Query about stopcocks and skin fittings

[Stooriefit]

Folks,

I have been checking over the seacocks on my boat and have decided that the raw water intake needs replaced. Rather than have the hassle of trying to work out if I have bought the 'correct bronze' I am thinking about using 'plastic' replacements for both the skin fitting and the ball valve. It seems to me these have a longer life expectancy anyway and I like the idea of fit and forget.

I have narrowed the choice down to Marelon made by Forespar and Trudesign. Trudesign will probably fit better into the space - the intake is down in the keel.

Before committing my self I wonder if anyone has any experience / comments (good or bad) on either of these products. Any other suggestions also welcome.

Many thanks

Alastair

 

[Sans Bateau]

Just been through the same process myself, in the end I bought DZR and gunmetal from ASAP.

 

[Ripster]

Just been through the same process myself, in the end I bought DZR and gunmetal from ASAP.

+1 did the same and used DZR. Could not decide if the plastic was hit or scraped by something, would it be strong enough - possibly?

 

[pvb]

I like the idea of Marelon, but I think that a metal through-hull fitting is inherently stronger. Perhaps a metal through-hull with a Marelon valve might be a good compromise? It's not difficult to buy DZR or bronze fittings.

 

[Sans Bateau]

I initially liked the idea of plastic, but if you look there are reports on 'tinternt of them sticking and needing lubing, not difficult to do, but have google and read for yourself, It put me off.

 

[Salty John]

I had Marelon seacocks and through hulls and they would be my choice again. They are immensely strong and not subject to corrosion, galvanic or otherwise.
I have no experience with Trudesign.
Whatever you choose make sure the thread on the seacock matches the thread on the through hull and whatever attaches to the inboard end of the seacock, such as a tailpiece to accept the hose. Threads can be tapered or straight (NPT or NPS) and you can't mix and match them. Marelon seacocks are NPS on inlet and outlet, metal seacocks are often NPS on one side (bottom) and NPT on the other (top).

 

[Caer Urfa]

Folks,

I have narrowed the choice down to Marelon made by Forespar and Trudesign. Trudesign will probably fit better into the space - the intake is down in the keel.

Before committing my self I wonder if anyone has any experience / comments (good or bad) on either of these products. Any other suggestions also welcome.

Many thanks

Alastair

Hi Alistair

I think you will find any good insurance company will take a very dim view of any 'plastic' underwater skin fittings.

If you think nothing will ever hit your skin fittings underwater and shear them off go ahead and fit plastic, but I want to sleep at night !

It's not rocket science in fitting the correct hull fittings, everyone has their own favorite, I personally have used 'Gunmetal' for years without any problems or needing to replace them http://www.asap-supplies.com/marine...infittings/gunmetal-skinfittings-bsp-standard

Also always sealed hull fittings with 'Korapur' Marine sealant again with no problems

Mike

 

[prv]

I think you will find any good insurance company will take a very dim view of any 'plastic' underwater skin fittings.

Good job your hull's not made of plastic then, isn't it. Oh, wait....

Marelon seacocks are a perfectly reputable option. I believe they're glass-reinforced nylon, much like a yacht hull. Not at all the same thing as the cheap white plastic hose fittings sometimes used well above the waterline.

Pete

 

[Salty John]

Yes, Marelon meets UL, ABYC and ISO standards for below waterline fittings. They've been around for about 30 years. They're actually glass reinforced nylon, Xytel, and are incredibly hard.

 

[mithril]

We bought a new Dufour 40 and one of its underwater skin fittings was plastic. First lift out I replaced it for boatyard recommended bronze/brass. I didn't like the idea of hitting floating debris and shearing it off. In later years I did put a hole in the hull but luckily it was just above the waterline. Hulls are much stronger that skin fittings and even they can be broken.

 

[ripvan1]

agree, silly remark about ins. co's - don't knock a proven product, or we'll get into an anchor-like thread

 

[tudorsailor]

I had marelon sea-cock on the brass skin fitting (!). I had the handle shear off when closing the sea-cock. Now have DZR sea-cock and skin fittings through-out

TudorSailor

 

[KellysEye]

All our throughulls are Marelon, as has been said they are imensely strong and don't corrode. I would strongly recommend them to anybody who is replacing throughulls.

 

[rotrax]

Hi Alistair

I think you will find any good insurance company will take a very dim view of any 'plastic' underwater skin fittings.

If you think nothing will ever hit your skin fittings underwater and shear them off go ahead and fit plastic, but I want to sleep at night !

It's not rocket science in fitting the correct hull fittings, everyone has their own favorite, I personally have used 'Gunmetal' for years without any problems or needing to replace them http://www.asap-supplies.com/marine...infittings/gunmetal-skinfittings-bsp-standard

Also always sealed hull fittings with 'Korapur' Marine sealant again with no problems

Mike

I think the blades of our Kiwi Prop are are similar reinforced composite material as the Marelon seacocks. It may be a bit simplistic but in this case it appears Bronze has been replaced with a modern plastic material. One would assume it has similar strength or it would not be used.

 

[Tranona]

There are mixed views of Marelon used in the engine compartment (OP is replacing an engine water inlet). The MCA will not accept it for coding because of the fire risk.

There is nothing wrong with that type of fitting except for the suggestion that the valves can stick if not operated regularly. However, unless it is in a steel hull, there is no clear advantage - and despite all the hype it is easy (and usually cheaper) to buy DZR.

 

[2Tizwoz]

My Brookes and Gatehouse skin fittings are plastic. Over thirty years old and no problems.

 

[CelebrityScandel]

If you are looking to using plastic and have any doubts whatsoever regarding using fibre reinforced through hull fittings and valves I suggest that you get a through hull fitting and try and "shear" it as some have claimed they are not reliable for. You will find that the advice they are giving, apparantly from positions of no experience whatsoever, is pure assumption as the fittings are extrememly strong and the best one can do is to distort them and that takes enormous effort.

Regarding valves one is not limited to the leisure marine targeted valves if wanting a seacock that will screw onto a through hull fitting as a good industrial valve supplier will be able to sell you (probably cheaper and better too) fibre reinforced plastic ball valves the lowest rated of which are rated for around 120-150 psi which is, of course, much more than any seacock is likely to ever face. They also have good teflon or similar seating surfaces, are ruggedly built and can be dismantled; we have used them for many years with never any problems at all and are also used by many good custom boatbuilders.

We have only had to dismantle them when it has been convenient to do so to get them into or out of tight corners as they have never required servicing apart from occasionally exercising them if they are in a situation where they are not regularly operated (as say in the case of deck or cockpit drains which are often needed to be left open all the time).

Regarding the insurance bogey the nay sayers on any matter throw up you will find that there is only potential for concern if they are fitted within an engine compartment (as I think another poster has already said).

 

[Stooriefit]

Thanks for all the replies.

The raw water intake I am talking about is situated in the keel away from the engine compartment so I'm not bothered about the issue of it catching fire. Frankly if the fire has got to where this seacock is then it will have burnt through 50% of the boat already and along the way will have consumed the hose that runs from the intake to the raw water pump. In any event not everyone wants to code their yacht.

After looking on the web I'm struggling to find any stories about the particular brands I mentioned having sticking problems. In any event bronze and DZR ones are equally liable to sticking if you don't work / maintain them.

Marelon and Trudesign are not just any plastic. As far as I can tell both companies have been making these products for about 30 years. I maybe wrong but as far as I can tell there doesn't seem to be any horror stories about these failing catastrophically either through being hit from the outside of the hull or from breaking off within the hull. Which at present can't be said about the numerous 'bronze varieties' many of which were probably bought assuming they were DZR. IMHO unless you buy solid bronze Blakes or Perko (at high prices) you can't be too sure about what you are actually buying. At least with Marelon and Trudesign you are buying known products at reasonable prices.

The insurance point is an interesting one although I'm tempted to think it is a red herring. Insurers at present are happily insuring new boats based on the RCD certification and yet if the reports in the press are credible new boats are being fitted with 'bronze' seacocks that won't last much longer than the 5 year min. requirement. My boat is 22 years old and the Marelon and Trudesign 'plastics' are expected to last as long as the GRP hull which is showing no signs of wear and tear. They are also specifically designed for underwater marine use and not something that is more suited to a domestic plumbing supply.

 

[Tranona]

IMHO unless you buy solid bronze Blakes or Perko (at high prices) you can't be too sure about what you are actually buying.

Blakes are not bronze - they have been DZR for many years. Perko may well be bronze, but suspect they will be very expensive.

DZR fittings are readily available, cheaper than alternatives and in a GRP boat will last as long as anything else.

This is not to deny the real problems that exist with some metal fittings, but it always seems, once you get the facts, due to use of the wrong material. This ignores the many thousands of boats fitted with DZR through hulls and ball valves which give no trouble.

The big advantage of Marelon fittings is for use on steel and aluminium hulls as they avoid the need to isolate the fitting from the hull, but that is not needed on a GRP hull.

 

[mithril]

I know its anecdotal but if the worst can happen then it usually does, luckily to someone else. And whatever is tried to be proved with anecdotal evidence can usually be disproved with a different story. Oh well!

We were in Lagos for the winter and a Dutch boat, 2 along from us, went out to anchor in Alvor, 5 miles along the coast. Alvor has a dredged entrance lined with large rocks to maintain a wide steep sided entrance channel. As they were leaving they got a rope around the prop and lost all drive causing them to drift on to the channel sides. A skin fitting sheared off and they sank.

The boat, one of the windscreen cruisers, was in the yard for a few weeks and we went aboard for a look-see. What a mess, how could so much mud come through a 2 inch-ish hole? It was sent back to Sweden for a complete refit internally. They lost a full season.
Maybe modern reinforced plastics are now stronger but its something I’ve not researched. I think you should.

Barry