| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1194.1 | Make it easy | ISLNDS::BAHLIN | | Tue May 02 1989 17:03 | 13 |
| Is your mast stepped on deck or keel? It might make a difference.
In general you want that lightning to get to ground by the most direct
route possible. Think of it as a high velocity water stream.
It will try to get to where it's going by the shortest unobstructed
route. This means no sharp bends (sweeping curves are better),
and not a lot of intervening connections (they will inevitably go bad).
The bottom line is that you are taming a very powerful force
(potentially speaking :^) )and if your wiring is not making it
easy, this force will find its own path. This self seeking is
what causes severe damage.
|
| 1194.2 | RE .1 | USMFG::RNICOLAZZO | Better living through chemistry | Tue May 02 1989 17:20 | 7 |
| The mast is deck stepped.
I was thinking about running the cable from the the back stay because
the dynaplate is mounted aft. This way i wouldn't have to fish the
cable through anything, and it would only have to be about 3 ft.
long.
|
| 1194.3 | DIRECT connections for lightning | DNEAST::PEASE_DAVE | I said Id have to think about it | Tue May 02 1989 19:55 | 22 |
|
When running for lightning protection, are you trying to dissipate
the charge to help prevent lightning, or trying to take care of a direct
hit?
The stay might disipate the charge ok. For direct hit protection,
a method that was described to me was to run a piece of copper pipe, thick
wall I think, directly from the base of the mast (thru the deck and a short
lead bolted to the mast) directly down to a dynaplate in the hold directly
under the mast. You probably have a post which ends a bulkhead directly
under the mast. You could attach the pipe to the bulkhead such that it
goes up thru the deck just outside of the mast mount plate. The placement
of the dynaplate might be obvious considering where the bottom ends up.
The location may be obvious, but the access may not.
Use a larger size dynaplate.
This was just a thought that was related to me. Your milage
may vary....
Dave
|
| 1194.4 | resistance | MPGS::SSMITH | | Wed May 03 1989 17:02 | 10 |
| I have no experience in this per se, but wouldn't you be concerned
about the electrical resistance of the backstay being sufficiently low?
In most systems the mast is the primary conductor in this case the
resistance might be high enough to blow the back stay away and you
could arguably lose the rig. Wouldn't the effort to snake a good
conductor be offset by this risk?
Hope this was just an idle concern. Good luck.
|
| 1194.5 | GROUND THE MAST! Also see note 952.* | HYDRA::HAYS | Can't go back and you can't stand still .. Phil Hays LTN1-1/Go8 | Thu May 04 1989 20:19 | 16 |
| RE:.0 by USMFG::RNICOLAZZO "Better living through chemistry"
> I just finished installing a Dynaplate and am not sure about the placement
> of the mast grounding wire.
GROUND THE MAST! The backstay will not do as good of a job protecting you
and your boat as the mast will. Hmm... Didn't we just finish going through
this a little while ago?
Anyways, the backstay will have over 100 times the resistance of the mast,
which means that a given lightning strike buildup over 100 times more voltage,
vastly increasing the chance of damage or death.
Phil
|
| 1194.6 | | SQPUFF::HASKELL | | Fri Jun 16 1989 15:17 | 19 |
| Crusing World mag July issue has a very indepth article on this
subject.
They recommend using AWG #8 wireand:
1. Ground each stay--fore, aft, upper shroud, and lower shrouds.
2. Ground the engine, gas tank, all electrical equipment.
3. Run a #8 wire the full length of the boat connected to the
Dynapalte and then connect all of the above to this wire.
Where possible, connect the grounding wires fron the standing
rigging to the plate directly.
4. Ground the mast.
Paul
|
| 1194.7 | | MSCSSE::BERENS | Alan Berens | Fri Jun 16 1989 16:13 | 10 |
| I'm surprised that the Cruising World article didn't mention that an
external metal keel is even better for grounding than a Dynaplate --
more area. One minor problem with using #8 wire -- it is expensive and
tends to be sold only in large quantities (like 500' spools). I would
think that soft copper tubing could be used instead. Connecting the
tubing would be easy -- flatten the end with a vise and drill a hole. It
has been pointed out that the heat from the current of a lightning bolt
might be enough to melt soldered connections. Better both a mechanical
connection (crimped terminals on wire) and a soldered connection.
|