I've also found that when 1-up on a F16 (A-cat or moth may well be different) that it pays to go to the least congested mark at the bottom gate. Less boats is more room for you to take down the spi and make a tight turn around the mark. In order to not waste much time on extra distance travelled make sure you have planned your approach well ahead and adjusted your sailed track accordingly.

Indeed this mark may well be less favoured but it is the better choice if the favoured mark is approached by you and 5 ot more other boats in a close procession.

If you are to late to make this decision then you'll just have to go for it and round together with the other boats. This will be hard but sometimes you can "slow down to win". This is can be a risky manouvre but does work well when the mark is heavily congested. Sail deep, till some 50-30 mtr above a beam reach to the mark, drop de kite earlier and then beam reach to the mark and round it really tight. Sometimes you can just pinch above the boats in front of you and you can always claim luffing rights to boats overtaking you. By sailing deep and a little away from the mark (A LITTLE) you have won yourself a free space of water to drop the kite with no hassle; as the sloop spi boats will come in hot to the mark and stay above you.

When rounding the A-mark (or offset mark); Dive deep and claim free water below you. Remain on the same tack if you effectively defend your free leeward water gybe immediately at the mark when you can't. Sloop 2-up spi boats will luff you up under spi when they can get behind you, bringing you in heaps of trouble. As you typically run deep you also don't want the sloops with spi to run over you and take you air. So defending you leeward water and also clean air but choosing the right manouvre/course is very important at after rounding the top mark. Remember the 1-up F16 strong point is running deep in clean air and free leewater with a hull just lifted under spinnnaker. You don't even have to trapeze, I mostly don't (but I'm 90 kg). Set yourself off right at the offset mark and you can make really good gains under spi.

And again race your own race upwind where you only try to minimize any hits. If you can stay with the pack then you are doing well enough. Make your gains on the spi rides !

Racing a F16 1-up in a larger fleet is a challenging activity, and does indeed seperate the men from the boys. When done right it is a major thrill and achievement.

Best of luck

Wouter