When there’s no room for error, even a small mechanical failure can make for a very bad day. In this case, one of the four main engines on Boston Harbor Cruises’ Regency remained in forward gear coming into Long Wharf and, with only seconds to figure out what was wrong and take action, time ran out. Regency crashed into Codziilla, then became wedged between a whale-watching boat and the harbor ferry Rookie. In the picture below, you can see the passengers on Regency’s top deck looking over to Codzilla in the foreground, that has been lifted and rolled toward the the wharf, with the ferry Rookie jammed between on the right.
Cruise ship loses power, collides into other vessels in #Boston Harbor @mcamk https://t.co/IBqsqkV1rC pic.twitter.com/9s6SIIlrm2
— Evan Kirstel (@evankirstel) August 13, 2016
We’ve ridden the ferry Rookie into Long Wharf in downtown Boston, a busy area with tour boats and ferries constantly coming and going and little room to maneuver. The ferries Claire and Rookie work the runs between the Charlestown Navy Yard and Long Wharf, doing alternate runs during busy times of the day. The video below shows docking and undocking of Claire and Rookie from the location where Rookie was hit, and the tight quarters the boats must operate in at Long Wharf.
The right answer in Regency‘s case, if you can figure out quickly enough that the engine is stuck in gear, is to kill that engine and operate on the remaining three. However, we know from experience that it’s very difficult to figure out what is going on quickly enough and shut down the affected mechanical system. Years ago we had a transmission control cable break when docking our last boat in tight quarters and relatively heavy wind. We got lucky and the cable broke during the shift from reverse to forward and left the transmission in neutral. Had it been in gear there’s no way we would have figured it out quickly enough and pictures of us would have been in the local boating magazines.
Thanks to Jonathan (http://mvdirona.com/general-comments/#comment-93820) for pointing this out.
Hi
I have just been reading your mechanical section. I am currently looking for a Nordhavn 47 or 50. Your comments are most interesting. I am simply writing to say thank you for making the effort to decimate all this knowledge to others. As an example oil analysis takes on an entirely different perspective after reading your considered comments.
Regards
Thanks for the positive feedback on the blog Richard. To be balanced, most of the experts I respect really like oil analysis. I’m just offering a different perspective based upon cost and hassle vs value and influenced heavily by us spending much of our time away from North America where it really is costly to send in sample and there is no way you are going to get the same oil you got in the US. Further complicating things, there are times when we are running on high sulphur diesel which isn’t ideal but it’s either that or learn to sail in some parts of the world.
We are careful to change the oil on the manufacturer recommended frequency if not earlier and we have invested in very detailed mechanical system monitoring with all the data stored every 5 seconds over the life of the boat. We know our lives depend upon our mechanical systems so we invest in protecting them and fully understanding them but, at least in our usage, oil analysis doesn’t seem worth it and my experience with oil analysis was always “looks OK but not perfect, better keep an eye on it” or “looks like a problem but won’t know for sure until we do a few more oil changes, better keep an eye on it”. I feel like I already keep an eye on it.
Damn auto correct of course it was disseminate.
I hear your concern on thermal issues with LiFePo4 and you are correct but any battery technology worth considering has a high energy to size ratio. Any of them can release a lot of energy. Even AGMs (Absorbed Glass Matt) have failure modes that can be nasty but there is no question that Lead-Acid technologies in general are well understood, well tested, and fairly thoroughly understood.
You were also pointing out that 3 volt LiFePo4 cells make it hard to isolate an individual cell from a battery bank and continue. Your right but this is also true of Lead Acid technologies. Lead Acid cells operate at 2.25V so you can’t actually shut them off individually as well. The house battery bank in Dirona is wired as 4 pairs of 12V batteries and you can turn off any pair of batteries since each pair forms a 24V bank and the 4 banks are parallelled. Each 12V battery in a pair are actually 6 cells so, even with our design, if we have a cell go bad, we can turn it off but, when we do, we are shutting off 11 other cells in two batteries at the same time. Since we have the 36 cells in the other three banks still able to run the boat we’re fine and can still run at 75% capacity. The same design is possible with LiFePo4 and, in fact, each bank would require slightly less cells since the nominal voltage of LiFeP4 is higher than Lead Acid.