Aphrodite 101 en France

Analysis and trimming of the Aphrodite 101



The Aphrodite is a relatively narrow craft which, when heeling only changes the flow of water on the hull relatively little (at lease when compared to the boat’s broader beamed sisters). There is, therefore, not so much asymmetry in the water line and, the flow disturbances which, on broader beamed craft are quickly indicated by weather helming during heeling, are either partially or totally absent here.

The keel and rudder are also drawn less "obliquely" through the water, but enough to reduce efficiency of both, mostly as a result of the surface reduction, which arises during heeling.


The balance rudder gives an unusually good steering also when subjected to heavy loading, and it is, therefore, necessary to make corrections for even the least signs of weather- or lee helming.

Think of a close reach with spinnaker in strong wind where the boat is being pressed without resulting in any substantially larger rudder pressure, until the rudder deflection becomes so great that the rudder either stalls or seizes in its bearings.


The position of the rigging and the mast trim are decisive for the sailing qualities: The mast is flexible in order to be able to flatten the mainsail during increased wind pressure. Thus the forestay’s curvature is influenced and thereby the shape of the jib. I-measure is very high.

The position of the shrouds behind the mast to achieve better forestay control has the effect that the deflection between the jib fitting and the deck is controlled by:


The jib classification permits a relatively large positive roach which will have a tendency to become straighter under increased wind pressure, and thus increase the profile depth (this is also a result of the forestay’s curve and the stretching characteristics of the sail canvas). The sheeting of the jib becomes, therefore, an extremely important factor for the sailing performances.


In the following we shall attempt to give a schematic analysis of the trimming possibilities on the basis of these conditions:

I Before setting the sails

When the mast is set in the step with a forestay length of 1174cm, it is centered sideways by setting the lower shrouds hand tight. Afterwards, the upper shrouds are trimmed gradually in at each side and are set as tight as possible. The lower stays are then eased out approximately 4 turns and the back-stay is hauled 10 cm (measured on the wire). The upper shrouds have become eased out and are tightened as taut as possible. The back-stay is eased out and will leave the mast with a permanent curvature of about 10cm.

The lower stays are now roughly trimmed dependent on the type of mainsail:

After this the mast will be tilted forward 3 to 8 cm sighted from the gooseneck to the black mark at the top of the mast, when both running backstays are set and the sternstay is slack.

II During test sailing:

We tack in approximately 5-7ms wind. Trim the backstay until the mainsail has the desired shape, set the backstay so that the forestay curves about 5 cm in the middle. The mast should be perpendicular on the beam, and the lee upper shroud "hand tight". The desired tightness is corrected on the new lee side.


In order to achieve optimum use of the mainsail it is now necessary to trim the curvature of the mast by means of the lower shrouds, so that the profile depth and its positioning measured as a percentage of the sail width and the distance from the mast is :

Wind force (m.s.) Profile depth (%) Depth point (%)
0-2 17 44
2-5 13 42
5-8 11 40
8-10 9-10 38
10- reefed 10-12 38

The measurements are taken at the profile stripes, e.g. if the profile depth is too large, the lower shroud is eased out, and vice versa.

If it is too far forward, the lower shroud and/or cunningham is eased out.

We now have a mast which is perpendicular on the beam and has the desired curvature fore and aft at a given backstay adjustment and wind force. In order to repeat this trim, we must emphazise the necessity of carrying out accurate and permanent marking of turnbuckles, running backstays and mainsheets together with the mainsail at the spreader height.


The jib depth is dependent on:

and should be (measured as on the mainsail as shown above):

Wind force (m.s.) Profile depth % Depth point %
0-2 20 40
2-5 16 40-38
5-8 14 36
8-10 12 33
10- maxi mini jib 10 33

Jib 2 should have the same shape as the maxi mini jib.

In order to achieve this depth, it is essential that the cutting is correct and the cloth elasticity the optimum for the purpose and also that the luff is stretched in accordance with the wind force. In other words, in a light breeze just enough to avoid the presence of wrinkles from the hanks or, in fresh wind, so that the stretch folds are not formed in the seems along the luff. It is also essential that the correct sheet point in relation to the mast slope has been chosen.

We can now alter the shape of the jib by adjusting the backstay. When a jib is set correctly, the forstay should fall to lee in the various wind forces (i.e. towards the centre of the sail) measured in cm from the straight line between the tack and the jib fitting approximately in the middle of the luff:

Wind force (m.s.)  
0-2 12-13 cm
2-5 6-8 cm
5-8 Max 5 cm

When the backstay is tautened as hard as this requires, the mast is compressed a little and the upper shrouds are eased out and both conditions cause the mainsail to flatten.

Sheeting and reefing:

Individually, we have now established the ideal shape of the sails to suit the various wind forces. However, the sea conditions must also be taken into consideration.

Beyond this, the finishing touch to the perfect interplay of the rigging and the capacity of the boat is obtained by sheeting and reefing:

The mainsail should be sheeted relatively loosely, so that the twist in the sail plane from the boom to the top batten is:

Wind force (m.s.)  
0-2 10 degr
2-5 8-6 degr
5-8 6 degr
8-10 8-10 degr

If this can not be achieved in a light breeze, the sail is too hollow at the top, and if the boat can not be kept in standing position in a fresh wind, then the sail is too closed at the bottom. In order to achieve the necessary twist in a correctly set mainsail, the travaller should be positioned as follows:

Wind force (m.s.)  
0-2 Max to windward, sheet very light
2-4 Max to windward, sheet harder
4-6 10-15cm windward from centre
6-8 5-10cm windward from centre
8-10 In the centre or up to 10cm lee with ISOmat

The position of the boom peak will then move from the centre in light wind to about 30cm to lee in fresh wind.

The jib is often sheeted too close to the centre line. The ideal for a well-trimmed jib and thus a well trimmed mainsail is measured in degrees.

Wind force (m.s.)  
0-2 8-9 or 51-57cm from the centre
2-4 7-8 or 44-51cm from the centre
4-6 7 or 44-45cm from the centre
6-8 7-9 or 44-57cm from the centre
8-10 8-10 or 51-63cm from the centre
10-14 10-12 or 63-76cm from the centre
14 … Over 13 or over 80cm from the centre


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