Friday, November 3, 2017

HULL DESIGN/PERFORMANCE: JBOATS VERSUS JPK, FIRST AND POGO.


I will be using the results of the last Fastnet to do that comparison. As everybody knows the Fastnet is one of the main European races and probably the one where we find better teams and more modern boats. They are not more because the entries are limited so it tends to reunite the cream.

JNA39
The race is an offshore one, goes from Cowes (England), around the Fastnet rock (Ireland) and finishes in Plymouth (England). Due to its course it has always varied winds. This year's edition they had light winds, medium strong winds, and as expected, lots of downwind and upwind sailing. A great place to look at the comparative performance of modern performance cruisers, or cruiser racers.

Archambault 13
I will disregard carbon pure racers and I will be focusing at the performance of modern affordable dual purpose boats with different types of hulls. Lots of them on this race: light boats based on open solo racers like Pogo or RM, with a huge beam and the max beam pulled to the transom, main IRC type designs, heavier boats with a moderate beam and the beam not so much pulled back, like the First, boats with a smaller beam and the beam even less pulled back like the Jboats and French modern designs, with a moderate beam but with the beam pulled back like the JPK or the Sunfast.
j122

I will be looking at real times (not compensated ones) and of course you will have to give allowances in what regards the boat length. Length for length you can compare directly but not when boats have different sizes. Some will say that sail area or displacement are also important but I don't care, for me the length is what matters most and eventually price, but we will not be looking at prices on this post. I will be looking only at boats with a length smaller than 46ft.  Bigger boats are not many and not enough to provide significant data.

Let's look at the real stuff, the real time the boats took to complete the race and let just focus on the boats that have made it in less than 4 days and 10 hours. A big disadvantage for the smaller boats, that proportionally for the same performance versus length should be allowed more time, but we have to set some limit. It is unfair for the little ones, but would allow us to see better how they compare, speed for speed with bigger boats.

Among these boats the fastest was an Archambault 13 that made the race in 3 days 13 hours 41 minutes and 08s (3 - 13:41:08), the next fastest was a JNA 39, the one on the big photo above. The JNA is a relatively new design from Joubert&Nivelt  and it could be the new 39 from Archambault, if the shipyard had not went bankrupt, since Joubert&Nivelt were the ones that designed their boats.

The JNA39, a much smaller boat was a blast making the race in only more 7 minutes  (3 - 13:47:59), truly amazing and no wonder that they have won the Fastnet (in compensated), family crew and all.
P12.50SF3600JPK1080XP38J122

The first Jboat was a J133 (3 - 17:33:05) took almost more 4 hours than the much smaller JNA 39 followed closely by an Arcona 465 ( 3 - 18:05:04) a Grand Soleil 43 (3 - 18:07:59), a First 44.7 (3 - 18:09:56) an Azuree 46 (3 - 18:48:40) another First, a 40 (3 - 19:55:18) closely followed by a Swan 42 club (3 - 20:01:20) a XP44 (3 - 20:12:28), a X41 (3 - 20:54:24) and a Grand Soleil 43 (4 - 03:25:03).

The next was a new J122e (4 - 00:57:34) that being slightly bigger than the JNA 39 took about 11 hours more and was beaten by the First 40 by 5 hours. Then a J133 (4 - 01:41:45), another J122 (4 - 02:27:54) and only one hour later came a  much smaller JPK 1080 (4 - 03:10:22) followed by two J122 (4 - 03:26:57) J122(4 - 03:32:42) another JPK 1080 (4 - 03:43:35), a X41 (4 - 04:11:29) and another two JPK 1080 (4 - 04:11:58) JPK1080 (4 - 04:28:07).
X133

Then a First 40 (4 - 04:31:13), a  Sunfast 3600 (4 - 04:36:56), a J122e (4 - 04:37:41), an Archambault 35 (4 - 04:38:45), a Sunfast 3600 (4 - 04:39:04) an X40 (4 - 04:45:21), a Sunfast 3600 ( 4 - 05:21:56) another X40 (4 - 05:22:41) a JPK1080 and only 3 hours later the 2nd J122 came a small JPK, a 1010 (4 - 05:33:52) with a duo crew, father and son, the ones that some years back won the Fastnet and that this year won the duo crew category and also its IRC class. What a boat, what a family!!!!

JPK1080

Then another JPK 1080 (4 - 05:38:50) a First 40 (4 - 07:08:42) an A35 (4 - 07:34:45) a X41(4 - 07:52:09) a First 40 (4 - 08:44:07) a JPK1010 (4 - 09:01:52) a J109 (4 - 09:21:35) a First40 (4 -09:50:05) a J120 (4 - 09:54:00) and a JPK 1010 (4 - 09:55:00) .........Pogo1250 (4 - 13:05:45) Pogo12.50 (4 - 12:26:17) Pogo2 Class40 (4 - 13:16:27) RM 1270 (4 - 17:46:43).

For obvious reasons I had to consider the results from the Pogo out of the 4 days 10 hours limit because none of them finished inside that time. Between the last sailboat that made it on the time I considered as limit and the Pogo, many boats of similar size, and smaller, made a better time.

Pogo 12.50
Another interesting consideration regards the huge number of Jboats racing (40) probably the brand with more boats racing, being the smaller the J105. Among the boats that made it on the considered period (fastest cruiser racers) there is only one Jboats smaller than 40ft, while we can find between Archambault, JPK and Sunfast 10 sailboats considerably smaller than 40ft, some much smaller like the three JPK1010 (33ft). There were two fast J111 racing but none was able to make the race inside this time period.

First 40
So what does this tell us about hull type and performance? The main traditional development line of IRC boats (First, Grand Soleil, Swan) performed very well, even better, the "French" type of boats with a similar beam but with a larger transom due to beam pulled aft (JNA 39, Archambault, JPK, Sunfast Azuree), not so well the Jboats, that are narrower boats with a max beam not pulled back and not good at all the very beamy boats with hull derived from solo racers (Pogo, RM).
JPK 1010 and J111

On another race, with more upwind sailing and nasty seas the Jboats could have made comparatively better. On a predominantly upwind race the J would probably be the fastest, on a predominantly downwind race, like a Transat, we would see the the Pogos shining and the "French" type of hulls doing even better regarding Jboats and traditional IRC racers (First, GS, XP). 

The point here is that there are not miracles and each type of hull has strong and weak points. But I would say that the type that seem to have a  better overall balance between upwind and downwind performance ia what I called the "French" line of development that includes for instance the GS 34 and the Diva 34 (recent posts), none of them French boats.

Besides the French I would say that I am not the only one to think that this is the best compromise and more and more performance cruisers are designed that way. This type of hull offers also the advantage to be easier to sail downwind solo and most of all to be more stable and easy on autopilot and that is not a negligible advantage on a cruising boat, being it a performance boat or not.

6 comments:

  1. Very interesting post as usual.
    When you say the "French Line" has a moderately large beam pushed aft... seems a bit vague...could you synthétise (is it possible ???) your conclusions about the "french" type of hulls (wrt IRC or solo downwind racers) in terms of measurable hull characteristics ; I mean for instance the "french line" have a B/L ratio between xxx% and yy%, a SA/D of ..., a D/L od... etc ?

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    1. Thanks! You are probably right but qualifying beam is a bit difficult since what was 30 years ago a large beam is today a moderate one (and has been increasing on the last years), so instead of going technical about it let me give you some examples that will clarify the situation:

      Taking as example 36 to 38ft boats, if we look for IRC or ORC derived cruiser racers with a “on tradition” style, the ones with the beam not pulled aft, we will have typically (beam in meters): XP38 – 3.70; Salona 38 – 3.62, First 36.7 – 3.55, Italia 10.98 – 3.65. If we look at a “narrow” boat like the J111 we will have a 3.29 beam or on a Luffe 3.6 a 3.16 beam.

      Looking at the beam of what I called “French designs” we will see that a JPK1080 has 3.60 and a SunFast 3600 - 3.55.

      So you can see that the difference between the “French type” and the IRC “traditional” type is not a bigger beam than the more traditional line of IRC developed cruiser racers but the beam being pulled aft. The big difference regards the posterior part of the hull and transom design, not maximum beam. It looks like that a JPK or a Sunfast are a lot beamier than what they really are, due to the big transom.

      Curiously we can see that the last models from Jboats are a lot less narrow than what they used to be, for instance the J112 has 3.6 beam and the new J 121 has 3.75 (the J122 has 3.63) so it seems that even Johnstone, the designer of Jboats, is now convinced that a beamier boat offers a better compromise in what regards overall speed.

      The Transom of the J121 has also been modified more towards "French" boat types, even if the beam is not pulled aft.

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  2. Paulo,
    Thank you very very much for the clarification.
    You really help all of us understand a bit more what we see on the water.
    Very amazing how an "apparently little" variation on beam longitudinal position makes such a difference.
    Probably the particular conditions of a given offshore race (sea state, beating versus downwind,... ) may change the outcome... However, you seem to think that it is more than that and that the said "French" line is more versatile... Right ?
    I am also wondering to what extend the designers design boats according to a given regatta campaign, (although the JPKs did well in the Sydney Hobard as well..) combining features of "downwind sleds and beating knifes" for a given program and consequently don't really improve the design art.... what you think ? We don't see any scows in those races after all... only in the mini.

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    2. The variation of max beam brought back is not a little variation because it redefines how half of the boat is designed (the posterior part). Note that the beam brought back can given origin to different types of hulls. I have explained that here:

      http://interestingsailboats.blogspot.pt/2014/04/solo-racing-crewed-racing-hull-design.html
      http://interestingsailboats.blogspot.pt/2015/02/does-cruising-boats-need-training-wheels.html
      http://interestingsailboats.blogspot.pt/2014/04/looking-at-comparative-cruising-boats.html

      The difference is in fact big because that type of transom can increase dramatically hull form stability at different angles of heel, depending on the design and increasing hull form stability means more power allowing more sail area.

      The play here is always between drag and power (stiffness). That’s the compromise that matters.

      I do think that the art of deigning better and faster sailboats are always in evolution and we will have always better and faster sailboats. On the last years what we have seen is that what you can gain downwind is more important (in time) than the little you can lose in upwind performance and the evolution of design shows that.

      On the middle sea race we had an incredible example of that seeing the Maxi CQS losing for Hugo Boss that is just a 60ft boat. Leopard another maxi was not far away. If you look at the tracker you will see that Hugo Boss lost enormously for the two boats in the very light stuff upwind but that on the upwind part, with strong winds was faster than CQS (even pointing less) and just a bit slower than Leopard and that on the beam reach and downwind part was a match for both boats.

      Quite incredible the performance of Hugo Boss upwind!!!

      Rambler was way faster but while CQS and Leopard are boats maximized for upwind sailing Rambler is already one of the new compromises with a big transom and a better performance downwind.

      You don’t see big rounded bows because that is already a too big compromise regarding upwind sailing, especially in bad weather. It is really good for downwind but too much of an unbalanced compromise.

      But if you look to the Rambler and Hugo Boss bows you are going to see that their bows are quite rounded. On the Hugo Boss case I believe it is not more rounded because the box rules don’t allow. You can see all that on these pictures. You have to copy/paste the links.

      http://4.bp.blogspot.com/-dxgxgRGykIg/Vfw0Y27rvgI/AAAAAAAAPbI/pqYgGxdIQzg/s640/12019979_1196324487048268_227693521935494729_n.jpg
      http://www.yachtsandyachting.com/photos/maxiyachts/yandy139913.jpg
      http://cdn.cnn.com/cnnnext/dam/assets/150501165613-rambler-88-yacht-st-barths-hill-super-169.jpg
      http://www.leopard3.com/imgs/racing/tech/1.jpg
      https://www.superyachttimes.com/system/legacy2/default/assets/Image/Events/2016-12-Hobart-Yacht-Race/2016-12-Hobart-Yacht-Race-08.jpg

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    3. Many thanks for considering my naive questions and giving the detailed answer and the links.
      I have work ahead now ! "du grain à moudre" as we say here :-) to gain a better understanding. Take Care.

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