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  #151  
Old 04-26-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

Quote:
Originally Posted by Jeff_H View Post
Brent you always seem to be worried about the things that can be engineered or designed around. Solving these issue does to take some additional care, but they are not all that hard to solve. If you are really worried about anchor rodes fouling the aft end of your bulb keel, but you want the sailing boostg that comes from a bulb, you simply run a cable from the very lower aft edge of the bulb to a spot on the hull well aft of the bulb to keel rodes out of there.

Engineering a skinny keel and its connection does require careful engineering, but the forces are well known, and it is a far easier engineering problem than designing something like a high rise building, which qualified professionals design routinely and which very rarely fail.



Your story about the 'Pipe Dream' is a good one. It shows how over time designers have learned to improve designs. Pipe Dream was optimized for a specific racing rule. Kinney had come into the profession when racing rules still restricted the use of separate rudders and so the design followed the 'traditional solution' of its day.

But around the time that 'Pipe dream' was being designed, designers began to experiment seriously with separating the rudder from the keel in one form or another. By the time that you owned your 'Pipe dream', it was pretty common knowledge that splitting the rudder from the trailing edge of the keel improved handling and lightened steering loads.

So what was radical in Kinney day, became a reasonably well accepted norm by the time you decided to modify your boat.

Even then designers were still learning how to design fin keel-spade rudder boats, and so these early fin keel boats had a mediocre reputation.

It hard to predict what radical idea will become the next norm. But your Angus Primrose story shows how an early experiment in boat design does not always tell the whole story. Angus Primrose's boat actually broached and pitch poled. He was known for designing boats which were lightly ballasted and which had a flaring bow with chine below the deck and a lot of buoyancy near the deck line. The version of the story that I read said that they punched that bow into to the back of a wave, and wiped out, getting rolled by the next wave. It was not about reducing beam, but about shaping his boats better.




But like many radical experiments, even the beamy boat world is making progress in dealing with its inherent deficiencies. When you look at the cruising versions of these beamy boats, they often have a lot of freeboard and high deck structures, which serve to destabilize the boat in the inverted position.

If you look at this moment curve for a Malo 40, which is not terribly radical adaptation of the beamier hull forms, two things seems obvious, first it has a positive stability to 130 degrees, and second it has virtually no negative stability when inverted to 180 degrees. I have seen a plot of a much beamier and more radical design which had positive stability to a bit over 140 degrees and achieved maximum righting moment at around 110 degrees. What I did not like about that plot was the very steep drop in stability between 110 degrees and 140 degrees which could catch a skipper unawares.



Jeff
I have run a flat bar off the botom of my keel to keep the rode from fouling it. It has been bent, something which wouldn't happen if the trailing edge of the keel were vertical. I make them all vertical now.
I dont see anything similar on the boats in the photos.
it is far easier to make a wider longer keel stronger, including it's support inside the hull, than a skinny keel. However you engineer the skinny keel, it wont be as strong.

Amazing how long it took the 'Experts" , with all their qualifications and decades of experience, to figure out what I did, with almost zero sailing experience. That shows the power of dogma.

Angus Primrose's boat capsized and stayed that way for a long time, something that didn't happen with narower boats . He calculated that even a small reduction in beam would give a huge improvement in ultimate stability. How he got capsized has nothing to do with that conclusion.

The Malo has negative stability either side of 180 dergees . Roll either side of 180 and you are in negative stability country. Many of the traditional boats Bob mentioned have positive stability to over 170 degees.
A high sheer gives positive buoyancy in the high ends, something calculations based on a midship sectiion doesn't take into account.
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Last edited by Brent Swain; 04-26-2013 at 08:12 PM.
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  #152  
Old 04-26-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

Gosh, "positive stability to over 170 degrees" that's impressive but I've never seen it one one of my conservative designs. Of course you have no righting moment at 180 degrees. That's what this is all about. Any upright boat right,side up or inverted has no stability. You have to heel one way or the other to get a RA. If the VCG and the CB are lined up there is no "arm" ( Righting Arm)And I don't do any stability calculations based "on a midship section" I use the whole boat. I do not use deck structure. The Queen's Birthday study showed that pilot houses did not help. Theoretically they should but they didn't Go figure. I have never used deck structure so in order to continue the apples to apples comparison of my designs I will not use deck structures. If there is foam in the mast do I use that too? No.

I am in total agreement with Brent about the weight of cruising gear. The typical cruiser does not want to saw the handle off his toothbrush to save weight. He wants tankage, spare parts, tools, watermakers, gen sets, copious amounts of ground tackle including lots of chain and a full sized guitar. This stuff takes volume if it is to be stowed and leave enough room for humans to live in the left over volume. This is not theory. To do this with any style and grace takes a boat with some displacement. No,,,it won't be a rocket and go planing off into the sunset. But you know what? Most cruisers don't have the skills or the eneregy to push a boat to planing speeds for days on end. They are comfortabvle and safe, SAFE, pushing the boat to hull speed and relaxing. Why design for a level of performance that is beyond your sailing ability or inclination to maintain. Better to design for good all round performance with a good safety factor for your structure and your stability while providing a comfortable ride and a comfortable home.

If you want to reach for the upper limits of performance you can decide for yourself what you want to leave behind. But when you arrive exhausted at the next destination and anchor next to a big, GUNBOAT catamaran you may have to rethink your idea of exactly what is fast. Because compared to that GUNBOAT the POGO is a PIGO. To go truly fast you need more than one hull. Now do we want to get into that argument?
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Re: Bob Perry's take on Wolfenzee's dream boat

I watched the final of the Volvo a couple of years back. They were interviewing the crews and to a man they said "Glad to be off it and never again". Even Magnus said that.

Riding a roller coaster is fun too but it's a lousy form of daily transportation.
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Re: Bob Perry's take on Wolfenzee's dream boat

JonB:
That is profound.
I think in my own inadequate way that is what I have been trying to say.
Yes, it can be done.
Do I want to do it?
No thanks.

Beautiful end to one component of this discussion.
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  #155  
Old 04-27-2013
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Re: Bob Perry's take on Wolfenzee's dream boat

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Originally Posted by bobperry View Post
I am in total agreement with Brent about the weight of cruising gear. The typical cruiser does not want to saw the handle off his toothbrush to save weight. He wants tankage, spare parts, tools, watermakers, gen sets, copious amounts of ground tackle including lots of chain and a full sized guitar. This stuff takes volume if it is to be stowed and leave enough room for humans to live in the left over volume. This is not theory. To do this with any style and grace takes a boat with some displacement. No,,,it won't be a rocket and go planing off into the sunset.
Yes of course. There is the typical cruiser, that are the majority and there are the cruisers that like to cruise in fast boats. They exist and even if they are not main market they are in enough number to justify shipyards to build production boats for them. Their number is not insignificant and they are growing in numbers as the number of production boats offered to them.

This is a also reality.

Quote:
Originally Posted by bobperry View Post

But you know what? Most cruisers don't have the skills or the eneregy to push a boat to planing speeds for days on end. They are comfortabvle and safe, SAFE, pushing the boat to hull speed and relaxing. Why design for a level of performance that is beyond your sailing ability or inclination to maintain. Better to design for good all round performance with a good safety factor for your structure and your stability while providing a comfortable ride and a comfortable home.
You would be right if those boats offered on the market for fast voyaging were based on crewed offshore (narrower) faster racers, boats that demand a crew to be sailed fast. That is the reason why cruising and voyage fast boats are increasingly based on solo racers.

Solo racers are designed to go fast and planning on AUTOPILOT. Take a look at the race movies, most of the time the boats go on autopilot even when the skipper is not sleeping and they are racing not cruising.

Yes these boats demand a sailor with some experience but they are very easy to exploit and to sail. Do you think that a difficult boat to sail could be offered as a charter boat for cruising to inexperienced sailors?

Quote:
Originally Posted by bobperry View Post
If you want to reach for the upper limits of performance you can decide for yourself what you want to leave behind. But when you arrive exhausted at the next destination and anchor next to a big, GUNBOAT catamaran you may have to rethink your idea of exactly what is fast. Because compared to that GUNBOAT the POGO is a PIGO. To go truly fast you need more than one hull. Now do we want to get into that argument?
Of course a big fast Multihull will be faster and there are more spartan cruising multihulls faster than the Gunboat 66 but do you know how much a Gunboat 66 cost? How many Pogo 50 you could buy with that money? Certainly you know that among 40ft cruiser multihulls the vast majority are not specially fast boats.

They are built for interior space not speed. Yes it is possible to have 40ft cruising multihulls faster than the Pogo 12.50 and there are some few on the market but then the interior space starts to be very small and going really fast on those boats require much more attention than on a Pogo. They can be capsized by the wind and sailing them fast is for very experienced sailors...and even so it requires a crew. They are also necessarily much more expensive.

Of course I am not talking about the Gunboat 66, I am talking about 40ft multihulls. That is why there is not a 40ft Gunboat and why the brands that propose really fast voyage multihulls prefer to offer them over or near 50ft. Smaller voyage cats are normally slower and heavier to allow less nervous and safer boats, taking into account its dimension.

Regarding those type of hulls (solo racers) they are fast on the trade winds and price by price they are by far the ones that offer the best performance in what regards fast cruising with a short crew and by a big margin.

Even in what regards pure performance last year on the ARC on the racing division we saw a boat similar to the racing Pogo 40ft with a crew of 4 or 5 beat a recent Swan 80 with a full (and huge crew). We saw a cruising Pogo 50 sailed by the owner the builder and some friends (not young guys) beat all cats and arrive among the first racing yachts, much bigger yachts with full racing crews. We saw also a cruising Pogo 12.50 with a small crew to arrive among the first surrounded by much bigger yachts.

Yes those boats are not for all, not even for the majority but they offer for the ones that enjoy fast sailing and cruising, the possibility to do that on a safe, fast and affordable boat.

You designed great cruising boats and I particularly like the Saga series but Pogos are pointing to a different market and different sailors, the ones that want, at half the price (or less), to enjoy a much more fast but spartan kind of cruising and voyaging. The success of the boat in what regards sales and that we can measure also on the number of boats doing the ARC shows that this is a valid concept, a concept that satisfies an existent part of the market in what regards voyaging and cruising. That market and the number of sails that wants that kind of boat is increasing.

I don't believe this has nothing to do with safety but with a more spartan comfort versus speed.

The Pogo 12.50 is a limit case (and yet it is a sales success) but there are also other very successful, fast and easy to sail boats based on the same type of hulls, among them the RM and the Cigale.

The efficiency of that kind of hulls in what regards safe and easy sailing is so evident that it is the main influence in what regards modern cruising boats and the reason is to provide very stable and easy to sail sailboats. All the NAs that are working for the big mass production sailboat companies reflects those influence in their sailboats, ones more than others but even German brands, that received that influence later are now deep in it. You have only to look to the more recent Hanse or Bavaria.

Has I have said, for the pleasure of sailing and has an all-round performance on a sailboat I prefer not so beamy boats and boats with a better performance upwind but I am not the typical cruiser.

Yes, I said that I have to work, and I have, but I could not resist: Pingo?

Regards

Paulo
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Last edited by PCP; 04-27-2013 at 01:47 PM.
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Re: Bob Perry's take on Wolfenzee's dream boat

Considering how much people put into boats, not only financially but of themselves, it is surprising the amount of dissatisfaction in what they have, for a number of reasons [1] people only have what they could afford and will settle for it till they can do better, [2] a marketing industry and/or culture that leads people to believe they NEED what is beyond their grasp (there is always something better) [3] Just an overall not being able to be happy with what you've got. I am extremely happy with my boat, this thread is a spin-off of a question I posed to Bob asking how the keel/rudder configuration could be done differently on the hull I have. What has resulted has actually been an incredibly informative thread on hull design which is also starting in on rig design. I would like to find an accurate # for my angle of vanishing stability (the only calculators I have tried put it at between 165degrees and 183degrees) I can give more specs to anyone who can figure that.

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Re: Bob Perry's take on Wolfenzee's dream boat

"183 degrees"? Now there's a first.

Wolf:
There is no quick and dirty way of getting a reliable number.
Find a kid with a yacht design program and the time to input your hull into his computer. That could take half a day if he knows what he is doing. Then you need a weight study to determine your VCG. Or you can do this by inclinging your boat at the dock. But you will need an accurate VCG if you want accurate stability numbers. Either way it's going to take some work to find an accurate limit of positive stability.

Is it just me or do any of the rest of you get the feeling that Paulo is a salesman for Pogo? Or is this common knowledge here?
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Re: Bob Perry's take on Wolfenzee's dream boat

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Originally Posted by PCP View Post
Certainly you know that among 40ft cruiser multihulls the vast majority are not specially fast boats.

They are built for interior space not speed. Yes it is possible to have 40ft cruising multihulls faster than the Pogo 12.50 and there are some few on the market but then the interior space starts to be very small and going really fast on those boats require much more attention than on a Pogo. They can be capsized by the wind and sailing them fast is for very experienced sailors...and even so it requires a crew. They are also necessarily much more expensive.

Of course I am not talking about the Gunboat 66, I am talking about 40ft multihulls. That is why there is not a 40ft Gunboat and why the brands that propose really fast voyage multihulls prefer to offer them over or near 50ft. Smaller voyage cats are normally slower and heavier to allow less nervous and safer boats, taking into account its dimension. Paulo
A couple of years ago we chartered a big mono in the BVI. The local head of ops for the charter company was French and had sailed across on his own mono - a nice older boat. When he was checking us out on the boat one of our group asked him about the big cats that comprised most of their and the other fleets.

With a classic Gallic sneer he muttered "Motorhomes".

The simple fact that some of them can be purchased with or without rigs tells the story in my book.
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Re: Bob Perry's take on Wolfenzee's dream boat

Quote:
Originally Posted by bobperry View Post
...

Is it just me or do any of the rest of you get the feeling that Paulo is a salesman for Pogo? Or is this common knowledge here?
Do you know any production boat that have you on a waiting list for more than a year on this times where all are selling less? If not, now you know one, the Pogo.

They don't go to boat shows (not even the Paris boat show) they don't make publicity, they do not make discounts and make the boat as inexpensive as they can, carbon mast and all. They don't need my publicity and I said already that the boat does not make my style.

That does not mean that I can't see the obvious: The boats are a huge success and there are a lot of sailors buying the 12.50 and the 10.50 as a fast cruiser and voyage boat: the boat makes the style of many.

They are clearly a great design and a great boat, one of those that will enter sailboat history as pioneers, like the Vailant, 40 years ago.

I bet that the new baby (also from Finot/Conq) that just hit the water some days ago will have an even bigger waiting list

I am talking about the Pogo 30:











Regards

Paulo
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Last edited by PCP; 04-27-2013 at 02:25 PM.
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Re: Bob Perry's take on Wolfenzee's dream boat

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Originally Posted by bobperry View Post
"183 degrees"? Now there's a first.

Wolf:
There is no quick and dirty way of getting a reliable number.
Find a kid with a yacht design program and the time to input your hull into his computer. That could take half a day if he knows what he is doing. Then you need a weight study to determine your VCG. Or you can do this by inclinging your boat at the dock. But you will need an accurate VCG if you want accurate stability numbers. Either way it's going to take some work to find an accurate limit of positive stability.

Is it just me or do any of the rest of you get the feeling that Paulo is a salesman for Pogo? Or is this common knowledge here?
I guess if 183 degrees actually were an accurate AVS that would mean that once you get to 183degrees you would actually be at 177degrees the other way so the boat would never reach a point of vanishing stability, wouldn't that be nice =)
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