Sit in any good marina, and you will see many beautiful, expensive, and delicate modern hulls maneuvering with ease. Widely spaced twin props with bow and stern thrusters and added integration, and it's as if they are on rails. Catermerans are the epitome of this; they turn at their own length.
Anyone who has docked an old, large, long-keel yacht knows a different world where docking takes more planning and often more lines. (pun intentional). You have tide and windage, way, prop walk, a single prop, and a single rudder. Docking Vanguard stern-too, in the Med, has fallen into the second category. Props too close for much torque, the bow thruster is inexplicably ineffective, and there is no stern thruster.
A test of seamanship is not a bad lesson to learn, but it is also not great for stress levels. A kick ahead with rudders over will turn her from zero speed, but not a kick astern. She will steer both ways above 3kN but not astern below that. We steer Astern by using a P or S prop kick ahead, but it is not enough to take the Astern way off her if you are gentle. We eventually got the hang of it all, but it must be choreographed and is not for the faint-hearted.
Last week's blog covered this annoyingly ineffective 15kW Sidepower bow thruster. Two problems became apparent. The first was the port tunnel prop. It had been replaced in the Med incorrectly and was free-spinning (spigot behind the prop boss was incorrectly aligned). That's an easy fix, and it made the difference between basically useless and "some thrust, but don't rely on it". We did that before discharge from the transporter. Then we discussed the protective grills that are occluding the tunnel area and causing turbulence. Today, a diver removed those, plus a quick cleanup around the area.
A brief before-and-after test is enclosed below—full Stbd, then full Port against slack mooring lines. The results were clear: 19 counts with the grills were reduced to 13 without the grills. A noticeable increase in thrust accompanied this reduction in the count. Though not obvious on the video, it's enough to heel her over against taut bowlines. It's safe to say that after 9 months at sea, we've successfully resolved our bow thruster problem. It now operates as intended making good use of the 15kW available to turn her bow with ease.
Chris Leigh-Jones
Note to "Kitt" - enclosed above as promised. - Chris