The Engine Room

The engine room is located in the aft 15 feet (4.6m) of the boat. Aft engine rooms offer many advantages.

The biggest of which is noise isolation. The engine, genset, hydraulics, diesel heater, and water maker are located as far away from the interior as is possible, with two sets of bulkheads between the salon (three for the forward cabin) and these sources of noise.

The second advantage is space. You have full headroom and the full width of the hull at the aft end with no fuel tanks (other than a small day tank) to detract from your machinery space.

A key requirement is easy access to the genset, and port side of the main propulsion engine. These are the areas which require maintenance, and both are totally out in the open.

Engine Choice

After exhaustive analysis we have given the FPB 64 a single engine configuration (compared to the FPB 83’s twins). The reason for this is simple – efficiency. The FPB 64 has a slightly different combination of hydrostatic properties which allows this approach (the FPB 83’s characteristics dictated the use twin engines).

By going to a single engine installation we maintain close to the FPB 83’s interior noise levels, have comparable range at a cruising speed of 9.5 to 10 knots (compared to the FPB 83 at 10.5 to 11 knots), and what has proven to be comparable or better maneuverability (and this is without using the standard bow thruster of the FPB 64).

There are further advantages and has better protection from debris and lines over the side. If you are going into cruising areas with ice, the centered single prop is preferable to a pair that are further outboard.

We’ve always thought the engine room should be as attractive as the rest of the interior and the engineering team at Circa have done a wonderful job with the aesthetics. You know immediately upon entering the engine room that this is a special place.

It is filled with special details, like these functional and aesthetic alternator belt shields.

Something as mundane as bilge pump and water maker exhausts are treated as works of modern art.

How about this CNC machined tiller, carved from a solid block of aluminum. Strong and beautiful.

There is excellent access to all systems. The water maker filters and control are to the right and fuel system left in the photo above. Note the large workbench and vice.

A double set of tool drawers is standard.

As is an extensive tool kit which only begins to fit in these six drawers..

We’ll close with this thought. For us. owning an engine room like this gives a wonderful sense of pride and confidence. Nobody else knows it is there (unless you show it to them), yet you know that there are few, if any, yachts of any size or price that have the equal.

Maneuverability in Tight Quarters

Sea trials have shown is that even without a bow thruster – and there is one in the forepeak – the space required to rotate the smaller FPB 64 with single engine is no more than the longer FPB 83 with twins (that 19 feet/5.8m difference in length is a big advantage). The combination of the huge rudder, 42 degree rudder deflection, and hull shape gives the 64 an amazing turning radius.

There are other factors at work in our favor as well. The fact that the FPB 64 has an enormously strong rub rail (the aluminum extrusion is 5/16″/8mm thick on its outboard face) designed to lay against pilings, opens up a variety of maneuvering options. So too does the electric winch and use of a “breast line” for pulling the boat into the dock. The fairlead forward of the anchor gives a perfect angle for springing the boat off pilings or a dock cleat. Between these factors, and the basic capability of the big rudder with close fitting prop, a thruster is rarely going to be required. For more details on maneuvering see Using a Bow Spring, Piling Pivot, and Maneuvering and Motion.

Still, there is a thruster fitted in the forepeak for the odd occasion when you need that last tap to push the bow onto or off of the dock. But we think you will find the same thing we have, that if the boat is correctly designed, the thruster is rarely, if ever, going to be used.

Drive Line

For the FPB 64 we are using a ZF 280 V-drive. The engine is a John Deere 6068TFM, delivering 236HP at 2400 RPM under their M3 rating. It is available with power settings between 182 and 300 HP, by changing the computer coding. This diesel is smooth running and robust. Torque maxes out at 1600 RPM, perfectly matching our needs at 9.0 knots and allowing a substantial additional power capacity when fighting head seas at cruising RPM.

This 236 HP engine has enough “grunt” to push the FPB 64 eleven knots at 90,000 pound/40,800 kg displacement (full load), which was demonstrated during initial sea trials.

John Deere tells us there are hundreds of thousands of these engines built yearly in plants around the world. They are used for gensets, in tractors and other farm machinery, in trucks, and in various industrial installations. The mechanics we talk to say this is an extremely reliable piece of iron. We used four cylinder versions of this engine in the FPB 83 and have been very pleased with them.


Still, this is the engine. So, the FPB 64 comes with a complete set of spares. A partial list includes:

  • Starter motor
  • Injection pump
  • High pressure fuel lines
  • Injectors
  • Complete salt water pump
  • Complete fresh water circulating pump
  • Computer control module
  • Complete set of engine sensors
  • A variety of gaskets, impellers, and other small items
  • Tools required to make repairs

Even though this is a very lightly loaded, super reliable engine, we still want to have everything aboard to fix almost anything that arises (and the training to know how to fit these spares). The odds are that most of these spares will never be used, but it comforting to know they are aboard.

Of course there is a high capacity fuel polishing system (with dual filters and dual fuel transfer pumps).

Get Home System

With all of these spares and lightly loaded drive line we still need to think in terms of what happens if we cannot use the engine for some reason. Fitting a wing engine is one approach. However, this is a big hit on engine room layout, making maintenance more difficult, and adds significant underwater drag which you feel every mile underway. A hydraulic system, using the genset as the power source for the hydraulic pump, could be fitted to the prop shaft. Both of these approaches are common in the trawler yacht industry, but neither of these systems will push a trawler upwind against any sort of breeze or seaway. The FPB – with its low windage and slippery hull shape – will do much better, but these “get home” concepts are not totally satisfactory, even for us.

They fail to address the main reasons we might need a get home system. The first concern is a bad batch of fuel. If we’ve got bad fuel aboard, then single engine, dual engine, or get home engine is not going to help. The second concern we have is with fouling the prop(s) with a drift net, or severely damaging the prop(s) by hitting debris or a whale. If the main prop is damaged, then a hydraulic get home system is not going to help. And if we’ve run over a whale, big log, or container and damaged the main prop, odds are any get home prop will have been done in as well.

We went through this same logic on the FPB 83, and after revisiting it here, we are convinced the best answer is the same as used aboard the FPB 83 – our “jury rig” (click here for more details). This is a relatively simple system to use, combining the two booms, and a specially made sail. During sea trials the FPB 83 sailed as close as 60 degrees to the true wind (smooth water) with this rig. Based on our limited experience during trials we think we could do a tradewind passage at between 50 and 100 miles a day. OK, that’s not very fast, but it will get you somewhere – several thousand miles if need be. And when you arrived at the end of the passage, the dink can be used as a tug to warp the boat into the anchorage.

So where does this leave us? In all our years of cruising, including a lot of miles in vessels which did not have the best drive lines, we have never had a diesel starting or running problem that could not be rectified within a few hours – and only a couple of these. This covers 30 years and hundreds of thousands of miles. Given the very robust gear being used on the FPB 64, the spares being carried, and the jury rig, we are very comfortable with the single engine concept and we love what it does for the range, noise levels, and engine room layout.

Miscellaneous Details

A couple of other details. As you might guess, we are anal about engine room access and cleanliness.

The engine beds are designed so you can get past the structure that carries the engine mounts to clean under the engine. The rest of the gear in the engine room also has full access for inspection and cleaning – which is why we have so much room devoted to the machinery space in the first place.

There is a to lift the engine or transmission, should this be required. The John Deere 6068TFM can be rebuilt in the engine room, using the lift system for access to the crankshaft.

Sound Levels

Finally, we need to address engine room noise and how it will affect the rest of the boat. To begin with, the horsepower requirements of this boat at 10 knots are about a third less than the FPB 83 at 11 knots. Less power means less noise with which to deal. Next, six-cylinder engines are smoother running, and somewhat quieter at comparable RPM and horsepower, than are the four-cylinder engines being used in the larger boat. Both boats share comparable insulation logic in the engine room and in the interior. The FPB 64 has one less bulkhead between it and the engine room than does the FPB 83. We think this negative will be offset by the lower power requirements and the smoother-running single-engine installation. Sound levels in the salon were measured at 57 dB at 1600 RPM and 61 dB at 1800.

How quiet is this? PassageMaker magazine’s editor, Bill Parlatore, measured the FPB 83’s sound level in the salon at 57 dB at 11 knots, and 54 dB at 10 knots (he said the latter was the lowest reading he had ever taken). One thing we know for sure, it is quieter than sailing on a modern performance cruiser.

For more information on the FPB 64 e-mail Sue Grant: Sue.Grant@Berthon.Co.UK..

Posted by Steve Dashew  (October 16, 2011)

2 Responses to “The Engine Room”

  1. Matt Says:

    Hi, just wondering what kind of propeller if used? and are there any specific features to your propulsion system?

  2. Steve Dashew Says:

    The question of props and the propulsion system needs to be the subject of a post in the future.