Electronics refit on Irwin 43

[colemj]

Originally Posted by adlib2

Thought I'd throw this in. On long ocean passages just remember GPS follows a Great Circle and Plotter shows Mercator.
Many a vessel has foundered on an Island or headland with AP following the GPS.
No substitute for the Eyeball.

[/I]

The AP doesn't follow the GPS - it follows the route on the chart plotter (specifically, it responds to XTE from that route).

Since pretty much all chart plotters can plot both rhumb line and great circle on the (typically) Mercator-projected charts, the problem you elude to does not exist.

Most plotters default to great circle when the distance is long enough to warrant it. On ours, drawing a route between two distant points gives a curved route line along the great circle.

Besides, none of this is relevant when within 200 miles of land. You won't hit land just because you are following a great circle instead of a rhumb line. The GPS coordinates of the land don't change (assuming they are correct in the first place).

Nothing substitutes for eyeballs ever in navigation.

Mark

[Terra Nova]

Originally Posted by colemj

The AP doesn't follow the GPS - it follows the route on the chart plotter...

And this is what makes integration so potentially dangerous--it can make a sudden turn, once it reaches a waypoint, an action that has reportedly caused collisions.

Connecting to a compass or wind direction sensor is not integration, but a normal installation; the AP is simply set for wind or compass input.

[colemj]

I don't know of an autopilot that will make a sudden turn upon reaching a waypoint. Ours can be intentionally set to a maximum of 30* automatic turn, but I have to specifically tell it to do so at a waypoint, and even then it beeps loudly at me when it does so. It is set to not have this capability as a default.

There are many things that make sailing and navigating dangerous. A windvane is probably the leading cause in pure numbers of shipwrecks due to automation. Falling asleep, or losing concentration at the helm is probably even more of a cause. Both of these far outnumber the "integrated autopilot" incidents.

How does an autopilot suddenly veering to a new wind direction differ from what you fear?

How many examples of an autopilot changing course when reaching a waypoint and plowing into another ship do you have? If this has ever happened, it is operator fault and not AP-related in the least. Who would even be using an AP with other ships within a few feet of them?

Your reasoning is not clean on this point - it is reinforcing what you wish to believe.

Mark

[Terra Nova]

Originally Posted by colemj

...There are many things that make sailing and navigating dangerous...

Your implication that, since there are many dangers inherent in sailing, why not add another? is very compelling.

[colemj]

My assertion is that integrated autopilots do not add any danger - or at least no more than adding a non-integrated autopilot or mechanical windvane. I disagree with you there and have stated my reasoning and logic - something you have failed to do.

You simply want to reinforce your unexamined bias and have so far refused to answer any of the questions or points I have made - instead resorting to ad hominem attacks and reinterpreting partial sentences of mine taken out of context.

I suspect you have very little experience with the actual subject.

Mark

[malyea]

I wanted to build from the AP up and have a single source supplier to avoid tech rep finger pointing. My research has made me confident that Simrad builds the best APs and all other system components are top notch.


I then selected the Simrad NSS MFD over the B&G (both are Navico units - same hardware just different software) because I fish offshore more than race and the NSS comes "fish finder ready" with Sonarhub that costs a few hundred $$$ to add to the B&G.


I decided on one IS40 multifunction repeater mounted next to companionway to complement the 9" NSS MFD (plenty big enough mounted in Navpod at helm). Repeater will show wind angle info primarily when sailing and depth info when motoring into a shallow anchorage. All info also available on MFD.


The AP is not integrated into the MFD so as to avoid a single source MFD failure leaving me with no ability to connect autopilot. The AP computer and controller are wired into all sensors/GPS for full steering capability - just not thru the MFD.


Simrad 4G radar selected for close range resolution and ability to set target warning rings. AIS and radar info will show on MFD and all MFD info will repeat at nav station in cabin via Simrad GoFree wifi to a RAM mounted IPad down below.


Now just need to install and test!

[colemj]

Originally Posted by malyea

The AP is not integrated into the MFD so as to avoid a single source MFD failure leaving me with no ability to connect autopilot. The AP computer and controller are wired into all sensors/GPS for full steering capability - just not thru the MFD.

Sorry, but you are mistaken here. The connection of your AP to the MFD occurs on the common N2K bus. Since there is no way for either of these units to function without being connected to the bus and its common components, they are connected/integrated by default and design.

This is not unique to your gear or its installation - it is how all modern instrumentation is designed. One must go to great lengths and use out-dated technology and equipment to do otherwise.

The only way to truly have these separated and non-integrated is to design separate bus systems with separate sensors and transducers for each. As long as they are connected on the bus and share a GPS, compass, etc, they are integrated by default.

You do not have to ever use this integration, of course, but the failure of the connected/integrated MFD will never preclude use of the AP (and vice versa).

Now your multiple single points of failure for both the MFD and AP are the N2K bus and the necessary sensors/transducers connected to it.

For some reason, that last statement sits just fine with the anti AP-integration crowd.

Mark