Masthead Code 0 (MH0) on a Saphire 27

07 Feb 14:43

Masthead Code 0 (MH0)

This sail is among others being used on the Volvo Ocean Race 65ft boats for light winds from 0 - 6kts upwind and also for reaching and stronger downwind legs. They use a material strenght of 13'600 DPI. This autumn, they added a so called J0, which is set on the bowsprit and sheeted with the jib sheet. The J0 is only about half the size of the MH0 but much stronger (23'800 DPI) and used upwind in 6 to 13kts. However, to use a MH0 and a J0 gets too much on a small boat like the Saphire and I concentrate on a fractional code 0 (FR0) and the masthead code 0 (MH0).

Picture: North Sails / VOR65

MH0 used on Saphire 27

On my Serafina I used a 45m2 big MH0 over the last season and reached very high speed limits. On tight upwind legs an apparent wind angle of 30° could be reached with very good speed. In true winds between 1.5 and 2 kts, the boat speed reached double wind speed. With increasing wind strenghts however, the advantage gradually shrinks and once you reach 6kts of true wind, you need to change to the normal 15m2 jib, otherwise the boat is overpowered and no real advantage results on tight upwind courses. It is very important, however, to have the mainsail boom significantly windwards over the centerline to open the jet between the sails and to use a lot of twist to depower the mainsail at the same time.

Picture: mainsail boom winwards over the centreline to open the jet between the sails

However, a big advantage is reached in angles from 40 to 60° apparent wind angle since the huge overlap of the Code 0 starts working really well. The boat quickly passes the theoretical hull speed limit and can cope with much bigger sized boats. The handling remains realitvely easy since the Code 0 uses a flying furler and can be rolled in easily. This sail presents an incredible potential especially if you sail in coastal areas on long courses or on bigger lakes like lake Geneva or Constance, where you have large crossings. And of course in all kind of light wind areas especially upwind.

Picture: huge overlapp of >200%, attached in the first third of the bowsprit close to the hull to achieve a higher forestay tension.

Thanks to the big surface it is possible to use the MH0 up to apparent wind angles of 120°, especially in stronger winds. However, it is important to accelarate in a tighter angle and to bear off slowly like on a catamaran to create the needed apparent wind for propulsion. As such, the apparent wind increases and you get the impression to always sail on a reaching course even though you are already going downwind. In strong winds, the MH0 can even substitute the asymetrical gennaker, whereas, however, the risk of broaching increases, since pressure is always leewards.

Picture: MH0 in a roughly 50 - 60° apparent wind angle, slightly open, creates an enormous propulsion

MH0 vs. FR0

Compared to a "fractional code 0" which does not go to the top of the mast (FR0), the MH0 can sail tigher upwind angles thanks to the huge overlap. The profile of the MH0 is somewhat flatter. This is due to the fact that the 30° angled spreaders are very long and if the sail is shorter, it cannot be closed in the same manner. With a bigger overlap the sail can be closed better and the deepest profile lies at around 45%, what gives a good up-wind-profile. On the other hand, the FR0 can be used in a bit stronger winds especially downwind. As such, the FR0 is between a reacher (A5) and the MH0 but on a small boat you probably dont use  both sails. For Saphire we use laminates instead of Nylon for both, the MH0 and the FR0.

Picture: FR0 on Saphire with a surface of 35m2

Nylon cloth streches too much and is not suitable for tight upwind legs. The classical Code 0 (FR0) on Saphire is 35m2 whereas the MH0 is 45m2, means almost 30% more surface. We use radial cuts similar as they were used in the past for the flying genoas. Upwind, the difference to the former flying genoas is not huge but both sails present a wider range of use, especially on reaching and also downwind courses.

Picture: approx 120° apparend wind angle with the FR0

Forestay tension

Contrary to the VOR65 we do not attach the Code 0 at the end of the bowsprit since we would not get enough tension on the integrated forestay. We go maximum 0.5m to the front ot the boat which gives us a distance of 0.7m to the normal forestay. This allows us to use a lot of tension on the integrated forestay of the code 0 in order to reach 30° apparent wind angle. The code 0 forestay replaces the normal jib forestay.

Picture: Bowsprit not fully extended

Picture: a lot of tension on the code 0 forestay to reach a closer upwind angle and to create a strong propulsion

Nylon vs. Laminat

Nowadays, the so called code 0's are widly used on cruising boats since the handling and the manoeuvres are easy, especially hoisting and retrieving is much easier than with a normal gennaker/spinnaker. However, most of the sails are some kind of compromise since most of the cruising boats hardly pass their hull speed limits. For this reason, often Nylon is used as a material for the code 0 but I think this does not come up to the expectations of the more experienced sailor but fits perfectly well the needs of a cruising sailor. For Saphire, we only use laminates.

Reacher vs. Code 0

If you use a reacher (A5), means a flat and small asymetrical gennaker as I use it on Serafina with a surface of 50m2, you can  change - depending on the wind force - from 60 to 70° apparent wind angle from the MH0 to the A5. With the FR0, you would change a bit later, probably between 70 and 80° - if at all. With a normal asymetrical geannaker (A2), a so called "runner", you would not change before 100° wind angle and stay with the code 0 - but again - all depends on the strenght of the wind. If you want three different sails is one's own decision. It can make sense depending on the area where you sail.

Picture: reacher A5, 50m2, flat cut

Cruising vs. Racing

To get a MH0 into any kind of rating system is difficult, if not impossible, since the mid girth is significantly less than 65%. To count as a downwind sail and to fit the Swiss Rating System, the mid girth should be above 65% (ORC 55 - 75%). Some sails are cut to fit the mid girth of >65% but a code 0 with such measurement will not sail well upwind since it becomes too round.

The use is rather for cruising or rating-free races or also under Yardstick. There, you can realy enjoy this sail since the handling is easy and the speeds you reach just stand for fun and pleasure.

Picture: easy change from one sail to another thanks to the flyign furler

Last year I sailed among others the Translémanique en solitair with the MH0 and I was very happy with the overall performance and ranking. However, the rating pushed me into a class in which I just did not have any chance. In SRS the sail was penalized by 10% compared to the normal sailplan with the standard jib which shows that the rating systems do not judge these sails correctly. They are being considered as upwind sails and with a huge overlap of 200% this becomes a huge genoa, who's surface is calculated in a linear way. As a result, Serafina was measured with 74m2 upwind sail area. In medium or strong winds you would hardly use the MH0 and then you would have to compensate the 10% disadvantage all in light winds. So, the MH0 brings a lot of fun in sailing and also when you aim at line honour, but not in rating systems.

Differently, however, in the Silverrudder race in Denmark, where only the boat lenght counts. What a fun to sail this sail! Thanks to the MH0 I could increase my lead tot he second boat in my class to nearly 12nm. Imagin the fun I had - even though I did not finsih - but that is another story. At least, it shows the enormous potential of these sails which, however, only work on boats that easily pass their theoretical hull speed limits.

Picutre: Serafina III at the Silverrudder Round Fyn in September 2017