Heavy Weather - GB42

The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
Sorry, may have misunderstood your question.
Yes have dodge feature but we found it to be slower to react than just steering with the throttles on our fairly calm delivery trip
But maybe we were wrong to do it that way. ???
Am hands-on learning twin screw powerboating after years of sailing with both a wheel and tiller, actually always preferred tiller.
Would sometimes invite non boating guests who would get confused with the teller
I could steer my car through high-speed rush hour traffic if so fitted as find it natural.
But looking for advice from you guys so set me straight if you think I am off course!
 
Under more extreme conditions I have found humans to be much better at steering wave than any autopilot

That's often the case, but depending on the boat and autopilot combo, you may find that the autopilot does better once the human starts to get a little tired. Some boats and autopilots do better than others in rough weather.
 
Under more extreme conditions I have found humans to be much better at steering wave than any autopilot

I think the exact opposite....Maybe the old auto pilots of the 70's 80's...But a modern auto pilot PROPERLY set up steers way better (less over steering) from my experience. I'll let Iron Mike have at it....
 
That's been my experience as well. I wonder if the size and speed of the pump zre a factor?
I think the exact opposite....Maybe the old auto pilots of the 70's 80's...But a modern auto pilot PROPERLY set up steers way better (less over steering) from my experience. I'll let Iron Mike have at it....
 
Okay. Interesting.
What brand name specifically.
And what do you mean by properly set up?
And off the wind too, with following seas?
Please advise
Thank you
 
Pump sizing is definitely a factor. I'd size towards the larger end of what's recommended. Generally if the boat tracks well down wind and is easy to hand steer, autopilot should do well. Keep in mind that the autopilot doesn't get tired, so if you can get it to steer well in rough conditions it'll be able to maintain that level of performance far better than you can. Depending on the pilot it may take some playing with settings to get it dialed in.
 
That's been my experience as well. I wonder if the size and speed of the pump zre a factor?

Fully agree a modern AP steers better than people. It's the computer using a bunch of inputs to learn the best path through waves.

A good AP will move the rudder less. It's not usually about pump size.
 
Pump sizing is definitely a factor. I'd size towards the larger end of what's recommended. Generally if the boat tracks well down wind and is easy to hand steer, autopilot should do well. Keep in mind that the autopilot doesn't get tired, so if you can get it to steer well in rough conditions it'll be able to maintain that level of performance far better than you can. Depending on the pilot it may take some playing with settings to get it dialed in.

I generally agree with you, and I haven't even used a super modern autopilot. There are times the autopilot could steer much better than I could because it didn't have to worry about remaining standing up.

However that only holds if you are steering a course or to the wind, something the autopilot knows about. Once you are steering to the seas, the autopilot doesn't (yet, as far as I know) have a camera looking around anticipating waves.

This is often the case with intersecting ocean swell patterns or in otherwise confused seas.

This can be the case going into the waves as you hunt for the smaller ones, often ones that have broken recently or where multiple wave trains have cancelled each other out a bit.

This can be the case running from the waves as you need to maneuver in advance of the waves. You won't be able to keep up with them unless you are a planing boat loaded with HP and fuel. You must avoid broaching and a boat like a GB will get tossed around a good bit with the wide flat stern. Especially so with twins I'd think, with smaller rudders.

There are no beam seas in this scenario as I wouldn't want to bet on if they are survivable.

Odds are you don't want to be out in those conditions, so ignore all that and just get good at understanding weather and having access to weather data.
 
I tend to agree with Sailor of Fortune till seas overwhelm the autopilot...then again at that point they may overwhelm most helmsmen's or boat abilities.

I have driven plenty of Furuno, Raymarine and Simrad APs and they all work the same in similar situations. As to sizing, sure that is important, but let's face it, many recreational boats are not designed to handle extreme sea conditions no matter who is steering, a person or Iron Mike.

As to tuned, there are often 2 adjustments on the older APs that are important. Not sure if called the same on all or even anymore but one would be the one that controls the amount of rudder used and the other controls the speed at which the rudder is turned. They have to be adjusted to match the conditions encountered and how the boat is reacting. They are similar to how a person steers also...such as a bunch of small, quick responses or slower major ones.

As to seeing and anticipating waves, while that may be true in some circumstances, much of the time I found I was not really doing much if in the open sea as patterns do occur but exactly where were almost impossible to react to, especially in limited vis or darkness. The biggest exception is breaking inlets where seeing where the breakers are is much more predictable. In breaking following seas in a powerboat, hand steering may be better, but at some point, you shouldn't be running down sea in a slow powerboat. That's because it is normally drogue time or turn around time as powerboats that can't handle going down steep wave faces without broaching or large pooping waves aren't going to respond to hand or AP steering safely for long. That to me is a survival situation and I think already discussed before that should not happen for several reasons.

If you have to stand at the wheel and hand steer into "possibly" better seas, and I have done it on boats without APs, its so exhausting and the helmsman is a lousy lookout/navigator if they are concentrating that much on waves and probably pretty fatigued after several hours. Short lengths of time doing it sometimes may be productive.

Not trying to insult anyone, just answering what I think was asked.
 
Last edited:
An eye opener is to be on a boat with the current computer enhanced machine learning APs. For sail NKE is one of the leading companies. The thing has AI and learns to anticipate the waves, wind gusts, even headers and lifts. Not only is VMG improved but so is ride as it decreases roll and pitch. Both slow you down to some degree.

One of the problem with using an AP is the reaction time of the steering. Direct linkage or rack and pinion maybe more reliable and faster than hydraulic piston systems seen in some boats. Any cable system is likely slower than all of the above. The characteristics of the rudder itself maybe a factor. Even a fraction of a second may mean less rudder angle for a shorter time allows course correction . Sailboat racers quickly learn the less you steer the quicker you go. So anticipating what input is necessary means a better ride and less risk of cavitation. You also appreciate a foil rather than plate may work better. A balanced spade maybe more responsive and require less input than an attached rudder with less risk of cavitation.

At present a high end AP that can learn will do a better job than a human in just about ANY conditions. Can’t find the article to link but a long explanation of the level of APs is available on Attainable Adventures. Expect to pay $20-30k for a decent set up so outside my pay grade for the way I use my boat.

Steering in heavy weather is exhausting. We used to flip to 15-20 minutes at the helm in heavy weather. Helmsman would be watched as watches were at least 2 up. As soon as there was any sign of fatigue helmsman was switched off. There’s no way that as a current mom and pop of our age could tolerate that beyond a few hours. So our planning has changed.

Peter rightfully pointed out there’s a huge variance in what people call heavy weather. He also pointed out you can go huge distances without experiencing serious adverse conditions. The Beaufort system is what the government and weather routers and forecasters use. That’s good enough for me. In decades of sailing underway I've been in 2 storms and no hurricanes. I’ve been close enough to a major cyclonic event to experience force 8 several times but not at storm level and not persistent for days. Have been in brief events but for long events it’s been gales. Suspect the majority of us doing coastal/near shore transits will never experience even gale let alone storm conditions. Think this discussion should focus on what we may actually see. Think thats Tstorms and squalls. For more sustained events most will be at fresh breeze or possibly force 6. But realistically expect only brief events of high winds. Remember it’s not the wind that kills you it’s the waves. With such brief event there isn’t time to build a seaway of significance. Similarly don’t expect to see waves >6’. Here a technique we used cruising should be sufficient. Head into the seas and go just fast enough to maintain steerage. Tack if necessary to stay away from shallow depths.
 
Last edited:
A long time ago I gave up trying to outperform the AP in rough weather. The AP is almost always better than me and it doesn't get exhausted. After I've found the best speed for the boat and conditions the only time I'm spending a lot of time looking aft at the seas is when crossing a bar in questionable conditions. The AP is steering the boat to a plotted course, I'm watching astern hands on the throttles. When a wave threatens I bump the speed up briefly to get out of harms way.
 
......Think this discussion should focus on what we may actually see.

We are getting ready to leave La Cruz at the northern end of Banderas Bay (Puerto Vallarta area). It's almost 90nms to out next stop of Chemala so around 14 hours. The southern tip of land that defines Banderas Bay (Cabo Corrientes - geometry reminds me of Point Lobo at southern tip of Monterey Bay, CA) is known for heavier weather. Forecast is 5-feot at 13 seconds from the west so on our Stbd beam. Although not forecast, I suspect there will be some localized wind gusts exceeding 20 kts. It's about as "heavy" as we want to see. The conditions are unchanged for as far as the forecast models show so waiting seems futile.

Peter
 
I have helped move several 42 GB Classics. Never in what I would call heavy seas.

Those are big heavy boats with a nice keel. They tend rock easy but the roll is comfortable until it stops, around 45 degrees and whips back.

In a following sea you are nice and the stern high up, and just a little throttle has you surfing the waves or powering through them.

There is a big difference between a 36 and a 42. The 36 is lighter, smaller, and much easier to get pushed around by waves and wind.

A 42 is comfortable in almost any weather. It will take way more than you. That is not an excuse to go get your butt kicked, but if it happens, just ride it out.
 
There is a big difference between a 36 and a 42. The 36 is lighter, smaller, and much easier to get pushed around by waves and wind.

There was a guy in my Huntington Beach marina with an old GB 36ft woodie. He used to take it back and forth from CA to Cabo. Somehow he fitted a 900 gallon water tank and he said he was fine with the motion. I'm sure that additional 2-3 tons of water really settled his vessel down.
 
We sail with an AP 80 Simrad, I don't know how it works with other APs, but the AP 80 resets all parameters after a course deviation of 10 degrees.
So the AP is constantly adapting, I've never had to take over.
The AP is powered by a GPS compass and the rudder rotates 2x 90 degrees in 7.5 seconds.
In practice, it only moves a few millimeters!

Mvg,

Pascal.
 
I too like the performance of Simrad. Used several models all the way back to Simrad Robertson when they bought out Robertson. They all adapt to changing conditions quite quickly.
We sail with an AP 80 Simrad, I don't know how it works with other APs, but the AP 80 resets all parameters after a course deviation of 10 degrees.
So the AP is constantly adapting, I've never had to take over.
The AP is powered by a GPS compass and the rudder rotates 2x 90 degrees in 7.5 seconds.
In practice, it only moves a few millimeters!

Mvg,

Pascal.
 
Mako- Question
Would like to hear more about the situation that was pooping your aft deck because our aft hatches are not water tight and the bilge space below freely runs into the lowest bilge of the boat in the engine room.
So would like to know the sea state and wind conditions that were causing that; and what was your speed?

I was 3 days in solid high-20 foot seas with occasional really big boys coming up behind us. Running at 8.25 knots in a 65 footer steelie. We shallow-tacked downwind and were constantly fighting the wheel to keep us on a straight course. Bumped up the throttle to keep water flow over the rudders. I hope to never be in conditions like that again, but I know I will. The AP could not handle it and by coincidence went down (easy fix once we tied up in Bodega Bay).

Your description of your boat sounds like the majority of boats out there, sail or power, few of which have watertight bulkheads. Water will run from the chain lockers all the way back to the rudder post. This may work fine for a weekender, but if you're planning on taking your boat far then consider trying to tighten up your bulkheads as much as possible and then install more bilge pumps of course, for each compartment. Ideally you will have 4 WT areas (chain locker collision, staterooms, engine room, steering room lazarette).

BTW, regarding to all the comments about autopilots, I would say they are spot-on with what I've experienced as well. I remember my older boat which was cable steered and had a Wood Freeman. Wonderful old school AP with an electric starter motor as its drive. However its ability to steer was certainly subpar compared to today's electronic APs. In heavy following seas I had to hand steer, usually in 2 hour shifts. A big challenge for any AP is that it can't see following seas coming up behind you. However, it was commented above that new AI technology lets the computer learn and anticipate seas. Not sure how effective that is because each breaking wave is different, but it's a step in the right direction. Can't imagine what the cost is for a unit like that though.

Just reread your first post. The focus of your thread is regarding heavy weather, so we'll avoid the obvious "just avoid it" response :)

Am only familiar with GB42's by reputation but it sound like you want to improve its offshore abilities and safety. I would think about reducing down-flooding in extreme conditions (engine intake vent location, pipe them down to below the sole plate if necessary), those rotten sliding windows, replace your windows if rather thin, look at your doors for watertightness, WT bulkheads, gasket or replace that aft hatch, hatches need to be secured down and not rely only on gravity, etc.

Regarding windows, the 1600GT captain who taught me told a story of delivering a GB42 off the West Coast, heading uphill (north) unfortunately into horrible seas. Big sea punched out the forward window, which of course turns the situation into a hellish condition. The 2 with him (boat's owner and then a friend) both bailed on him when they finally reached port, and then he finished the delivery solo. So when I started going offshore I would carry precut plywood sheets, fasteners and power tools. However nowadays I would prefer to replace the windows. Double the thickness of the glazing with laminated tempered glass. Even if the glass shatters, the lamination will hold it together. The chances of blowing out a well-bedded window like that are minimal especially if you are conscientious about avoid heavy weather.

Then think about adding roll stabilizers. Roll is not fun for anyone even if you never get seasick. Plus it's dangerous because it quickly leads to fatigue, which is certainly not what you want when fighting through storm conditions for days on end. There are plenty of threads here on TF about stabilizers and perhaps your solution might be simple rolling chocks (bilge keels) which are not very expensive to install and should knock off 1/4 to 1/3 of your roll. That, combined with tacking to avoid beam seas, will improve your quality of life offshore.

Wow this turned out to be a long response, ha.
 
I can hardly believe what I'm reading. Using an autopilot in rough weather because it outperforms hand steering??? Maybe I need to upgrade my Simrad 26/27. It's 20 years old and doesn't have artificial intelligence. In more than 2 foot following seas, it seems to have very little intelligence. 10 to 15 degrees swings off course are standard. When taking the helm in hand, I know that when the stern lifts I need to start my correction (and determine which way to correct) even though I've yet to be thrown off course. Otherwise, I veer off as much as the AP.

Where I boat, non-AP transits because of sea state only last a few hours. I can put up with that and save the time and expense of a new AP (and probably steering gear replacement). But hearing that an AP can steer better than a helmsman in rough weather is impressive. What crazy gadget will they come up with next; self-steering cars?
 
Last edited:
I can hardly believe what I'm reading. Using an autopilot in rough weather because it outperforms hand steering??? Maybe I need to upgrade my Simrad 26/27. It's 20 years old and doesn't have artificial intelligence. In more than 2 foot following seas, it seems to have very little intelligence. 10 to 15 degrees swings off course are standard. When taking the helm in hand, I know that when the stern lifts I need to start my correction (and determine which way to correct) even though I've yet to be thrown off course. Otherwise, I veer off as much as the AP.

Where I boat, non-AP transits because of sea state only last a few hours. I can put up with that and save the time and expense of a new AP (and probably steering gear replacement). But hearing that an AP can steer better than a helmsman in rough weather is impressive. What crazy gadget will they come up with next; self-steering cars?

It depends a bit on the boat too. Some boats track better than others in following seas, so some need more predictive input than others. And sometimes a slight change in speed can make the boat easier to steer in a following sea.

With your existing AP, it sounds like it may not be responding fast enough to keep the yaw within a reasonable range. You may be able to improve that by adjusting settings on the AP unless it's already at the limit of how quickly your AP drive can move the rudder.
 
The key to the new AP performance magic is the input from the sensor core. In older systems like my Benmar, you simply had a magnetic heading. The new AP sensor cores have 9-axis input (3‑axis gyroscope, 3‑axis accelerometer and 3‑axis compass) that allows the AP to track the boat movement in three dimensions. This allows, for example, the AP to sense the approach of a following wave and take corrective action.
 
You’re actually kidding, right?
 
No one needs an autopilot if they are true yachtsmen and women.
 
No one needs an autopilot if they are true yachtsmen and women.

I surely hope this is a kidding statement. Do you have to have an autopilot, no, but they surely help. They allow the pilot to keep situational awareness since you don’t have to watch the compass constantly. You can just check the heading occasionally and use the free time to lookout for hazards and other boats. Besides it helps you from getting as tired by steering all the time. I have had surgeries on both shoulders and they tire out pretty easily if I am steering all the time, particularly in heavy weather.
 
You're absolutely correct. No one needs an autopilot. Or steering other than chain and cable. Or Radar. Or GPS. Or chart plotter. Or a VHV with more than 3 channels. Or. Or. Or.

I worked the early decades of my career with chain and cable steering, a magnetic compass, a time piece some way to take bearings and paper charts. Without so much as a rudder indicator. Yup. It can be done. But why?

An AP makes it safer because the watch can do all the other things they are supposed to be doing besides chasing the compass card back and forth. An AP makes it more pleasant. I don't NEED one, but I sure as heck want one and if a boat I have doesn't have a functioning AP is will soon.
No one needs an autopilot if they are true yachtsmen and women.
 
Well, she is an amazing yacht, drive her with confidence, allow her to make her way even if it wallows. She is an amazing yacht. Don’t worry about what everyone who never had one says, just enjoy her wonderful motion. GB FOREVER
 

Latest posts

Back
Top Bottom