The Sails and Sail Plan

When I purchased my Catalina, the first question was at which wind speeds can it be sailed and what sails and sail reefing are needed.

During initial navigation tests on a lake I have determined that with full sails (standard jib, standard main), at 10 knots true wind speed measured at 2 meters above water level, the ride is comfortable and the boat makes close to maximum hull speed, so this is Comfortable Wind. At 15 knots the heeling is acceptable, the speed compared to 10 knots may increase just a few percent. This wind I call the Maximum Wind. Over 15 knots it begins to look like a fight against the elements, and there is no gain in speed (except on full courses), just more heeling and leeway. It does not mean that I cannot sail in winds higher than the "Maximum" wind speed, in fact, I actually enjoy being heeled like 45 degrees and feeling superman fighting the elements... But this is not true seamanship, and if it is ok for one hour trip, on the long run you will be exhausted or the mast will break. So I do believe that these "Maximum" wind speeds should not be surpassed on purpose.

Please also note that the standard reporting of wind speed (for instance, in forecasts) is based on a height above ground of 10 meters, and most sailboats have the anemometer installed on the top of the mast. 10 knots I mentioned for deck are equivalent to about 12.5 knots at 10 meters above waterline, and 15 knots at deck are equivalent to 19 knots!

When I initially purchased Catalina, I had a standard jib (9.7 m2), a standard main (9.3 m2) with one line of reefing, and a genoa, about 14 m2.

The sails I use now are the following:

  • Main: 9.3 m2
  • Main with first reef: 7.2 m2
  • Main with second reef: 4.6 m2
  • Standard Jib: 9.7 m2
  • Storm Jib: 3.0 m2

There is one important issue which should be considered in the discussion: the hull and rig windage. The lateral windage area of Catalina is about 5.5 m2 (including mast, boom, rigging, etc.), and the front windage area (also including rigging) is about 3 m2.

The discussion and the tables given below do not consider the effect of this windage. However, in strong winds and with small sails, its effect is enormous: for instance, the storm jib is 3 m2, and the front (or rear) windage cross section is also around 3 m2. So the total area doubles on full courses, and on courses close to wind, the leeway induced by the drag from the hull above waterline will preclude any sailing up-wind. (There are two caveats as to the value of the cross-section area of the hull, first, the hull shape is relatively round and aerodynamic, and therefore is not as "efficient" as a sail, either for pushing or for dragging, and second, it is very close to the waterline, where the wind speed and consequently wind forces are considerably weaker than higher up where the sails are).

 

All the tables and values given below are based on standard wind at a height of 10 meters

Power Equivalence

This table presents the wind values which are necessary to obtain the same drive power as for "Comfortable" and "Maximum" wind speeds. That means, if I sail under main with second reef and a jib, I need to have 22 knot wind to have the same speed as with unreefed main and standard jib at 19 knots.

Equivalent Wind Speed (knots)
Sail Combination
Comfortable
Maximum
Main + Jib 12 19
1. Reef Main + Jib 13 20
2. Reef Main + Jib 14 22
Main 18 27
Jib 18 26
1. Reef Main 20 31
2. Reef Main 25 38
2. Reef Main+Storm Jib 20 30
Storm Jib 32 47

 

 

Heeling Equivalence

This table presents the wind values which are necessary to obtain the same heeling force as for Comfortable and Maximum wind speeds. That means that if I sail under the main with second reef and a standard jib, I need to have 23 knot wind to have the same heeling moment as with unreefed main and standard jib at maximum wind speed. Note that the values are slightly different from the previous table, because smaller sails have lower points of attack, and so the heeling moment is less and therefore a stronger wind is needed to achieve the same heeling than is the case of the previous table.

Equivalent Wind Speed (knots)
Sail Combination
Comfortable
Maximum
Main + Jib 12 19
1. Reef Main + Jib 14 20
2. Reef Main + Jib 15 23
Main 17 25
Jib 18 28
1. Reef Main 20 30
2. Reef Main 26 40
2. Reef Main+Storm Jib 22 33
Storm Jib 38 57

 

What is the point of this table?

The Heeling Equivalence Table gives wind speeds which may be used as guidelines for reefing and/or changing sails.

Basically, one would have to select the sail plan on the basis of the "Comfortable" wind, and consider changing to a different combination when the wind speed surpasses the "Maximum" wind.

It may sound complicated, but suppose that the expected wind will be around 25 knots. Possible combination would be double reefed main (26 knots) and double reefed main with storm jib (22 knots). If the wind would increase, let us say to 35 knots, the first combination (double reefed main with storm jib) would be too much, and we would have to reduce the sails (by lowering the storm jib). Double reefed main alone can work up to about 40 knots. Now, obviously one has to consider that at too high windspeeds (40 knots), a fuller course may be safer, and on a fuller course, a storm jib is much safer than the main. But the general principal stands.

So to summarize all this technical details:

If we disregard the action of waves, and provided that the sail plan includes smaller-sized headsail and deeply reefable main, a Catalina 22 is perfectly controlable up to about 40 knots wind, and maybe more, and can be sailed on broad reach at wind speeds of up to 35 knots. Making reasonable headway against the wind is limited by a maximum wind speed of about 30 knots due to high windage of the hull.