Moving J/109 speed sensor to centerline


San Pedro
This is how I did several J-105 speedo’s. Cut a section of stringer out. Made a Fiberglass tube, about 5” diameter. Glassed it in. Bored hole, rebated core, filled with epoxy. Taped a stir stick at hull surface. Removed flange from speedo tube. Masked everything, buttered it up with thickened epoxy, and set it in. Next morning, I sanded the outside tube edges flush. Instantly cured tack to tack error!



Super Anarchist
As an amateur team, with limited time for training, we always want to sail the boat as close to 100% as possible. In one-design you get really good references sailing against similar boats, but with a J/109 or J/111 you spend most of your time sailing on your own.

For this, you need calibrated instruments that work.

The really big benefit is that when PolarBSP% = 100% you can focus on what's really important; strategy and tactics. And when it's 90% you can put in all your effort for 2 minutes to get that fixed.

When I coach new teams, I see them struggling with questions like "is this fast", "are there current", "has the wind gone right", "should we go to J3", "is this a good angle downwind", etc etc. ALL those questions have a definitive answer so why speculate and argue.

So I see spending a weekend to get the speedo mounted properly is a small investment to be able to answer hundreds of important questions during the season.
Its different here in the US. Plenty of 109 or 111 events to sail OD in. I see your point though.