Using the trim tab is a powerful adjustment. It is important to think of it in the same way as adjusting the sail trim. The advantage of a trim tab is that the foil effectively becomes asymmetric and therefore the keel area can be reduced. One can also adjust the amount of asymmetry for the different situations. My first impression using the tab on this boat is that it is very easy to use too much. If you use 10 degrees you can physically see the boat moving sideways! It is designed to be a fair fit with the keel fin at a 5 degree angle however, 7 degrees seems to be a good average number when sailing upwind. In stronger winds I consider using less tab angle when the boat is sailing at speeds of 8.3 knots or more. I view the trim tab as operating in a similar fashion to an aeroplane wing flap. Any time the boat speed is really low you should generally use slightly more tab angle to prevent the boat (and foils) from sliding sideways. One should also use more angle when the rudder is being unloaded, such as rounding a bottom mark or at the beginning of a light wind tack. Tactically it should be possible to briefly use 9 degrees or more in order to squeeze someone off. Downwind I suggest using almost no tab unless you are reaching at higher heel angles, where you should use 1-2 degrees.
When tacking, the helmsman should release the tab just after the boat has passed head to wind. The mainsail trimmer should pull the tab onto the new side just before or as the boat loads up on the new tack. Genoa trim is critical for a good tack and it is important not to release too early. Obviously a flapping genoa is a lot more drag than one that is trimmed so I like my guys to eliminate the number of flaps during a tack to the minimum.
Good sail trim is highly rewarded in this boat. The mainsail is very big and with full battens one must always be careful of over trimming the headsail. In most conditions some backwind in the mainsail is desirable upwind but not so as to totally invert the battens. So the genoa trimmer needs to keep a constant look out for the mainsail trim and in gusty conditions be ready to ease the genoa car back in the stronger puffs. In choppy conditions it may be better to ease the genoa sheet rather than adjust the genoa car. Upwind, the reaction to trim has to be fast so I prefer the genoa trimmer to be hiking and to use a dedicated grinder to jump inboard and grind the sheet on the central pedestal. The loads on the sheets are not very big so I believe it is advantageous to have a lighter grinder for upwind trimming.
The headstay ram is a powerful control for adjusting the depth of the genoa and powering or depowering the boat. Once the wind is more than 7-8 knots, I think it pays to sail with a relatively straight headstay. But is very important to sag the headstay in under 6 knots and aggressively so in under 5 knots. Sag also effectively narrows the sheeting angle of the big headsail which is good in light winds but negative above 8 knots.
The boat balances well at relatively high heel angles upwind because of the symmetric volume distribution, but it is important not to sail the boat too heeled. The boat is a light displacement boat and so it is important to twist the mainsail. The combination of mainsail trim and tab angle is a key adjustment and both controls are operated by the mainsail trimmer. My feeling is that it is better to sail with the mainsail relatively twisted and sail at higher upwind speeds, relying more on the trim tab to produce the height. The optimum rudder angle is between 3-6 degrees and the mainsail trimmer can see both the tab and rudder angle on a readout on the central grinding pedestal. Similarly I do not like to carry the traveler too high, except for in very light winds (under 6 knots) where the traveler can be trimmed well above centreline.
What sail when?
Depending on the design of your sails these ranges could change, but as a rough guide for the sizes my feeling for upwind is <11 knots genoa 1, < 15 knots genoa 2, genoa 3 >15 knots. Downwind I believe the cross over between the small and large gennaker is between 7-8 knots.
For the gennaker gybes (when the sheet is lead around the outside) the timing of the ease of the sheet is critical. The biggest mistake seems to be trying to float the sail through rather than easing the sheet early while there is still plenty of pressure in the gennaker. The objective is for the gennaker clew to blow as far forward as possible before the new sheet is aggressively trimmed on. Obviously the grinder at the central pedestal must be ready in the low gear with the overdrive function on. The helmsman needs to concentrate on performing a relatively smooth turn with a slight delay in the middle of the gybe to allow the new gennaker sheet to be trimmed in before heading the boat up to a tighter angle. Whoever casts off the old sheet must be sure to control the tension just enough so as to prevent the sheet dropping over the bow. For winds below 10 knots, I favour leading the gennaker sheets inside. It allows less ease in the sheet at the beginning of the gybe and a faster trim of the new sheet. It also means there is no possibility of the sheet falling under the bow. When in doubt, lead the gennaker sheet on the inside.
Downwind it also seems to be important to press the boat up and sail at higher speeds. The higher the boat speed the more critical it is to position the crew weight aft. As soon as the boat speed exceeds 10 knots it is better to move the crew weight aft. It is important to load the mainsail because this has a positive effect on the flow over the gennaker. It should look slightly overtrimmed compared with the normal trim on a conventional boat.
When sailing upwind, the topmast backstays are a useful control for mast bend. The check stays should be set so that when the backstay is fully tensioned the mast bend matches the luff curve of the mainsail to produce a fairly flat but controlled mainsail. In light winds the headstay ram should be eased to allow the aft edge of the mast to touch the back of the deck collar which induces a little bit of pre-bend. The backstays do not seem to have a big effect on the headstay tension which is primarily tensioned by the headstay hydraulic ram, but they are still important. The pitman controls the backstays so it is important to establish accurate marks for the various settings. I feel it is important for the pitman to not release the backstay too early when tacking in order to keep the mainsail and genoa as flat as possible as the boat luffs towards head to wind. Ideally the mainsail should be trimmed on a bit leading into a tack to allow the helmsman to use slightly less rudder at the beginning of the tack. The new backstay should obviously be trimmed on during the tack so that the headstay is sufficiently tight coming out of the tack. Only in winds below 6 knots does it pay to carry more sag in the genoa luff.
It is critical to use the short sheet on the genoa for the gennaker sets. If the genoa is eased too much the gennaker will be harder to hoist and may be caught behind the genoa battens. It is also critical not to hoist too early and to let the apparent boatspeed burn off slightly before hoisting otherwise the sail will blow too far backwards during the hoist. The gennaker is a big sail and the timing of the hoist is important.
The grinder on the central pedestal is a key position in this boat. They must be aware of all the tactical situations and be set in the correct gear and linked into the correct winch. This grinder can operate both the primary winches and the mainsheet winch. Rounding the bottom mark or when dipping another boat for example, it is usually preferable to top handle most of the genoa and grind the mainsail in to help the boat turn smoothly by using the correct combination of sail trim and rudder.
Gennaker hoists and drops:
Gennaker hoists and drops are an important area to make gains. First the bowman must take care to control the foot of the sail as the tack and pole are being extended. If any part of the foot of the sail is permitted to touch the water (even when the gennaker is already half hoisted) it can result in the sail being trapped in the water. It is important in all sets that the helmsman keeps the boat relatively flat while the gennaker is being hoisted.
In strong winds my advice is to wait until the boat is relatively flat and heading downwind before tightening the gennaker tack. The halyard should be hoisted using the windward primary winch set in overdrive. I advise having two people operating the pit, one for the gennnaker tack and pole controls and one for the halyards. The genoa halyard can be fully released as soon as the gennaker is more than three quarters hoisted because the soft hank system nicely contains the genoa on the foredeck.
For the drops it is important that the helmsman bears off and fully unloads the boat to enable the sail to be pulled in. Again the foot of the gennaker must be controlled by the bowman until the sail is fully lowered. It is possible to use the string line to drop and this may be lead onto the mainsheet winch or one of the primary winches. This type of drop takes excellent coordination with the pitman and grinders to ensure all lines are released at the right instant.
Crew weight is an important factor and so is good hiking. There are no class rules restricting or governing hiking so only the ISAF rules govern. I like to get everyone other than the pitman (who is tensioning the backstay) and the central grinder hiking out of a tack. Stability through hiking is most important when the boat is accelerating so strong hiking immediately out of tacks and gybes is very important.