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Elie · 23-02-2017, 06:00

Quote:

Originally Posted by buzzstar

You have added nothing to change my mind. But its not what either one of us think. Aside from the fact that I truly doubt that you (or at least your boat under sail) moves fast enough to out run the waves, or even equal them (no broaching while running/surfing wing & wing), and I do not think you want to simply slide sown the backside every time -or do you? I'd love to hear from an actual naval architect. Any around and willing to comment.

Maybe one will engage in a writing moment. Anyway, I am pooped for now.

This has nothing to do with froward speed of the boat, but to the ability of the stern to rise fast enough to avoid being swamped. The idea of wide boyant stern section is to give volume to rise to the waves. This is aided by relativly light displacement but more importantly by the low moments of inertia created by centering the displacement in the middle of the hull, not in the ends. Strangely enough The wide stern, light boats of modern design track pretty well in runing, even in big waves. I never broached or lost control while surfing large swells. Naval architecture has made huge progress since the '70's mainly because of the reserch and developpement of fast racing hulls(imoca 60 for exemple) and that progress has percolated to the production of cruising boats by reputables architects and major boats builders.

buzzstar · 23-02-2017, 13:04

Quote:

Originally Posted by Jim Cate

For RBK and others:

I quote Bob Perry (perhaps you have heard of him?)...

"Years later, with the IOR making people angry, a reactionary movement sprung up in the cruising community. Heavy, slow, salty, Colin Archer type double enders propelled by the Westsail movement were the accepted boats for offshore cruising. For some reason double enders were seen as safer offshore boats. This probably came from the Colin Archer lifeboat tradition. But there were all sorts of strange theories as to why the double ender was the best hull form for offshore. “The stern parts the following seas.” I call this the “Moses effect”. Maybe the stern parts the following sea because there is not enough buoyancy aft for the stern to rise to the following sea. “There is more reserve buoyancy aft.” This is certainly not true in a boat like a Westsail with almost no stern overhang at all. There is almost no buoyancy aft. Ok, fine, what about a canoe stern? Yes, a canoe stern can give you far more buoyancy aft than a Westsail type stern but a nice broad transom stern with some overhang will have far more buoyancy aft than a canoe stern. “In a double ender the heeled waterlines are more balanced.” Yes, in most cases this is true and it’s a good thing but I’m not certain it makes a boat more seaworthy or sea kindly. It does make some boats easier to balance over a wide range of heel angles.
Then why did I make the Valiant 40 a double ender? Marketing! It was just assumed that offshore cruising boats had to be double enders and rather than buck that trend I decided to go with it and at the same time add my own twist to the shape to try and improve the performance of the double ender."

So, you see, there are some folks who agree with my statements above.

Of course, he could be wrong and the good feelings folks right...

Jim

Some. Not all. You might have noticed a change in your terminology from what
you previously said. "Reserve buoyancy" has become "buoyancy." Is there a difference? I do not know, but I will look it up. I recall a review of a canoe stern design some years back, what vessel I do not recall, where the reviewer was very impressed with the extra reserve buoyancy the design provided over both traditional transom designs and typical double enders. I will also attempt to determine how a vessel with a cut out transom might have more reserve buoyancy than one that has more space providing buoyancy but essentially the same mass. Moreover, have have in mind one more or less double ender design which I think defies the claims you and Mr. Perry appear to be making even if the previously mentioned terms are the same. I will attempt to find the information later today and respond -either way. One very important point, both you and, even more obviously, Mr. Perry have knowledge that far exceeds mine, but it is not automatically and always correct by definition. Lot's to do, and so little time. I'd rather sail, but cannot right now so maybe it will keep me out of trouble.

**Jim Cate** · 23-02-2017, 14:28

Quote:

Originally Posted by buzzstar

Some. Not all. You might have noticed a change in your terminology from what
you previously said. "Reserve buoyancy" has become "buoyancy." Is there a difference? I do not know, but I will look it up. I recall a review of a canoe stern design some years back, what vessel I do not recall, where the reviewer was very impressed with the extra reserve buoyancy the design provided over both traditional transom designs and typical double enders. I will also attempt to determine how a vessel with a cut out transom might have more reserve buoyancy than one that has more space providing buoyancy but essentially the same mass. Moreover, have have in mind one more or less double ender design which I think defies the claims you and Mr. Perry appear to be making even if the previously mentioned terms are the same. I will attempt to find the information later today and respond -either way. One very important point, both you and, even more obviously, Mr. Perry have knowledge that far exceeds mine, but it is not automatically and always correct by definition. Lot's to do, and so little time. I'd rather sail, but cannot right now so maybe it will keep me out of trouble.

Ahhh, Brian, you just won't be satisfied...

Quote:

I'd love to hear from an actual naval architect. Any around and willing to comment.

You asked for comments by an actual naval architect. I gave you just such comments.

Now you say he isn't "automatically and always correct", despite being one of the most successful practitioners in the biz. He is also one of the few NAs who are willing to express themselves truthfully in the face of "market pressures" which encourage parroting the company line.

I give up.

You are entitled to believe whatever you wish to believe. I will continue to believe what logic, simple physics, personal experience and the council of experts like Perry have shown me.

And please, all of you: we are discussing factors of seaworthyness, not aesthetics. I too think that some canoe stern vessels are very handsome, and that some modern, "fat-assed" vessels are less so, but that is not the subject of concern here.

Jim

buzzstar · 23-02-2017, 15:35

Quote:

Originally Posted by Jim Cate

Ahhh, Brian, you just won't be satisfied...

I give up.

Jim

Resignation accepted. [From the issue, not the forum] That settled, many, most, some would agree that even the experts are not perfect. Art, science, and engineering advance and develop in various ways, with questions being among them. I do not know Mr. Perry, but I would be surprised if he feels he knows it all. In any event your surrender saves me some research, but I do have another unrelated matter to work on to occupy my time. Now get some rest, you seem frustrated. Thanks.

buzzstar · 23-02-2017, 15:44

I just thought of something very much related, and definitely not from a trained expert, but a self taught one. If I recall (this is not research but simple memory) Fatty Goodlander, in one of his books, talks about cockpits and impliedly flotation in a rather different manner. Not because the stern fails to rise fast enough, but because a wave top breaks off and falls onto the vessel's stern area. I do not remember if this is a matter for center cockpits, small cockpits, or open transoms, but it is akin to being pooped, but somewhat different. I'll be thinking 'bout it so be prepared.

zboss · 23-02-2017, 15:47

The only time we have gotten a lot of water in our Cabo Rico cockpit, it was from a large wave rolling over the starboard forward quarter and down our side deck. I assume mostly because of our low freeboard and the unusually wind against current we were fighting.

rbk · 23-02-2017, 19:08

Yes very aware of Bob and what's he's done, read his book and swapped correspondence a few times online as many have. Bob also makes it abundantly clear that he didn't design nor does he try and take credit for designing the 'canoe stern' and that he borrowed a lot of his design features from the likes of Archer, Atkins, Neilsen, Herrschoff, Garden and a Crealock and worked his boat speed magic on them. Bob also never cruised having designed some of the most prolific cruising boats, he is and always was a racer. Here is some more from that quote you provided:

"They said why don’t you try a test article to see if we can work together. I decided to write an article on double enders. I decided to interview a few other designers for the article and get their thoughts on double enders. I asked each one, “Why is a double ender better?” They all said it wasn’t better than a transom sterned boat. All except Bill Crealock who said the double ender was better but when I asked why he couldn’t or wouldn’t tell me. I also asked these designers what kind of boats they personally sailed. All but one sailed a double
enders."

So all these designers keep designing and building them and owning them, people keep buying them and cruising them around the world so they are all wrong and you are right and I've already wasted too much energy on this.
The lack of buoyancy helps to keep the stern from going vertical on large waves causing racing/surfing which induces broaching as your bow slows and stern gains speed. Being slow to rise helps to keep the vessel closer to hull speed. More speed equals more potential energy, the closer you can stay to hull speed the better, which is why most cruisers carry a series drogue, wraps or sea anchor. As a whitewater kayaker of over 20 years I can tell you surfing waves in a kayak with a square transom would end quite badly very quickly which is why they don't make them; with the exception of transom canoes which are used for motoring :wink

Bob

oregonian · 23-02-2017, 19:28

Hello Octavious. Your interesting questions have
sparked some debate, though off topic. It has been suggested that the boats you have mentioned lack sufficient reserve buoyancy. As a delivery skipper with plenty of experience on the matter, I can assure you that every boat you suggested has more than enough reserve buoyancy. Yes, some have more than others but there is no problem with any of them. What I am witnessing on this thread is, once again, our “experts” saying some pretty ridiculous things.
Jim Cate says “So many of the “heavy long keel, double ended crab crusher” enthusiasts fail to understand that the slow and stately motion at sea, they love, is matched to being easily pooped when the vessel fails to rise rapidly to a steep and high sea, overtaking from the stern.” “Easily pooped”? Jeezas!
I just called a few friends to get some data. I have 90,000nm on a Westsail 32. I have delivered 12 others. My friends and I totaled nearly 200,000nm on Westsails and Alajuelas. (Alajuelas have a skinnier stern than a Westsail and a lower freeboard) Together we report 3 occasions where water has come over the stern. Other than a brief inconvenience, there has never been any concern for the safety of the boat or passengers. At the very least, Jim Cates comments are a gross exaggeration. Personally, I believe them to be something else.
UNCIVILIZED suggests that the boats you mentioned won’t sail well in under 10k of wind. I counter that perhaps UNCIVILIZED should practice sailing in light winds. He frequently suggests that you “look at PHRF ratings”. Does he need to be reminded that the PHRF ratings are for EMPTY boats and that a boat may easily not sail within 60 seconds of it’s rating when loaded for cruising, which is what the OP will be doing.
On another thread there is the topic of “Why this forum is changing”. May I suggest that one reason is because the frequently posting “Experts” are so frequently espousing very poor information. Many who recognize this, simply aren’t interested in participating anymore.
Thank you, and good luck Octavious with your boat search. And don’t hesitate to look at something that may have been designed a hundred years ago. The Naval Architects of the past fully understood how much reserve buoyancy was enough.

rbk · 23-02-2017, 19:40

Also when was it ever concluded that the cockpits were designed to be pooped as a function of design? They are designed to shed the water or take on limited amounts if and when it does happen. Personally I'd feel better with a shallow quick draining cockpit versus a deep waist high enclosed well and two one inch scupper for drainage, take in very little and get rid of it quick, that's the design feature.

**Jim Cate** · 23-02-2017, 19:49

Quote:

The lack of buoyancy helps to keep the stern from going vertical on large waves causing racing/surfing which induces broaching as your bow slows and stern gains speed. Being slow to rise helps to keep the vessel closer to hull speed. More speed equals more potential energy, the closer you can stay to hull speed the better, which is why most cruisers carry a series drogue, wraps or sea anchor. As a whitewater kayaker of over 20 years I can tell you surfing waves in a kayak with a square transom would end quite badly very quickly which is why they don't make them; with the exception of transom canoes which are used for motoring :wink

Bob, the above is just incomprehensible to me. Vertical stern? Bow going slower, stern going faster? Using a drogue to keep a boat near hull speed, not to slow it way down? A slow rising stern helps keep a boat near hull speed?

I will bow to your 20 years kayaking experience in river white water, for I know nothing about such craft, other than that they are somewhat different than a ballasted sailing yacht.

But I have been sailing in the ocean for over 40 years, and in a variety of boats in many different seas and for a lot of miles and my experience and observa varies from what you describe. You don't want to believe me, or the other folks who have noted similar experiences, or the specific statement Perry makes relative to the buoyancy of double ended hull shapes... OK, so be it.

My initial posts here reflected my understanding that narrow sterns with little or no overhang were more prone to pooping than more buoyant shapes. I am completely convinced that this is so, for the reasons that I have stated, and that Perry has also stated.

So, as I said to Brian, I give up and leave the thread to you.

Jim

UNCIVILIZED · 23-02-2017, 20:03

Quote:

Originally Posted by oregonian

I
UNCIVILIZED suggests that the boats you mentioned won’t sail well in under 10k of wind. I counter that perhaps UNCIVILIZED should practice sailing in light winds. He frequently suggests that you “look at PHRF ratings”. Does he need to be reminded that the PHRF ratings are for EMPTY boats and that a boat may easily not sail within 60 seconds of it’s rating when loaded for cruising, which is what the OP will be doing.

You might want to eat some salad & get your s**t together prior to maligning my sailing experience. Something about which you know naught. But to clarify, probably 60-70% of my sailing experience has occurred in light air. Over the span of several decades, & many tens of thousands of sea miles. A lifestyle period which garnered me enough racing trophies to fill up a garage.

As to PHRF ratings, they're an easy to use yardstick by wich someone can compare the relative speeds of various boats. It's far from a perfect rating system. But it's been around since what, the 80's. Which, since that time, at least 3, if not more, major rating systems have become extinct.
So other than compring the polars of various boats to one another, it's the best tool at hand for speed comparisons. Period.

And yes, obviously when a boat's heavily laden, it'll be slower than it's rating. But so will every other boat when laden. So that if 2 boats to be compared are equally loaded, then it's probable that they'll perform about the same when sailing against one another in accordance with their PHRF ratings. This, unless there's a huge size disparity between them, where one's a little boat loaded to the gunwales, & the other is a 50'er where the owner really paid attention to weight when loading her out for cruising.
AKA common sense applieslapply commen sense here.

If you care to back up some of what you're saying with facts, I'll listen. But until then...

So let me know when you've found, & are ready to post polers on the performance of the designs in question. Most of which can't hit hull speed until it's blowing in excess of 20kts.

rbk · 23-02-2017, 20:36

Quote:

Originally Posted by Jim Cate

Bob, the above is just incomprehensible to me. Vertical stern? Bow going slower, stern going faster? Using a drogue to keep a boat near hull speed, not to slow it way down? A slow rising stern helps keep a boat near hull speed?

I will bow to your 20 years kayaking experience in river white water, for I know nothing about such craft, other than that they are somewhat different than a ballasted sailing yacht.

But I have been sailing in the ocean for over 40 years, and in a variety of boats in many different seas and for a lot of miles and my experience and observa varies from what you describe. You don't want to believe me, or the other folks who have noted similar experiences, or the specific statement Perry makes relative to the buoyancy of double ended hull shapes... OK, so be it.

My initial posts here reflected my understanding that narrow sterns with little or no overhang were more prone to pooping than more buoyant shapes. I am completely convinced that this is so, for the reasons that I have stated, and that Perry has also stated.

So, as I said to Brian, I give up and leave the thread to you.

Jim

Jim, break down a broach. What happens...bow digs in and starts to bite and slows, stern rises and keeps speed, stern catches up to bow, by this time you are full broach ready to be rolled, this is called window shading in the paddling world (think roller blinds) as you're rolled in the trough of the wave. Yes paddling is different in that kayaks as flat bottomed and surf much better, until you catch an edge (chine) and your bow slows (or stern if you're surfing backwards) causing the stern to abruptly catch up to the bow and voila you broach. A good thing to point out is is is very difficult to surf swell, you really need the top to start breaking in order to make it easier not that it can't be done but you require additional power (engine or sail). Big flat fat teansoms are designed to reduce squat in order to sail faster, in steep breaking waves you rise higher and gain more speed and controlling the helm becomes a chore. These are the conditions we sail in regularly and the reason for our choice. Not everyone sails these conditions and that's why there's more than one type of boat and everyone is entitled to his or her opinion.

GWB · 24-02-2017, 10:20

Can you take a picture of your garage full of trophies?

I'm skeptical that someone who thinks heavy boats can't sail in light air, knows much about sailing at all.

Quote:

Originally Posted by UNCIVILIZED

You might want to eat some salad & get your s**t together prior to maligning my sailing experience. Something about which you know naught. But to clarify, probably 60-70% of my sailing experience has occurred in light air. Over the span of several decades, & many tens of thousands of sea miles. A lifestyle period which garnered me enough racing trophies to fill up a garage.

As to PHRF ratings, they're an easy to use yardstick by wich someone can compare the relative speeds of various boats. It's far from a perfect rating system. But it's been around since what, the 80's. Which, since that time, at least 3, if not more, major rating systems have become extinct.
So other than compring the polars of various boats to one another, it's the best tool at hand for speed comparisons. Period.

And yes, obviously when a boat's heavily laden, it'll be slower than it's rating. But so will every other boat when laden. So that if 2 boats to be compared are equally loaded, then it's probable that they'll perform about the same when sailing against one another in accordance with their PHRF ratings. This, unless there's a huge size disparity between them, where one's a little boat loaded to the gunwales, & the other is a 50'er where the owner really paid attention to weight when loading her out for cruising.
AKA common sense applieslapply commen sense here.

If you care to back up some of what you're saying with facts, I'll listen. But until then...

So let me know when you've found, & are ready to post polers on the performance of the designs in question. Most of which can't hit hull speed until it's blowing in excess of 20kts.