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Tuesday, August 23, 2016

Gravel Barge Flips in Seattle Ship Canal

Wow, a gravel barge just flipped in the Seattle ship canal.  It was tied up at Salmon Bay Sand and Gravel, actually three barges side by side.  The middle one flipped and come down on top of the outermost barge.  They were loading or unloading at the time, so presumably some excessive imbalance caused it.  The two entangled barges are drifting free and appear to have come up against a pier.  We are directly across the canal and heard it and have been watching since.

The police on scene reported to the CG over VHF that all people were accounted for, no injuries, and no fuel spills.




Monday, August 1, 2016

Auto pilot 2.0 - Furuno NavPilot 700

Almost 18 months ago in this article on my Electronics 2.0 refit, I mentioned that I was moving from a Simrad autopilot system to a Furuno NavPilot 700 series AP.  Here's the brief explanation that I gave:

Dual Furuno NavPilot 700 auto pilots.  Unlike the Simrad pilot, you can actually build up two independent pilots using the Furuno gear so you really have a hot standby.  When I was first evaluating the Simrad gear, I sketched out a dual pilot system and Simrad told me in no uncertain terms, confirmed in writing, that it would work as I expected.  Well, after hours and hours and lots of swapped out equipment, I can tell you with certainty that it DOES NOT work.  Simrad now confirms that it doesn't work, and has never been designed or tested with dual pilots in mind.  Anyway, the Furuno pilots let me finally build the dual system that I wanted from the start.

I've been using it for a while now (probably 3500 miles) and can give a good report on its performance and capabilities, at least in the context of a trawler.

As you can see in the excerpt above, having a redundant auto pilot was an important objective for me.  Actually, our goal has been redundancy for all critical systems, and I certainly consider an AP to be one.  The fatigue level for anyone standing watch is substantially different (like no comparison at all) if you are hand steering vs just monitoring what's going on and watching for logs etc.  From day one the goal was to have two completely independent auto pilots from the control panel all the way through to the steering pump.   That way, if any component fails, you can switch over to the other pilot and keep on going.

I'll save you the drama, but the Simrad pilot can't do that - at least not without a lot of hassle and external switching over from one pilot to the other.  That, plus a hand full of other issues with the
Simrad pilot caused me to switch to the Furuno NavPilot 700.  Doing so was a risk since I had no idea whether I would be making an improvement, or just trading one bag of problem for a different bag.  It turns out to have been a big improvement, but also included a small bag of new problems.

Here's what I like about the NavPilot 700:
  1. All the components that make up the NavPilot are NOT interconnected via NMEA 2000 (N2K).  Connecting everything via N2K like Simrad does it is really nice in theory, but given all the issues with N2K, I now favor segregating critical components whenever practical.  The control panels daisy chain together via CAN bus, but it's a closed and dedicated CAN bus used only by a single NavPilot.  The rudder reference sensors are also directly hardwired to the NavPilot computer.  This means more wires running back and forth through the boat, but it also means a more dependable system.  Pulling wires is something you suffer through once, yet dependability you enjoy every time you run the boat.
  2. Three different control panels are available, along with at least one wired remote.  This gives lots of flexibility to set things up in a way that works best for you, and that fits your available space.  In my case, I was severely constrained for dash panel space, and the small control panels allowed me to fit two with out a problem.
  3. All the control panels have a roto dial control knob.  When the pilot is automatically steering to a particular heading (Auto mode), the dial makes it really easy to adjust the heading in both small and large increments.  I find this much easier than just having buttons to press.
  4. The NavPilot computer supports a variety of interfacing options, not just N2K.  This gives flexibility, plus it provides a way  to have an alternate control path from the chart plotter running Coastal Explorer to the NavPilot.  I now have things set up so the pilot will continue to follow my route even if N2K fails completely.
  5. The NavPilot has a very good (one of the best I've seen) way to manage source selection for all the external instruments used by the pilot.  For each one (GPS, Heading sensor, etc), you can select up to three different devices, and prioritized the order in which the pilot should use them.  It will then pick the highest priority device, and automatically fail over to the next one on the list if the current device fails.  While I was making adjustments and getting everything to work, I encountered a number of these automatic failovers, and other than an alarm from the pilot alerting you that it changed sources, it just kept on steering like nothing happened.
  6. There are no issues with two pilots on the same network, through I do only power one on at a time.  Two on the same network, even powered on at different times, totally messed up the Simrad pilot.
  7. The NavPilot has a much better set of tunable steering parameters.  There are three different sets of parameters that you can set up for three different sea states.  With a click and a dial, you can select which set of parameters you want to use.  This has worked out really well and has allowed me to fine tune the steering parameters.
  8. And last but not least, the pilot steers the boat very well.  Nordhavns can be hard to steer.  They are very heavy, move relatively slow, and have big stabilizers.  Throw in some sloppy seas, and the pilot works hard.  I was always happy with how the Simrad pilot steered the boat, but I can say that the Furuno pilot is at least as good.  Throw in the selectable parameter groups, and I'd give it a nudge above.



Controls for dual pilots (inactive one covered), and programmable groups of steering parameters

Several different control panels, all with roto-dial controls
That's a lot to like, and as a result I've been very happy with the NavPilot.  However, it's not without its shortcomings.

But, as background for discussing one of the shortcomings, it's worth talking about follow-up steering controls.  Smaller boats don't use these, but bigger boats do.  They are lever controls that essentially give you power steering, and very fast power steering at that.  There are two flavors; Follow-up, and Non-Follow-up.

A Follow-up (FU) lever is the easiest to understand.  It's a lever or knob that is used to position the rudder.  Center the lever and the rudder centers.  Turn to 15 deg port and the rudder goes to 15 deg port.  Turn hard to stbd and the rudder goes hard to stbd.  It's a bit like a tiller on a small boat and, to its name, the rudder "follows" the Follow-up lever's position.  These are indispensable for maneuvering larger boats where manually turning a wheel just isn't fast enough.  Our wheel, for example, is 10 turns hard over to hard over, and it's not a one hand operation.

Follow-up (FU) steering control


A non-follow-up (NFU) control is a little different, and has three distinct control position.  Centered, there is no rudder movement.  The rudder stays in whatever position it's in.  Hold the lever to the right and the rudder moves to the right.  As long as the lever is held to the right (it spring-loaded and will pop back to center if you let go) the rudder will keep moving to the right until it hits its stop.  Hold the lever to the left, and the rudder starts moving to the left.  So rather than commanding a rudder position as you do with a FU control, you are commanding rudder movement with a NFU control.

Non-Follow-up (NFU) steering control

With that background, here's the list of shortcoming in the NavPilot 700:
  1. Very limited support for Follow-up and Non-Follow-up control levers.  Furuno only makes one very simple follow-up (FU), and resells a couple of FU and NFU levers from other vendors.  But the bigger problem is that the NavPilot only supports a maximum of two FU controls, and even then it doesn't do well.  On our boat we need a minimum of 3 FU controls; one each in the pilot house, port wing station, and stbd wing station.  And there is an argument for one on the fly bridge and another in the stern station.  And even with two, operation is highly problematic.  Each FU control has an on/of switch.  When you switch one on, the pilot enters FU mode and you can steer from the FU control.  That's fine.  But if you turn the other FU control on at the same time, it operates both of them in parallel.  Electrically the control is very simple and consists of nothing more than a potentiometer which is just a variable resistor controlled by a dial.  When you connect two of them together, you get very unexpected steering results and the rudder veers off in an unexpected way.  The only way the boat steers correctly is if you make sure you only enable one FU control at a time - something that my feeble mind has trouble doing.  I'll be steering from the pilot house, then step out to the wing station to make a final approach and dock.  If you forget to turn off the pilot house control and turn on the wing control, the steering goes haywire.  Not good when docking.  This is something that Simrad does much better than Furuno.  With Simrad, you can have an arbitrary number of FU controls, and each has a "take command" button.  When you take command from one station, it automatically disables any other station.  It works much, much better.  This is an area where Furuno really needs to do some work, and it makes it very hard for me to recommend the NavPilot for boats that need more than one or two FU controls.  However, I have come up with a solution that completely solves the problem, though it requires a lot more work to build than I expect most people will be willing to do.  I'll cover this in another article later on.
  2. Surprise, surprise, the NavPilot has some N2K problems.  For some inexplicable reason, it sends out repeated requests to all devices asking for the Humidity PGN.  These requests go out about every 7 seconds and all devices have to stop and respond in one way or another.  It's mostly benign, but totally brain dead and creates a bunch of unnecessary traffic and potential disruption to other important traffic.  I've reported this to Furuno but they have brushed it off and don't appear to have any plans to fix it.
Fortunately, I've been able to work around both these issues and have a pilot that I'm very happy with.

It's probably worth a few minutes to talk some more about the dual auto pilots since that was such an important consideration.  I mentioned earlier that I only run one at a time.  More specifically, each is on a separate power breaker and I have an interlock that ensures only one is powered on at any time.  I'm actually pretty sure that this is NOT necessary, and that I could leave both powered on at the same time as long as I made sure not to activate them both, i.e. I'd always have to be sure at least one is in Standby mode.  But that's subject to operator error, so I prefer the breaker interlock.  The only down side is that if one pilot fails, I need to power up the second before it can be made active.  But that only takes about 30 seconds, so is really not a problem.

Dual Accusteer continuous duty steering pumps


To ensure everything works, I alternate between the two pilots about once a week.  So I'll run on one for a week, then switch to the other for a week, then switch back.  In the pilot house there are two control panels, one for each pilot.  I leave the cover on the pilot that's not in use so it's easy for the operator to know which one is active.  On the fly bridge there is only one control panel connected to pilot #1.  I figure if we are operating from the fly, we can just use that pilot.