"Larry"

If you have the electronics hooked to the starting battery, YES DO NOT
OPERATE ANY ELECTRONICS WITH THE STARTER! Awful transient voltage spikes
are caused by inductive kick in the starter....

Well, there is the first good reason I've heard for a separate starting
battery on my boat although I've always agreed that all powerboats and
larger sailboats should be set up that way.

Although my total electronics package is only about $1500, I'd still like to
protect it, primarily so I don't fimd myself without something up in the
wilds of Canada.

Options:

1) Remember to always run down the companionway and flip the instrument
switch I start or stop the engine. Not good in heavy traffic areas or to
goose the boat out of a potential jam in tight spots and fluky winds.
Anything requiring memory at my age is always suspect

2) A waterproof Instrument Master Switch next to the starter button. Easy
to implement, visual reminder. Only drawback would be waiting for GPS to
find birds again after starting or stopping engine unless I remember to
press any key to keep it going on batteries.

3) A NC relay wired into the starter circuit that disconnects the
instruments when the starter button is pushed. When the button is released
however, isn't there a chance that the magnetic fields could still be
collapsing through the starter coils after the relay releases? I was taught
on aircraft that shutdowns are more of a hazard than starts. Same GPS
restart issue as above.

4) One of my scientist girlfriends back in Woods Hole a few decades ago was
always fiddling with something called a voltage clamp while studying squid
nerves. Isn't there something that could be inserted in the feed to the
instruments that would restrict voltage spikes? There isn't on aircraft
but, if you ever want to hoot and hollar, get a tour behind the panel of a
GA aircraft. Not much progress since the Wright brothers there. Parts are
incredibly expensive because the FAA requires them to be replaced with
factory original or equal and Radio Shack doesn't sell stuff that cheap and
crude.

5) Install an aircraft size (for my little engine) starting battery totally
separate except for a VSR or battery combiner to charge the house bank after
the starting battery is brought back up. Since these mostly seem to connect
the batteries when the engine is running, it seems like start/stop
transients could still find their way through. Space is a big issue with
this option on my boat as is getting into the engine room to install and
properly anchor another battery box.

I'd really like to go with 3) or 4) if you think they would work and could
point me in the right direction.

BTW I spent most of yesterday morning gonig up and down the ladder on the
boat, walking around the boatyard, and squirming in and out of the engine
room being filmed for the Titanic show. The producer thought the short "who
is this masked naval architect?" clip should show me working on my boat.
The editor may ditch it later but there's a good chance you will see my boat
and engine room on the next Titanic show. It's currently scheduled for July
first but may be moved up. You'll see why option 5 doesn't appeal.

--
Roger Long