Re: [AlbinVega] questions: thru-hulls

[chris20636]

Has anyone replaced the through-hulls themselves? I plan to replace the gate valves this winter while the boat is out of the water. I have not noticed any leaks around the through-hulls. I usually go with the adage "If it ain't broke, don't fix it". However, if this is a "non-nightmare" task, I might attempt it. It seems to me the biggest hurdle would be to remove the old through-hulls. Are they glued (epoxy?) in place? Or is it just mechanical fastening with some sort of sealant. Can they be pryed out? or is some sort of cutting and grinding needed?

While on the subject, if I don't replace the through-hulls, are there available in the U.S. (West Marine, Boat US, or Boaters World) seacocks that will fit the Vega through-hulls? The ones I've seen in the cataloges are U.S. measure. Do I need to order from an international (metric) source?

Thanks,
Chris
V-2933
Chesapeake Bay, USA

 

[wxt8981]

Hi Chris;

I've replaced all the through-hulls. Basicely, it's a mechanical
fastening- though some
through-hulls are ducked away under the zink or some other (difficult to
get to) place
and the job becomes a nightmare. But be patient- and all will be okay.
The (new) seacocks are US measure (if you get everything at Boat US
etc.). These stores
(hopefully) should give you advise about the job (though I've found some
of the salespersons
would be better of selling donuts.
Wilhelm V-257

Chris Stevens wrote:

 

[hielke007]

Hi Chris, yes I\'ve replaced a few. Heated the nut-ring up with a
paintstripper (turbo hairdryer type) and unscrewed them with force.
After that I could click them out with help of a rubber hammer.
As far as I know (I might be contradicted now) there are no metric thru
hulls. Even the ones we buy in Europe are " inches / gas thread.
No problem there. Just remember to not entirely screw them close until
the sealant is dried out.
Success!
Hielke
V1033 Drivfjäder in Holland

 

[dobermanct_dave]

For what it's worth- I do recommend replacing all of the old through-hulls.
If there has been any galvanic corrosion, they could be weakened and not
show it.

 

[wxt8981]

Good point! There are more boats ruined by galvanic corrosion than any
other kind- if
your boat is docked at a marina.
Whenever I see an electrical cord leading to a boat- I insist on seeing
the charger. You wont
believe how many people with expensive boats use car battery chargers.
And those WILL
kill your boat!
Wilhelm V-257

BACHAND, Dave (Info. Tech. Services) wrote:

 

[bbach1949]

Chris: I replaced all the gate valves on my 1971 Vega V1071 with bronze
Apollo ball-type seacocks. Removing the thru-hulls was amazingly easy -
after removing the nut on the inside, use a wood block with a hole slightly
bigger than the outside diameter of the exterior flange. With this as a
spacer on the outside and a bolt and nut with fender washers on both inside
and outside, you can tighten the nut and the through-hull fitting will ease
out into the hole in the wood block without damaging the fiberglass. I
wouldn't just bang it out with a hammer - Vegas are tough but no sense
risking cracking the hull. If you want to see a drawing of this technique,
get Don Casey's book "This Old Boat". Get the book anyway since his advice
is worth the price.

Gate valves worked for 30+ years, but as an engineer friend told me, so did
underground fuel and heating oil tanks. Look what happened there! I agree
that bronze is a safe bet, but plastic (marelon) valves are used regularly,
and are de rigor for aluminum boats. They can melt but I've seen boats where
lightning has blown out a bronze through hull by melting the glass around the
fitting. Just my humble opinions. Bill Bach

 

[chris20636]

Thanks all, for through-hull and valve information. I guess I will do the job right, and replace both valves and through-hulls.

Bill (and group),
I considered using marelon for through-hulls and seacocks, NOT because of price. This seems one of those boat items where it doesn't pay to go inexpensive since failure means a probable sinking. I considered them because, as someone brought up, of galvanic corrosion protection. It would seem to me that plastic would negate this worry. I haven't heard the sea stories of melted marelon. However, I have heard sea stories of frigid water causing weakening and failure of the plastic. Since there is 6 inches of snow outside and the temps were down to near single digits (Fahrenheit) last night, this is my biggest concern with marelon, at the moment. Sea Story? Or real concern? Since I can combat galvanic corrosion by wiring the bronze to a zinc, but can't fight the cold weather, I am leaning heavily towards bronze, at the moment.

Chris

 

[brockhaus77]

I have heard a lot of "lore" about galvanic corrosion and the horrible
danger from other boats that have the wrong electrical connections in
the marina. Being a physicist (but not a technician), I'd appreciate
very much a clear explanation what it is that these boat owners (maybe
unknowingly me?) do wrong and how it affects other boats. I.e., how is
the grounding wire and the two phases typically connected to the
charger and the rest of the boat's electric system, how SHOULD they be
connected, and what goes typically wrong when using a "car battery
charger"?

Thanks - Sebastian

 

[chris20636]

Hi Sebastian,
I can't really answer your query in detail. However, a quick look at Nigel Calder's, Boatowner's Mechanical and Electrical Manual reveals that some car battery charger's do not use isolation transformers. "The neutral wires on both sides of the transfomer are in common with the DC ground side. In a reverse polarity situation these chargers will create strong stray currents." He also writes, "This can happen quite easily with the insertion of a two-prong plug in a receptacle the wrong way around ..."

Such stray current corrosion is a seperate issue from galvanic corrosion. However, in either case, the flow of electrons either from stray currents or from dissimiliar metals in contact (galvanic), supposedly, cause weakening of the metallic structure.

Calder's book also gives some trouble shooting advise on how to test for these conditions.

Chris

 

[dobermanct_dave]

Hello-

I have never actually seen it either. However I do see how it could happen.

If your boat is using shore power, and either the charger's output or the AC
shore power ground is connected to your boats common ground (assuming your
through hulls/shafts/rudder are bonded to the negative terminal of your
batteries!) there is the potential to create a ground loop. Knowing that AC
neutral isn't actually zero volts, but often around 5 or so, there is a real
possibility to create measurable currents. Also if the battery charger is
creating some voltage over ground, there could be stray currents.

The currents may not be great, but over a summer could do great damage.

Dave- Vega 2917.

 

[wxt8981]

The biggest problems are these cheap care chargers. (Beware! Many so
called "Marine
Chargers are no better!!!!)
The problem is that these chargers release AC and DC current, while a
good marine charger
only releases DC current.
You can check that very easy with a Volt-meter. If your neighbor (in a
marina) uses such a
cheap charger and has the polarity reversed, the you'll find out soon
enough that your boat is
disintegrating. That's the reason I always check other boats- it's easy
and may safe you a lot
of money!
Wilhelm V-257

brockhaus77 wrote:

 

[hielke007]

Good morning Wilhelm (and all interested in the subject),

Sounds like you make good points here, but aren't you assuming that all
the metal parts (i.e. through hulls, shaft etc.) are connected to ships
ground and each other?

The through hulls I use are not connected, only to a hose and also
my gearbox is isolated from the motor (Volvo MD2010) This means that
there can't run any current...

I think the theory described below -even being very viable- is more mend
for steel ships and the polyester Vega makes a pretty good isolator by
itself. I might be wrong and ignorant here...
Best regards,
Hielke van Oostrum

 

[stevebirch2002]

Hi All

In answer to this long-running question. I have never heard of a Vega sinking
through the galvanic action. Thorough checking of all seacocks and thru-hull
fittings should be made every year when yo apply ant-fouling etc. The
Scandanvian Vegas never seem to have an anode fitted and the fittings on these
always seems good though The Baltic is less salty and therefore less of an
electrolyte. I think the answer is just common sense and check fittings every
year, doesnt take too long.

Kind Regards and Happy Christams to all Vega ownersSteve Birch Vega "Southern Comfort" V1703

At 12:11 16/12/02 +0100, you wrote:

 

[mike_184_us]

Hi all.
Stephen, I have to correct you
In scandinavia we also use zink anodes - of course we do - anything else would be stupid.
I use anodes sitting behind the propellar - original Volvo Penta that are a little expensive. I use used ones when I teach about galvanic corrosion.
When boats are laying side by side in a marina, there will be a potential between two boats if the main plug isn't conneted with the two "legs" excately same way.
Here we use 230 volt ac - US use 110 volt ac - but in Europe there will be a potential of half voltage - 230/2=115 volt ac - between two boats laying side by side. Becouse of the very low current that will run, it have no matter, but there will be enough current to proceed the galvanic process.
You probably know the problem in your home too - from your hi-fi.
If you have low frequenzy noise in your speakers, it is almost certan that you have two or more units plugged "wrong way". If these units are made of aluminium, and you touch two units at the same time, you will feel vibrations, and you probably will feel a little electric shock too.
If all boat owners would use tree "leg" plugs, and continue with that on all main units - and connect the cores same way - there would be no problem.
Merry Christmas everyone - and a happy new Vega sailing year
Karl Erik - Vega #1941 - Denmark.
Stephen Birch steve@... wrote:Hi All

The
Scandanvian Vegas never seem to have an anode fitted and the fittings on these
always seems good though The Baltic is less salty and therefore less of an
electrolyte. I think the answer is just common sense and check fittings every
year, doesnt take too long.

Kind Regards and Happy Christams to all Vega owners

 

[brockhaus77]

Just out of curiosity,

what exactly do you do when you check other boats - do you board them
when the owner is absent and poke around (where exactly?) with a
voltmeter? What do you connect your two probe wires to? Did you ever
get into trouble with an uncooperative owner?

Thanks for all the advice, though! I am beginning to understand at
least one potential problem - if one of the phases from the AC hookup
(the "neutral" one) is connected to the boat "ground" (all the metal
parts and the negative battery terminal") a current can flow to the
next boat over if it is PROPERLY grounded (with the grounding prong of
ITS AC power connection).

Greetings - Sebastian

 

[wxt8981]

Hi Sebastian;

I ask the owner- it wouldn't be a good idea to step onto another boat.
Check with a voltmeter, you should only read DC current.

I have a shut-off system on my boat. I disconnect both, positive and
negatrive, hence when I charge, the wires go only to the batteries.
That way I don't have to worry about my next boat having the polarities
reversed.
Wilhelm V-257

brockhaus77 wrote:

 

[wxt8981]

Hi Stephen;

yes, the sleeve was an original one and I replaced with same. Though in the
meantime I've installed another engine (a Yanmar diesel) and now I have only
a shaft (no reversing gear but a gear box.).

Wilhelm V-257

Stephen Birch wrote: