YANMAR’s latest inboard diesel

A Common Rail

YANMAR’s latest inboard diesel is compact and powerful.

One of YANMAR’s initiatives is to “explore technologies that combine efficiency, high performance, and environmental friendliness” into its products, including recreational marine engines. Its been doing so since 1971 with the introduction of its first purpose-built engine for recreational use. Fifty years later, YANMAR debuted the 6LF series, a six-model lineup of common rail marine engines from 485 mhp to 550 mhp (478.3 hp to 542.4 hp). Installations of the new 6LF series began earlier this year, and the first one in Europe was a repower last August in a Magnum 40.

Environmentally Friendly

Keeping in line with YANMAR’s “environmental friendliness,” the 6LF line of marine engines meet EPA Tier 3 emission standards. The series also keeps in step with YANMAR’s “Best in Class” efforts for all its common rail marine diesel engines by making them fuel-efficient. Common rail engines are built with a direct fuel injection system that feeds solenoid (electromechanical) valves instead of a fuel pump feeding unit injectors that combine the injector nozzle and injection pump in a single component.

The 6LF engine “features YANMAR’s proprietary fuel mapping and a larger mixing elbow for reliable and consistent output performance,” says Jules Riegal of Saltwater Stone, YANMAR’s marketing firm. The YANMAR 6LF series and all its common rail engines minimize fuel consumption and optimize performance with precise, digitally controlled fuel injection that increases efficiency as well as reduces emissions and noise.

Electronic Control

Another aspect of YANMAR’s best-in-class efforts is interconnectivity. The engine is designed to integrate with the latest electronic components and multifunction displays for engine monitoring and control.

“It is custom engineered to offer direct connectivity to NMEA and J1939 CAN bus networks,” says Riegal. “It comes available with a number of standard and optional features, including single- and two-pole (12V/24V) installation, various ZF gears, and custom secondary alternator options to meet nearly any complex application.”

The 6LF series is operated by the VC20, YANMAR’s second-generation vessel control system. Based on the J1939 CAN bus system with a dedicated network to the engine, the system directs all engine and transmission functions, including joystick controls, and shows engine alarms and diagnostic codes in the display.

The control system also integrates with YANMAR’s complete lineup of common rail engines, ZF transmissions, and drives for sail, power, and light-duty commercial vessels to
55 feet.

Time to Repower

The compact and powerful 6LF series engines are a good choice when your boat is still comfortable but the engines have lost their efficiency. Old engines can lose horsepower, consume too much fuel, and require increased maintenance that makes for more downtime.

The Magnum Marine 40 was known for its speed and agility back in the ’80s and reached into the 60-mph range. It was a one-of-a-kind model, so it’s a keeper, but it had two 20-year-old mechanical 420-hp diesel engines and, over time, the performance didn’t compare with today’s engines. The boat was repowered with twin 6LF 530 engines along with new components, and the results were obvious: improved speed and fuel efficiency with low vibration and decreased engine noise.

There is the option to rebuild the engines, but YANMAR suggests that it might be worth the investment to repower if the rebuild costs 40 percent or more of the price to install new engines. Life expectancy, warranty, and the latest technology are also things to consider.

YANMAR’s 6LF series is available in three outputs: 485 mhp, 530 mhp, and 550 mhp, all with a 3,000 rpm rated speed. The inline, 4-stroke, 6-cylinder, water-cooled diesel has a number of accessory options along with a global service network. yanmar.com

-by Steve Davis

How To Improve Your Prop Performance

Check other factors before you blame the prop. Here’s how to improve your prop performance.

When a boat runs poorly, propellers often get blamed. If the engines are in good shape, it’s only natural to get “propeller tunnel vision” and start indicting your blades for not doing their job. Before you yank out the prop puller and start trying new wheels, remember that props must work in harmony with the rest of the boat. If other parts of the vessel are not in top shape, then the prop can’t save it.

“Some people seem to view the propellers as isolated and independent from other important factors, such as the power and condition of the engine, or the weight, or the cleanliness and capability of the hull,” explains Jim Thelen, sales engineer for Acme Marine in Big Rapids, Michigan. “I’ve seen people buy numerous new propellers as if to assume that sooner or later they will find the one prop in existence which will ‘fix’ all other possible concerns and transform their performance by something outlandish.”

More than just a proppy face

There are some boat owners who take the oversimplified view of propellers merely in terms of diameter, pitch and number of blades. That’s like defining all automobile tires only in terms of diameter and width. Propeller design and manufacturing differences affect engine load, speed, power, plane time, smoothness, and efficiency.

“Some propeller factors which should be accounted for by a professional are the size of the blades or the amount of surface area in the propeller blades (often indicated as DAR or EAR), Cup (which affects load/engine RPM much in the same manner as pitch) and pitch distribution (varied, constant, cambered),” says Thelen. “The point is that one manufacturer’s twenty-by-twenty four blades may not be equivalent to another
manufacturer’s twenty-by-twenty four blades.”

What’s amiss?

The hull’s condition can also significantly affect performance. Thelen describes how one boat’s power and speed relative to published or reported performance was down. “He tested the new propeller I recommended and still, his RPM and speeds were down significantly.”

Thelen went through his usual litany of questions about boat weight, engine service, cleanliness and condition of the hull, possible modifications to the boat, and altitude. Nothing revealed itself until he dug deep enough to get the owner to admit that the boat had been moored in warm ocean water for a long period which resulted in a rough bottom. “It wasn’t until he had the bottom stripped and refinished that he gained the speed he was looking for,” says Thelen. “We had him into the correct propeller from
the start.”

Extra Load

An overweight vessel can also be a problem because, over the years, boats usually get heavier, not lighter. Stuff goes on board every weekend, but not all of it comes off, and it can really add up. When add-ons and enclosures increase wind resistance, or a dirty hull increases flow resistance or when engines get tired, the boat slows down, and the original props can become overpitched. Sometimes you can improve your prop performance by simply chucking some stuff.

“The original props may not be achieving sufficient RPM relative to the engine manufacturer’s RPM ratings,” says Thelen. “The loss of RPM and potential overloading can cause power loss, speed loss, slower plane time, and potential engine damage, especially in terms of long-term use. The most common approach is to reduce propeller pitch in order to achieve appropriate wide-open-throttle RPM.”

To determine if the propeller is working its best, “It’s important to keep an accurate log of one’s boat model and weight, engine model number, manufacturer’s RPM specifications, transmission or V-drive gear ratio, current prop size, etc.,” says Thelen. “Most engine manufacturers place an ID tag on their engines which indicate s horsepower and RPM specifications.

Determining appropriate propellers basically involves running the boat (with typical or average load) at full and verifying that the engines are achieving the expected or recommended RPM at WOT [wide open throttle] and that the boat is achieving reasonable, expected speeds.”

Thelen suggests that if RPM readings are below the manufacturer’s WOT recommendations, then the propellers are likely overloading the engines. If the actual WOT RPM reading is too high, then the propeller is likely underloading the engine and, perhaps, a different propeller can improve speeds.

Data is King

Data and proper care of all facets of your engine can help to improve your prop performance.

But before you start swapping out props, verify all the data: boat weight, engines, gears, current props, speeds achieved. It’s nearly impossible to get a precise propeller answer if the reported data and specifications for the boat are off the cuff, guesstimated or vaguely recalled from several years ago.

“Complete data, accurate numbers, and double-verified specifications can produce very accurate propeller recommendations,” says Thelen. “I urge people to verify all their boat, engine, gear, and current propeller data with their own eyes and to write everything down.”

Thelen advises that having a spare propeller is a good idea. “Most people don’t go very far with their automobile unless they have a spare tire,” he says. “And most people aren’t very happy being without a boat on the first day of their vacation because of a damaged prop.

Furthermore, there are so many different types and sizes of propellers in existence today that no one can carry them all, which means that the waiting time for a replacement, for some props, can be months rather than weeks. So if you like your boat and if you want to be able to continue using it when the surprise moment comes, then I suggest carrying a spare.”

acmemarine.com

By Doug Thompson, Southern Boating May 2019

Volvo’s Hybrid IPS

Volvo Penta’s popular pod drive is going green with a Hybrid IPS.

Eco-conscious captains might feel fuel is flowing foolishly when throwing down the throttles to quickly get to running speeds. It’s called “the holeshot” in performance boating—a measure of the time and effort to go from zero mph to get on plane or reach cruise speed. As the engines gulp fuel, the thought of all those petrol dollars being burned out the exhaust pipes can be nauseating.

Based on its battle-tested, highly successful pod propulsion Inboard Performance System (IPS), Volvo Penta takes the next step with a hybrid concept that might be the alternative to all that foolish fuel consumption. Hybrid concepts have been kicking around for years—Northern Lights launched its Hybrid Marine System in 2011—but the knowledge from Volvo Penta’s IPS system gives the company a step forward in hybrid propulsion design and their goal to provide electric power solutions by 2021.

“Our hybrid IPS system is currently designed for boats from thirty-five feet up to one hundred twenty feet,” says Niklas Thulin, Volvo Penta’s director of electromobility. “The IPS hybrid system is planned initially for the eight- to thirteen-liter engine range, suitable for powering vessels such as ferries, pilot and supply boats as well as yachts. It will be similar to the traditional Volvo Penta IPS installations with two to four individual drivelines (engine/electric motor/pod).”

More Flexibility

A recent Volvo Penta press release detailed how a hybrid provides a flexible solution that maintains the high efficiency offered by the hybrid IPS system and adds the ability to run in zero-emission environments. With full torque from the electric motor available instantly, the boat will maintain responsiveness and controllability and provide a more efficient holeshot using electric power as well as the ability to run at 10 to 12 knots in electric-only mode.

The new hybrid configuration allows boats to operate in low and zero emission zones expected to go into effect around the world in the coming years. The hybrid also brings additional benefits, such as lower noise levels, vibrations and running costs.

The hybrid IPS concept design features a clutch and electric motor added between the engine and the IPS pod. The boat runs in an electric-only mode with the clutch open and with the clutch closed, the boat uses diesel and electric power in parallel. The captain selects the desired drive mode through the familiar IPS system control interface.

“The electric motor can provide more torque than the combustion engine at low rpm, which makes it very useful at maneuvering and low speeds,” says Thulin. “The combustion engine will have more power at higher speeds and, therefore, be the main power source from half to full speed.”

Electric-Only

The electric motor is supported by Li-ion battery packs that are charged by either external AC or DC chargers or through the primary diesel engine. The battery packs are modular in nature and allow owners to customize their design and performance whether for commercial or recreational use.

Electric-only cruising is extended with more battery capacity, and frequent external charging allows for the use of a smaller diesel engine to lower fuel costs. Service costs are lowered as well with the effectively maintenance-free batteries and fewer operating hours on the diesel engine. Volvo Penta will continue to support customers in tailoring a prop-to-helm configuration based on the specific application needs.

“Our solutions will be based on proven technology within the Volvo Group based on more than ten years of development of electrified solutions,” adds Thulin. “With the deep application knowledge, the solutions will be fit for a purpose and adapted to customer needs…. We’ve also got a great team of naval architects that are able to analyze precisely what energy content is necessary to move a vessel with a given hull at a certain speed.”

The parallel hybrid IPS system is in the early stage of development. It’s being validated at the company’s test center in Gothenburg, Sweden. A test boat is planned for sea trials in early 2020. Customer input will play an important role in the development of the system, which is expected to reach the commercial market in 2021, followed by a leisure boat option soon after. Volvo Penta’s commitment to offer customers flexible technical solutions will evolve this system into more hybrid technologies and all-electric drive variations.

By Doug Thompson, Southern Boating December 2018

Engine Hazards

Engine hazards to watch for

Whether your boat is powered by an outboard, an inboard-outboard or a diesel, there will be engine hazards.

Anything that has moving parts requires oil and gas and gets hot under load will create potential engine hazards. When an engine is housed in an engine room, like most diesel-powered boats, the hazard increases due to confined space. That risk is with the addition of generators, pumps, electrical equipment, and batteries. Additionally, the risk for hazards increases dramatically if the room is also used for storage.

Whatever type of engine powers your boat, the first thing on the list is to keep the area around it clean.

Fire

One of the greatest fears onboard and the most obvious danger in the engine room is fire. It’s a life-threatening event, but fire is a result, not a hazard. Fuel, oil, lubricants, air (oxygen), and the hot surfaces associated with the machinery create a highly combustible situation.

First, does the engine room have a fire suppression system? Where are the extinguishers? Are they the correct rating for the type of fire (“B” for liquid, including oil and fuel, and “C” for live electrical equipment)? Is the system or are the canisters charged? Are there enough to put out a fire completely? “There’s a natural assumption by boat owners that their fire systems work,” says Scott McErlane, former yacht engineer and service technician for Sea Coast Fire. “However, I’m amazed at how many boat fire systems don’t actually function.” And that’s true with every system on board. Don’t assume things just work. “If there’s a fire pump or means to put out a fire, prove [to yourself] that it functions.”

A broken hose can lead to additional engine hazards.

When inspecting the engine, generator, and steering system, check for cracks or signs of leakage in and around the fuel and hydraulic hoses. “There’s a potential for fire danger from a high-pressure fuel leak on the engine or from high-pressure oil in your hydraulic system finding a hot point in the engine room and flashing off,” says McErlane. It’s also important to check the raw water cooling hoses. Ruptured seawater lines can cause severe short-circuiting and arching in electric motors (alternators), electrical panels and other exposed electrical equipment, which can cause a fire. Even though hoses looked good at the beginning of the season, their condition from sitting for an extended period of time can change after they’re used.

Batteries

Batteries are also a fire hazard. Because they are consistently under a charge, they can overheat as they age. “When batteries are charging, they [can] emit hydrogen, a highly flammable gas that is potentially explosive,” states the U.S. Coast Guard’s Boat Crew Seamanship Manual. A battery’s lifespan is between two and four years, and McErlane suggests the owner/operator replace it at around three years. Also, be sure a marine-rated battery charger is used. It will turn off or go into “float” mode when the batteries are full. Never use an automobile battery charger.

Cleanliness is key. Oil- or fuel-laden rags and trash are a fuel that, when hot enough, can spontaneously combust. Remove them after an oil or a fuel filter change or after cleaning a spill. The U.S. Coast Guard’s seamanship manual lists the following preventative measures to practice:

Keep oil and grease out of bilges.
Clean up any spilled fuel or lube oil immediately and properly dispose of it on shore.
Stow cleaning materials off the boat.
Keep all areas free of waste material.
Use proper containers for flammable liquids.
Be alert for suspicious odors and fumes, and vent all spaces thoroughly before starting the engine(s).

Flooding

Besides fire, flooding can also put your life at risk. Seawater is pumped in to cool the engine, generator and air-conditioning systems. Where are your thru-hulls are located? Do the valves shut off? Do your bilge pumps work? How about the floats? Did you check?

“Seawater is corrosive and more aggressive on metal fittings,” says McErlane. It’s important to check the condition of the hoses and connections that carry the water to various bits of machinery. “Every ten years, rubber hoses should be replaced,” McErlane adds. And don’t forget your propeller shaft seals. Whether your boat utilizes a stuffing box, face seals or lip seals, they all use raw water for lubrication, and the hoses providing the water flow also need inspection. Remember, seawater and electrical connections don’t mix.

Other Engine Hazards

Now that it’s creeping into late summer and the boat’s been in the water for a few months, it’s important to be aware of some hazards that may not be life-threatening but can cause serious problems.

Marine growth can restrict water flow in the boat’s cooling systems. It’s not so much a problem in the engine’s heat exchanger or generator because the water isn’t sitting in the piping, but it can affect an air-conditioning system that runs constantly or sits below the waterline. If the system cycles on and off more often than usual, it might be time for a cleaning.

Losing an engine or steering creates a potentially dangerous situation. “The other side of good boating is that you’ve got to have a plan B,” says McErlane. “If something fails, what are you going to do?” Can you lock a rudder? If you have two engines, can you run on one? Do you know a single engine’s limitations when running without the other? “With a boat, you don’t have roadside assist,” he adds. Have redundancies, carry a few spare parts and inspect your boat’s systems before you leave the dock. As Benjamin Franklin said while addressing fire safety in 1735, “An ounce of prevention is worth a pound of cure.”

By Steve Davis, Southern Boating August 2018
Photos Courtesy of Inker Boats Owner’s Forum and Pimp My Gen2

Clean Fuel for Happy Cruising

9 out of 10 problems with diesel engines are the result of contaminated fuel. We’ll show you how to keep your fuel system in tip-top condition.

According to national repair statistics, 9 out of 10 problems associated with diesel engines will be the result of contaminated fuel. Here’s how to keep your fuel system in top condition and avoid becoming a statistic.

One of the major differences between gasoline and diesel engines is the way they use fuel. Gasoline is simply a fuel that’s burned to produce heat and power, but diesel fuel also acts as a lubricant, which is why it feels oily. Diesel engines also circulate more fuel than is needed to produce power. This extra fuel not only helps lubricate the engine but also carries away excess heat.

The key to keeping a diesel engine happy is clean fuel. The reason for all of this clean fuel hubbub has to do with your engine’s fuel injectors. These precision-tuned components deliver a precise, ultra-fine mist into the combustion chamber. They don’t like contaminants, and even microscopic specks of dirt or water can wreak havoc on the combustion process and your injectors.

Fuel filters are the first line of defense. A typical diesel fuel system contains a larger primary filter mounted on a bulkhead near the engine and a smaller secondary filter mounted on the engine itself. The primary filter does the lion’s share of fuel filtration, while the finer mesh secondary unit does the clean-up work by filtering out any microscopic particles of grit and water that make it past the primary. Many diesels will also have a second primary filter plumbed into their fuel system allowing you to change a clogged filter while keeping the engine running.

Primary filters should have a clear sediment bowl and allow you to visually check for water or sediment—part of your daily routine while cruising.

Fuel filters should be changed when dirty but prior to affecting engine performance. This can be accomplished by replacing filters at regular intervals—X number of hours or annually, for example. A more accurate way to monitor filter performance, however, is by installing a vacuum gauge at the primary filter. This provides a visual representation of fuel flow restriction through the primary filter or conversely, how hard it is for the engine to suck fuel through it. The higher the gauge pressure, the more clogged the filter is and the more pertinent the need for replacement. To help keep bad fuel from entering your tank in the first place, use a multi-stage fuel filter funnel when taking on clean fuel. Popular examples of these include the Racor Fuel Filter Funnel (ph.parker.com/us/en/fuel-filter-funnel) or “Mr. Funnel” (mrfunnel.com).

Even with your fancy new filter funnel and other such precautions, the best option is always to purchase the cleanest fuel possible. Choose marinas that have a high rate of clean fuel sales and thus, fuel turnover. One of the best marinas I’ve ever seen in this regard was located beside a major highway and also served as a truck stop. If you have any doubts about the cleanliness of the fuel down at the Rake ‘n’ Scrape Fritter Shack and Marina, pump some into a clean glass jar before fueling and let it sit a few minutes to see if any water and dirt settle to the bottom. If you see either, buy your fuel somewhere else.

But buying clean fuel is only half the battle. Two of your biggest enemies in the battle for clean fuel are water contamination once on board and during long-term storage. Diesels use pressure to generate combustion, and when water enters the engine it turns to steam, which has the potential to blow your injectors to pieces. Water also mixes with the sulfur in your fuel to create sulfuric acid, which can cause internal engine parts to corrode.

So how does water get into your fuel tank? One way is through the tank’s vent system. Unlike the closed fuel system in your car, a boat’s tank is vented. This open system lets moisture in where it can condense on the inside walls of your tank due to daily heating and cooling cycles. The more air you have in your tank, the more moisture and potential condensation. To combat this, the recommendation is to keep your fuel tank fully topped off (up to 95 percent), particularly during long-term storage. Another common point of entry is your fuel tank deck fill due to damaged or missing O-rings. Fuel fills located on side decks are especially vulnerable in this regard (particularly on sailboats) as they can ship a lot of water during rough passages, heavy rains or even during wash downs.

As water enters your fuel tank it eventually separates and settles to the bottom, a common problem with long-term stored fuel. That’s when it gets buggy. Microbes thrive in this water and their only goal in life is to eat and multiply. Sure, you can add biocides after the fact and kill them, but the problem lies in disposing of them afterward. In the case of dead microbes, they’ll lie in wait at the bottom of your tank until that first rough passage and then rise up zombie-like to clog filters and wreak vengeance on your fuel system or worse still, your engine. The best strategy (particularly for long-term storage) is to treat your clean fuel with stabilizers and biocides before a bug issue occurs, and prevent water from entering your tank in the first place. No water, no critters.

Spring Cleaning? Don’t Miss the Engine Room!

Spring cleaning your engine room has long-term benefits.

A dirty engine room is like dirty fingernails; it says a lot about your boat’s overall cleanliness. The accumulation of dust, sea spray, oil, and other fluids in the engine room can affect a boat’s value as well as the boat’s seaworthiness. The boat may look great outside, but it is sick inside and may be dying. “A boat that’s a mess down below can be difficult to repair when there is a problem,” explains Issy Perera, owner of Apex Marine in Miami. “That’s why a clean engine room and pre-flight check at the dock is so critical. Keeping a tidy engine room offers three advantages: It preserves the value of your boat, prevents issues before they start and helps you spot bigger problems faster.”

With some vigorous spring cleaning, boat owners can separate engine room clean-up into three areas:

• Mechanical issues associated with the engine

• Electrical issues with batteries and connections

• Auxiliary systems such as seacocks, sea strainers and watermakers

When it’s clean, problems are seen.

Perera puts down clean, oil-absorbent pads in the engine room so that he can see immediately if there are drips or leaks. During his frequent checks of the engine room he scans for dust that may be a sign of a worn or slipping belt, or if there’s smoke or residue from a leaking exhaust hose.

Anything out of place—loose clamps, wires or hoses—is obviously a sign that something is amiss and needs to be checked out. “There’s an awful lot of stuff in play in the engine room,” says Perera, who runs his 51-foot sportfishing boat to The Bahamas with friends and family. “Once you make a habit of getting down there and cleaning every time you go out, you’ll begin to notice things. You become very in tune with your boat and can also perform vital fluid maintenance.”

Making sure oil is at the proper level and changing it regularly benefits your diesel engine in innumerable ways. While a diesel engine may run at low rpms, it’s still working hard whenever it is running, and the engine oil does more than lubricate moving parts and reduce friction. Oil also keeps pistons and cylinders cool, and protects the walls, valves and turbochargers by acting as a sealant to stop corrosion.

Whether or not to change your own engine oil depends on your mechanical skill level. Most new boats have oil-changing pumps that make it easy to get the oil out, but older boats don’t have such conveniences. You’ve got to get down and dirty to find the oil pan and drain the oil. The bottom line is changing the oil can be a big job that’s not worth the hassle. However, it’s a great idea to know how to change filters and add oil when needed.

Eye on electricity

“Some people will start to spray water all over the engine room, and that’s when things can really get screwed up,” warns Perera. “You have to know what you can and cannot spray. That’s why it can be a benefit for some boat owners to have a qualified marine professional do the maintenance on their boat so they can just turn the key and go.”

Many diesel engines use sacrificial anodes known as “pencil zincs” to counter galvanic corrosion. It’s important to check the zincs often and replace them when they are worn out. “If you let those zincs expire you can have major problems,” Perera cautions. “I’ve seen them wear out after three or four months. Now, they don’t use zincs on all brands, so boat owners need to check their book and find out and then know how to change them when needed.”

Many of today’s diesel engines use covered plugs and connectors for the electrical system, but if you do have exposed connections, there are ways to ward off corrosion. Boeshield T-9 is a spray-on product that creates a film over the exposed connection and protects it from the saltwater environment.

Focus on the fluids

Many boat owners don’t give thru-hulls and seacocks much thought regarding maintenance. They might think of thru-hulls, made of bronze or plastic, as finished-off holes in the boat, and seacocks, also available in bronze or plastic, as simply valves that can be opened or closed. However, when there’s a serious failure of a below-the-waterline thru-hull and seacock, the boat can sink or an engine can burn up when deprived of cooling intake water.

Thru-hull fittings and the seacocks attached to them function as gatekeepers, allowing water to pass into and out of the boat. Thru-hulls are both above the waterline for bilge and A/C water discharge, and below the waterline in combination with seacocks for raw-water intakes for engines, generators, A/C systems, washdown pumps, and more.

When doing maintenance, test bronze thru-hulls with a pocketknife by poking into the flange. If you see bright shiny bronze you are okay, but if you uncover pink, flaky material, it’s time to replace it. Likewise, plastic thru-hulls can crack and leak. Thru-hulls can be fouled by barnacles, and you want to check the seacocks to make sure they open and close smoothly and that there are no leaks.

One cool tool

Finally, Perera recommends every cruising boat owner have a wet vacuum that’s always at the ready. Wet vacs allow for the fast removal of accumulated water, which helps prevent bacterial growth as well as keeping the area clean. “We can help customers clean up their engine rooms, but sometimes it’s a do-it-yourself job and that’s where you have to have the wet vac,” Perera says. “You don’t want standing water or fluids in your boat, and again, any fluid is a sign that something is wrong. Fix the problem, eliminate the fluids, and you’re going to be a much happier boat owner.”

— By Doug Thompson, Southern Boating Magazine January 2017

Hull-Prop Relationship

The prop you select must synch with both your engine and your hull.

Do you feel a vibration when your boat is running at speed? Does the vibration occur at high speeds and go away at low speeds? Or does it occur at low speeds and disappear at higher speeds? If it only appears at high speeds, your propeller may be too close to the hull, or the prop may have a bent or damaged blade. If the problem appears at low speeds it might be that the shape of the hull is causing a change in pressure in the area where the propeller is operating.

There are many factors that affect the interaction of a propeller and the hull. They include the hull shape, the proximity of the hull to the propeller, or whether the propeller is operating directly behind the hull (in the case of a single prop) or to one side of the hull in the case of a twin screw vessel. In addition, the speed of the vessel must be taken into account. Slow-speed boats generally have different problems than do vessels that get on plane and run at planing speeds. Boats that run at extremely high speeds have even more complex issues resulting from hull/propeller interactions.

If your hull and propeller are not optimized, they could be costing you money. For example, your small fishing boat’s skeg/keel is large enough to protect the single propeller should you go aground. However, it might also be reducing the efficiency of the propeller, meaning that replacing a dinged or bent propeller could be less expensive than having a skeg to protect it.

Inboard Installations

Having a hull, keel or other obstruction in front of the propeller causes loss of efficiency. The actual loss varies with the size of the obstruction. For example, the rather extreme example shown in Figure 1 pictures a two-blade propeller behind a thick skeg or keel. Every time the propeller is vertical the water flow is blocked by the skeg producing vibrations that could reduce the efficiency of the propeller by as much as 50 percent.

Figure 2 shows a better solution. Here, a three-bladed propeller is used and moved farther away from the keel. Another solution would be to taper the keel where the water flows toward the keel, but this is not always possible when the keel is laminated during the building process. (When the boat is being built, the person laying the fiberglass into the hull might have to get their hand down into the skeg area to be sure it is sufficiently reinforced.) On this boat, the turning radius would be enhanced by extending the rudder up to the hull at the top to get more “end plate” effect from the hull.

Figure 3 is an even better solution in that the skeg/keel is cut away in front of the propeller, allowing the water streamlines to flow more efficiently toward the prop. The rudder is taken up to the hull, and the skeg is deep enough that the propeller is protected. From a design standpoint, it would be smart to have a strut from the bottom of the keel to support and protect the bottom of the rudder, but you can’t have everything.

A far better solution—but one that uses more fuel—is the twin engine installation shown in Figure 4 (see opening header). Even though twin engines use more fuel, the efficiency of the exposed propellers is greater. Notice the keel is slightly deeper than the bottom of the propeller and only the prop shaft interrupts the flow of water to the propeller blades. The rudder is directly in the path of the propeller blade and operates at high efficiency.

All of these solutions, however, increase the boat’s draft. To reduce draft, many builders install a tunnel in the hull as shown in Figure 5. (Keep in mind that to reduce vibration and hull/propeller interaction, there should be at least 10 percent of the propeller diameter clearance between the hull and the blade tip.) By locating the prop in a tunnel, draft is reduced and some efficiency from the end plate effect of the hull is gained. However, Figure 6 shows how not to install a prop in a tunnel.

It would appear that the tunnel was built into the mold and either the designer did not take into account the width of the engine, or larger (and wider) engines were installed, pushing the shafts farther outboard. The propeller appears to be much smaller and farther away from the tunnel thus reducing its efficiency and increasing fuel consumption. The prop and rudder are both deeper than the hull and will be the first parts to hit should the boat go aground.

Finally, we come to Figure 7. The boat builder has taken great pains to ensure moderately clean water gets to the propeller but has then added an additional strut and inverted U-bar protection for the propeller and rudder. The rudder has several horizontal fins to either redirect water flow across the rudder or structurally strengthen the vertical portion of the rudder blade. All of these additional fins add resistance and increase fuel consumption.

Outboard Installations

The beauty of an outboard installation is that the engine can be installed at any height to locate the prop below the hull. Figure 8 shows a pair of outboards installed with the anti-ventilation plate about level with the boat bottom. This puts the propellers in water flow that’s only obstructed by the lower gear case. The anti-ventilation plate is designed to prevent air from being sucked down the lower unit and into the propeller where it can cause loss of thrust. The outboard in Figure 8 is at exactly the right height for a moderate speed. Figure 9 shows a similar set up on a catamaran hull with the anti-ventilation plates right at the hull bottom.

On faster vessels, the anti-ventilation plate is often located two to three inches above the boat bottom, but putting the engine higher may result in poor cooling water intake and an overheated engine, so care must be taken to locate the engine correctly. Figure 10 shows a faster speed hull with triple outboards. Notice how the anti-ventilation plates are about three inches higher than the hull bottom. On faster hulls, the strut/propeller/rudder drag (or resistance) is the largest single factor holding the boat back. For this reason, the shafts might pass through the transom to reduce drag, with the propellers some distance astern of the hull.

Another common case occurs when the propellers are supercavitating props with a straight trailing edge to reduce cavitation and loss of thrust. Arneson drives are typical of this drive train. To reduce drag on the fastest of hulls, only the lower half of the propeller is in the water. The shafts are then turned to steer the boat, eliminating rudder drag.

Roger Marshall, Southern Boating Magazine June 2016

Mercury Active Trim

Mercury Active Trim can improve boat performance

Could manually adjusting the trim of your outboard engine or sterndrive be going, going, gone—just like manual stick shifts in cars? Mercury Marine’s new Active Trim system uses GPS speed and engine rpm to efficiently trim your drives for the best performance. Boat trials at the 2016 Miami International Boat Show, where the product was launched, revealed consumers love it.

Hardly anyone requests a manual transmission in cars today, but manual trim in boats has been common. For outboards, adjusting trim is the process of tilting the entire engine and propeller up or down, which affects how the force of the propeller raises the bow out of the water for a more efficient and comfortable ride. For sterndrives, trim is adjusting the drive up or down. Trimming the engine improves fuel economy and allows the boat to take advantage of the engine’s horsepower propelling it. Mercury’s Active Trim works with both outboards and sterndrives.

“What makes Active Trim work is the patented GPS-based control system—we are the only company that offers it,” explained Rob Hackbarth, Mercury Marine’s category director for controls and rigging. “Unlike other automatic trim systems […] that use only engine rpm to control trimming, Mercury’s Active Trim controls the trim in accordance with boat speed and engine rpm.”

Mercury Marine is a $2 billion division of the Brunswick Corporation. Also under Brunswick are leading boat brands such as Bayliner, Boston Whaler, Meridian, and Sea Ray. At the Miami show, Active Trim was available for consumers to try on more than 20 boats from 15 brands.

“It’s a hard feature to describe to someone because the boats don’t look any different,” Hackbarth said. “The driver has to experience it. That is when they really understand. Passengers out on a test drive will stare back at the engines. Yes, the engines are trimming up and down, just like they are supposed to, which is the whole point.”

A small information control pad on the dash that relays the Active Trim information allows the user to select profiles, and also contains the GPS unit. “Active trim is for entry-level and expert boaters,” said Hackbarth of the project that began in February 2015. “When we first started many people’s first thought was, ‘I know how to trim an engine and so do a lot of other boaters. Why would we need this?’ Then they tried it and got used to it fast. Active Trim simplifies boat operation while improving engine performance and decreasing fuel costs.”

For new boaters, Active Trim allows them to immediately trim their engines properly with no intimidating learning curve, or monitor and adjust trim constantly upon changes in boat speed or turns. Because the system uses boat speed from the GPS to make its trim-sender adjustments, when the boat slows down in a turn Active Trim responds accordingly for the ideal ride. This feature solves problems with the engine or drive trimming up instead of down, if the propeller breaks loose in hard turns.

“Five trim profiles are available that accommodate nearly any boat application from small runabouts to cruisers to high-performance,” Hackbarth said. “There’s nothing complicated. At install you just run the boat and select the profile that is best suited for that application.” After installation, the profiles allow the operator to further personalize Active Trim to their driving style and compensate for changes in boatload, operator preference and weather conditions while maintaining complete auto operation.

Active Trim works great for boats with a wide trim range and can be overridden with the regular manual trim buttons, though auto mode can be easily re-engaged. Once the boat passes the 50-mph mark, Active Trim no longer moves the engine. It resumes automatically once below 50 mph. On faster boats such as bass boats in which the operator wants to get the last mile per hour out of their boat, Active Trim can be overridden so the engine can be trimmed out fully for top speed.

What does Active Trim not do? It can’t sense when you are in shallow water, so it won’t automatically trim up the engines to not hit bottom. It also won’t work if you don’t have GPS connectivity, such as going under a bridge or if the GPS conks out. In that case, you have to trim the engine manually.

The Active Trim panel is compatible with analog and digital gauges and has been specially designed to accommodate mounting in a broad range of boat applications. It does not require the use of a multi-functional gauge, and the only special tool needed is a 54-millimeter hole saw. Active Trim can be ordered with new boats or retrofitted using a kit as long as the engine is Mercury SmartCraft capable.

The Active Trim option is priced at under $500. “We wanted to keep the cost down but offer a complete kit,” Hackbarth said. “That’s why we include a GPS unit within the panel. It works with nearly our entire four-stroke product line [excluding 40- to 115-horsepower tiller models]. You are good to go with the kit and can even upgrade our 40- to 115-horsepower outboards that use analog trim—we include a digital trim sender in the kit for those engines.”

Even boats with quad 400-horsepower Mercury Verado outboards or surface-piercing drives can use Active Trim. “We have a kit for high-performance boats called Performance Active Trim,” Hackbarth said. “In boats with surface-piercing drives there is not a big trim range, but it still works. Now if you have a Boston Whaler with four big outboards, then Active Trim is very helpful. It syncs all four outboards, so on a busy waterway there is one less thing to worry about.”

— By Doug Thompson, Southern Boating April 2016

INFORMATION
mercurymarine.com

Volvo Penta Power Punch

Volvo Penta pairs their new D11 diesel engine with IPS950 pod drives for a perfect combination.

Green and clean may have a fuddy-duddy reputation to some people—good for the environment but some say not much fun—however, Volvo Penta is changing that with its new D11 725-hp diesel engine. When paired with the company’s new IPS950 pod drives, the robust powerplant is more fuel efficient and pollutes less.

The D11 engine’s innovative technology creates an optimized air and fuel pressure ratio, which increases combustion efficiency. After-cooling provides more engine power, and on the exhaust end it simply emits less particulate pollution. That’s because the new D11 engine must comply with the world’s most stringent environmental legislation, U.S. EPA Tier 3, which comes into force this year. The particulate emissions requirements are 40 percent lower when compared with the old Tier 2 levels.

“The IPS800 and 950 are matched with the new 625- and 725-horsepower D11 diesel engines, providing a perfect combination of torque, speed and maneuverability for 40- to 60-foot flybridge yachts and sports cruisers,” says Marcia Kull, Vice President, Marine Sales North America, Volvo Penta of the Americas. “The result is two new and reliable drive packages both with a unique high torque.”

At the 2013 Fort Lauderdale International Boat Show last fall, the Tiara 50 Coupe was equipped with the D11-IPS950 package. In fact, the boat builder designed the 50 Coupe specifically to utilize the new engine. “Tiara has enjoyed a very successful engineering and working relationship with Volvo Penta from the beginning of the IPS system in 2005 in North America,” says David Glenn, marketing director for Tiara Yachts. Tiara was one of the first manufacturers to incorporate that entire IPS system in a boat, which was the 40 Sovereign at that time. “With the Tiara 50 we took the same approach,” Glenn continues. “We designed the hull around the D11 engine to take advantage of the higher fuel efficiency and the EPA ratings. The IPS950 drive line gives you less drag, and we positioned the engines and drives accordingly to take advantage of the CG (center of gravity) and loads. It runs well and is very nimble around the docks.” On the all-new Tiara 50, the technologically advanced D11-IPS950 power package in a twin application is matched to a successful ocean proven hull. This delivers a solid ride whether enjoying a calm day cruise or pushing the vessel to island getaways far offshore.

Cruisers Yachts is developing new 50- to 58-foot coupe and bridge models for 2015 utilizing the D11 engines and IPS950 drives. “We are closely tied with Volvo Penta on this project,” offers Jon Viestenz, Cruisers’ regional sales and product development manager. “It’s exciting and the engines and drives offer a wide range of performance options.”

Offered in three power classes—625, 670 and 725 horsepower—the D11 engines also provide more powerful torque, improved drivability and reduced noise levels compared to other engines in these horsepower classes. “The new D11 series is based on the latest technology within the Volvo Group, and has been optimized for marine use,” Kull adds. “The result is a compact, powerful engine series with new and improved basic design. In addition to a wider range of power classes, the in-line, six-cylinder diesel engines are enhanced with a large number of technical upgrades.”

The engines use the latest generation of the Volvo Penta electronic platform, the Electronic Vessel Control (EVC). The latest generation of EVC enables an additional number of features for increased security and control, and improved functionality.

“We have further enhanced our twin-entry turbo where each exhaust pulse maximizes charging pressure,” explains Thomas Lantz, Chief Product Manager at Volvo Penta. “This gives an extremely powerful torque already at low RPM. The engine responds instantly to operator commands and provides improved drivability with stronger acceleration.”

Pairing the D11 engine with the new IPS800 and 950 drive packages provides higher torque, better drivability and significantly less noise. With steerable drive units and double forward-facing propellers, the Volvo Penta IPS system provides about 30 percent lower fuel consumption and 20 percent higher top speed compared with traditional shaft installations.

Inside the IPS unit the mechanical compressor increases the charging pressure directly from low RPMs and creates an even more powerful low-speed torque. Together with the double forward-facing and counter-rotating propellers the boat operator enjoys an extremely good grip in the water. “The drive packages are more responsive to commands and together with the joystick control, the result is significantly improved maneuverability,” Lantz adds.

The D11 series and the new IPS models are based on the same installation dimensions as before, which could help reduce costs for boat builders. All fuel and oil filters, oil dipstick and oil filler are gathered in the back of the engine where they are easily accessible for servicing, which allows for easier maintenance. The IPS installation is delivered in a complete package from Volvo Penta. In comparison to a setup with shaft drives, the installation time is reduced by more than 50 percent.

By Don Minikus, Southern Boating February 2014