B&G autopilots

[GRIT]

I haven't seen it work yet, but I've set it to "respond" with gusts of more than 10 knots. I'll set it to 2 knots, and see what it actually does. I have the "heel" response level set to "off". And the maximum angle set to 20 degrees. (I assume this is turning angle (boat or wheel, I don't know).

We're trying to get south, so my "testing" time is limited, but I'll let you know when I get it done.

Cheers.
Paul.

[BigBeakie]

Originally Posted by GRIT

I haven't seen it work yet, but I've set it to "respond" with gusts of more than 10 knots. I'll set it to 2 knots, and see what it actually does. I have the "heel" response level set to "off". And the maximum angle set to 20 degrees. (I assume this is turning angle (boat or wheel, I don't know).

We're trying to get south, so my "testing" time is limited, but I'll let you know when I get it done.

Cheers.
Paul.

Thanks Paul. I just got a response back from B&G to my questions on this.

In summary, the manual is wrong. The gust response function uses "a lot of data - it is not just heel angle". It also uses changes in AWA & AWS to work out what is a gust and what isn't, according to the user defined parameters in the menu.

Also note this comment from B&G: "It is important to understand that Gust Response is designed to add rudder to hold a course, and therefore to prevent the boat rounding up into wind and broaching (monohull) or putting at increased risk of capsize (multihull). These performance modes only work downwind (default angles are 110-165 TWA), we have tested implementations sailing upwind, but we find that the natural response of most boats (gust, natural slight luff as wind increases, brought back to course by Pilot) is perfectly fine upwind."

I'm curious what other owners of performance-design cats think of this last statement.

What is the risk of a wind induced capsize if the TWA is less than 110 ?
Put another way, if you're sailing on a beam reach with TWA at 90 ( therefore below the H5000 default angle of 110 TWA referred to above by B&G) in say 15 knots TWS, and you get hit by a gust that is 15 knots above average TWS, would that not concern you somewhat?

Using our design as an example; our SSpd is 22.3 knots and KSI is 37.5, so I don't think I'd be relying too much on the response of this Autopilot to keep upright

Disclaimer: I'm not denigrating this AP, I think it's great! And if Vendee boats are relying on it, that says ALOT! Just asking if there is a wind strength and angle scenario ( not to mention sea state) where your boat could still be blown over....

Very interested to hear the thoughts of some more experienced skippers with fast cats.

[GRIT]

Well that's disappointing. When I was making inquiries about this pilot, I was told, by the B&G Rep, it would turn down wind, to lessen the effects of large gusts (as you said, from 110 and further downwind). If it's just giving more rudder to keep the course, it seems my old raymarine did that just fine.

Perhaps it's keeping the AWA at the same angle? It's not much use to keep the compass course the same, if there's a large gust.

As I mentioned, I'll try it out and let you know what it does in real life.

Cheers.
Paul.

[fxykty]

Originally Posted by BigBeakie

..."It is important to understand that Gust Response is designed to add rudder to hold a course, and therefore to prevent the boat rounding up into wind and broaching (monohull) or putting at increased risk of capsize (multihull). These performance modes only work downwind (default angles are 110-165 TWA), we have tested implementations sailing upwind, but we find that the natural response of most boats (gust, natural slight luff as wind increases, brought back to course by Pilot) is perfectly fine upwind."



I'm curious what other owners of performance-design cats think of this last statement.

...

Eeeek! The only TWA angle where luffing up is appropriate is <40 degrees, where the sails will immediately start luffing and lose power. But remember that the turn upwind adds the turning force to the heeling force. That’s why bearing away is appropriate for TWAs 40-165 - the turning force counteracts the heeling force. This is especially significant at higher boat speeds and with the gust induced acceleration that a performance cat will experience.

[fxykty]

Originally Posted by BigBeakie

Thanks Paul. I just got a response back from B&G to my questions on this.



In summary, the manual is wrong. The gust response function uses "a lot of data - it is not just heel angle". It also uses changes in AWA & AWS to work out what is a gust and what isn't, according to the user defined parameters in the menu.



Also note this comment from B&G: "It is important to understand that Gust Response is designed to add rudder to hold a course, and therefore to prevent the boat rounding up into wind and broaching (monohull) or putting at increased risk of capsize (multihull). These performance modes only work downwind (default angles are 110-165 TWA), we have tested implementations sailing upwind, but we find that the natural response of most boats (gust, natural slight luff as wind increases, brought back to course by Pilot) is perfectly fine upwind."



I'm curious what other owners of performance-design cats think of this last statement.



What is the risk of a wind induced capsize if the TWA is less than 110 ?

Put another way, if you're sailing on a beam reach with TWA at 90 ( therefore below the H5000 default angle of 110 TWA referred to above by B&G) in say 15 knots TWS, and you get hit by a gust that is 15 knots above average TWS, would that not concern you somewhat?



Using our design as an example; our SSpd is 22.3 knots and KSI is 37.5, so I don't think I'd be relying too much on the response of this Autopilot to keep upright



Disclaimer: I'm not denigrating this AP, I think it's great! And if Vendee boats are relying on it, that says ALOT! Just asking if there is a wind strength and angle scenario ( not to mention sea state) where your boat could still be blown over....



Very interested to hear the thoughts of some more experienced skippers with fast cats.

Sorry, previous post totally messed up. Trying again.

Eeek!

The only time that luffing up is appropriate on a performance cat is with TWAs <40, where the sails immediately start luffing and losing power, hopefully faster than the turning force adds to the heeling force.

At TWAs 40-165 the appropriate gust response is to bear away, hard at smaller angle and less hard at bigger angles. That the way the turning force counter-acts the increased heeling force. This is especially potent with performance cats that accelerate easily and quickly.

I note that 110 TWA is the angle for our boat where TWS and AWS are equal - narrower angles mean the AWS increases with boat speed increases and wider angles mean the AWS decreases with boat speed increases.

The B&G behaviour is great for monohulls and possibly charter-type cats that generally don’t accelerate easily, but not at all appropriate for performance cats.

[BigBeakie]

[I][/"The B&G behaviour is great for monohulls and possibly charter-type cats that generally don’t accelerate easily, but not at all appropriate for performance cats."I]

I'm not jumping to that conclusion re performance cats by any means. I have investigated further and that has turned up a seriously knowledable and experienced local electronics tech who knows exactly how the H5000 works in reality.

It certainly is very capable of quickly reacting to sea state motion as well as sudden wind increases and changes of direction.

BUT, using the Gust Response may not be the best option to use, because as we've found out, Gust Response is meant to be a temporary course adjustment, and it will bring the boat back to the original course. This may not be what you want if there's been a wind shift associated with a squall or front. It would be better to use the capability of the H5000 to steer to TWA and then if the wind persists, you are not heading back to the course pre gust.

So, I now feel much more reassured that this AP will be good for bluewater voyaging for a performance cruiser.

[JustMurph]

Originally Posted by GRIT

Well that's disappointing. When I was making inquiries about this pilot, I was told, by the B&G Rep, it would turn down wind, to lessen the effects of large gusts (as you said, from 110 and further downwind). If it's just giving more rudder to keep the course, it seems my old raymarine did that just fine.

Perhaps it's keeping the AWA at the same angle? It's not much use to keep the compass course the same, if there's a large gust.

As I mentioned, I'll try it out and let you know what it does in real life.

Cheers.
Paul.

I think the pilot will do exactly what you want, but it does it using TWS response, not gust response. My understanding is that the intention of gust response is to hold your course during a gust. TWS response will turn down when the wind speed exceeds the long term average TWS, in effect limiting the AWS you’re seeing.

[GRIT]

Thanks JustMurph.

I've been reading up on it, and I've been coming to the same conclusion. TWS and AWS seems to be the key here, and keeping the AWS down would be the goal. As FxYkty says, that'll require falling off, up to 40 degrees or so, when luffing up would be the better choice.

I've noticed B&G makes interesting choices in naming things, so I just have to learn the lingo. I have a course computer, AND a CPU! Imagine my confusion As you say, "Gust response" isn't what I was thinking.

I haven't done my tests yet, as we've been trying to make time, going south.

The H5000 is supposed to be able to be programmed with nearly unlimited variables, via computer. I'll be looking into it a little more closely, before I get the big code 0 flying.

Cheers.
Paul.

[JustMurph]

The naming of features and components certainly leaves something to be desired! I'm looking at making the upgrade to a NAC3 or H5000 based system in a year or two, so please do keep us all updated on your progress!

[GRIT]

I'll be happy to do that.

Cheers.
Paul.

[smj]

Originally Posted by GRIT

Thanks JustMurph.

I've been reading up on it, and I've been coming to the same conclusion. TWS and AWS seems to be the key here, and keeping the AWS down would be the goal. As FxYkty says, that'll require falling off, up to 40 degrees or so, when luffing up would be the better choice.

I've noticed B&G makes interesting choices in naming things, so I just have to learn the lingo. I have a course computer, AND a CPU! Imagine my confusion As you say, "Gust response" isn't what I was thinking.

I haven't done my tests yet, as we've been trying to make time, going south.

The H5000 is supposed to be able to be programmed with nearly unlimited variables, via computer. I'll be looking into it a little more closely, before I get the big code 0 flying.

Cheers.
Paul.

How far south are you headed?

[GRIT]

We're aiming for the Bahamas, probably the Abacos.

Are you down that way?

Cheers.
Paul.

[smj]

Looks like we will be spending the winter in the Keys

[GRIT]

No snow! Keys sounds good. I have to be out of the USA for a few months, so we'll try our darndest to get to the Bahamas.

Cheers.
Paul.

[JRSHAW]

Rabbi

Tnx for the in-depth personal review of B&G AP
You stated below that you used
"B&G electronics, specifically Triton 2 instruments with N2K network sensors, Triton 2 AP control head and a NAC3 autopilot course computer, the Precision9 sensor and the N2K rudder feedback sensor.
I just bought the boxes from Simrad and did everything myself."

Curious if you have upgraded since and what you would recommend

I hasve an older monohull - 38 foot cheoy lee 20,000 lbs

Tnx in advance

JS

Originally Posted by rabbi

@rom: In a 2016 Lagoon it must be previous generation electronics. The Triton 2 range was introduced sometime in 2016, IIRC it was late 2016.
Especially in terms of AP control the Triton 1 is already "old" these days, and I'll explain why.


Our first cat had a 1998 B&G AP with a 1Hz electronic compass. So all it knew was the current heading compared to what it was 1 second ago. The AP was pretty slow to react but still doing OK most of the time.

Next cat had a factory installed 2006 Raymarine AP with 10Hz electronic compass. Already much better and capable of handling the worst weather once it was configured correctly (it came with powerboat settings).
But it could only sense and react after significant changes in heading and could not anticipate any current or future course change based on movements.


Current generation APs "feel" the movement of the boat through a constant stream of sensor data about course, heading, speed, wind, rate of turn, pitch, heel, ... and can act before the boats actually changes course, just like a good helmsman does.
But... interpreting a ton of raw sensor data and converting this data stream into a stable course is a complicated thing. As this is new technology for small pleasure craft I expect every generation of APs to be better than the previous one. Better in terms of "converting raw sensor data into AP actuator control to achieve a stable course". Not necessarily better in terms of reliability and longevity, thats a different story.
No clue which manufacturer is ahead of the pack today, and this is likely to change with the software generations (not necessarily AP hardware). In a few years this learning process will be a thing of the past, and all APs should be more or less equal.



With regards to B&G:
In 2017 I replaced the failing Navman electronics on our 2008 Lagoon 380 with a set of B&G electronics, specifically Triton 2 instruments with N2K network sensors, Triton 2 AP control head and a NAC3 autopilot course computer, the Precision9 sensor and the N2K rudder feedback sensor.
I just bought the boxes from Simrad and did everything myself.

Once installed the commissioning is almost automatic. The instruments guide you through the shoreside commissioning for rudder end points, hard-over times, minimum & maximum power settings, etc. For seatrial commissioning the AP does a few pre-defined turns to auto-calibrate the rudder gain, counter rudder, etc.
Its all really all dead simple.


There is of course a ton of things you can configure for the AP, but in reality you just don't need to.
The steering has been reliable for us from the beginning in all wind or sea states. This setup has been excellent so far (one season and maybe 900nm).


The only complaint, and this is where I think further development will make a difference, is that it sometimes reacts too quick:
We are sailing with wind at 160 degrees, and one wave after the other arrives from the same direction. The human helmsman knows that the boat will turn a few degrees as the wave lifts the windward hull but will turn back as the wave passes. So he just does nothing, as both changes compensate each other for each wave that passes.
The AP on the other hand will compensate both of these small course changes. Not a problem, but simply unnessary activity.

I changed a few settings to reduce unnecessary activity, for example increasing damping for wind changes.


As said this is for the B&G Triton 2 with NAC3, feeding the standard L&S hydraulic drive that was factory installed on our Lagoon 380.