Boats for Following Seas

[Fisherman]

So what designs or factors enter into making some boats better in following seas than others? I've read a lot of posts on other sites where the discussion leads to some boats being better in following seas than others. Maybe this question has a complex answer, but if there are some main points on which someone can educate me, along with some of the reasons why some boats are NOT good in following seas, I would be very appreciative. I will be fishing mid to southern CA, where the ride home in the afternoon is almost always a downhill ride. I am interested in a response tailored more for a 25-30 ft OB powered sport fishing boat.

[falmouthmetal]

Just get a Pacific and be done with it

[Fisherman]

Just get a Pacific and be done with it

Thanks. Seems as if that's a common solution I get to a number of questions I've had. There ARE other good builders out there; Pacific appears to do a good job though.

I would be glad for some design information pertaining to the original question, if anyone knows how to answer it or refer me to somewhere I can find the answer myself.

[welder]

We need to get kmorin on this thead to explan what makes a hull design good in following seas.

[kmorin]

welder, others here would be much better doing this than I will but here's a few factors for Fisherman.

The balance of forces pushing on the hull when the seas are coming from behind the line across the hull amidships is not fixed. There are a three main conditions and each one would have its own set of measurements about hull performance in these conditions.

First if the boat was traveling faster than the seas, next the boat traveling at the same speeds as the seas, last if the seas were overtaking the hull and passing it by. In each case hulls behave differently, so making general statements gets a little be complicated or 'risky' because what is true of one shape in one sea state is not true of that shape in all others.

IN general; the response to the helm and the hull's "performance" as response to the helm input is described as 'good or better' in a following sea. The main forces involved are working on two ends of the hull. The hull floats/moves/pitches/rolls/yaws around its center(s) of flotation and buoyancy (the difference will confuse here so it ignored) and the immersion of the hull in both ends results in different forces on the hull.

So hulls with better following sea behavior/performance/reliability are those where the balance of forces fore and aft, at any given speed of travel are most 'balanced' and therefore manageable.

Very sharp and deeps V's forward would allow a hull to plunge deeper into a wave back than a less V'd hull and that second hull may not have as much wetted area forward; so the hull is not 'stopped' or slowed as much and the forces sideways/transversely/broaching the hull are less compared to a another hull.

Now to contradict that statement: if the stern of the boat above had two large outboards, with large skegs providing a huge lateral area, that may be enough to counter the deeply immersed bow and keep the boat moving in one direction instead of letting the stern slew sideways and broaching the hull?

Back to balance. Since there are nearly limitless conditions of immersion, resistance and forces from different directions pushing on the the hull, discussing this accurately is not very simple. We'd have to take a heading relative to the seas, and the hull shape (or two) and speed; then begin that discussion.

In general, trying to describe the balance of these forces at different speeds, and sea states is a big job because there are so many vectors/factors/forces influencing the movement.

Factors besides speeds include the shape and area of the stern, lateral area of the hull, the V of the hull in all locations, the heading compared to the seas and the size of the seas compared to the LOA of the hull. But that is not the extent of the factors influencing the handling in following seas.

Not sure if this is any help? but I'd try to reply to specific questions, the OP is little open ended, not intentionally I'm sure.

Cheers,
Kevin Morin

[peterbo3]

We get our share of nasty following seas down this way as the prevailing wind is SE & we run a westerly course to get back home from 35 miles out on occasion. As Kevin implied, every boat is different & the sea is never constant.
Soooooooooooooooo........................ IMHO the answer lies in the head of the person at the wheel. If you know what you a doing, a canoe will get you back in. Conversely, a fool may roll a well designed/built 30 footer.
Experience is the key & the best way is to learn from somebody else. Learning from your own mistakes is good, providing you survive to put what you have learned into practice next time.

Jest sayin ................

[Fisherman]

Kevin,

Thanks for your post. I am not surprised this is a very complex question to answer with so many variables. One thing that you said that stood out to me is the idea of having a balanced boat. I can understand why this is important.

I am wondering a little about how the shape of the transom affects things. Probably a complex issue, but if you have any general comments, I'd be glad to hear what you think about the angle of the transom (some boats are straight vertically, some are angled back [is this called flam also??], OB engine brackets, floatation pods, etc.) There are many different designs out there. And I suppose the transom design is really only important if the boat is going slower than the waves?? Maybe that part of my boat isn't that big of a deal since I hope to have plenty of power to stay up with the waves, if not even pass them up if safe to do so.

And peterbo3, thanks for pointing out the user part of things. Very true.

[kmorin]

Fisherman,
Different hull speeds allow or create different forces from the transom on the boat's movement in a following sea. When the waves overtake, they have the most effect, when moving with the seas less and if running before the seas least force and effect.

I guess the worst case is a vertical flat transom in an overtaking following sea because the transom has the least contribution to changing the waterplane so the amount of pitch by the stern or lift is least -compared to the rising waterline as the hull is overtaken. The raked aft/'leaned back', not called flam that I'm aware, transom will increase the waterplane area aft as the waterline rises so the lift/buoyancy of the stern is greater with an aft leaning transom therefore the boat lifts over a boarding wave overtaking that hull.

This is no a pure gain because as the stern is lifted the bow is pitched down to some degree. That increases the wetted area and drag very quickly, and if this force is more on one side than the other - heading is not exactly with the sea's direction- then the boat's helm is pushed by the higher side this is veering. This (can/may/contribute to) leads to rolling as Peterbo3 mentions.

Fan tails, rounded sterns, and counter sterns, all variations on a theme are intended to provide less flat area and more rounded or 'bow like' area for oncoming seas to push against. So raking a transom aft, and having some rounding both help to make the hull more stable at the helm with less 'slewing' or veering around as seas overtake the hull.

A famous hull shape on the Oregon coast is the Bartender by George Calkins. http://www.bartenderboats.com/ This is a planing, double ended hull with a stern almost identical in shape to its bow, providing a shape that could handle seas from the stern just as power boats handle them by the bow. You might notice the similarity to ocean going 'life boats'?

engine mounts/brackets

If a sea is overtaking a hull, the ultimate issue is boarding by the stern. If the water comes aboard the hull has to be decked to allow the hull to shed the water. In outboard powered boats we need the seas to lift the boat by the stern not board, but the torque of the vertical drive shaft and vertical weight considerations limits the distance from the power head to the prop. Therefore we end up with a 2' high engine mount and that is a 'weak link' in the height of the sides/transom in keeping water out.

A full height transom with some engine mount, whether a bracket or a full cut away after platform, allows the engine to be low to the water, but to ultimately lift the hull when a following sea overtakes the hull and the waterline potentially gets that high. The engine mount/bracket/stern cutaway also provides some buoyancy to help float the power and planing bottom in most cases. And the side area of the bracket/cutaway stern is less than a 'square' corner of the hull with a topsides to full height transom so there is a small reduction is side wise force, that far aft the center(s).

Sorry that I don't have time to do an illustrated post to show some of these ideas in images. I'm not that much of a wordsmith, so if I don't resort to pictures most of the ideas I express are not as clear as they might be with pictures.

Cheers,
Kevin Morin

[AlloyToy]

Just get a Pacific and be done with it

Not that easy...Halloween 2009 I got caught in one hell of a mess coming back from the SEC of the bank to Green Harbor after a successful morning of tuna fishing. Strong surge of following seas combined with winds that came up from no where made for one of the worst conditions I've ever been out in It was one hell of a white knuckle ride home and many upon many times "follwing seas" would cause bow steer and we would plow and take gallons of water over the bow in which I had to throttle up to displace the water.

Not disputing that a Pacific is a well build boat however I would not sell the boat on it's ability to perform "the best" in following seas.......

[welder]

Alloy, I just have to ask, in those sea conditions you were in at that time (the white knuckle part) is there another 23 foot boat that you would have felt safer in? Also , I have to ask again , did the deck drain good enough for you or would you want a little bigger scuppers ? Not trying to push ANY boat here just want your opinion.

[AlloyToy]

Black Beard, thanks for the kind words. My grandfather always said "if you tell the truth you only have to tell it once" Honestly I love my Pacific and love my hull modifications even more They are built like tanks, fuel efficient, easy to trailer, 23' boat that is manageable alone, and very seaworthy

Les, I have to answer honestly and hope I'm not fined for mentioning I had a 20' Maritime Skiff. One of the most seaworthy 20 footers I have ever been in but not a 23' as you mentioned. At the time of my purchase of my Pacific I was (and Jay knows the former two owners very well and I'm sure has the utmost respect for them) torn between my 23' Pacific and a 23' Maritime. I have no regrets with my decision of the 23' Pacific but will also say that Maritime boats are very seaworthy boats.

In regards to the scuppers. It was November 2001. We trailered my 20' Maritime up to cod fish the South shore near shore cod grounds. It was blowing hard but the boat design would handle the steep 3' chop all day long. Well as we got closer to noon the winds increased and the 3' chop went to un-timed 3-5 foot seas with a very large 5 thrown in to keep us on our toes. Out of no where an even larger sea broke over the bow dodger and completely filled the boat ankle deep with water. I throttled up and raised the bow up and in seconds the 2" scuppers completely drained all the water in the cockpit. I was amazed at the performance especially with the wall of water we punched through. I was also amazed that the wave did not demolish the bow dodger.

The bow design is more along the lines of a Whaler. Paul & Bev both former owners of Maritime Boats, and former employees of Boston Whaler when they were in Massachusetts did a great job designing and building boats for the waters we encounter here in New England

Pic of my 20' hull #0001 (bough first boat built) And we still own a Maritime 14' for skinny water fishing.....

Now back to Alloy I can't afford the fines

[kmorin]

If we don't keep relative shapes in groups, the discussion will loose hope of helping anyone on this topic.
The plastic boat hull shown has three separate elements, most plate boats have one. A Pacific's topsides are a single piece of material, the molded boat has three varying flams (maybe flairs?) so the performance into a sea/wave/swell is not the same.

If we took two skiffs with a 10 degree deadrise at the stern, both 72"/6'/3m wide chine they would float the exact same weight at the same waterline depth. If we added a 6" chine flat to one and not the other, the chine would add a 1' of beam so the same weight would float higher with a lower waterline. Further the amount of weight to sink the boat an 1" deeper would be much higher for the wider bottom.

Wider is greater displacement is more flotation for the same LOA hull. So if the bow of a skiff is made of a single sheet of metal, it will not have as much lift/buoyancy/pitch upward as the 'same' hull with steps that lean out farther and farther. The deeper the water climbs the stepped or 'planked' shape (like the molded skiff shown from the stern) the more the waterplane area changes AS THE WATERLINE RISES..... therefore as the boat is more immersed in a wave, the more the hull lifts- yes it will slow down and may slam your face on the dash/helm/windssreen but the stepped hull allows a wider shape as it gets deeper. The width change is not uniformly proportional to waterline depth, it increases very rapidly and therefore does not act like the single sheet side skiff.

I don't have pictures of a skiff I did 40 years ago that had a second topside panel and was inspired by the North Carolina bows of the larger sports fishermen. But it worked very well, it was just expensive as hull features go. That skiff was dry enough that I ran it about 54 miles one night in 20+ seas and was not in danger. I learned that by plunging off a huge roller and finding out I could did not have enough weight in the entire boat to plunge the bow below the water's surface. It scared the stuffing out of me, but when I saw that water being flung out virtually horizontally after my failure to stay on the wave back, I realized I'd been saved by building that idea into the skiff.

So we can't include molded shapes with plate shapes in a side by side comparison- because the waterplane area changes are not similar so their following sea handling/performance is not going to be comparable. If you built a welded hull of the same shape as the three panel side molded skiff then there could be a comparison but they are two different shapes for now.

This is why a welded aluminum panga would be such a fine sea boat.

cheers,
Kevin Morin

[Fisherman]

Kevin,

Thanks for the info. I read through a couple of times, and understand what you said.

Alloytoy, thanks for your honesty on the Pacific.

[welder]

AT, no fines here brother, we ALL appreciate the honest answers. No one boat does it ALL.

Kevin, well written Boss, thank you.

My Dad told me to tell the truth because, It's less sh!t you have to remember.

[AlloyToy]

Kevin,

Always enjoy reading your posts

Appreciate everyone's input.....that's what makes AAB so awesome

[DwayneJ]

Personally, never really had any control issues in following seas - Its all been fun. I have been caught out in poor conditions but once the wind and seas were behind, the boat handled it very well. You are more than welcome to come out with me if you are in the area and current conditions would be a good test. You would then have something to compare to irrespective of whatever hull you choose.

Dwayne

[Fisherman]

Thank you Dwayne. I'm about 6 hrs north of you. I would like to start getting out on other boats. Thanks for the offer.

[DwayneJ]

Thank you Dwayne. I'm about 6 hrs north of you. I would like to start getting out on other boats. Thanks for the offer.

You are welcome. I will send you a PM with my contact details just in case you get down this way.

[JETTYWOLF]

I wanna see more pics of pointy bowed glass boats



Seriously I've found less bow weight, bow sharpness, and as Peter said....boat driving skill (throttle hand) can help make a following sea, more fun to be in.

[jj225]

Fisherman, since you're in Central CA. you should know about the Radon hull. Really no better hull for running in a following sea although it's a plastic boat. It just beats the hell out of you running uphill lol. Be interesting to know if
an alum. builder could shape a hull like a Radon/Davis.

[Fisherman]

jj25, yes, I'm very aware of the radon hull...have ridden on a Davis 25 several times as my friend has one. I wonder why that hull has such a good reputation for following seas? What properties does it have that make it perform well?

I have wondered about having aluminum radon hull too.

Thanks for your response.

[jj225]

Well if you've ridden in a Davis you should know unless you've never been out is a big following sea. I owned one for 6 years and I can say w/out a doubt the reputation is well deserved. Boat is unbelievable imo. Try taking your hands off
the wheel in a 10' f.s. and see just how well the boat tracks. Straight as an arrow. Never once did it broach on mine or the others that I've been on.

As for the the properties I think it's the combination of how the hull is designed. It doesn't have a sharp V. More modified. Then you look how the bow has the wide flair at the top (it's perpendicular to the water) and the bottom almost seems to have the strakes run all the way out on either side of the V so it forms a cup if you will. The deadrise at trasom is 18 degress so it's pretty stable in the back half. But I'm not expert. Just remember there's always a trade off. Oh and I don't think there's any alum. builder that can form a hull the way the Radon hull is designed imo. Alum. can old bend so much.

I loved my Davis but won't get another one. Just way to expensive. I'm looking at another tin can boat (own a North River) that I can use for both f.w. and salt. Can buy a brand new one for what a 10 year old Davis sells for.