use is typically limited to when a boat either is moving very slowly or at a dead stop.
The three major players in the bow thruster arena are Sleipner (Side Power), Vetus and Lewmar.
Pros & Cons
If you have ever owned or operated a single engine cabin boat (inboard, I/O or outboard) or dual console and have experienced the dread of docking or maneuvering in a crowded marina while challenged by strong winds and/or current, installing a bow thruster might be your best move to solve this problem. When out for a fun day on the water with family or friends, your focus should be on enjoying every second of the day as opposed to stressing about docking your boat at the end of the day. Essentially, a bow thruster puts the bow’s lateral control right at your fingertips with push-button ease.
Although bow thrusters offer welcome assistance for single engine craft, they can also be convenient for twin, trip or quad outboard engine powered sportfishers, especially for those wind-against-tide situations when working counter-rotating engines is not moving the boat exactly as planned. The following are some pros and cons of bow thrusters:
Pros
- Easier docking and maneuvering in tight spaces.
- Improved boat control, especially bow control in strong winds or currents.
- Allows the operator to have more precise boat positioning in a variety of close quarters scenarios.
- Can be helpful in certain fishing situations, to either hold over a spot or control the drift angle of the boat.
Cons
- Can be costly, with the average installation for a 25- to 35-foot boat being anywhere from $10K to $15K or more.
- Requires a dedicated, heavy duty 12-volt power source apart from your boat’s starting and house batteries, with switching and wiring that must be connected to your engine’s charging system.
- Can be a detriment to certain fishing scenarios, especially in shallow water. Unlike electric trolling motors, bow thrusters can make quite a ruckus, spooking wary fish and throwing them off the feed.
- Requires periodic maintenance that can only be done when the vessel is high and dry.
- Depending on the amp draw of your motor and the dedicated battery that supports it, continuous run time might be limited to 6 minutes or less, before the battery’s state of charge does not support the heavy amp draw or the motor gets overheated. Recharge time of the battery might also be longer than expected, based on the alternator charging capacity of your engine. LiFePO4 batteries are usually best for these types of applications due to lighter weight and increased run times, but only if your boat’s entire electrical system is running on lithium iron phosphate batteries. LiFePO4 batteries typically can’t be in the same E-system with lead acid types.
- Bow thruster tunnel and motor must be installed by a professional to ensure system and water tight integrity. This is probably not a DIY project. According to latest boating insurance industry statistics, over 40% of boat sinkings result from faulty underwater through-hull problems.
All Are Not Created Equal
The latest crop of bow thruster electric motors have some distinct advantages over their recent predecessors. Not long ago, most bow thrusters offered a full on/full off capability. Basically it was either all in or totally off. Over the past few years, some of the major players have evolved to using what they call “proportional thrust” brushless electric motors.
I spent a few hours talking to the Vetus factory folks and a few local installers, both at the New York and Miami boat shows back in January and February. According to the Vetus factory reps I spoke with, “Bow thrusters can take the stress out of docking by giving you sideways control of the movement and position of the bow of your boat. They work by rotating a propeller in a submerged tunnel mounted athwartships (90 degrees) to the keel and located near the bow and/or the stern. Traditional thrusters offer two modes, on and off. Our Bow Pro thrusters are one of the few thrusters on the market to offer full proportional control. This means you get to decide how much thrust you need, a little or a lot.”
With Vetus’s innovative DC-to-DC charging technology, you can be confident that your thruster will always be ready to use as much as you need, without fear of overuse or overheating issues. You can even take boat control a step further with the available lock-and-hold feature. Hold your boat in place while you handle the lines, allowing the rest of the family to relax. Thrusters are not just for docking. Having total control of your boat is important in any tight situation or when handling your boat with a big tuna on the line. Perhaps the best part of a Bow Pro thruster is the maintenance-free, brushless induction motor. Less maintenance means less hassle and more carefree time out on the water.”
Getting Started
I spoke at great length with two noted aftermarket bow thruster installers, Joe Molinaro of East Coast Bow Thrusters (ecbowthrusters.com) and Robert Helmick of Florida’s Mastry Engine Center (mastry.com), who helped break down the step-by-step process on how to take this project from conception to completion.
- The initial step is to determine if your boat is a candidate for a bow thruster installation. Call the manufacturer and seek their advice on where to place the bow thruster, the recommended tunnel diameter and what make/model thruster they have used successfully in the past.
- Both installers recommended getting a high capacity 31-series AGM (absorbed glass mat) lead acid battery as the minimum requirement for the most basic bow thruster installation, even for the smaller sized motors. Although LiFePO4 batteries will typically afford longer run times and repeated discharges with minimal hiccups, this works smoothly if your boat is currently using this battery chemistry to start. If not, an AGM lead acid should be the choice.
- Once the tunnel size, motor capacity and battery type have been chosen, it’s time to get the boat high and dry and on blocks.
- Installers use a specialized hole saw and drill assembly tool that cuts a clean and balanced hole on either side of your fiberglass hull. The position of the hole is determined by a factory formula that takes numerous variables into account and places the motor where it will have optimum effect on producing the requisite thrust to move the bow on demand.
- Before the hole is cut, the installer preps both the outside and the internal space for the tunnel and motor to be installed, including projecting wiring runs and determining the best place to install the battery. Sometimes this requires moving hoses from through-hull fittings and cutting out foam flotation for the area where the motor will be mounted. As part of the tunnel installation process, stringers, bulkheads, foam flotation, through-hull fittings, hoses and wires all need to be taken into account prior to making the cut into the hull.
- Once the hole location is finalized, cut and the tunnel shape is matched to the deadrise of the hull, most installers used a vinylester putty that is water resistant to seal the pieces together for a water tight fit. The shape of the hole in the hull and nearby strakes might also need to be faired to allow a clean flow of water into the tunnel to prevent cavitation and to maximize propeller efficiency during operation.
- The thruster motor is installed into the tunnel so that the prop is centrally located, to allow for equal efficiencies port and starboard. This typically requires the motor body and leg to be slightly offset in the tunnel. Once again, this is where an experienced installer adds value to the process. All connections are then sealed to ensure they are waterproof.
- All system wiring harnesses, switches, fuses and the joystick controller are installed.
- The tunnel-to-hull connection is fine-sanded and matching gelcoat is sprayed over the area to seal it.
- A barrier coat is applied to the work area followed up by two coats of bottom paint.
- The thruster prop is stalled and a dry run conducted to be sure that all systems are a “go”.
- The boat is wet tested and sea trialed to ensure a safe and seaworthy installation.
Pro Tips
I recently spoke with one of my good industry buds, Long Island Marine Surveyor Capt. John Lowe, who also runs an inshore charter business out of Stony Brook in the Long Island Sound for blackfish, striper and sea bass trips. After a lifetime of running single diesel inboard boats, his latest “formerly used” vessel, a 31 Eastern flybridge downeaster named Bad Penny, features a bow thruster that has made a world of difference when he is docking in cranky wind and current conditions. Capt. John shared that he would be “totally lost” without his new bow thruster capability and also uses his toy to fine-tune setting up over his favorite deepwater fishing spots in the sound.
The Fisherman’s Mike Caruso expressed a similar sentiment with his bow thruster installation, which features an all-in-one joystick control of both his single Yamaha F350 outboard and his Vetus bow thruster, courtesy of Yamaha’s Helm Master EX integration. I’ve been out with him a few times and have observed firsthand his ability to position the boat in a perfect fishing orientation over deepwater structure and then employ his Minn Kota electric trolling motor to “spot lock” his boat over the best structure that’s holding the most fish.
But where the bow thruster and joystick controller really does its thing is docking the boat in high wind and or fast moving current conditions. The enclosed wheelhouse of his Steiger 255 Miami, while great for keeping the crew weather-protected in nasty elements, acts like a sail in a stiff breeze and the thruster really goes a long way to counteract the negative influences of wind and current on his docking abilities. It is a total game changer and I have been on the wrong side of that equation to know how frenetic it can be when trying to tie up at the end of a long day in unfriendly conditions.
The main benefit of Mike’s Helm Master EX’s joystick controller compared to Capt. John Lowe’s is that the Yamaha setup is a single integrated joystick controller, where one hand controls both the bow thruster and the engine operation. In comparison, the 31 Eastern Bad Penny requires separate hands on the throttle/gear shifters, in addition to a hand on the thruster’s joystick, plus a “third hand” for the wheel, all of which requires some practice to get it right in times of stress and some serious hand/eye coordination.
| MAINTENANCE TIPS |
Like anything else to do with boats, having a periodic maintenance plan goes a long way to keeping things working right, especially when you need it most. The following is a guideline on how to keep your bow thruster up to specs each season:
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