Following Seas

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The builder of my boat and his buddy attempted to transit the southern entrance to San Francisco Bay. Their boat was busted when it hit bottom due to waves. Buddy drowned and builder made it ashore.
 
One thing to keep in mind is the speed of the breaking wave is often 12/13 knots. If the boat is traveling less than the speed of the breaking water, your rudder action is reversed.
 
Rule of thumb travel slower than a following sea so you don't
spill your rum and get home safe!!!!!!!!!!!!
 
Whatever else you might be able to do, having as much weight as possible aft always makes a boat track better in a following sea. Marine Trader/CHB models are notoriously bad for broach tendency normally, but for reasons too complicated to explain here, mine had most of it's tankage aft in the lazaret, and was absolutely fantastic in a following sea. :thumb:
 
Last year I had following seas quite often as I was cruising north. I mostly travelled at 8kn. If the stern was getting pushed around and being a bit squirrelly, increasing to 9 kn made it a lot better.
 
If you're in steep following seas and barely keeping the boat from broaching, stay out of shallow water and away from headlands. The wave get steeper there. I've seen 20' waves become 50' over a couple miles near a headland. If it gets too bad, you have to turn around and face the waves. In twins, if you're reversing one engine to keep from broaching, it's bad. Broaching in steep waves can kill you.
If you're spending much time on the ocean where the weather can get bad fast, it's worth keeping aboard some kind of sea anchor. Fishing in the North Pacific, even with waves breaking over the wheelhouse, with a sea anchor, I have survived (so far).





 
I've been reading posts where folks encounter rough rides due to following seas causing broaching. My question (maybe silly) is " how fast are following seas? I ask this because we are considering a single screw 40 ft, 30k pound semi displacement boat. If we get a big enough engine where I could (when needed) run at 12 to 14 knots would this be enough speed to make the ride safe in typical following seas? If not, I'll save $$ and get the smaller engine and just try to avoid these situations.

Speed is one way of dealing with broaching, but another is having a boat designed to be under control in following seas.

Boats with a wide squared off transom, small rudder and flat aft end with minimal keel will always have a high risk of broaching. Having extra speed may help at times, but you would have to use that speed wisely.

It's a whole lot easier just having a boat designed to have the waves pass safely under them.
 
Last year I had following seas quite often as I was cruising north. I mostly travelled at 8kn. If the stern was getting pushed around and being a bit squirrelly, increasing to 9 kn made it a lot better.

Right Brian. And I suspect the extra control is not so much from the extra power moving the boat through the water faster, as the wave is still probably travelling faster than the boat, but the extra prop-wash over the rudder(s), gives more rudder control to move the stern sideways to help retain directional control, even if the boat is going slower than the wave.
 
There are many ways to help your boat survive bad conditions.



One thing I have learned though the years....


Skippers that escape survival conditions almost instantly learn that their "planned" tactics aren't working, and adjust or experiment.....then because of their overall experience and/or luck, they find the right tactic.


What works for one boat in a certain set of conditions should never be thought of replacing YOUR experience with YOUR boat....the variety of conditions should be experienced if you plan to ever cruise where safe harbor may not be an option.


I pushed limits through my whole recreational boating career of 50 years or so to get that experience, after one season of assistance towing, I knew I was still a long way from "experienced".


Push your limits slowly or under the guidance of an experienced hand that also knows your kind of boat. Learn "feel" as it is as important as "theory".
 
Learn "feel" as it is as important as "theory".
So true! If the boat isn't an extension of you then you won't be able to sense and adjust as need be.
 
PB I suspect that what you mean is to be in tune w what’s happening and make evasive actions ahead of time. Like when yo feel (sense) a wave from aft is starting to seriously push on the port quarter before the stern moves seriously to stbd throw in a big dose of stbd rudder ... turn as fast as you can to the right. And bash the throttle.

That’s about all you can do. But you can’t do that fast enough w 6 turns L to L steering. What I’ve dreamed about is two turns L to L and power steering. Like a car. But there’s always 100 things more important to do. So I work a bit at the helm. My boat is 3 turns L to L so control is in the bag but on long runs I have to work some. With a small rudder and 6 turns you’re at the mercy of hull design, weight distribution, timing and what you can do w the power at hand.
 
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If he was agreeing with me....that's NOT what I am saying (steering)....unless you are emphasizing the "100 other thing to do" such as.....


Its about knowing whether your boat can handle 5 foot breaking seas from astern or is it time to turn around....or go fast...or go slow...or be using a drogue and what kind for what sea state, or when to steer straight down sea or at an angle, etc.....


Most everyone eventually learns to steer...but that is handling...not survival tactics.
 
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My ride has 6.6 turns lock-to-lock, and has electric/hydraulic power steering. I am strongly considering modding it to get to like 3.5 turns. I either need to go to higher capacity helm pumps or a smaller displacement rudder cylinder. Or both.

When I built the boat I was "gifted" with the big rudder cylinder which saved some $$$, but resulted in slow steering. I've learned to manage, but it still annoys me sometimes. If running in snotty following conditions, it would sure help to be able to snap the rudder around quicker than I can now.

The power steering makes it effortless, but one downside is it is limited in how much fluid it can flow. Try to turn the wheel faster than system can pump, and it feels like a brick wall, can't go faster than it can go. Increasing helm pump capacity won't fix this, but a smaller rudder cylinder will.

This boat did not originally need PS, it is a vestige of some prototype design work since abandoned. Decided to leave the PS in place.
 
Where we keep our boat (The Merrimack River in Massachusetts) is one of the worst inlets on the US east coast. It's fine unless there is a strong easterly swell against a strong outgoing tide. You learn how to deal with it, but lots of speed is never the answer. At most, you need enough speed to ride the back of a wave in. That is about 12-14 knots. Going out against the waves the best speed is usually even slower.

Ken

Bostonian here. I've heard about the Merrimack from The Hull Truth forum. I won't be going into that river anytime soon.

It reminds me of the west end of the Cape Cod Canal. With the right tide and wind direction you'll see 6 footers stack up there all day long. Real 6 footers, not an online forum exaggeration. Lol
 
Ill take a bad day at west end of the Cape Cod canal any day over bad bar conditions at Merrimack river entrance.
 
My ride has 6.6 turns lock-to-lock, and has electric/hydraulic power steering. I am strongly considering modding it to get to like 3.5 turns. I either need to go to higher capacity helm pumps or a smaller displacement rudder cylinder. Or both.

When I built the boat I was "gifted" with the big rudder cylinder which saved some $$$, but resulted in slow steering. I've learned to manage, but it still annoys me sometimes. If running in snotty following conditions, it would sure help to be able to snap the rudder around quicker than I can now.

The power steering makes it effortless, but one downside is it is limited in how much fluid it can flow. Try to turn the wheel faster than system can pump, and it feels like a brick wall, can't go faster than it can go. Increasing helm pump capacity won't fix this, but a smaller rudder cylinder will.

This boat did not originally need PS, it is a vestige of some prototype design work since abandoned. Decided to leave the PS in place.




Through all my research on boat steering, I have learned that 5 to 6 turns for a total of 90 degrees of rudder swing is normal and most small pleasure craft use this.



This is a good read about steering systems.

https://www.sbmar.com/articles/marine-hydraulic-steering-systems/
 
Thanks for sharing that steering systems guide. Very informative. I have long been concerned that my 6.5 turns L-L was an abnormality and a sign of a “weak” system. Nice to get a more complete picture of how the different components work together.
 
My experience is just the opposite! Sometimes, putting a little more coal on the fire (speed) results in a much more comfortable and manageable ride. As the seas get higher, I prefer riding the back of the wave. I prefer larger engines that give me the option to adjust to the seaway. On calm days, I travel at trawler speeds to save fuel and enjoy the sea.:blush:

I agree completely!

In a significant following sea I’ll often use power to surf, making the ride very plesant.
 
Memories - This thread reminds me.... My first "big" boat was an 35' Owens called the Nightcrawler (I didn't name it!) that was actually 36'. It was the 1958 NY boat show entry for Owens. They added 1' to make the salon bigger. It was "gold plated" for its day, meaning the interior of the entire double planked mahogany hull had been varnished and had brass kick plates above the props, plus other niceties. It also had miserable updraft carbureted Hercules engines. It had been originally a sedan, but was converted to a flybridge sport fishing boat.
Once, when coming back from a scuba trip, I was about to enter the pass into St. Andrews Bay near Panama City, FL. I observed that the pass was extremely rough, as the outgoing tide was meeting a strong onshore wind. I sat outside the pass, on the south side for a while and was prepared to wait until the ebb flow or wind abated somewhat. We had pulled a smaller cuddy cabin boat in from miles out in the Gulf of Mexico as they had had engine troubles. There was also a woman and at least one child on board. After awhile, he got his engine going and hollered that he was going go through the pass, but if he had more engine trouble to come and get him. That pass, under certain bad conditions is best to stay on the north side, and under other conditions, it is best to keep to the south side - but never go up the middle in bad conditions - which is exactly what he did. He got about a quarter of the way through and his engine quit again. He and his family were in dire straits 6-8' waves in a very confused sea. So, I proceeded ahead towards his position. At one point our boat was lifted up about 6-8' or more on a column of water, then, with a swoosh, slid off the column of water into the trough. I had been sitting at the upper helm for better vision, but when the boat was lifted up, I bailed off to the lower helm. I can still vividly remember looking at the bow, sides and stern as the boat momentarily sat up on the top of the column of water, and the realization of how easily the boat could pitch-pole or roll and that my weight was making the boat more unstable, being at the upper helm. I threw him a tow rope and pulled him over to the relatively calmer north side of the channel. Under tow, his boat behaved remarkably well for the conditions, as well as the fact that it wasn't a long tow to the north side. As we got clear of the jetties and into calmer waters, he again got his engine going and cast off the tow rope. I never saw him again.


Later, when I had our 46' sailboat, I frequently ran the inlet in adverse conditions. I used to go "sail-fishing" (Putting a fishing line out while sailing in whatever direction the wind gave me a good trolling speed. One year I caught 78 Spanish mackerel plus other fish). Often, when I returned home after 6-8 hours of sail-fishing, the inlet was very rough. I usually favored the north side as it was deep, the south side has a shoal area just inside the jetties. (That boat drew 6.5'. ) I miss the Wayward Wind - a Starratt & Jenks 45. When I brought her to Panama City from the Chesapeake Bay, I endured the aftermath of a previously unreported storm on the Atlantic - reported 20-30' seas when we got within reception range of the USCG - Savannah, GA, (waves seemed much greater!) The strange thing, though, was that there was no wind, just huge waves. I learned then, that the boat could take much more than I really liked.
 
Remembering sailboat racing down Hurricane Gulch in SF Bay in the sixties, sometimes having knockdowns with spinnaker, shoving the boat 90 degrees directionally to the side. With the steep five-foot following waves, recovery was rapid and exciting.
 
Wayne,
Yes I remember the Owens boats. Heavy on glitter both chrome and varnish. They offered a 26 footer in the 50’s where the whole hull and everything else was varnished. They had some awkward lines and windows w too much glitter but they were good boats. They were heavier than the CC and others and built a high quality plywood boat.
 
Thanks for sharing that steering systems guide. Very informative. I have long been concerned that my 6.5 turns L-L was an abnormality and a sign of a “weak” system. Nice to get a more complete picture of how the different components work together.




You're welcome. I'm happy it helped.
 

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