Tech Net W-X-Y-Z    

Query: Are propane water heaters recommended?
Comment:
I had an older one and removed it. The igniter was scary. (Dyad)

RECOMMENDED
An RV propane shower water heater works great. It mounts outdoors. Needs stainless steel screws, but includes propane regulator, handle, and hose. About $110. [2009] (Shamal)

Paloma Brand works well. (Shearwater)

THINGS THAT WORK
Auxiliary water heater element:
Nichrome wire wrapped around the body of the water heater, finished with metal-backed tape. Draws 20 amps for three wraps. (C_Language)

Query: What's the best watermaker feed pump to protect the main pump from running dry?
Comments:
Use an air conditioner pump. (Fooling Around)
An air conditioner pump could be a problem due to it using alternating current on a DC boat system. (C_Language)
Use a 12 volt bait-well pump which would be good for continuous use too. (Dyad)
In addition to the pump, put a Y valve bypass around the feed pump to protect the main pump. (Discovery)
Update solution: Replaced the pump with a bait-well pump, as recommended, and it's working well.  It solved the problem of recycle on/off which burned out the old pump.

Issue: Reduced output.
Comments:
Use an acid-based cleaner to remove calcium build-up.
Install a new membrane since your's is twelve years old.

Issue: I'd like a source for high pressure hoses.
Suggestions:
Rubber Specialties (Naked Lady)
Amazon Hose and Rubber (C_Language)

Query: How can you tell if the carbon filter is saturated?
Comment:
You can't tell by smell or look if the filter is saturated with chlorine or not.  Change the filter every three months.

Query: What's the standard pickling process?
Comments:
1.  Place two tablespoons of preservative in the filter canister, then fill with warm water with no filter.
2.  Set recycle valve to circulate.
3.  Follow by flush.
Comments:
There's no danger in using a too high concentration of preservative. It's just wasteful.
If there's no way to recirculate, just use 5 gallons of pickling solution. (Dot's Way)
Use a rubber band to remind yourself if the filter is in or out at recommissioning time. (Salty Paws)
Pickling filters are available. (C_Language)

Issue: Cannot successfully tighten 1/2" male nipple to female fitting. 
Comments:
Use a nylon washer to use as a compression piece.
Rescue Tape can help hold fittings together where access is limited.
Use an over hose as a sleeve with hose clamps.
No room to work? Split the hose sleeve, fill it with silicone, clamp.
Use food grade silicone grease.
Update: success. Cleaned all parts with an emery cloth and used light coating of silicone on the fitting before reassembling.

Issue: The salinity meter sometimes reports 0.
Comments:
Use ohm meter to check for loose connections.
Look for an open circuit somewhere in the system.

Query: I need a new watermaker. Any comments on Spectra clark pump?
Comments:
Spectra clark used to have problems with o ring failure years ago, but this has been fixed by the company.
Spectra recommends not running two pumps at the same time due to pressure getting too high on pump heads which leads to failure on seals.
It gets 7 gallons per hour at 6 amps.
Pre-filter came with a single 5 micron filter.
An added plankton filter is even better and won't change the output or quality at 105 ppm.
Spectra is a good company for customer service.

Issue: Failure of control circuits for watermaker.
Solution: Study the wiring diagram. Rewire motor contactors and product valve as necessary with simple toggle switches. Use direct wall outlet wiring if appropriate. Operate watermaker manually until proper parts can be obtained. (Paydirt)

Query: Which pumps are most cruisers using?
Comments:
Village Marine Tech; considered very reliable.
Cat Pump, which is easily repaired.
Aqua Pro; which is the same as Village Marine as they share the same phone number and address.

Issue: Watermaker gets hot to the touch; has no fan with the motor.
Comments:
It's most likely designed to run hot.
If it gets hotter on the generator, it may be a problem with the generator output frequency.
If you smell something, it's too hot, otherwise it's okay.
Place a 12 volt fan in the space. It works.
Low voltage at the pump will cause it to run hot. Check voltage.

Issue: Low water flow; very small amount of discharge.
Suggestions:
Pump may be airlocked, possible air leak on the input side.
Purge the feedpump.
Check for leaks on the suction side.
Watch electrical current draw. If the watermaker is doing it's job, the draw will increase.
Check the inlet strainer.

FLUSHING
Do not back flush with chlorinated water into the watermaker. That will ruin it.
Use the watermaker every day and you'll never need to back flush it.
Flush every day in hot weather due to faster algae growth.

MEMBRANES
Query: How long should a well-maintained membrane last?
Comments:
Have seen them last up to seven years.
Five to seven years is the average lifespan.

Query: Where can I find a replacement membrane for the Spectra?
Comments:
Boundless Outfitters of Boca Raton, FL (Discovery, Dyad)

If watermaker is running slow, two hours at 2/3 pressure will clean the membrane. (Kismet)

To easily remove end caps from membrane housing, use the watermaker feed pump pressure to help remove them.  Leave retainer clip in feed end, and remove clips in brine end.  Slowly increase the feed pressure.  The end cap will pop off gently at low pressure. Reconnect hose after draining. (Discovery)
Query: Is it a messy process?
No, if you drain the housing first. However, pressurizing with air only may cause the end cap to pop off quickly, and this could be dangerous.  Be careful.

Do an easy fresh water flush after each use. (Salty Paws)
New membranes can be purchased online for significant savings. (Trumpeter)
Before purchasing a watermaker, check it's membrane for compatibility with parts from other manufacturers. (Dyad)

FYI: Sodium metabisulfate, which is a compound that will pickle a watermaker, can be found at homemade beer brewing suppliers. (Cat Tales)

Spectra recommends not making water in areas that have a grayish caste.  Small particles move through the pre-filter then clog the membrane. (Mon Amie)

THINGS THAT WORK
Use a funnel and a hose to redirect and collect water from small leaks that pool where they can't be normally reached. (Trumpeter)

Issue: The sending unit on the water tank is stuck. I disconnected the leads, but it still reads full.
Comments:
Probably a bad wire.
Disconnect the other gauge that shares the display for diagnosis.
It may be a display module problem.
Sending unit may have a broken wire.
Selectively check wires by touching various combinations. See if display responds.

Issue: Found a bad O ring on inlet strainer.
Comment:
I had the same problem. I increased the diameter of the inlet hose to 3/4". It worked for the high volume system. (Shamal)

Issue: Pressurized fresh water system now has air in it; no leaks found.
Comments:
Look at the suction side of the pump.
Pressurize water tank to find the suction side leak.
There may be a crack in the diaphragm of the pump.
May have a leaky hot water tank.
Update: Still need to replace diaphragm, but fix will work for awhile: Silicone Vacuum Grease on the diaphragm worked. It's a food grade product by Dow-Corning. (Salty Paws)

ODOR REMOVAL
Query: How to remove odor from water lines?
Comments:
Use 1-2 cups of bleach in the lines and let sit about an hour.
Avoid bleach if water tank is aluminum.

After a bleach flush, use baking soda to remove chlorine taste.
Clean the screens at the faucet. That may be the source of odor.
Shore water may be the problem.
Use a charcoal filter.
Carbon filters will become saturated by chlorine, allowing the chlorine to flow through and damage watermaker membranes.
If vinyl lines are old, ,replace them with polyethylene. Vinyl will absorb odor over time.
Successfully flushed with bleach and used city water through lines for several hours. (JCD)

Remove charcoal filter during cleaning to prevent clogging it. Use baking soda to clean up and remove the last bit of odor from lines. Then reinstall the charcoal filter. (Destiny)

FRESHNESS
Use 1 quart peroxide per 100 gallons of water in fresh water tank. This will keep the water in good condition and will not be detected by taste. (Salty Paws)

Peroxide is safe for aluminum tanks and watermakers.
Vinegar will stun algae, but will not kill it.
Baking soda also works, but makes tea taste weird.
Use bleach in the tank to kill algae; but not in an aluminum tank.
Bleach in the water tank will boil off in 7-8 days in warm climates.
Cooties tend to grow on the warm and sunny side of the boat.

Use 1 gallon of bleach per 100 gallons of water for shock cleaning.
Use 1 cup of bleach per 100 gallons of water as a preventative.

FYI: Chlorine from city water will dissipate in up to 72 hours if there's airflow across the surface. (Salty Paws)

Pool testers will detect chlorine levels. (Kumbaya)

SALT CONCENTRATION
Do a taste test.
At 250+ ppm some folks can still taste the salt.
150 ppm is good water.

We use a Tracer brand hand held salinity tester. (Mon Amie)
Hanna Instruments makes a reliable tester also. (C_Language, Renaissance)

TANK GAUGES
Wema is a good brand.
Blue Sea brand is good.
Wema is accurate to the gallon. (Shamal)
Tank Tender is a very reliable system. (Dyad) Make sure there are no kinks in the tubes. (Dragon Seeker)

FYI: New polyethylene hose also comes in red and blue to color code hot and cold water. Home Depot carries it.

Water Pumps
Issue: SHURflo pump started leaking at the housing seal.
Comments:
Replace diaphragm housing assembly.
May have a hairline crack.  Pressurize the pump off line to locate possible leak.
If you use a sealant to repair the seal, just finger tighten until set. Then fully tighten for a better seal.
SHURflo has an adjustment for pressure. It may be set too high.

WATER TANKS
Query: How to repair pin holes in water tank?
Comment:
Drill out the holes with a 1/2" bit, then use a tap to give JB Weld or other epoxy an opportunity to grip well.

THINGS THAT WORK
Create new diaphragm out of  a Hypalon patch kit. It works. (C_Language)

Issue: I want to save files from hyperterminal to a second GPS. Cut and paste results in lost data.
Suggestion:
Use the capture text command to transfer text from one GPS to another.

Query: How to download them from the GPS? (Nobeltec v 7)
Suggestions:
Transfer with card. With hyperterminal, cut and paste with their undocumented ascii file.
Make a waypoint and give it and odd name, then do a computer search for that name, which should locate that file.
Nobeltec has an upload/download wizard.
Route transfer: the default is 8, but that can be increased to add characters for longer names.

HELPFUL SOFTWARE
Easily transfer routes and waypoints to Garmin with GPS Utility. This versatile software program can be downloaded as freeware or upgraded to shareware. (Shamal)

GPS Babel is a free and easy general purpose program to convert and transfer routes and waypoints. Works with CSV formats too. (Dyad)

(also GPS, OpenCPN)

Query: Is there a way to get weather faxes and briefings from NOAA through e-mail?
Comments:
Yes, you can get faxes via New Orleans. Open Airmail and go to fax. A click on the clock will give options for downloading of weather reports. (Soulmates)
Airmail - Modules > Internet Access > Settings or Setup.
Get text versions via e-mail by subscribing to Saildocs.com.  They are the "Internet Service for the Bandwidth-Impaired." No cost. (Salty Paws)

On Winlink, go to the catalog drop down box.  Up to 700 weather sources are there to choose from.

Weather maps through Airmail take about 20 minutes to download. (Scaramouche)

Pactor 3 is significantly faster than Pactor 2. Look for Pactor 3 broadcasts for weather info. (C_Language)

Kindle 3G will access weather info.

For weather faxes, CTTY is a good program that costs about $20. It works with speakers and is faster than Airmail. (Abraxis)

Upper sideband 6501 at 1700 ET, Coast Guard High Seas Weather.

BASRA broadcasts weather reports on SSB 4003 at 0630 a.m. daily.

The Waterway Net includes daily weather info.  SSB 7268 at 0745 a.m. (Valkyrie)



SUBSCRIBE TO CHRIS PARKER'S
Marine Weather Center.
Live daily weather reports on the SSB.



Online Sources
Grib.us has a downloadable product called uGrib, which if you like wind barbs, looks clean.
Passageweather.com (Salty Paws)
Sailflow.com
Storm Pulse for storm tracking. Tracks all major weather events. (Discovery)
Swellinfo.com
Wind Alert.com (Blue Highway)
Windfinder.com gives current wave heights, direction, etc. to make it easier to to decide whether offshore is a good option.  (Blackfoot)
Comment:
It's also good for wind direction and speed. (Cat Tales)

(also Pactor 3)

RECOMMENDED
BernzOmatic AL-3 4043 Aluminum Soldering Rod, brinell hardness 100; working temperature 700-750 F.
  "This alloy is especially useful in soldering aluminum windows and doors and miter joints. Ideal for sealing holes in aluminum boats... Useful in repairing outboard motor castings... Unexcelled for high strength and long service."
  The fact that you can weld aluminum with only a propane torch makes these must-have items. (St Jude)

SUPPLIERS
Sears
Ace Hardware
Aluminumbrazingrod.com

SERVICE
Capo Welding on Riberia Street St Augustine.
You can pull right up to their dock. (Dyad)

THINGS THAT WORK
MAPP for torch welding. It's an excellent gas for torch work. WallyWorld carries it. Using MAPP, rather than propane, will give hotter, better results. (Gypsy Sails)

Query: Is the waterproof ALFA directional adapter any good?
Comments:
It works fairly well.
It has mixed reviews.
It's not really 100% waterproof. It's connectors are vulnerable.]

Query: If I install a wifi cable on the backstay, will it interfere with the SSB antenna that's there?
Comments:
It should be fine if you're not running them both at the same time.
Unplug both ends of the wifi when using the SSB.
Wifi shouldn't be exposed to the saltwater environment. It will fry something eventually.
It will interfere with GPS.

Issue: My Air Card has a broken connector to the external connection.
Comments:
Try data-alliance.net for parts replacement.
The price of wifi adapters has dropped.  You may be better off buying a new one.

Issue: There's a Zoom Air Card available for cell phones.  I'd like information.
Comments:
It will work, but will not be fast enough for Skype, etc. You'll need to be within range of a Batelco Tower.
It's better than dial-up, but nowhere near the speed of DSL.
GSM Zoom card recommended for use in the Bahamas.  It will also work in the states.  GSM cell phones use Simm cards.

Query: Is there such a thing as an outdoor-rated wifi antenna?
Comments:
EnGenious makes one. It's well under $100. Don't put the box itself outside.
Use a PVC box to protect the unit from weather.
Visit HyperLink Wireless.

Query: How does cell phone wifi work?
Comment:
Your service uses your cell signal to connect and creates an access point on your boat.

Query: Where can I find a good wifi signal booster?
Suggestions:
EnGenious 200 mw wifi adapter. It plugs into the USB port.
The EnGenious with a 9DB antenna boosts signal by twice.
Terk brand wifi antenna.
Fivemiwifi is reported to be excellent. Pricey.
8.7 DB omni-directional antenna. Find one at Netgear.

Issue: EnGenious adapters failed from corrosion on connectors which broke on the USB on connector board. This happened to two of them. (Abraxis)
Comments:
Goop or BoeShield T9 on connectors may help prevent problems.
Re-house the unit in a new sealed box.
Try ALFA. It has presented no problems; reliable.

Heads Up: Wifi cards and adapters literally burn out from overheating in hot weather. Suggest using a fan or locate it in a physically cooler space. (Dyad)

ALFA does not work on a mac. (Calypso)

RECEPTION
We replaced 3' lengths of connected cable with one 15' cable. It improved the signal tremendously and removed line loss. (Salty Paws)

Side by Side Live Test Results:
ALFA and EnGenious Adapters
After using both adapters onboard, the live test of the two showed no change in the receive signals. At 500 milliwatts, almost no difference. The critical factor is receive gain; the antenna. Remember, the goal is receive sensitivity, not transmit. (Valkyrie)

In my side by side testing, the ALFA out-performed the EnGenious. ALFA can be found at data-alliance.net. [2010] (Abraxis)

PC Pitstop through-put tester checks total through-put on your wifi connection in live time.  Free. (Salty Paws)

SECURITY
Things that Work:
Since we all use wifi that is 99% unsecured, there is a risk of others snooping on your traffic.  As recommended by PC World, software is available to create a VPN (virtual private network) by encrypting the communications with the access point.  Hot Spot Shield is available as a free download from Anchorfree.com.  It's not a resource hog. We've been using this, and although it does require an extra step to start it, it seems well worthwhile. (Salty Paws)

Firefox has an extension plug-in to secure all.  And Gmail has an encryption option.  For more info on wifi security read Wifi Security User's Guide online. (Salty Paws)

RECOMMENDED
Wave RV Marine antenna. Have had good luck with it. (Scaramouche)
Comment:
It has a chip set inside which gets confused when several others are in the area.  Very waterproof. (Rachael)

PDA.net has an app for Smart Phones that allows the phone to work as a wifi connection to your computer. (Valkyrie)

ALFA AWUS036NH connects at 2000 mw, works faster, better, sees more stations.  Cost, including shipping was $30 at buy.com. (Salty Paws) [2011]
Or purchase through data-alliance.net. (Time Enough Too)
Marine Grade ALFA outdoor wireless with waterproof housing at Amazon. About $40 (C_Language) [2011]

Free Download Drivers for the ALFA adapter.  The latest driver allows you to adjust power output. (Siren, Salty Paws)

Island Time PC builds custom computer and wifi systems for cruisers. Very reasonably priced. (Discovery, Dot's Way)

(also cables, computers, internet)

Air Breeze will not spin freely after a strong wind event.  Gives two LED light blinks.
Comments:
It may be a failure of the mother board.  The two blinks point to that as a potential problem.
Remove wires running from the stator to control board. It should spin freely with stator disconnected. It's a test to see if the stator is shorted.

Issue: Air X stopped working just 30 days after being service. Brushes are intact and all connections are good.
Comments:
Adjust voltage. It may be too high.
Use a drill to spin the blades to test it.
Use a bolt as an adapter for testing.
Turn solar panels off.

Query: Where to purchase replacement blades for the Air X?
Comment:
Find them at silentwindgenerator.com.
Spreco blades will fit Air X.

Issue: The blades are out of balance.
Suggestions:
Clean up any corrosion. It builds up on blades and can unbalance them; it also may crack the housing.
When replacing blades, use TefGel. It works to prevent corrosion.

Issue: The Wind Bugger stopped working suddenly and the output is way down.
Comments:
Connect the diode to the battery directly.
Bypass the diode.

NOISE
Clamp diving weights on the wind generator mast. The extra weight mass baffles the noise. (C_Language)
A guy-wire could be helpful, by adding tension. (Salty Paws)
Cut the pipe in half. Put it back together with a rubber bushing in between. (Brilliant)
Add axial load to the bearings to reduce the noise. Use a spacer for the job. It will only slightly reduce speed. (C_Language)
Low-clearance bearings are quieter now and also have improved startup time. New blades from Portugal are extremely quiet. (C_Language)

care
Remove the prop hub when the unit is new, and use Tefgel or Never Seez to make sure you can take it off later if needed. (C_Language)

Remove the blades for long term storage. (Salty Paws)

Spray blades with Rustoleum paint to protect the fiberglass. (I Wanda)

Use two coats of any kind of spray paint and sand between coats to protect. (Discovery)

RECOMMENDED
D400 12 volt Wind Generator. They're made in England;  Trans Marine Pro is the U.S. distributer.  I've been pleased with mine. (Luna Sea)

Air Marine brand.  The only difference between the land version and the marine version is the housing. Buy the land version and save.  It can be painted if desired. (Rejoice)

Issue: The windlass loses power.
Comments:
Check all connections.
You should have 12 volts or more under load.
Check the transmission, the oil may need replenishing, the bearings may need grease.

Issue: Cone clutch cannot be tightened sufficiently. I've used spray paint to look for contact points. Looking for ideas to make better contact.
Comments:
Use valve grinding compound.
[counter:] Above may cause damage.
Use a brass shim-like material between the two surfaces along with grinding compound.

Query: I cleaned a lot of muck out of the windlass foot switch.  Before reinstalling it, should I use grease or lube inside?
Comment:
Use Lanocote. It works. Fill the entire space with it, since it's just a small space, it's fine. (Salty Paws)
Update: I used the Lanocote. It gets too stiff in cold weather and so the foot switch wouldn't turn off.
Comment:
Use dialectic grease.

Issue: Windlass fails to run during lifting; solenoid has been replaced.
Comments:
May need new brushes.
Brushes may be sticking. Clean them.  Tapping motor with soft hammer may help.
Thermal circuit breaker in motor may have tripped.
Voltage may be low; windlass then runs too hot.
Feel for heat on wire connections.

Query: How to increase the friction for the clutch? It's metal on metal.
Suggestions:
It may have had a 1/4" thick rubber-type ring which may have worn off.
Leather might work as a ring.
Try a grinding compound on it, then lubricate.
Use solder to find any irregularities.

Query: What lubrication to use on my old, unknown brand? It's a manual and has a dip stick.
Comments:
Use 90 weight gear oil.
Check the seals and and go slow with the fill.
Carb cleaner will rejuvenate the seals.

RECOMMENDED
A windlass can be rebuilt professionally at Lauderdale Battery. They also do all kinds of electrical work. (Blown Away)

Issue: I'm using XP on a notebook computer with serial to usb converter.  I get BSOD when transmitting.
Comments:
It may be radio interference.
Try using low power, which can be found through the Winlink audio control.
Try running on battery alone.
Go online and pick up a new driver for your usb adapter.

Query: Where can I find the offset frequencies menu?
Comment:
It's on the Winlink drop-down menu.

Issue: While offshore, Winlink on 3 megacycles caused crash of the auto pilot and other instruments.
Comments:
Try to reboot.
Disconnect different devices and nodes and use the simplest configurations to isolate the problem.
You may need ferrites when using 3-6 megs.

Query: How to remove large e-mails before downloading them when out of wifi range?
Comments:
Use Telnet connection. (Dyad)
Use preference options for size. (Destiny)
Grib files are immune to file size restrictions. (Bees Knees)
On Thursdays, on the Waterway Net, there's a Winlink expert available to answer questions. 7268 lower sideband.
Update: success. On the drop menu > Winlink 2000 > options message [set file size/capture options]. Will automatically delete anything above your set limit.

Query: Is Winlink compatible with a Mac?
Comment:
Yes.  It will run with a virtual XP configuration. See VirtualBox.org (free program).

Issue: Loss of mouse control when logging our of Winlink.
Suggestions:
Turn off terminal window before turning off radio.
Look at system device manager; use disable option for mouse.
Disable plug & play to the Edgeport adapter.
(see jumping mouse - for specific instructions)

BANDWIDTH SAVING
I have found that I can often succeed with email connections under very poor conditions by using Airmail's Telnet session.  The bandwidth requirement is so low that it will usually work when other browser based apps will not. (C_Language)
Winlink will not resend old messages.
Winlink deletes Chris's weather reports that are older than 2 days.

FYI: You can manage your own white list. Instructions are found under 'FAQ' at the Winlink site. (Blackfoot)

Winlink Spam Control instructions from Winlink. (Salty Paws)

Winlink online  (also winmor below)

"A New HF Transmission Protocol for Winlink 2000"
Winmor is similar to Winlink/AirMail but uses the PC sound card as a modem instead of Pactor. It's not as fast as Pactor 2 or as easy as Winlink. Good alternative for folks that don't need much bandwidth. And it makes a good back up or to have as a spare. (Cat  Tales, C_Language)

(also Winmor article by C_Language)

Issue:  Which works better Cetol or Armada?  
Comments:
Armada is better. It worked and patched in well. Cetol can be orange and Cetol lite is less orange. Armada is clear. (Second Sally)
Cetol is not as able to withstand abrasion. (Barefootin)
Natural Cetol looks like regular teak when cured. (Experience)
Our boat yard folks really like Cetol; Armada is less expensive. (Kismet)

Query: What would fix rotting underwater wood on my centerboard? The piece is no bigger than a 2x4.
Comments:
West Marine carries a wood repair product called
Git Rot. It's very good stuff.
Recreate the piece out of Corian.
Recreate the piece out of puck board (a vinyl based product).
In any case, use nylon screws for attaching.

FINISHES
Bristol Finish is a varnish and holds up well outdoors.

Minwax and Benjamin Moore both carry excellent water-based varnishes. (Dyad)

Tung Oil works well and is easy to apply. Durable. (Salty Paws, Beluga)

Ultimate Sole is a good finish for floors. It's high gloss and non-skid. (I Wanda)

FILLER
Elmer's brand Wood Filler. Paints beautifully, durable, easy to work with.
(Dyad)

THINGS THAT WORK
Vinegar cleans woodwork. (Barefootin)
..

(see satellite radio)
...

Zebra mussels are found in certain bodies of fresh water. Although they are killed in saltwater, they still cling until scraped off. (Dyad)
..

Query: My boat is kept in semi-fresh water.  The zincs still look perfect after nine months. Are the zincs even working?  Should I swap to magnesium?
Comments:
The zincs may be working just fine. You may not have electrolysis problems where you're at.
Electrolysis is much less of a problem in fresh water.
Magnesium was needed in the fresh water of the Great Lakes due to pitting problems, but magnesium will deteriorate quickly in salt water.
Set multimeter to milliamps. Put copper in water.  Measure from copper to boat ground.  Lower is better. (Naked Lady)

Issue: Erosion of bottom paint around the Dynaplate; especially the ground plane.
Comments:
Engine tied into the Dynaplate too.
Shore power at marinas exacerbate the problem.
Use galvanic isolator on AC system while at dock.
FYI: Galvanic isolator is also known as zinc saver.
Reduce electrical current leaks.
Compressors for the fridge can be a source of galvanic corrosion. Isolate mechanically. (Celebration)
Comments from Mon Amie:
Disconnect all electric except radio, which is connected to dynaplate.
Run heavy duty cables from engine to batteries and central ground bus. Do not connect dynaplate directly to this bus.

Query: How long should zincs last? Ours last less than a year.
Comments:
Depends on your cruising grounds and habits. When we dock behind our house, the neighborhood boat lifts eats them up. (Trumpeter)
Extended marina stays will eat them up quickly. Use sacrificial zinc. (Bees Knees)
Try larger zincs.
A grouper zinc at dockside will last 3-4 years. (Salty Paws)

SHAFT ZINC
Godfrey Zinc has a brass collar and lasts a year. It has never loosened up. Costs more, but lasts longer. (Mon Amie)

THINGS THAT WORK
Use a small pure silver (99.9%) bar. Hang it overboard with an ammeter to determine if you're over or under zincked.  Garfield Refining has silver. (Alcid)

FYI: You can make your own zincs.

RECOMMENDED
Discount Marine Supply online (Hershey, PA) has the best price on zincs, even with shipping. (Destiny)
Boatzincs.com has incredible prices and selection. (Trumpeter, Salty Paws)

Read
Seaworthy Magazine April 2011 (found by Valkyrie):
"Outdrive Corrosion Mysteries and How to Unravel Them"
Also "The Current Scoop on Galvanic Corrosion"

(also props, running gear) ..