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Old 05-13-2012
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Re: Pogo 12.50 - JPK 38

Quote:
Originally Posted by EricKLYC View Post
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The problem of those designs has to do with going fast upwind with waves

The bigger the waves the worse is the performanceThat has to do with wave drag that is increasing exponentially in that boat when crashing through wavesmaking it lose more power than the one the boat can generate over other type of boatsOf course the big power needed to go on those conditions and the big wave drag make also the boat very uncomfortable in that particular case. 
Our very first experiences in strong wind-against-tide conditions tend to confirm this. It needs quite hard work at the helm to keep the boat comfortable.
That type of boats has a big beam but has I have showed with some designs made by Finot the "footprint" of the boat, the wet area, is not bigger than on a narrow boat when the boat is sailing. It has even advantages because as it is a diagonal one it has a bigger LWL. The wet area has to do with weight and surface of keel and rudder and the Pogo is very well design in what concerns that and not only that

The problems going upwind with waves has to do with this:

When the boat passes a wave, the wet area increases as the wave passes through the hull, the bigger the wave more the hull boat will be "surrounded" by the wave and in this case the drag is not only that little footprint, but most of the hull surface and here that big beam and big overall hull surface represents a huge disadvantage regarding a narrow boat.

The narrow one will also be "surrounded" by the wave but because its hull surface is a lot smaller the wave drag will be a lot smaller.

Narrow boats, even with a big draft and lots of ballast will not manage to have the RM (Power) of an open type boat. What happens is that till a certain size of wave and sea condition the Open type of boat is capable of compensate its bigger wave draft with sheer power at the cost of a bigger pounding.

After a given sea condition and size and type of wave even all that extra power will not be able to compensate the increased wave drag and the narrow boat will go away with a much more softer ride, wasting less energy in its movement because the sea and waves offers much less resistance to its movement.

Of course that narrow boat will be much worse downwind because downwind you don't get wave drag and the flat and bigger hull makes less pressure over the water (not so deep in the water for the same weight) and helps the boat to surf sooner. The control of the boat is also better with less roll motion.

Racing boats or fast boats chose different types of compromises between those two contradictory requirements in what regards hull shape associated with the required ballast to each shape of hull. That has implications on the final weight of the boat and that has also to do with the boat performance.


Quote:
Originally Posted by EricKLYC View Post

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I have saw that 40 class racersthat are a much more powerful boat than your Pogohave not good performances when they got nasty weather upwindOn the last "around NZ race really nasty weather lead to the abandon of the Pogo 40 class racer that was having a bad performance, beaten even by narrow old boats, but that were really very bad conditions. Other boats with the same type of design also experienced difficulties and an overall bad performance. The guys on the Pogo were good, they are one of the main racing teams on that side of the world and the only one that races (for years) with a 40class boat on ocean races. It is the same team that had made several Sydney-Hobart with that boat. 
These kinds of boats perform very differently in different kinds of races. No wonder, they are after all “open” designs resulting from so called “box rules”. But I still cannot explain why the 8.50’s performed so badly in the Transquadra and 10.50’s didn’t even compete, while the 6.50’s keep on killing everybody in the Mini Transat, since both are mainly downwind races.
The racing Pogos are excellent boats that performs well racing. The Pogos on the mini category among the production boats were always winners and it is obvious that in what regards 6.5m boats that is the shape of hull that performs better solo on downwind races. I have to look better to see if they have some limitation regarding ballast, but I think we can assume that.

The hull shape that performs better is not a fixed equation it changes with length, becoming proportionality less beamy. It could have to do with that associated with the ballast differences a narrower hull will require for a competitive power (a bigger ballast ratio).

The answer is I don't know. First the hard facts and then an hypothesis to explain those facts. I am afraid here I am still looking and collecting the hard facts:

Even if that raises suspicion, a Pogo 10.50 never made the Transquadra and even if it had made I would only take conclusions on several boats, preferably sailed by top teams.

Last year an Opium 39 raced with not bad results, even was the first to arrive on Madeira among the ones that come from Barcelona (smaller number) but when they all raced together to Martinique the boat (or the crew) was not a match for the faster boats and smaller boats like the A31, JPK 10.10 and 9.6, Sunfast 32 and A35 that was the first to arrive.

Of course this has to do with short crew (solo or duo) good amateur sailing, on a downwind transat and I really need to have more boats of that type racing to reach a conclusion even if the fact that the Pogo 8.5 is not a contender on that race is an hard evidence.

Regards

Paulo

Last edited by PCP; 05-13-2012 at 07:39 AM.
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