Following Sea

First thing is slow down and let the following sea slide under the transom, secondly, if you have an auto pilot, set it for heavy sea state and watch how it reacts, you will find that an autopilot does not oversteer as much as a regular helmsman, takes a bit of practice to not oversteer. You may find of course that every so often the autopilot will really throw you off course which can be risky, use it as a guide to see its normal reaction to steering corrections, will surprise how little it actually moves the wheel, of course if you have hydraulic steering, you will not that reaction, but, less reaction on the wheel is important.
If it gets really uncomfortable you may have to do some tacking to reduce the problem.

I have to disagree with you. The post is a fast boat. Use it. Ideally, you want to ride the back/top of the wave. If you let the wave catch your narrow transom on a SF it'll try to turn you sideways (Yaw). Also stay on manual steering. An autopilot reacts. It can't anticipate. By the time it tries to correct a yaw you're into it. I once followed a 43 Ocean out of Hilton Head heading for St. Augustine in about a 15' following seas. We were also on a 43 Ocean. First I'm looking at his transom, next I'm looking at his bow rail, and so on All the while his mate is hanging off the stern chumming. Once I got him off his autopilot he was fine and so was his mate. As you go down the front of a wave your bow will stop at the bottom and your stern wants to come around. You could easily broach by the time an autopilot reacts. You need to actively steer to keep the boat straight. Same when overtaken by a wave.
Use all your tools. Once coming into Ocean City on that 43 Ocean I was running from full speed forward to full speed reverse, using the rudder and the tabs to keep her straight. Autopilot would have put us on the jetty for sure.
Finally, keep your head on a swivel. Check the waves coming to you so you can anticipate what move will be needed.

Sounds like hard work and broach avoidance instead of pleasure cruising..to each his own I guess.

Running in a heavy following sea IS a lot of work. Beats sea sickness or broaching though.

NYCAP123 was on a good point, When you have the power, use it. Stay on the back of a swell and ride her in.
We have a constant running pilot pump motor, really fast on adjusting rudder. It still can not hold anything in a bad following sea.
It's feel and anticipation.
During your day outside, run off forward tanks first (if available). Relocate the mother-in-law out of the AC and aft. Raise the tabs and keep your hands on the throttles. As the depth changes, the period of the swell may change. Micro adjustments and keep your cool, including having the mate gag the mother-in-law. (been there, done that).

When you and the water are moving at the same speed your rudders do nothing. Steering is done with the throttles and gears. If you start moving faster down the front you can also steer with your tabs. Your rudders are your most ineffective tool until you can get some speed over the water. That's the 2nd reason you don't use autopilot in a following sea.

It all depends on the boat and conditions. Going slow is good advice in an inlet

When i run offshore with following or quartering seas unusually end up steering manually. Again it depends on boat with with the top heavy Johnson 70 I run (skylounge with Waverunner and 15' Rendova, no stabs) hand steering makes a big difference whether running at 10kts or 20kts. As NYCAP said, APs react whereas the human brain can feel and anticipate what s coming. It's a work out but rapid steering inputs in anticipation of the boat hawing and rolling, can greatly reduce the motion. I usually watch the burgee pole atvthe bow and By catching and correcting as soon as the bow starts turning, It's almost like having stabilizers, well not quite but it helps...

The key is to know the limits of your boat

I'm not sure I agree with all of these statements.

First, the water beneath the wave surface does not move with the wave, unless you are in shallow water, such as might be the case with running an inlet with breakers. At sea, the only thing speeding/slowing the boat is the effect of gravity as the boat tries to run down/up the incline of the wave. In this instance, the rudders have the same acting force as when there are no waves. (Think about it, the boat still makes a wake, right?). If a boat broaches in deep water due to a following sea it is a function of both turning while going too fast, combined with the gravity effect from the slope of the wave.

"If" you are in a shallow wave (breakers) the surface friction of the bottom does create a situation where the water can be moving in the same direction as the waves. In this instance of a following sea, the force on the rudder wil be reduced, and the rudder will become less effective as the speed of the water increases. However, both rudders and tabs rely on differential water speed for effective force. If the boat and the water are moving at the same speed, neither rudder, nor tabs, wil have any impact on a boats directional control. For effective control, you need to either get the boat moving faster than the water, or be **** good on the throttles/gears. A broach is more likely in this situation, because the wave surface is often steeper, and the surface waters can be running faster than the waters below, increasing the sideways force on the boat.

My advice to any new boat owner (and the advice I use for myself) is to avoid running an inlet with breakers, unless you know the inlet, and the boat performance, real well.

With all due respect Mark, I don't think we're talking about running with calm seas here, and in rough seas a 3' draft is running predominently in surface water. When you're riding the waves they're moving.

Your last sentence is very good advice. I always expected to die coming in an inlet. In my estimation very few boaters will encounter anything quite as dangerous. Coming in you're looking at he backs of the waves and can't see what they're doing until you're on top of them. We have a particularly dangerous inlet by me (Moriches) that claims on average about 4 boats a year. They go out in the morning at high tide and it looks beautiful. They come back in the afternoon when the tide's running out and the wind waves are built up only to find that there's about a 50' hole to enter. Too far west and they're pushed into the jetty or onto that bar, and from west-center to east they're on that bar with crashing waves. From the ocean side it all looks about the same until you find yourself on top of a breaker. Come off it and you could find yourself in 3' of water.

With the same due respect, the water molecules don't move (appreciably) in a non-breaking wave. The surface water moves in an orbital fashion, up and down with the waves, in conjunction with a slight back and forth motion. It's the same phenomena as making a wave with a rope ... the rope itself does not move forward. In fact, if you are on the downside of a wave, the (slight) horizontal direction of the water will be opposite the direction of the boat. Accordingly, the rudder offers the same steering force in rough seas, as it does in calm seas, given a constant forward speed. That said, on the upside of a wave, your speed will be slower, and the you will have a (slight) water movement in the direction of the boat, somewhat reducing rudder effectiveness.

Running inlets aside (which I'd only do if I was **** sure I would have rudder control via enough speed) I can't imagine trying to use differential thrust to control the boat in a rough following sea. What would we all do in a single engine boat?

That's an entirely different strategy as it also is with a slow boat. That requires setting yourself carefully for the push and hopefully have a bigger rudder than you find on most twin screw SFs. Sort of like the difference between Karate and Judo. Both skillful and effective, but very different.

We use what tools we have. Rudders won't do you much good on the back of the waves, but will have more effect when you get moving ahead of it. I'd use a paddle or a bucket on a rope if that's all I had, but I prefer twin screw and lots of hp.

We had a 46 Post for awhile (4 yaers), and she did swap "ends" sometimes, especially when coming back from our longer fishing trips. I attribute some of it to burning most of the aft fuel and she would be a little light in the stern. I know bigger rudders would have helped, but you have to check the current steering systems capabilities befor you upsize the rudders, as you do not want to exceeed the steering cylinder's rating.
We also had a dinghy and davit on the bow, and all chain rode for the anchoring conditions out west. I would certainly keep the bladder tank aft if you have a safe location for it.

The Post 46 has a relative deep forefoot along with shallow deadrise at the transom. Coupled with aft fuel tanks, it can certainly highlight difficulties returning from a long run as you burn the aft fuel and shift the lcg forward.

Is there an easy and quick fix? Probably not, you just have to be aware of your boats tendencies and operate it with that personal knowledge.

For the most part, weight aft will be better for this boat than weight forward, (and this is true for most SF) but I recall the cockpit scuppers were fairly low and you could get some annoying sea water in the cockpit corners when fully with fuel/gear and just fishing stationary. Certainly put on scupper "flappers" to prevent soaking your shoes.

My autopilot does a pretty good job in a following sea - right up until the seas get just a little too big and then its always turning the wrong way. You can tune it to work a little better but it can't see the waves and doesn't know when to start reversing the helm. A good helmsman will learn the boats behavior and will anticipate the next yaw and reverse the helm before the yaw gets started. As long as you are outrunning the waves the autopilot will be fine. At some point though you will no longer be able to outrun the waves.

If you are planning a long trip I would assume the autopilot will not be useable and prepare shifts that way. Also check the operation of the helm and the quality of the hydraulic fluid. A small difference in operation will save a lot of fatigue over the voyage.