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ALLAN WARD · 28-04-2012, 04:14

I have a custom built S/S waterlock/drip tray which sits very neatly below my engine.I am now aware that with the combination of exhaust gases and salt water,this eventually leads to pitting ( corrosion ) which will result in leaks ,flooding the bilges. I believe the solution is to remove the waterlock,fill the unit with an epoxy type product and then spin the waterlock to line the interior walls and then drain the excess product. Has anyone had any experience with this problem and which products should be used to protect the inner walls of the waterlock.

RabidRabbit · 28-04-2012, 05:03

Fiberglass waterlift mufflers are pretty cheap. One of the few boating products resonably priced. The stainless one on my boat lasted 37 years before springing a tiny leak. And the replacement was only $130 at defender.

RabidRabbit · 28-04-2012, 05:13

Also,It never pays to have custom anything. It just means big bucks and more refit work to install a mass produced unit, new hoses, mount or pay to have another custom one built. Custom seems neat but really comes back to bite you in the ass and empty your wallet. The only guy who wins is the guy who built it $$$ and the next fellow to get the job to build a new one, again $$$.

sy_gilana · 28-04-2012, 05:27

Don't get me started. There are photos on our web page about these waterlocks. The epoxy coating will not work. Trust me on this...
I built a food factory once, you might know the product as Weetabix. We had 12 rotating steam powered retorts that cooked the grain with a mixture of salt and sugar. The "FDA" equivalent required us to use Stainless Steel 316L. They retorts lasted on average 6 weeks before springing a leak. I had one made with a low grade of SS, 3cr12, and it outlasted the others by a factor of 8. I then had one made up in boilerplate as an experiment. It lasted years and years. The corrosion you are talking about is a chemical reaction that erodes the steel, the Cr that is contained in stainless steel must be in an O2 rich environment. In an O2 depleted environment, the crevasse corrosion runs rampant (same reason you never have a stainless swivel or shackle on your ground tackle, and others)
Gilana was built to Lloyds 100/A1 scantlings. Our whole exhaust was stainless steel with rubber vibration bellows. The generator too had a 55Lb stainless box aqualift, with enough capacity to hold 3x the runback of the exhaust system.
I have removed, welded, fixed patched and cursed, until one day I chucked them out and put in a GRP one on the Detroit, and a plastic one on the Gen. I chucked the SS exhaust lines and replaced with exh. hose. I have never looked back since. IF you epoxy coat, you deny oxygen to the steel, precisely by coating the steel you will destroy it.

Get yourself a Vetus, or equivalent lift, and say good friggen riddance!
Trust me...

boden36 · 28-04-2012, 16:08

Agree with the above. Our SS waterlock has been rebuilt numerous times due to crevice corrosion. Next time will be a fibreglass one. Unfortunately we can not fit an off the shelf model.

Regards,
Richard.

hellosailor · 28-04-2012, 17:27

Allan, I suspect that unless you literally fill it with epoxy and coat it multiple times to try ensuring some thickness builds, you'll have problems anyhow. It might be more effective to have a new one fabbed up from fiberglass, and then at least you know you won't have more problems to come, or questions about how well the coating went.

IIRC there are also latex or other non-epoxy tank liners on the market, designed to coat the inside of fuel and other tanks. I don't know if those materials would be suitable for exhaust use, but would suggest looking into tank lining products because they are designed to coat, adhere, seal and build sufficient thickness to protect a tank from corrosion.

Cheechako · 28-04-2012, 17:31

Epoxy doesnt like hot water very well... dont ask how I know!

Chief Engineer · 28-04-2012, 17:58

tightwads use bondo

ALLAN WARD · 29-04-2012, 04:14

Many thanks to all of you who have replied,it is appreciated.Lining my beautiful custom waterlock does not seem to be an option so l need to move to plan B. The problem is that the Shearwater has very flat aft sections from behind the keel which results in shallow bilges around the engine box leaving little room for a decent sized water lock to contain the run back from a fairly lenghty exhaust.I need to re-design this system.

**noelex 77** · 29-04-2012, 04:42

Redesigning the system will probably not be easy. Make sure you follow all the guidelines so you do not end up with water in the engine.
If a commercial water lock will not fit, get someone to make up aspare in SS. It will last several years at least and you can always patch or reweld it for a tempory repair.
You can also custom make one out of fibreglass, but you need to use polyester. A boatbuilding friend of mine recommends aluminium water locks he claims they last forever ( or at least much longer than ss ) and are easy to custom make
I have had a few plastic ones split at the seems, so they are not foolproof.

**Wotname** · 29-04-2012, 05:02

Is there enough room around the existing SS one to laminate polyester GRP on the outside of it?

donradcliffe · 29-04-2012, 05:22

When my custom waterlock started to leak, I put a layer of fiberglass mat around the outside (excluding the top) with epoxy. Problem solved for my lifetime.

athene · 29-04-2012, 09:00

We had a similar problem with the custom-made s/s waterlock on our Oyster 435. Had a replacement waterlock fabricated in Turkey, which last precisely three seasons before corroding through. Fortunately, by then Vetus had launched a new, compact waterlock designed to fit in tight spaces (see Vetus-Shop.Com : Vetus Waterlock Muffler NLP50 50mm (Vetus NLP50)). Fits a treat and the engine is quiter now as a bonus.

GORDON KNIGHT

ALLAN WARD · 29-04-2012, 09:18

Once again,thanks for the great response.The one major issue l forgot to mention is that this entire waterlock/drip tray unit sits beneath my Perkins Prima M50 so it involves lifting the engine to remove it. You will probably think crazy idea but at the time l thought building one out of S/S was the best plan i.e. fit for life. I quite like the idea of possibly glassing the tank section so that if it leaks it would be contained in the fibreglass outer cover.