We have been discussing auto pilot requirements with one of our clients and we thought a review of what makes a good pilot system might be of interest to you.

To begin with, the moderate beam and balanced lines of our hull shapes require very small inputs of rudder to correct course. 99% of the time we could get away with substantially less powerful pilots than the notes which follow indicate. However, it is that one percent of the time, when we are running before a strong gale, or reaching across big seas, that we want the best pilot characteristics. We are willing to help the pilot think, but we do not want to hand steer, ever.

The worse the weather, the more we want the pilot to do the work of helming.

OK, lets start off on a nice broad reach, with the wind at 150 degrees to the boat, 16 foot (5m) waves, and 30 knots of wind. Perfect conditions to make a quick passage down wind under sail or power, if you can control the boat.

For the autopilot this starts with compass response speed. Fluxgate compasses are inherently slow, averaging about 1/2 second on for updating the pilot. This gets worse when headed north. 1/2 second is too slow for good control – the pilot is already behind the curve before it knows to generate a course correction signal. The answer is a fluxgate compass fitted with a heading reference accelerometer, which speeds the updating process to .05 or less seconds, and is not subject to northerly heading error.

Next comes the rudder actuator system, typically mechanical for smaller yachts and hydraulic for larger. Maneuvering in port, and for slow speed steering in heavy weather, fast rates of turn are required. Our standard is ten degrees per second, or eight seconds hard over to hard over.

Normally steering can be achieved with small forces on our hulls. With the 78 foot ketch Beowulf, carrying two spinnakers on a broad reach, average power required was less than 1/16th of a horsepower. Yet we carried half HP pumpsets. This created a bullet proof system, spending most of its life loafing, with the power to provide required steering force in horrible weather. Rudder actuators are no place to skimp.

But high rudder turning speeds can instigate oversteering, and force you to slow down or lose control. Factors which affect this include slop in the steering system and or rudder position sensor linkage, and response speed of the rudder actuator. Dynamic braking can be used with hydraulic systems to more accurately control the rudder and allow higher rates of turn, and some systems can vary rudder response speed.

There are three basic controls set either manually or automatically by the pilot control head. First is sea state (also called dead band). The higher this setting the more the course is allowed to wonder before the pilot starts correcting. Surfing downwind on the FPB 83 Wind Horse we will often open the sea state to five or more degrees, reducing rudder action to a minimum (Wind Horse is very well behaved). On the other hand, when maneuvering in tight quarters this will be set to zero.

Next comes Rudder Gain which controls how much the rudder turns in response to angle off course of the boat. We usually have rudder gain set to its minimum off the wind in nice weather, and set to eight or ten in heavy weather.

Counter rudder helps prevent oversteering with some types of designs (we do not need this).

One of the decisions to be made with autopilot choice is do you want easy and fast access to these three controls? Or, are you content to leave them alone and access them through a computer menu?

Although most of our yachts fit back up hand steering systems, these are almost never used. Even docking or maneuvering in tight quarters the power steering function of the pilot is used. It is much, much faster at turning the rudder than anything a human can do. This raises the question of the type of manual steering control to be used. Our own preference is for what is called a “follow up” controller, where the position of the control knob roughly corresponds to the rudder angle.

How this steering control is turned on when you want to assume control is an important consideration. Think of this in the context of steering the boat in dangerous seas, when you have been at the helm for 18 hours straight, with the pilot in auto mode most of the time. When that breaking sea comes at you from right angles can you hit the power steering button without fail?

We have left the control head for last. Beyond adjusting the pilot response with sea state, rudder gain, and counter rudder, the bells and whistle feature are of little interest to us. We are after reliability and fast control of the rudder.

Which brings us to redundancy. We have been using WH Autopilots for the last 25 years, and they have proven to be reliable in the extreme. Still, we fit two totally redundant systems as standard to every yacht we build. There are two isolated hydraulic systems, two pumpsets, two rudder position transmitters, dual compasses, and control heads. This gear is wired so any component of one pilot can be easily plugged into the opposite system.

If you want to see how all of this plays out offshore visit our online videos. There are some good big wave surfing videos aboard the FPB 83 starting here (be sure and watch parts one and two). Another segment, this time a North Atlantic gale is here. There is also some good Southern Ocean surfing footage aboard Beowulf here.

Have a close look at the interaction between the Bruce anchor and the mooring pennant in the bottom right corner of this photo. When thinking about anchor storage consideration must also be given to chafe from:

• Mooring pennants such as this.
• Anchor rodes from second anchors used to back up the primary anchor.
• Chain snubber lines.
• Use of a parachute anchor.
• Towing.

All of these functions relate to the stowage system for the primary anchor.

Same problem here with the mooring pennant except this is with a plow type anchor.

The solution can take many forms:

• A fairlead integrated into the bow roller assembly like we are using on Wind Horse and the FPB64s.
• A second anchor roller which projects clear of the primary anchor flukes (with heavily radiused cheeks).
• Closable fairleads either side of the bow roller used with a bridle.

In adverse weather this small, and rarely used detail, can make a huge difference.

We’re getting close! Circa are starting to remove the protective coverings on the cabinets and prep the boat for launching. You are looking here at the galley.

The Owner’s suite is now complete except for the cushions on the seat to starboard and carpeting.

While this is a big improvement on what we have been showing you, once art work is installed on the bulkheads the ambiance will be on a much higher plane.

The bunk has walk around space for easy access to the outboard side.

And finally an attempt to show you the bathtub/shower, most of which is hidden behind the bulkhead on the right.

Moving now to the completed office. We are at the forward end here, looking aft. As previously mentioned the shelf is sized for notebooks and manuals.

We love this design feature. Room to work with a pair of big monitors, with space for the printer, files, and lots of general storage.

A finished guest cabin, looking forward.

Here we are looking to starboard, down the entry hall to the guest suite. The head is aft, to the right.

And finally, the aft starboard cabin, looking forward.

This makes a great extra guest or crew cabin, or it can be used for storage of engine room spares.

Check back frequently as there will be lots of updates, including the first shots of the FPB 64 afloat next week.

Handrail design and positioning is a tricky art. You want the rails where they are convenient to use, and easy to grip, but not overbearing aesthetically. The photo above is on the starboard side of the entry landing on the first FPB 64.

Over the years we have found that about 1.5″/37mm is a good clearance between handrail and adjacent surfaces. Within a couple of weeks you will see the handrail layout throughout the first FPB 64.

You are looking at the Murphy mechanical gauges in the engine room. Notice that the center “Engine Oil Pressure” is reading 50 PSI. The engine is being tested (along with all the other systems).

Meanwhile the interior is starting to have its protective coverings removed. We are looking here at the aft guest cabin, from the aft end forward.

Head compartments are notoriously hard to photograph. This is the aft head area.

The aft section of the office.

Still in the office, only now looking at the forward end of the desk. There is lots of room for full sized monitors. For example, the first boat will have a 27″ Apple Imac + a 30″ Cinema display on the desk.

This will give you an idea of the electronics layout with the three monitors in place. The monitors are for charting, radar, and sonar.

Moving to the next bay in the shop, FPB 64 #3 is shown here.

An interesting view of the anchor sprit and the fairlead for snubber lines, etc.

Still on FPB 64 #3, this is the aft starboard cabin adjacent to the engine room. The topside stiffeners are incorporated into the interior design.

We’ll close with this photo of the fuel tank area on FPB 64 #4. Note the tight baffling in both directions. This close spacing of baffles reduces liquid movement which has a positive impact on noise and motion.

Check back often as we’ll be posting photos as the interior of the first FPB 64 is exposed.

It is often hard to find enough space for one let alone two dinghies. So when this motor yacht passed us in Falmouth Harbor in the UK we grabbed the long lens.

The sailing dinghy is sitting on an elevated frame, over the door into the salon. The framework is designed so chocks can be easily changed.

There are a couple of considerations here:

• The height of the storage platform will make it a little awkward to use in anything but smooth water.
• The lifting boom needs enough clearance above the elevated dink for the bridle and halyard blocks.
• The weight of the dinghy sitting high is a hit on vertical center of gravity.

In a lot of situations this approach could make sense.

We’ve been using flat plate attachment bales for our lifelines for the last 30 years. These are exceptionally strong with lots of weld surface to carry the load. In short they last.

The marine standard to create an attachment point for lifelines is with stainless rod, typically about 3/16″/4.5mm, welded to the pulpit or boarding gates. There isn’t much weld area, and over time, between the effects of bending and corrosion these terminations are prone to fail. If you have rod bales, keep a close eye on them, especially the top life line attachment point.

We’ve been noticing these Ovni 43s for years. The hard chine hull with its bare aluminum topsides stands out, and the fact that these boats are designed to sit on land or ice is additionally intriguing.

We saw Lady Salope first in Bergen, Norway,

Her 74 year old owner is single handing and after we helped him work into a very tight berth, we took him back to Wind Horse for a fashionably late dinner of left overs. We were invited for a tour of his boat the next day.

The Ovni 43s have a flat bottom, centerboard, and hinging rudder at which we are looking above. Three feet (90cm) of water and you are afloat.

Most of her halyards and reef lines end up back in the cockpit.

She has a Max Power retractable thruster to which the flat bottom lends itself.

The salon is nicely designed, with the typical galley abeam of settee which has become so common.

The table leaves fold on top of the base, and are held in place with timber runners. Simple and effective.

This deck hatch privacy cover is also a simple way of solving the light and privacy problem.

We don’t care for this locker hardware system. The left door is held in place with an old-style finger latch. These do not have a good record in heavy going. The push latch on the right hand door is solid, but only as long as the right hand door is in place.

The Owner’s stateroom forward is very spacious for a 43 foot yacht.

There are a pair of quarter berths aft. The starboard side is for storage and shares its space with a 5kW diesel genset. The port side (above) is used at sea.

Robust aluminum construction, extreme shallow draft, and the ability to dry out makes the Ovni 43 an interesting concept.

I’ve got a Sea Brake drogue and am looking at rigging up the lines to tow it…

The manufacturers data sheet that came with it said to use polypropylene …I talked to my rigger and he said “What ? that’s nuts….I think you need 3 strand nylon or polyester to give some stretch and give for the load”

I contacted the Sea Brake folk and they said …no don’t use polyprop, use braided polyester …correct me if I’m wrong but that’s what our jib sheets are and they are low stretch..

So now I’m a bit confused…

BTW the Sea Brake is a canvas-like material which is tapered at each end with gaps in the sides aft of the largest dia and a hole at the aft end…

I’d be interested to know what you think

Best regards to you and Linda

All the best

Alan

To begin with we have a long and successful history of using heat treated Grade 70 chain. But this gets little respect with a regulatory authority with whom we are discussing the classification of one of our yachts – hence the following comments.

When you look at chain in a catalog it is usually displayed with a working load limit (WWL) or safe working load (SWL). To arrive at this figure a factor of safety is applied, a divisor into the ultimate or mean break strength for the chain in question.

These WWL/SWL factors of safety are on part based on service to allow for degradation, in part based on regulations, and part a simple CYA (cover your posterior) for lawsuits.

To compare different sizes and alloys of chain it is necessary to remove the SWL/WWL factors and get at the mean break strength.

Here is some interesting comparative data sent to us by Washington Chain, our source for Acco/Peerless chain products, based on the chain being hot dipped galvanized.

• 3/8″/9.6mm Grade 70 – break strength 24,000pounds/10,880 kg
• 1/2″/12.6mm Proof Coil – break strength 18,000 pounds/8160 kg
• 5/8″/16mm Proof Coil – break strength 27,600 pounds/12.500kg

Note that the 3/8″ Grade 70 is significantly stronger than the 1/2″ Proof Coil and within 13% of the strength of the 5/8″ Proof Coil.

Some will argue that the heat treated Grade 70 is more brittle and less able to absorb shock loads, which is true. But we have the real world experience to indicate that, for our yachts at least, the shock loads are minor compared to the MBS of the heat treated chain.

One other figure to keep in mind. Assuming you carry 300 feet/90meters of chain, the 3/8″ will weight in at 408 pounds/185 kg. The 5/8″ weighs 1107 pounds/502kg. That is a huge increase in weight forward and a negative in terms of motion and steering control (which is degraded through increase bow down trim).