February 14, 2017 Hours spent building to date: 3,406
February is a cruel month in New England. We always get a few 50 degree days early on (60 degrees this year) then get slammed. So between a blizzard, a regular snowstorm and a weather-delayed trip to New York, it has been hard to keep up a head of steam on Tardis.
Nevertheless, the bow thruster installation is done, and the doors are up to their fourth coat of varnish. The installation is quite complex since the thruster needs its own battery, a very heavy fuse, an emergency off switch, two-part paint inside and out, and finally bottom paint in the tunnel itself. But when I plugged in the controller today and hit the switch, it buzzed away mightily and looks and feels extremely solid.
According to the manual and a friend who has worked in boatyards for 40 years, once the thruster is sitting up on the tunnel, and all wired up, that’s it. But it has always seemed to me that in a heavy, cork-screwing sea, the weight of the motor bouncing around would put an awful lot of torque on the connections between the motor, tunnel and planking. I had a surveyor look at the installation on Memsahib, a 50-year-old conventional wooden boat with all kinds of plank movement going on, and he suggested building s substantial support cradle to hold the thruster motor absolutely rigid at all times. We did, and experienced no problems. Tardis is much more stable to begin with and the thruster and tunnel are much smaller, but I decided to add bracing to be absolutely sure the motor would never move. Vetus makes this easy with a sort of dome on the motor, which means I could fit a piece of plywood and brackets that would both hold the motor down and prevent any side-to-side movement.
Next up will be exterior varnish, hanging the doors and decking.
Thruster installation complete
Thruster fail-safe bracing
Flash makes a terrible picture, but there the prop is in it’s tunnel, ready to spin
Varnish buildup on the cabinet doors
February does have some consolations — Chatfield Brook in our favorite dog walking area
The Tardis Project 
Looks like you’ll be ready for a spring launch. Question…will you have a generator? Will you be installing a parallel switch to be able to access power from the house batteries to your start battery? How about a video of the launch day and first running of Tardis?
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No generator for now — just big batteries and for an outboard, a pretty good-sized alternator (27 amp and you are running it all the time). The battery combiner/isolator combines the batteries when it senses a charging current, and isolates the start battery when the house batteries are drawing current (and I do have an emergency switch). The thruster is on its own charging system, so in a pinch I could simply haul it back to the engine and use it to start. The boat will be leaving the shop for the engine in early April (I think). Lots of pictures and video then.
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All looking great so far, and I have followed all the way with great interest, but now I have a question, are you going to fit a screen of some sort over the bow truster tunnel ?
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On ships and superyachts the bow thrusters have bars running across them that are sort of oval in section to let enough water pass through to create thrust. But my manual says than on a small thruster not much can get in that would damage it and I would lose too much thrust, so I’m leaving it as is. Once or twice on Memsahib I thought something might be in the tunnel, but I just did a quick reverse and if there was anything it blew out.
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Are you using an automatic charging relay? If so, Is the thruster charger in the ACR circuit?
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The thruster will have its own charger, a Sterling battery-to-battery. It draws current from the house batteries when it senses a charging source and the house batteries are up to snuff. Avoids running huge cables to the back of the boat.
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