Re: Jeanneau Attalia
Issue i see is you are using gps speed! so if you are going 4 knots on one leg/tack, but 6 on the other........do you have a 2 knot current against on the slow, so 4 knots plus 2 knots current equals the 6 knots on the other leg. Or the other leg has 5 knots boat speed plus one knot current. Other leg is 5 kntos boat speed less one knot current.
Reality is here, you need to look at the knot meter, NOT the GPS as your only measure of speed. GPS will tell you over the ground, knot meter tells you actual water speed. As noted, over the ground can be different than water speed!
speed for me is in the mid to upper 5's, sometimes low 6's for 10-15, 15-20 depending upon the sail up, can be over powered with a 155, and need to go to a 140 or a 155 with a reef. upper 5s and lower 6's upwind, surf into the low 8's down wind, with 6 pretty consistant. I can usually do .5 knots boat speed per knot of wind down wind to a degree.
You might also check the mast center same with spreader area. are the spreaders the same ht to the deck on ea side. along with is the tension on the shrouds correct. Not to loose etc.
She drives me boat,
I drives me dinghy!