Contrary to what is usual I am not posting about this boat because I find it interesting but because I find it impossibly dangerous for doing what the class mentor, the same that created the Golden Globe Race, has meant it for: a Globe Race disputed on this sailboat, to take place in 2024.
The profile design looks nice, kind of an old mini with a bigger freeboard, big protection over the entry hatch and an old wind pilot, the general aspect is solid, kind of look of a TT machine, a boat able to sail anywhere and the truth is that it had raised a huge interest and has been publicized on some of the main yacht magazines, including the biggest of them all, Yacht.de.
The boat is to be built at home by the "racers" using plywood, the plans are from the Polish yacht designer Janusz Maderski and cost only 300€. The complete boat would cost around 6000€ for a basic version, and 20 000€ for what is described as a fully equipped boat suited for bluewater racing.
Probably you are thinking that at least two mini-racers, that are only 0.8 m shorter in length, have already circumnavigated and that was not that dangerous because both had made it, although both had broken their masts in capsizing situations, having one of them the mast replaced and the other jury-rigged.
Except that a mini-racer stability has nothing to do with the one of this boat. Stability on a sailboat comes from hull form stability, which has to do with beam, with lowering the boat CG, that has to do with B/D, with draft and type of keel and comes from displacement.
It has also a great deal to do with displacement because RM is obtained multiplying displacement by the lever (GZ) that is obtained measuring at each point of heel the horizontal distance between the center of gravity (CG) and the center of buoyancy (CB). This video helps to understand how the lever (GZ) varies with heel and if you want to know more about this there are two links below, one to the site of the video, other to an inexpensive book that explains the basics of stability on a boat.
http://sailskills.co.uk/Stability/stability_site_map.html
https://books.google.pt/books?id=Rtg6T9kMZkUC&printsec=frontcover&hl=pt-PT#v=onepage&q&f=false
That is why generally a bigger and heavier sailboat has more overall stability than a much lighter sailboat and why some very heavy small sailboats can have better stability than what their size leaves to suppose, but of course, to sail well a sailboat needs to be light, more even if it is a race boat and therefore having a heavy sailboat is not a good idea in what regards sail performance.
That's why the small 6.50class mini, having to be light to be fast, maximize all the other ways to increase RM without adding weight, increasing the lever (GZ), namely through beam and through lowering the CG. That's why the 6.50 mini is so incredibly beamy.
The center of gravity is lowered on the 6.50 mini through a big B/D, an efficient lead torpedo keel and a big draft (2.0 meters on protos, 1,6 on Series). The lowering of the CG increases not only overall positive stability but even more AVS and safety stability but also reduces greatly negative stability, making the proportion between the two much bigger.
The Mini Protos needs less ballast for about the same needed RM (to pass the safety stability tests) due to a bigger 2.0 meter draft. The 1.60m draft of the Production boats makes them more adequate to compare its stability with the one of the 5.80 class, which has 20cm less draft, but a not very different keel with a lead torpedo.
Let's then compare a production Mini 6.50Class dimensions, for instance, a Pogo 3, with the ones of the new 5.80class:Regarding hull form stability the 5.80 is not only 0.8 m shorter (5.70 to 6.50) but has 0.7m!!! less beam. Regarding the keel, the Pogo has 0.2m more draft (1.40 to 1.60) and 245kg more ballast (220kg to 465kg, more than the double !!!) displacing the 5.80 only 220kg less than the Pogo (700kg to 920kg) for respectively a 31.4%B/D and a 50.1%B/D. And of course, that uncomparable superior B/D effect is maximized, regarding the one on the 5.80Class, due to a bigger draft.
As you can see looking at the drawing of the new 5.80 class, it seems that the boat is just a slightly smaller, much less beamier, older designed 6.50class, but the stability of the two boats has nothing in common and while the mini is an offshore boat, to be sailed not in strong sea conditions, the 5.80class is a coastal boat and it is irresponsible to propose this as a boat for a circumnavigation race that passes in places and seas where the conditions are much stronger than on the low latitudes of the Atlantic on the calmest period.
Comparing the two boats, the 6.50mini will have a much better overall stability, incomparably better safety stability, and a much higher AVS. The inverted stability would be much smaller and the considerably less windage and a much superior stiffness will contribute to a far better dynamic stability.
Reading the above one may think that a Class 6.50 Mini-Racer is an extraordinarily seaworthy boat for bluewater racing and crossing oceans, when it is really a boat on the limits of what is considered safe for doing that. The mini racers on a transat are accompanied by several support boats, 7 last year, that are there to provide a quick help if anything goes wrong and to relay VHF distress messages.
If you follow the mini transat you know that it is raced on the season when conditions are better to make an Atlantic crossing from France, that even so the departure date is frequently postponed for safety reasons due to bad weather (like last year), and that some times the race is just stopped, bringing all boats to safe ports to wait for conditions to improve, as it was the case in 2013.
There is also another difference: mini sailor racers to participate on the mini transat have to qualify themselves for it and have to do a 650Class 1000nm solo race or several ones totalizing 1500nm, having at least 500nm of those being made solo.
This assures that all the sailors doing the Transat have considerably minimum experience and know their boat very well.
Looking at the new 5.80 class and taking as an example what the requirements are to race a Transat on even smaller boats (by the same NA) we will see that it is enough to have 18 years and "the skippers are participating on their own risk". No previous solo racing experience on that boat (Setka 5.0) verified. It seems that race this year is going to be a success at least in what regards participation since there are already 10 entries.
http://www.maderski.pl/setk--przez-atlantyk-2020.html?fbclid=IwAR0h0IPgaimv3twVTX1N8DHe13F2ochia1oSkSgp9Bc_1KkD4xsaj3Y8lN4
It starts from Portugal, November 2020 and it seems to me that they don't have a clue on what the sea condition can be in November there.
The frequent bad weather in November between France and the Canary Islands is the reason why the Mini-Transat starts in September/October from France and the reason they wait some time on the Canary Islands before going South.
It is to be sure they make the last leg on the best possible weather window, which is in November.This race on these boats is famous in Poland and it is already on its 3rd edition, in 2012 they were 5, only two finished but in 2016 all 8 boats finished on a Transat that experienced exceptionally good and fair winds.
You can see the conditions on the tracker below and I can tell you that rarely have I seen so good conditions and I follow several transatlantic races every year. Most of the time the max winds are of 30kt or more and on this particular year max winds stayed in the lower 20's. You can check that on the link below.
Of course, it is possible to cross the Atlantic in very small unsafe boats and get away with it most of the time but that does not mean an acceptable risk. For instance, on the ARC they only accept ClassA sailboats with 30ft minimum. Obviously, as the success of the 2016 edition showed, it is possible to do a Transat with much smaller boats and get away with it, most of the time. The question here is where you put the line in what regards seaworthiness and safety.
I salute the courage of those that want to race solo bluewater in manifestly unsafe sailing boats for ocean racing, but sailing competitions in crafts that do not offer minimum safety requirements should not be allowed and that is why World Sailing demands specific stability requirements and safety equipment on boats for participating in Ocean Races that draw that line at what they consider an acceptable safety and minimum risk.
Note that I don't have anything against somebody risking his life the way he wants, sailing or otherwise, but that should not have anything to do with sport. There are many sports that involve risk and Ocean Solo Sail Racing is one of them, but the risk has to be a controlled one and all the measures needed to diminish that risk should be and are taken.
Sailing as a sport should be regulated within acceptable risks without creating significant conditions to put sportsmen and other people's lives in jeopardy, namely, the ones that will have to rescue some of those who participate in excessively dangerous races, races where rescues will not be a small possibility but a big possibility.
Not to mention the cost of those operations and the increased risk that someday those costs will be passed to all of us through the need for compulsory rescue insurance for offshore sailing.
If you want a small reasonably seaworthy sailboat for offshore sailing instead of building one of these buy a second-hand old mini. There are many not competitive anymore that can be bought for the same that would cost to build a 5.80class sailboat or if you want to build yourself a boat there are plans to build one like these on the link below by Dudley Dix (above on the photo):
https://dixdesign.com/didiminiMk3.htmhttps://mini650projectdubai.wixsite.com/mini650projectdubai/blog/page/3
And if you want a more competitive 650class racer in plywood/epoxy, there is this option:
https://www.voileetmoteur.com/voiliers/actualite-voile/un-mini-6-50-biosource-pour-les-constructeurs-amateurs/89636
I love solo sailing and I do it in the Algarve, Portugal. I own a Beneteau Evasion 25, I had Westerly 22 from the 70' and before a 18f german home made. My best experience was crossing to Azores, semi solo, on a Fountaine Pajot 44 catamaran, brand new, helping a friend. What a trip.......
ReplyDeleteFreeboard vs lenght looks amazing, calculation for side sea in the south (-40) should give frightening results... and then drift...
ReplyDeleteA Big Beam is Dangerous
ReplyDeletewww.inquirer.com/philly/hp/news_update/20070712_Trans-Atlantic_sailor_capsized__hung_on_-__lived.html
It is the "Beam / Hull Depth" ratio what determines if the sailboat is safe or dangerous along with the vertical position of the center of gravity
That has no sense. What makes a sailboat dangerous are many factors.
ReplyDeleteIn what regards beam, it increases the positive stability (more dificult to capsize) and increases also inverted stability, more dificult to get back on its feet again.
What counts as positive is the positive area (the bigger the better) and the relation between the positive and the negative stability. Again, the bigger the better.
It counts also as positive the bigger or lesser righting moment (in proportion with the displacement) the boat is making at 90º and the bigger AVS the better.
And of course, it counts also the boat displacement that, with all factors being the same, the bigger the better.
That boat is a 20 year old design, a Pogo 8.50 a small boat that is relatively safe for offshore work in relatively moderate conditions and its owner was pushing a bit the envelope because he crossed the Horn with it, but even so I doubt it would pass today the certification for Class A, as the Django 7.70.
As you know when a modern boat is inverted, except race boats that can play with the water ballast, it is not able to re-right itself except if a smaller wave than the one that capsizes it, hits the boat.
I don't know the conditions that led to the capsize but on the photo the boat is on flat waters and therefore without any possibility of re-righting itself.
Also the boat was flooded and a flooded boat has no intact stability anymore but a compromised one. I dont know the reasons for the flooding but it can have to do with the main hatch to be open or even with the seacoks to be open a thing many forget to close when sailing and that can have dire consequences in a circumstance like this one.
"What makes a sailboat dangerous are many factors"
ReplyDeleteCaptain Obvious
your first reaction to something that sounds strange to you because you do not understand it ... is to immediately release a "no sense"
ReplyDeleteGreetings and have a nice day
It seems to me that it is you that don't understand the basics about sailboat stability. Maybe you should read some more about it.
Deletehttps://interestingsailboats.blogspot.com/2014/03/stability-1-misleading-information.html
https://interestingsailboats.blogspot.com/2016/04/rcd-increases-minimum-sailboat.html
https://interestingsailboats.blogspot.com/2019/05/please-rcd-certification-for-bluewater.html
Not sure i follow your logic regards stability above.
ReplyDeleteI don't consider myself an expert - far from it (its not my day job), but i do know a little about boat stability calcs from some amateur design work.
1. Firstly I understand that boats don't capsize solely based on wind hitting the sails - this is obvious, but has to do with the descrption of form stability of a mini transat racer above. They carry beam aft in order to carry sail and comply with the class rules regarding ballast. Boats capsize (and i mean go past their AVS) mainly due to wave action (probably also in consort with wind, but wind alone will most likely only take them to a broach situation if designed correctly and they don't downflood).
2. Being knocked down (as opposed to capsized) is (relatively) fine, so long as the hull maintains its watertight integrity and the AVS is not reached. The boat will come back upright so long as it does not reach its AVS.
3. The area under the 'positive' side of the AVS curve indicates the force required to push a boat into a capsize. Things such as a coach roof, hard chines, and a pilot house etc all provide a resistance to this as they should be considered to provide rolling resistance (chines) and increased bouyancy that needs to be overcome as they are forced under the water (presuming they are still intact). A boat with a narrow beam will have less resistance to this inital force than one with a wide beam. However this works both ways, a wide beam also resists being turn back upright.
4. The area above the 'negative' portion of the AVS curve indicates the force required to push the boat back upright from its equilibrium state upside down. Again a large, intact coachroof helps here and a narrow beam is beneficial in reducing the effort required. In order to right itself from this state the boat must be hit by a wave of sufficient force that it overcomes the state of equilibrium the boat is in (i.e. pushes it back into the positive AVS side of the curve). The greater the difference between the positive and negative AVS areas, the greater the difference in energy required to capsize the boat, and then right it again. Therefor usually related to how long the boat stays inverted after a capsize - all things being equal.
So consider the shapes of the mini transat racer and the mini 580. Take two extremes to show the point - One is like a surfboard with a keel (the mini transat racer) and one it more like a cigar tube with a keel (the 580). The surfboard is happy upside down as well as right side up (in equilibrium). It will take a lot of force to push it back upright after a capsize (therefor they have to cant keels/ fill or empty ballast tanks to help them add this required energy - requiring input from the sailor on board to overcome the inverted stability created by the wide hull). The cigar tube isn't very happy upside down, in fact it probably won't have a negative AVS - it simply won't stay upside down. It requires zero input from anyone on board to right it again. This could be considered a more seaworthy boat. Obviously the cigar tube is an extreme example, but the principle is used effecitvely on some search and rescue lifeboats - they are not stable upside down due to a huge, watertight superstructure, they will always self-right so long as the boat is intact.
An extreme example for sure, but on a scale where the surfboard is at one end and the cigar tube is at the other it becomes obvious where the two boats being compared above lie.
Sure there are a bunch of other seaworthiness factos such as boat strength etc, but assuming as you are above that neither boat falls apart or floods, the boat that self rights without input from any one on board is clearly the more 'seaworthy'.
I have on the blog some articles about boat stability and what you say is basically correct, except in what regards the last part where I do not follow: the mini 580 is not a cigar type boat and it has an inverted stability, meaning it will need a wave to re-right it when inverted.
DeleteOne of the things that counts most in what regards seaworthiness is not only the energy needed to capsize the boat, but the relation of that energy with the one needed to re-right it, from a capsized position.
It is the proportion between the energy of those two waves, the one needed to capsize the boat and the smaller one that is needed to re-right the boat up, when it is inverted, that is important.
But of course, if the relation is the same or close, what you want it is a boat with a much bigger positive stability because it will be much more difficult to capsize and when a boat capsize bad things can happen, from losing the mast to water entering the boat.
And the 650 mini racer without having a worst relation between positive and negative stability has a much bigger positive stability and will be much more difficult to capsize, and therefore will be a much more seaworthy.
Note that the mini is beamier but has a much lower center of gravity due to a much superior B/D and more draft. That will compensate for the extra beam.
And you are wrong about the Series 6.50 mini to have water ballast. That is specifically forbidden by the rules.
As important as dynamic as static stability is dynamic stability and if in what regard to have small area appendices (keel and ruder) both boats are similar, but the 580 mini has a much higher freeboard and that will act as a lever when a wave breaks over the boat increasing in much the rotating movement that can lead to a capsize.
But I was wrong about one thing on the article, it is possible for a 650 mini to be certified as a Class A boat. It is the case with the Pogo 3 series boat but of course, impossible to certify a 580 mini.
Proto 650 have water ballast.
DeleteWhen capsized, it is actually GOOD thing that water goes into the boat. As the boat fills up with water it loses its stability. The more water inside, the less stable it becomes, and then it will turn again, this time to the upright position. The wider shape of MINI 650 will most likely require much more water inside then 580 to get that effect. So, 580 is likely to be more safe in that regard. And 580 can be build with positive flotation, although I am not sure how this would affect the amount of provisions you can then take with you for a longer passage. Ultimately, it is the integrity of the boat that counts. And I think Mini 580 is ultimately stronger, but that is just my opinion. By the way, I own a Mini 650, and I am just in the process of selling it and getting a 580.
ReplyDeleteYes, a boat flooded will have less stability so if inverted it will be rolled more easily but when it is on his feet again, it will also have less stability and be easier to roll.
ReplyDeleteSo, unless you like to be rolled and rolled again on bad sea conditions, to have a flooded boat is always a very bad idea.
If you have a 6.50 mini and are changing it by a Mini 580 you are going to regret it. Try to test sail the 5.80 mini first.
What is the 6.50 Mini you have?
I am no expert in this field -not even a gifted amateur. But on the class 580 website, I found an article on the stability of the 580. They claim a point of vanishing stability of 142 degrees. I was under the impression that this is quite a respectable value. Am I mistaken, don't you believe the designer's claim, or is there something else going on? I would be very interested in your opinion on the matter.
ReplyDeleteThe article in question can be found here:
https://www.classglobe580.com/flottation-complete/
Hi,
DeleteThe point of vanishing stability (AVS) has to do with lots of things and it is a value that in what regards seaworthiness and stability has to be looked with several other factors.
The reason that boat has a high AVS has not only to do with a low CG (B/D, draft, type of keel) but mostly due to a high freeboard (that is continued by the cabin) and a sealed mast that brings buoyancy.
But contrary as what would have happened if that value was obtained mostly by a low CG, those two factors (freeboard and mast buoyancy) will not increase the force necessary to prevent the boat to capsize to 90º, neither the recovering speed from that position.
A boat capsized at 90º will have much less positive stability and a much smaller wave can finish the job and invert the boat. That is why the force the boat is making to return to the vertical at 90º is a value as important as the AVS itself.
You will have a boat boat not difficult to capsize (much easier than on a mini 6.50) but a boat that after being inverted (if everything remains intact) will return to the upright position without much dificulty.
However if the boat is rolled by a wave the changes are that you will end up with a boat without mast, and therefore with a higher AVS. The higher freeboard will make also easier for a wave to capsize the boat because it offers a big surface to create a rotating moment and many things can go wrong when a boat is inverted.
I hope this will help you to understand better the 580, that if it is as inexpensive as they say to build, it will make for an interesting sailboat for coastal cruising with some offshore ability, but far from a boat suited for a circumnavigation with acceptable risks.
Not even a 650 mini, even if considerably more seaworthy and able to cross oceans on the right season, should be considered for a racing circumnavigation due to inadequate safety.
That does not mean that if such a race was made with them the majority would not be able to do it, but a percentage of them would not, and between those there would be a high probability of dire consequences, including death and that is not acceptable in a sport.
Thank you for your extensive reply. I'm beginning to think that boat design is as much art as it is science. At the very least it can sparks some heated debates, as witnessed above. Fair winds and following seas to you, sir! Sanne
DeletePogo class40 AVS 128 degrees. Mini 580 AVS 142 degrees. The absolute minimum AVS for Design Category A is 100 degrees.
ReplyDeleteAnd a log (cylinder) has a 180 degree aVS and keeps rolling all the time.
DeleteThe AVS is not the only point to sailboat seaworthiness. Overall stability is as important as the AVS and a Mini 650 has a good AVS (it depends on the model but over 120º) and a much bigger overall stability than the Mini 580, meaning that will be much more difficult to capsize.
Furthermore while on the Mini 650 the good AVS is obtained due to a low CG on the Mini 580 (that has a higher CG) the higher AVS is obtained due to a high freeboard, a high cabin and the mast, that is closed and full of foam.
All that will give a better AVS, will contribute to re-right the boat (assuming the mast does not broke when the boat is rolled) but will not contribute to a better overall stability, as the lower CG of the Mini 650 does.
Log has 0 degree AVS. Initial or form stability has nothing common with capsize resistance.
DeleteI do not understand your point. Inicial stability is part of the overall boat stability and as so contributes to capsize resistance.
DeleteHull form stability, the one that is generated mainly by the hull form, is part of the overall stability, it is not only generated at small angles of heel (initial stability), and as so contributes to capsize resistance.
Don't know much.about the mumbo jumbo above, but I have built quite a lot of them,.and sailed even more. Never really been into racing per se, and that may make the difference. My two bits worth.
ReplyDelete1. If you want to get to your destination fast, fly, don't sail.
2. Boats don't capsize or sink. Skippers do.