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Catalina/Capri 25/250 Sailor's Forums

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Updating through-hull fittings ?

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tomh
1st Mate

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USA
83 Posts

Initially Posted - 02/29/2012 : 07:46:12

I read somewhere that the brass nipple through-hull fittings on my 1978 C25 should be updated. I thought that the recommendation was to go to a flanged plastic fitting but when I talked to a couple of repair shops, they told me that plastic is never used underwater. Has anyone had experience with this?

Tom

1978 C25 "Karma" #790
Toledo Beach Marina
LaSalle, Michigan

Edited by - on

Ape-X
Admiral

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USA
662 Posts

Response Posted - 02/29/2012 : 09:43:46

bronze seacocks. some will argue plastic is ok, though many recommend against plastic as you mentioned.

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Prospector
Master Marine Consultant

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Canada
3159 Posts

Response Posted - 02/29/2012 : 09:52:33

Mine are all plastic. They feel cheesy to operate. I would prefer bronze as well.

The plastic ones will bind if not lubed annually. Once they bind, you risk busting a handle off to get them to close.

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 02/29/2012 : 10:01:55

I have never lubed Marelon (glass reinforced nylon) seacocks), just cycle them at least once a month. Bronze or Marelon are both fine, but bronze does subjectively feel more substantial.

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OLarryR
Master Marine Consultant

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USA
3462 Posts

Response Posted - 02/29/2012 : 10:10:51

Well, calling it a comparison between Plastic and Bronze seacocks is not exactly accurate. They generally do not make seacocks out of plain plastic. What has been used and widely accepted is Marelon seacocks which are a proprietary glass reinforced plastic matl with tensile stress far greater than plastic and much closer to bronze. Bronze these days is not pure bronze and so many of the bronze seacocks being sold may not be to the advertized tensile strength of bronze and being a ,ower grade bronze may gic=ven time be subjected to corrosion if in seawater. They would hold up very wellbut just trying to point out that things are not quite so simple as comparing plastic to bronze. Marelon seacocks do not corrode. Below is a table I tried to paste into this posting and while it is listed vertically and hard to make out what it indicates, you can at least compare the tensile strengths or the different matls. Many of the later Cat 25s came with Marelon seacocks. I have not heard of many or even a few of these seacocks failing. I am sure there are some instances of failure with Marelon seacocks and there are also failures of bronze seacocks. if you do a search on Marelon vs bronze seacocks on the web, you will see that there is quite a debate over which is better. Both are UL approved.

My Cat 25 has Marelon seacocks. They are over 22 years old. If it can hold up for 22 years and I decided to replace them, I would not hesitate to buy Marelon seacocks. But bronze is okay as well and bronze is used probably on all larger and commercial boats...Then again what quality bronze are they furnishing for small seacocks....I think it then becomes a more even playing field.

Marelon® Comparision Chart

U.V. Degradation
Corrosion Resistance
Abrasion Resistance
Tensil Strength**
Flexural Modulus***
ABYC* Reg.
U.L.* Reg.
Total Score

MARELON®
10
10
10
10 (27,000psi)
10 (1,300,000mPa)
10
10
70

NYLON
6
10
5
10 (12,000psi)
4 (410,000mPa)
0
0
35

ACETAL
5
10
6
5 (10,000psi)
5 (450,000mPa)
0
0
31

PVC
3
10
2
3 (5,015psi)
3 (434,000mPa)
0
0
21

POLYPROPYLENE
8
10
7
2 (4,150psi)
2 (75,000mPa)
10
10
29

BRONZE
10
4
10
10 (35,000psi)
10 (15,000,000mPa)
10
10
64

BRASS
10
0
10
10 (45,000psi)
10 (11,000.00mPa)
0
0
40

* MINIMUM PHYSICAL PROPERTIES REQUIRED FOR APPROVAL ARE: Tensil strength 10,900psi 75mPa. Flexural modulus 500,000psi 3480mPa

** Value by test to ASTM D638 (American Society of Testing & Materials) Marelon is a registered trademark of Forespar Products Corporation.

***Value ny test to ASTM D790 (American Society of Testing & Mate

Edited by - on

Stinkpotter
Master Marine Consultant

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Djibouti
9080 Posts

Response Posted - 02/29/2012 : 10:12:08

You're right about doing the upgrade--the early models' "to-hulls" (bronze pipes set in mushrooms of resin) have literally crumbled in some people's hands when they removed them. If you Google "marelon vs bronze", you'll get a lot of inconclusive discussions in sailing forums. In a marina, Marelon is unaffected by stray current, or galvanic corrosion from a metal fitting attached to it, and is ABYC-approved for use below the waterline. The debate goes on...

Edited by - Stinkpotter on 02/29/2012 10:16:30

OLarryR
Master Marine Consultant

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USA
3462 Posts

Response Posted - 02/29/2012 : 10:30:01

I should have also added regarding the comments that the Marelon seacocks can get hard to turn the handle and some may fear that the handle would break. When I puchased my Cat25 from PO, the seacocks were indeed hard to turn the handles and I was also concerned that the handle(s) would break. What I do besides regularly cycling the valves, since my boat is generally in the water year-round, I take advantage of the short peruiod of time it is out when I get it annually pressure washed, to shove some grease up the inlet with a small brush from outside the hull. Then once the boat is lowered back into the water, I will cycle the seacocks to spread that grease on the seats and I have found doing this annual maintenance keeps the seacokcs fairly easy to turn with no danger of having to apply excessive force to open them and risk a handle breaking off. I suspect many boatowners do not regularly cycle the seacocks, maybe never for those that do not use the sinks. Even if the seacocks are always maintained in the closed position, it is a good idea to perform periodic cycling and/or annual greasing/cycling to keep to maintain easy operation. If they are never hard to open/close, then I would skip the greasing and just periodically cycle them as was already mentioned in above postings.

Edited by - on

islander
Master Marine Consultant

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USA
4024 Posts

Response Posted - 02/29/2012 : 11:24:14

I think he wants to know about replacing his thru-hulls, not the sea-cocks.

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britinusa
Web Editor

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USA
5404 Posts

Response Posted - 02/29/2012 : 12:44:45

I looked up the subject on [url="http://www.practical-sailor.com/issues/26_16/psadvisory/4072-1.html"]Practical Sailor[/url]

Paul

Edited by - on

redeye
Master Marine Consultant

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3476 Posts

Response Posted - 02/29/2012 : 13:01:58

<< they told me that plastic is never used underwater. >>

might be a terminology issue..

The white plastic "thu hulls" you see on the market are made for scuppers above the waterline. Never use them below ...

Marelon might be referred to as plastic, but you are really talking about a resin composite product.. they work great.

Bronze works great also.

Some places the bronze can get into an electrical field and get eaten up pretty quickly. A friend of mine just had that happen in Tampa.

Last year I had a Perko bronze valve and thu hull installed on mine and it is just as stiff as the marelon valves often are.

The professional that did my bottom job preferred Marelon and I had already bought bronze...

http://www.perko.com/catalog/category/underwater_hardware/product/434/

I used one of these and I'm in fresh water...

Edited by - redeye on 02/29/2012 13:11:42

jerlim
Master Marine Consultant

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USA
1484 Posts

Response Posted - 02/29/2012 : 14:12:19

After reading the insights of the dangers of the bronze pipe through-hulls, I set about to change mine, valves too. I'm here to say that it took a small pony and 4 scouts to remove the first through-hull. It was secure beyond my imagination... but once started I continued until it came out eventually and I changed the hardware (research previous threads to gain useful insights on redrilling the hole...) but choose to let the second valve/through-hull assembly stay as built...

Edited by - on

TakeFive
Master Marine Consultant

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2272 Posts

Response Posted - 02/29/2012 : 14:24:51

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jerlim
 ...I'm here to say that it took a small pony and 4 scouts to remove the first through-hull. It was secure beyond my imagination...<hr height="1" noshade id="quote"></blockquote id="quote">
Sounds like 5200 strikes again!

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 02/29/2012 : 18:57:50

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RhythmDoctor
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by jerlim
 ...I'm here to say that it took a small pony and 4 scouts to remove the first through-hull. It was secure beyond my imagination...<hr height="1" noshade id="quote"></blockquote id="quote">
Sounds like 5200 strikes again!
<hr height="1" noshade id="quote"></blockquote id="quote">

I think he's referring to his to-hulls and if so, there's no 5200 there.

Edited by - on

tomh
1st Mate

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USA
83 Posts

Response Posted - 03/01/2012 : 06:41:38

Ray,

you're right that it's terminology. I was using "plastic" as a general term. Thanks for clearing that up. This forum is proving to be a great educational opportunity for me and I know for others. Thanks to everyone.

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