Wayward waypoints, a bow-down boat and strange white powder
I have an integrated nav station, and I work out my waypoints on the chartplotter before I head offshore. I also do this before I start the engine to get out of the harbor. After starting the engine, though, the waypoints either disappear or are scrambled. “Low battery during engine starting” is what the manufacture of the chartplotter says. — Henry Meyer, Sandusky, OH
GORDON WEST REPLIES
I don’t agree with the manufacturer. I have seen the problem many times and even once did a plot of voltage sag during en- gine stating at the nav gear power input jack. Low voltage is not the problem. What I did discover on an oscilloscope was engine starter spikes getting into select marine electronic devices, scrambling and sometimes erasing waypoint memories. These starter motor spikes look like a data burst and can cause havoc on electronics wired in to interconnected batteries down below. The solution is to turn off the navigation gear at the circuit breaker feeding the voltage to the equipment before starting the engine. Just turning off the plotter before engine cranking may not be enough isolation. Another method that may work is to isolate the starting battery from your electronics house battery, although even this may not prevent small spikes to infiltrate gear during engine cranking. So, work up the waypoints, save them to memory, then power down the plotter, flip off the circuit breaker and give the engine a start. Once it’s running, turn back on the switches and the saved waypoints should show up as soon as your gear and GPS settle in.
NOT FLOATING ON LINES
Q: I have a 1974 Fuji 35 ketch, and we recently repowered from a Perkins 4-107 to a Beta 38. I do not know the weight difference, but it must be significant as the vessel now sets bow down 3 or 4in. What suggestions do you have to even it out? — Jon Reiswig Love, Juneau, AK
DON CASEY REPLIES
The difference in weight between these two engines is just under 200lb, not accounting for other bolt-on components. That means that if the bow-down attitude is attributable just to the repower-
ing, a 200lb crewmember standing directly above the engine should put the boat back on her lines. If that does not happen, there is something else going on: the fore/aft position of the engine, perhaps, or a modification of tankage. As for a solution, you have to find a way to take weight out of the forward part of the boat and move it aft. Relocating batteries, tools, chain, anchors and tanks tends to provide the largest effect.
STRANGE WHITE POWDER…
Q: My MD78 Volvo Engine has white powder appearing around the thermostat, block drain pet cock and portions of the head-to-block joint. The powder tastes like salt. Is there something I should do about this white powder to maintain the continuing excellent performance of my 35-year-old raw water-cooled engine? Early in my 16-year ownership of this vessel the powder began appearing. — Gerald Allen Stege, Via firstname.lastname@example.org
NIGEL CALER REPLIES
It seems a little hard to believe that all these components have taken to leaking saltwater, so maybe you are seeing minor galvanic corrosion with perhaps one or more small saltwater leaks. Regardless, personally, if the engine is otherwise running OK, I would not touch it! Once you start messing with it you will need parts, which you will then discover are hard to find and outrageously expensive. With an engine of this age, so long as it is running well you are generally best off doing nothing more than diligently performing routine maintenance and operating it until it fails, at which point you throw it away (or donate it to a museum) and don’t try to fix it!
CURVES FROM FLAT CLOTH
Q: I have recently bought a new genoa for my boat and I keep marveling at how beautiful the sail shape is. It really does look like the wing of an aircraft. I was wondering how sailmakers take flat pieces of cloth and turn them into a perfect aerodynamic shape. — Dexter Chernin, Bloomington, IN
BRIAN HANCOCK REPLIES
I assume you are talking about paneled sails, like a cross-cut sail. There are two ways that a sailmaker adds shape. The first involves the way the bottom of each panel is shaped, which is in the form of a long curve. The lower edge of the fabric is then hand cut along the curve, or cut with a laser cutter. After that, this curved section is stuck to the top of the panel below, where attaching a curved panel to a straight line induces shape into the sail. This is done at each seam so that you end up with a smooth, even shape from the foot of the sail to the head. Sail designers will also add shape to the luff curve of the sail. Specifically, while there will need to be some allowance for headstay sag, the designer might allow a little less than what’s needed for the sag, so that there is some “extra” fabric. This extra fabric is then fed into the body of the sail, which in turn, adds shape.
An MFD can “lose” its waypoints when subjected to power surges while the engine is starting
GORDON WEST IS AN ELECTRONICS EXPERT WHO SPECIALIZES IN RADIO COMMUNICATIONS
DON CASEY HAS WRITTEN MANY BOOKS AND ARTICLES ON MARINE MAINTENANCE AND REPAIRS
NIGEL CALDER IS AN AUTHOR AND EXPERT ON BOAT SYSTEMS AND DIESEL ENGINES
BRIAN HANCOCK IS A SAILMAKER, WHITBREAD RACE VETERAN AND CREATOR OF GREATCIRCLESAILS.COM
An oscilloscope shows the kinds of spikes that can affect a multifunction display