S/V Soggy Paws - CSY 44 - Dave and Sherry McCampbell

Under Construction - Last Updated: 7 Aug 07.

Future Additions:
Cutlass Bearing Installation
Bow Eye
Dynaplate
Fishfinder Transducer

On Soggy Paws, for grounding, we use a 18"x 5/8" mast top aluminum spike connected through the mast and heavy copper wire to a 10'x2"x1/4" copper grounding bar mounted underwater on the hull. The three radios and the tuner all have quick disconnects, but I still have coax grounds to install. We use the oven and microwave as faraday cages for computers/electronics that are out but not permanently installed, and metalized shielding bags for all stored electrical/electronic equipment. So far no problems; I hope it stays that way.

The idea for the copper bar lightning ground came from the ABYC rules for boat lightning protection. Here is a link with a good discussion of lightning protection systems and the ABYC rules from a custom yacht designer dated 2007-09:

www.kastenmarine.com/Lightning.htm Here's what he says (comparing a 12' strip to a 1 sf plate):

"The ABYC suggests the use of a grounding strip, rather than a plate. The ABYC rule states: 'A grounding strip shall have a minimum thickness of 3/ 16 inch (5 mm), and a minimum width of 3/4 inch (19 mm).' A strip approximately one inch (25 mm) wide and 12 feet long (3.7 m) has nearly six times the amount of edge area exposed to the water, which will improve the dissipation of charges. 'The grounding strip, if used, shall extend from a point directly below the lightning protection mast, toward the aft end of the boat, where a direct connection can be made to the boat's engine'.
A grounding plate, if used instead, should be solid, rather than the sintered bronze type often used as radio grounds. The sponge-like structure of the sintered bronze plates may, in the event of a strike, allow the instant formation of steam, which could blow the plate apart, resulting in possible severe damage to the surrounding hull".

Your 4x6" grounding plate is probably a sintered Dynaplate, or similar, meant for use with an insulated backstay and an automatic antenna tuner to provide a connection to seawater as a ground plane (not ground) for an HF radio. As indicated above it should not be used as a lightning ground.

My copper bar is thru bolted to the hull on the port side running from about the forward main cabin bulkhead aft into the engine room. It took me some time to get the bolt spacing right so I could access them from inside the boat and not run them into a floor stringer. Two of the 3/8" bolts are nearly even with the mast so that I could get short runs of 2/0 wire to each from the mast without much bend. The connections need to be really solid, so I did the mast thru bolted connections while the mast was out of the boat 12 years ago.
I think the info you often see in lightning literature referring to a plate is old, and the bar recommendation is more recent. Several universities, including Florida and Illinois, and others, including NOAA and ABYC, have done a great deal of recent research on this subject. It is worthwhile knowing the source and date of info you read, as the recommendations are changing as new info becomes available. If you Google boat lightning grounds/protection you will find much more info on this, including this useful tidbit on Kasten's site:

"The top-most end, or air terminal, should be a sharply pointed spike. Alternately, a wire 'brush' type terminal can be placed at the masthead, with the bristles pointed upward. There are several claims that a single spike is more effective than a brush for dissipating the charge built up by the boat".

My spike is 5/8" aluminum, about 18" long. I threaded the bottom so I could bolt it through a web in the mast cap. I also have a short 6" spike I used when in the Fla Keys running under the 65' bridges. We have the 18" one on now that we have no bridges to go under.

Of all the scary things about cruising and boat ownership, lightning scares me the most. Not only because of the potential for huge repair expenses, but also because of the very real threat of loss of life. It is a serious subject worth careful consideration by anyone using a boat.

External Sea Strainers

At the advice of several lobster fishermen in the Keys I got rid of internal basket sea strainers 11 years ago and installed an external screen filter. There are several types, but all have a removable heavy screen plate with small holes to allow water, but nothing else of any size, to pass through. The Keys are terrible for grass getting into standard strainers, and was a real pain for me to have to dump it often while doing Boy Scout charters there my first year. Since I changed to the external screen, I have never seen grass or anything else in my raw water system, and I do check it periodically.

It might not be a good solution if you have one of those racing CSYs, but it sure eases my cruising workload. It really is a great help in screening out floating junk. Anything that it doesn't screen out will be so small that it will go all the way through your raw water system without causing a problem (except sand).

They come in several sizes and the biggest fits over both my engine raw water and refrigeration cooling water thru hulls. So your thru hull spacing is like mine you may only need one for the two most important intakes on the boat. The one you want is rectangular, has a slide out screen plate, and one end is higher than the other.

I bought mine years ago from Lewis Marine in Ft Lauderdale and recently bought a new screen from them. Here's the source for external raw water strainers with removable screens: Lewis Marine, Ft Lauderdale, Fl, fig 6826-Hull Intake Strainers w/ Slide Out Removable Screens, Part Nos 2349-2352, spare screens available, Mfg Tournament Marine Products by Buck Algonquin

Sen-Dure makes one without a removable screen and Groco makes one with an opening front door and SS screen. I like the Buck Algonquin one best. They are not cheap but they sure do work well, and you really only need one to cover the engine and refrig raw water intakes. I am using round strainers, fig 8561 over the commode and galley SW intakes.

Prop Guard, Line Cutter, Rudder Guard

While operating in the Florida Keys during lobster season, fouling trap lines in the unprotected prop is a constant problem. Dave and Jim Dill of Chilly Pepper designed this fin guard for the prop after considerable thought and consultation with the commercial lobstermen. It is heavy enough to handle almost any line but will still break away without damaging the hull in a heavy grounding. It is constructed of a 1/2" foam core with one layer of fiberglass cloth on each side and another layer around the edges. It is firmly bedded in an epoxy trench cut into the keel stub and then faired with epoxy and cavasil additive. It does a good job and guides about 75 percent of the trap lines under and away from the prop.

I have also installed a fiberglass tab between the aft end of the skeg and the forward end of the rudder to prevent a line from getting up into the gap between them. It is fastened only to the bottom of the skeg with 3 small SS screws. And finally I have installed a line cutter on the shaft just forward of the prop.

The photos below show the new shaft as it was originally installed in 2005, with about 10" between the aft end of the cutlass bearing and the forward end of the prop. Within two years I had to redo the installation because the extended length of the shaft wallowed out the cutlass bearing as the prop whipped around. The correct distance should be no more than 4 times the shaft diameter or 6" max. I cut the shaft to allow about 5", just enough room for the line cutter and the zinc. Now two years later all is well.