autopilot adjusting speed to not pound into waves

[seandepagnier]

I know from rowing you can keep a lot of water out of the boat by slowing down and speeding up depending on the waves.

So it makes sense an autopilot could do this, in my case I would consider it for an electric kayak but the same principle applies to other boats. Really the autopilot needs to do it because both course as well as speed are adjusted together, for example slowing down and facing the waves, then speeding up and bearing off between sets.

Since electric drive can quickly change power output, they have a clear advantage here, but I am not finding much info for autopilots that support this, and how exactly they do it. If anyone has more knowledge I would like to read about it and which autopilots commonly used on boats have throttle control.

[Joh.Ghurt]

Up to now I haven't encountered any autopilots which also control the throttle. I've only seen units controlling the helm. Is that a new development on motor-yachts? On a sailboat is wouldn't make much sense, would it?

[Sailmonkey]

I’ve never seen an autopilot with throttle control, outside of a DP (dynamic positioning)system on support vessels. Warning to Sean’s sensibilities, most of this is oilfield centered.

https://dynamic-positioning.com/proc...ogeli_2015.pdf

[Nicholson58]

An electric kayak weighs nothing so will respond to variable input and waves instantly. Try a foot throttle (trolling motor).

This is pointless on a heavy large boat whose design intent is to deal with waves. The last thing I want to do is loose my momentum under way. We are also running diesel. Not good to be constantly changing Rpm. Bad for the engine an will waste a lot of fuel.

[tkeithlu]

The computer logic to adjust speed according to sensors (bow up and down?) we have not even invented yet would be awesomely complex. Perhaps someday autonomous automobile logic could be adapted to the task. I think we'll be using our Mark I brains for this job in the foreseeable future.

[Joh.Ghurt]

Originally Posted by tkeithlu

I think we'll be using our Mark I brains for this job in the foreseeable future.

Do you know anyone constantly fiddling with the throttle when cruising through waves? On motoryachts you may adjust the trim tabs from time to time to adjust for the sea state, but beyond this, what else makes sense?

[goboatingnow]

Originally Posted by tkeithlu

The computer logic to adjust speed according to sensors (bow up and down?) we have not even invented yet would be awesomely complex. Perhaps someday autonomous automobile logic could be adapted to the task. I think we'll be using our Mark I brains for this job in the foreseeable future.

Oh the sensors are widely available.

The issue is there no point it’s not good for the engine and the momentum is too big in the first place.

[JBP]

You can also control pounding with helm control, though I don't know of any auto pilot that does. I know very painfully that mine does not.

[moseriw]

Easy. Convert to a long keel yacht.

[guyrj33]

The multi axis sensors are most definitely available and are probably already being used in most modern autopilots.
As pilots we have the advantage of vision which we use to anticipate the response needed to navigate the next wave. A system could be built with radar and cameras and trained using machine learning techniques to anticipate the next wave. For now we'll have to be satisfied with systems that only deal with the current wave.

[jmschmidt]

You need auto-throttles to do this if under power and sensors to read all the variables like wave height and direction and probably several others. Sounds real expensive to me. Probably will require some for of AI to coordinate the variable with you system's capability.

Why don't you just make the adjustments manually. Oh, I get it, you want to sleep comfortably with no one on watch.

[lordgeoff]

Originally Posted by seandepagnier

I know from rowing you can keep a lot of water out of the boat by slowing down and speeding up depending on the waves.

So it makes sense an autopilot could do this, in my case I would consider it for an electric kayak but the same principle applies to other boats. Really the autopilot needs to do it because both course as well as speed are adjusted together, for example slowing down and facing the waves, then speeding up and bearing off between sets.

Since electric drive can quickly change power output, they have a clear advantage here, but I am not finding much info for autopilots that support this, and how exactly they do it. If anyone has more knowledge I would like to read about it and which autopilots commonly used on boats have throttle control.

Autopilots manage headings. Have ZIP to do with speed.

[Dsanduril]

Originally Posted by lordgeoff

Autopilots currently manage headings. Have ZIP to do with speed on recreational boats.

Commercial shipping frequently has a “speed pilot” function of the autopilot system.

This function will relieve the operator from constantly monitoring the speed of the vessel and constantly changing the thrust order at the handle when external forces such as wind, current and waves are changing the ship speed along its route.

Speed control - arrival mode
An arrival time is set for the destination and the system will calculate automatically the required set speed in order to reach the destination at the defined time.

Not quite the level of control the OP is talking about, but the basics of speed control certainly exist in commercial AP systems.

[C420sailor]

First of all, great job thinking outside the box.

Second, as mentioned, a simple multi-axis AHRS would have more than enough fidelity to determine the exact orientation and acceleration of the vessel, instantaneously.

The big problem, to me, is 1) lack of sufficient thrust-to-weight to effect a sufficiently rapid acceleration and 2) the total lack of a predictive capability. A human rowing through the water knows what’s coming—an AHRS-aided system only knows what is happening right now, what has happened, and can only extrapolate current trends to guess at what is coming next. You’d need some decent adaptive learning going on for this to work well.

Coupled with the inertial lag from a big boat with not a lot of power, the system will have a really hard time keeping up, and may even enter a state where it is completely out of sync with the sea state, making matters worse (divergence).

I’ve seen this happen many many times in airplanes in rough air, where the fancy autothrottles just couldn’t keep up, and the A/T system began to ‘saw’ the throttles as it got more and more out of sync...sometimes cycling between idle and full power. Uncomfortable. Clicking out (going manual) was the solution.

[seandepagnier]

Originally Posted by C420sailor

First of all, great job thinking outside the box.

Second, as mentioned, a simple multi-axis AHRS would have more than enough fidelity to determine the exact orientation and acceleration of the vessel, instantaneously.

I have a basic algorithm using inertial data to predict future orientation using neural networks (tensorflow). I am developing it for implementation into pypilot (free software autopilot) to be able to anticipate hopefully eliminating the lag time from measurement to reaction which potentially reduces power consumption as well as oversteering. One of the advantage is, it gets to consider what it will do with the rudder (and potentially throttle and/or sheets eventually) commands which greatly improves, the future prediction as opposed to only predicting based on past data.

From this it actually tries lots of different future commands out to figure out what it thinks it will be doing in the near future to end up with the best result.

The big problem, to me, is 1) lack of sufficient thrust-to-weight to effect a sufficiently rapid acceleration

As mentioned people with diesel dont get to try this because it is bad for their engine. For electric drives: they can really do it, and it is a clear win for electric propulsion to have dynamic throttle not only for comfort but also for improved efficiency in waves.

and 2) the total lack of a predictive capability.

Wait until I plug a camera into my prediction network with a few convolution layers.

A human rowing through the water knows what’s coming—an AHRS-aided system only knows what is happening right now, what has happened, and can only extrapolate current trends to guess at what is coming next. You’d need some decent adaptive learning going on for this to work well.

Coupled with the inertial lag from a big boat with not a lot of power, the system will have a really hard time keeping up, and may even enter a state where it is completely out of sync with the sea state, making matters worse (divergence).

Not sure about making matters worse (unless it is exploring rather than exploiting) but essentially, yes, the larger the boat relative to the wave as well as less power this concept makes less sense.

The other use for autopilot throttle control is to hold in place which is a bit different. It could be really useful to have this function if the anchor starts dragging for example. It is also something people fishing want for whatever reason.

I envision it also in survival situations, when a rouge wave appears, the autopilot instantly recognizes and evades. Even if it uses 3% of the battery in 30 seconds: it is better than taking damage.

I’ve seen this happen many many times in airplanes in rough air, where the fancy autothrottles just couldn’t keep up, and the A/T system began to ‘saw’ the throttles as it got more and more out of sync...sometimes cycling between idle and full power. Uncomfortable. Clicking out (going manual) was the solution.

Interesting feedback! I think this is just an example of that particular control system failing to perform as "going manual" is just a different control system.