Hull Shapes and Behaviour in Heavy Seas

[thataway41]

Some comments on larger boats and short handling. I grew up in the 1940/50 era on a 26' boat whose hull was like a Star, arc bottom, hard chine, but with high freeboard, a small trunk cabin and outboard rudder. It would pound easily going to weather, but was fast off the wind. I raced, mostly offshore, for 30 years in fin keel and ULBD boats. For cruising we built a 38 foot fiberglass canoe hull, with a moderately long fin, and skeg in front of the rudder--18 hp Saab diesel engine. After a 5 month shakedown cruise, my wife wanted a larger boat. We ended up with a full keel 62' ketch. The majority of the time the two of us sailed her easily. We had redundancy in the autopilot system, and an 80 hp Ford Lehman engine. Our average speed was 6 knots. We cruised for 4 years, and 41,000 miles. On the East bound Atlantic crossing we had hurricane force winds and heavy seas for 5 days. The Canaries to Barbados crossing was 15 days all under sail. The larger boat is a more stable platform for cruising. Comfort is more important than speed. You want a sea kindly boat.
We also wanted a long range under power--and carried 700 gallons of diesel, giving us a range of about 3000 miles. We had 500 gallons of water, but Also a water maker. Not so much as for the necessity of finding water, but having potable water and never had waterborne illness.

Motion sickness: Despite having over 250,000 miles at sea, I do get seasick on occasion. Usually it is the first 24 hours, during the first night , in a light displacement vessel with a snappy roll--not in slow roll vessels. We are all different.

I would advise that at least you get some sea time as a crew member offshore--to understand what it is like, and see how you are affected by the motion.

Although our adventures with a 60' boat turned out well; we knew some folks who purchased a well founded 65 footer. The "whole family" --3 kids and eventually wives--were going on their voyages. About a year later, I got a call from the owner. Could I fly to Panama and help him bring the boat back to Long Beach, CA.? (where it was put up for sale.) All of the "Crew" had abandoned the adventure.

Don't underestimate the work and time involved in outfitting a bare hull. To do it right takes a significant amount of time. Have the whole family involved.

As to the steel vessel with the air cooled Lister engine--I would think that the air cooling would be a real negative, especially in the tropics. Figure replacement of that engine--and the costs.

Good luck with the adventure.

[Cpt Pat]

Originally Posted by rlg

... purchase a ship shape,smaller, more well known and trusted boat to learn what you need, that has a generally accepted resale value. Then move on if need be when you feel more confident to pick a long term choice.
Im almost certain this will be cheaper, easier, and faster when all is said and done.

Good luck
Rob

Good advice. I purchased my 26 foot Ariel with that intention. But there's a hazard: I fell in love with her; with my connection to the sea in a smaller vessel, and how I could play her like a violin single-handed in sea states that sent everyone else back to the harbor. And when I crew or ferry a larger boat, I find it hard to suppress a yawn. Meanwhile, my savings for my "next bigger boat" have just accumulated because of my reluctance to give her up.

I've considered several bigger boats that just came and went, while telling myself that boats are like buses: wait ten minutes and another will come along.

[MartinR]

Originally Posted by thataway41

As to the steel vessel with the air cooled Lister engine--I would think that the air cooling would be a real negative, especially in the tropics. Figure replacement of that engine--and the costs.

Good luck with the adventure.

These engines work, also in warm weather. Many of them pull stationary pumps in Africa. There are advantages, no cooling water, no through hulls. Simple, reliable.

There are disadvantages of course, like heavy, not very efficient, cooling air goes out somewhere, noise.......

[NevisDog]

Originally Posted by Metal Boat

Here is a vid of a 39' Halvorsen Freya doing 9 Knots with very little pressure wave.
...
I am really enjoying this thread it has taken on a life of its own and its creating valuable debate......

You fooled us all - you know far more about boats than you let on!
But yes, some really interesting and diverse opinions, I'm learning heaps, you takes your choice.

How many teenagers in your family again? I'd be going 'big', with individual cabins for each, if you want to live aboard in harmony. Living aboard can save pots of money but refitting while living aboard would require even more space. Depends whether you/your family want to spend years on a 'project' (remember to multiply your best estimate by 3 - not many families would survive that but yours might) or just do the normal annual (read 'interminable') maintenance on a boat that's good-to-go.

Freya 39 was very near top of my wish list, but that was for the two of us.

[Rightbrainer]

I recommend David Gerr's book "The Nature of Boats". Gerr is a well-known naval architect and in this book he explores the many trade-offs inherent in boat design. Easy to read, but technically based.

https://www.amazon.com/Nature-Boats-...rds=david+gerr

[s3raphim]

HIGHLY recommend that you read John Kretschmer's book Sailing A Serious Ocean. Kretschmer has probably logged more blue water passage hours than anyone currently alive, and this book goes into detail on his approach to voyaging, including an extensive section on best hull types, best sailboats, best practices, etc...

You can check out the book here at Amazon.

[wingssail]

Originally Posted by s3raphim

HIGHLY recommend that you read John Kretschmer's book Sailing A Serious Ocean. Kretschmer has probably logged more blue water passage hours than anyone currently alive, and this book goes into detail on his approach to voyaging, including an extensive section on best hull types, best sailboats, best practices, etc...

You can check out the book here at Amazon.

It is interesting to note that Kretschmer sails Quetzal, a fin keeled skeg rudder performance boat.

[Icarus]

I built a lot of metal boats for clients over the years, personally I have owned four ranging from 36'to 72' if they are constructed right with easy access to the hull there is no problem. If you can give the name of the the design I can tell you more about the boat.
Keep in mind that some so called yacht designers are questionable and have no sailing experience.
If the hull has been properly prepared, grid blasted and epoxy primed then its worth the while to consider the vessel.
Galvanic corrosion is in my opinion your number one enemy.
As for ancient Lister engines spare parts are very hard to find, forget the copies made in India, rubbish.
You will be motoring a lot, windward 'performance' is nil. Anything will sail downwind, tacking downwind is awkward to say the least. Weather helm, balance? Hyd steering?
It certainly is a big lump of boat weighing probably in excess of 30 tons...

Best of luck
Icarus, Australia



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[MartinR]

Hull speed is not an absolute limit. It just requires significant more energy to exceed it. Racing boats do it all the time, though. Most cruising boats can not do this, except when surfing down waves. The big difference between the logs and the racing boats is the performance when at lower than hull speed, though. And most of the time, we sail under these conditions.

[Cpt Pat]

Originally Posted by MartinR

Hull speed is not an absolute limit. It just requires significant more energy to exceed it. Racing boats do it all the time, though. Most cruising boats can not do this, except when surfing down waves. The big difference between the logs and the racing boats is the performance when at lower than hull speed, though. And most of the time, we sail under these conditions.

You put it very well.

My own vessel often exceeds hull speed. If you watch the video I posted earlier in this thread, you will see my heavy displacement boat exceeding hull speed - and not while surfing. But it requires much more power to get an extra knot. It's a not a hard limit, but it's expensive in terms of power required.

The hull speed formula defines an arbitrary speed where the propulsive power needed to exceed that speed increases rapidly, and departs from the ordinary formula of force needed to achieve a given velocity.

> The big difference between the logs and the racing boats is the performance when at lower than hull speed, though.

Yes, absolutely! An efficient hull will accelerate faster and need less power at less-than-hull speed (and above). At hull speed, there is a distinct point of diminishing returns for money spent, and stability sacrificed, to achieve more speed. It's a personal value judgement if someone wants to, for example, spend twice as much money for a less stable boat, to go 10% faster. Of course that may be a good bargin for a racer, but it may not be a good choice for a cruiser.

An extreme example is the America's Cup race in the S.F. Bay. Those boats would fold up and fall apart in ocean swells - one did fold up and take the life of a crewman. Their keels were designed for flat water, but they sure were fast! Still, I can't imagine anyone would want to take an ocean cruise on one. It'd be suicide.

I may not have been clear in my opinion: one should be cautious about choosing a boat designed for racing to use in cruising. You may be paying a lot more for a fast boat that, to get around the constraints of physics, sacrificed stability for speed. And I know this is controversial. It's a controversy that's been raging since before I was born (a long time ago). I'm not the first person to bring it up.

[Jim Cate]

Yes, absolutely! An efficient hull will accelerate faster and need less power at less-than-hull speed. But my point is: all displacement hulls have the same hull speed constraint. At hull speed, there is a distinct point of diminishing returns for money spent, and stability sacrificed, to achieve more speed. It's a personal value judgement if someone wants to, for example, spend twice as much money for a less stable boat, to go 10% faster. Of course that may be a good deal for a racer, but it may not be a good choice for a cruiser.

Hull speed is, as posted above, a kinda vague point, but no one will argue that it does not take rapidly increasing power to gain small increments in speed it that realm.

BUT, cruising includes sailing much of the time in conditions where hull speed is not attainable due to lack of wind. And it is in these intermediate speeds where a more modern hull and appendage package will definitely out perform the type of hull that you are so passionately defending. Wetted area and parasitic drag from appendages are the major sources of drag in those speed zones and surely you don't believe that the traditional full keel is better there, do you?

And then your thoughts on hull speed... perhaps the ultimate sustained speed for two boats of similar LWL but differing hulls may be the same, but it may take considerably more wind to get the full keeler up to that speed than its more slippery brethren... and that matters, too.

Finally, you have posted above that modern hull shapes can't be hove to* and are unsuitable for off shore sailing in all sorts of ways. You may find it hard to believe, but the anchorages in distant from yachting center locations (say Marquesas or the Solomon Islands for instance) are full of such vessels... many with woefully inexperienced crews. Inexperienced, yet these boats have kept them safe for thousands of miles. I have no problem with your preference for the boats you like, but object to your blanket condemnation of all other types as being unseaworthy. I don't think that you have shown that to be true, and my own observations, both of our boats and voyages and the many, many others that we have encountered supports that belief.

Jim

* The first two fin/skeg boats that I've done ocean passages in (Yankee 30 and Palmer Johnson Standfast 36) both hove to quite nicely. In heavy winds (Gale force and above) using a backed storm jib or storm staysail and deeply reefed main. OUr current boat has too much windage forward to maintain a hove to attitude reliably, but will fore reach at ~ 2 knots with no headsail at all and the triple reefed main pulled well up to windward... a nice stable condition, but lacking the slick obtained when hove to properly. Has worked pretty well for us, but we've only done ~60,000 miles in her, and never at sea in more than strong gale conditions so far.

[Cpt Pat]

Jim Cate, I'm being honest here, not sarcastic when I admit that maybe I'm a wind snob. Like how the super rich don't understand how life can be sometimes difficult for the rest of us. "Just take a million dollars out of petty cash!" I have so much wind here that I almost never take out my first reef. And I'm perfectly happy on the days we don't have 15 knots of wind to be doing 4 knots in 8 knots of wind on my genoa. So I appreciate your point.


On the other hand, we get wicked swells. In fact, just outside my harbor on some days we have the biggest surfing waves in the world (Maverick's Beach). Those waves reflect right across the mouth of the harbor. And to seaward, sharp short period swells of 10 to 12 feet are very common. On average, you need to go to Alaska or Korea to find more challenging conditions in large sea areas in the northern Pacific. I hold the firm opinion based on my experience that a full keeled boat has more yaw stability than a boat with a "Brewer Bight", and a boat with a Brewer Bight has more yaw stability than a fin keeled boat. I'll defer to Robert Perry to explain the keel types in more detail: https://books.google.com/books?id=t5...20keel&f=false

A fin keeled boat depends on forward motion (lift) to create stability. A full keeled boat does too, but it has some significant residual (static) yaw stability even at a dead stop. You can test this: try to yaw a boat with a fin keel in its slip by grasping the bow rail. Next, find a full keeled boat of comparable size and weight and try to yaw it in its slip. I'm sure you'll find the fin keeled boat requires dramatically less force to yaw. That's what makes them such a joy to dock compared to a full keeled boat. Many fin keeled boats can be yawed in the length of the boat, pirouetting around the keel.

Both types of keels can be hove to. I haven't encountered yet a boat that won't heave to. You'll probably find the fin keeled boat makes continual "S" turns, the radius depending on several factors - but it will heave to. But which type is more stable in that configuration?

Let's try a thought experiment:

Imagine both types of boats, equal in all other respects except their keels, hove to side by side on a starboard tack in a storm. Both boats have a water speed of 2 knots. The seas are 30 feet with a 20 second period. The wind is 40 knots. At the wave crests, both boats are stable. But down in the troughs, there is very little wind because the upwind crest blankets (blocks) most of the wind. Down in the trough, the wind is 5 knots on deck, and variable in direction. Both boats come to a stop in turbulent wind and water.

Which boat, fin or full keeled, do you believe is more likely to have its bow yawed through the eye of the wind's direction at the wave crest? And if either boat is yawed 20 or more degrees past the eye of the wind (to starboard), what do you think will happen next upon rising out of the trough?

The helm is being held over hard to port (steering hard to starboard). The jib will no longer be taken aback and the boat will rapidly begin to make way. The main will swing from the port to starboard side. The helm will still be commanding a hard turn to starboard, the boat will heel radically as the wind comes up on the port beam, the boat will continue to turn rapidly to starboard (if it doesn't get knocked down) until the stern passes through the eye of the wind, the boom will then crash to the other side (assuming it or the rigging doesn't fail), and you'll eventually - if you are very lucky - find yourself back - hove to as you were before. This is why yaw stability is so critical to heaving to in a storm.

The title of this thread is: Hull Shapes and Behaviour in Heavy Seas. I'm trying to address what I've experienced. I am not trying to claim that, in general, there is any superiority between full and fin keels. I think that's a matter of individual taste. The opinions I have expressed here are not entirely original. They partly my own experience and partly derivative of experiments conducted, many are described in: "Seaworthiness - the Forgotten Factor."

I do personally prefer not to have to continually swing a wheel of tiller on a boat just to keep a course in swells, and it's my (however limited) experience that my arm gets tired much sooner on a fin keeled boat. But that's just my experience.

[JPA Cate]

Thinking about this thread has motivated me to talk about two issues that may not have occurred to Metal Boat: (1) advantages to cruising couples of having an easily driven boat for the smaller crew person and (2) the sequelae for having an easily driven boat in terms of quicker passage making.

(1) I am smaller and less strong than Jim. Having a boat now of the same tonnage as our previous 36 footer means that I could still sheet in the genoa hard on the wind when we got her. [Now, with damaged shoulders, I use the Milwaukee tool.] Loads, on the wind, and in stronger winds increase, so keeping to a lighter displacement easily driven fin keel and skeg rudder boat has made my life easier.

(2) Having good light air performance means saving fuel and engine hours, too. We sail when others motor. In coastal cruising, it means we can leave after the other guys and arrive with them and ahead of some of them. It means more sleep if needed. It means taking advantage of really gentle weather and still having pleasure in the actual sailing, rather than having to wait for 25 to 30 for the boat to get out of it own tracks. In strong trade winds, we did one 200 n.mi. 24 hr. run. It was boisterous. But even at 180 n.mi. days, you just reach your destination sooner than with 100-120 n. mi. days. Less time at the mercy of the mischievous weather gods, as it were.

I don't know about you other guys, but I guess it's a personality thing with me, I'd rather be making progress towards my destination than hove to, waiting. I'd also rather slowly reach back and forth in clear water, well off, before going into a new to me harbor, over heaving to for the wait for sun and good visibility, but that's another story.

Ann

[Capt.Tom]

Originally Posted by Thalas

Great looking boat, but yeah a handful for a single-hander.

Question for anyone who might know.. I understand that the radar is on the mizzen mast to not interfere with the jib, but doesn't the main mast then affect the radar signature in about a 10 degree arc right in front of the boat? Or is the outbound signal wide enough that it "wraps around" (sorry for the awful technical term) the main mast and can catch any reflection?

The radar will see the mast at a distance of how many feet ahead of the radar it is but not interfere with its operation elsewhere...
Try this to understand. .. assuming you have two good eyes....
Put your finger straight up in front of your face; about one inch from your nose. Does that block your view ? Even moving your finger 6 inches away, you can still see.
Millions of sailboats are set up this way, no need to worry, it works.

[Capt.Tom]

Originally Posted by Metal Boat

Hi All,


thanks for the replies. I realize this boat is large and will cost much, but I probably should have been more specific. I am an aircraft mechanic by trade and I plan to do all/most maintenance myself. I have taken a redundancy and will sell my home. I have a family of five and we plan to live aboard full time and the expenses of the boat would be replaced instead of the cost of maintaining a property on land. I am from Australia and the cost of a house and mortgage payments are insane here. I have two fit able teenage sons to help me sail and my wife and daughter will also be able to assist with other maintenance tasks. The boat is available for a ridiculously low price and even just to buy it and clean it up to sell I would make money. The idea is to build up to coastal cruising and then travel further afield. I appreciate all the sobering comments..

Wow, lots of kids. You might want to rethink that 5 kid thing.... lol.
I don't know your costs of owning a house in Australia. That would be interesting to hear about. I have an '86 Hunter 40 Legend. Expenses on that are about 20k a year. Costs on a boat increase logarithmically when you increase size. I can imagine a 65-foot yacht costing in the realm of $50,000 a year to maintain. In my estimate I am including dock space. I am not including taxes.

The downside of owning a boat is that you pour money in constantly and get nothing back except for pleasure. The upside of owning a house is, the house may increase in value over time where is the boat most likely will decrease overtime and constantly cost you more the longer you own it.

Don't get me wrong, I love to sail, but, make sure your whole family loves to sell all the time. Take them out on a two-week cruise and see how they still like it. If that boat is so cheap, there's got to be a reason. Find out what docking costs from vessel that size. You and your children we'll have to get out of bed, leave the boat and walk up the dock to use the bathroom and showers.

I could go on but I'm just trying to give you a Miner wake up call.

Captain Tom