Cheoy Lee Lost Off NC

[Strygaldwir]

First let me say congratulations for getting off the boat safely Susan. That is by far the most important thing, as you have no doubt discovered.

Marelon has some outstanding properties. I replaced all my through-hulls with titanium several years ago. This was largely to address leaching and corrosion issues. When I did so, there were no titanium valves. That being the case and not wanting to experience any issues with galvanic corrosion, I used Marelon valves. I replaced them in 2004 and have checked all of them every time I haul. So far, there have been no degradation issues. At the 10 year mark, I might consider doing a preventative replacement, but still have a few years to go.

The second and probably most important point relates to the issue of saftey. I have had the privilege of doing several professional deliveries now. On of the lessons I have Really learned is "no mater how well maintained, or new, stuff breaks on boats" (want to say that again for emphasis!). We go over everything before we put out to sea. The list takes us almost a day to go through. Still, stuff breaks on boats! The most important thing we go through is our ditching routine. Who does what!!! Who pulls out the raft, who grabs the ditch bag, who calls for assistance, who deploys the dinghy... We make sure everyone knows the routine in an emergency situation. (Vest first, I pull life raft out of storage, cut dingy straps and man aft crank for dinghy, attach painter to dinghy, Throw in water at abandon decision.) So, we spend time making sure we can get to everything we need to abandon, we make sure all the safety equipment is in good order, we check the ditch bags to make sure no surprises in there. We don't count on someone being able to get to us quickly, but we do have multiple EPIRBs aboard. When necessary, I have brought my own along.

So the point is, STUFF BREAKS ON BOATS be as prepared as possible when it does.

[NeptunesTrident]

Originally Posted by zeehag

ok, then, splain why it is that 316 cracks at the bends and 304 doesnt.

316 cracks at the bends because it is not a ductile as 304. That crome molly is really pretty hard. 316 cracks when it is bent. If not visable at the time of the bend, there are microfractures for sure. 304 is more ductile. It has less of a tendency to crack at a bend. But it will.

Its a question of mechanical properties. Not how strong it is.

But dont get me wrong. I am not promoting 316 over 304. I think you made the right choice for the application.

[Cheechako]

if a chain plate is designed well and not at minimum size, the metal in the chainplate will be far stronger than the rest of the rig componants. 316 is more corrosion resistant than basic 304, corrosion is what typically kills chainplates, so 316 would be best. Regarding bending, it has a lot to do with the amount of cold work in the plate or bar used. Bar may have a lot of cold work in it, often so much so that it is magnetic. in general, most 300 series stainless is bendable to a 3 or 4 t bend ( 3 or 4 times thickness of the metal) through 180 degrees. Your chainplates will never see anything remotely near this bend. if you really want to worry about reducing corrosion in 300 series stainless, after fabricating them, have them solution heat treated, reducing all the stress, then have them finely electro polished.

[tropicalescape]

Originally Posted by mintyspilot

Susan,

I have read the postings about your boat and your experiences on it and I would like to contribute to the discussion.

First, let me set out my qualifications to pontificate on marine engineering: I know absolutely nothing about it whatsoever. However, I do know one or two things about aviation engineering and accident reporting which are (or should be) germane to this discussion.

I am a solo pilot and I have decided to save up and try a life on the ocean wave so, like you, I have lots to learn. Unlike you I am nowhere near the purchasing bit.

In an aviation accident report, those involved in the accident are never named. The purpose of the report is to help other pilots understand why the accident occurred and how it could have been avoided or minimised. Even when names are known, pilots are never chastised or "picked on". Anyone involved in aviation has this attitude to safety and disclosure pounded into them from day one.

As a result, I have found some of the comments made here totally alien to my way of thinking. This is an accident report. It is a learning opportunity. It should not be an opportunity for mudslinging. In balance I must also add that I was heartened to see that most of the posters reacted in a positive and constructive way.

This leads me to my second point. It is standard practice in aviation for a part to have a "lifetime". Even parts that appear 100% OK are discarded when they reach their mandated lifetime. This even applies to entire aircraft. Every aircraft has a maintenance logbook which lists everything about the aircraft. How many hours has it flown? How many landings have the tyres had? When was its last 50 hour engine inspection? When were the control cables last changed? etc etc.

It seems to me that a safety critical part such as a seacock should have a mandated life well within its expected failure lifetime. If past experience shows that (say) a seacock will fail in 10 years then they would have a mandated 6 year life.

Do boats lack a maintenance log of this sort?

I know one thing for sure. Reading this story has convinced me to institute an aircraft-like schedule on any boat I get my hands on. Seacocks shall be my first replacement.

Thank you for sharing your experiences. I shall remember them and apply the lessons.

If seacocks are responsable then it was "pilot error" at the end of the day..if you give it an aircraft inspection..DVC

[bassman1956]

316 is slightly more susceptible to stress corrosion cracking.

[sabray]

Originally Posted by bassman1956

316 is slightly more susceptible to stress corrosion cracking.

Huh 304 has a a higher strength 316L is more corrosion resistant. When using/ replacing 304 materials it is common to upsize to compensate for the slight strength loss with the added benefit of better corrosion resistance. I have never heard otherwise till now.

[zeehag]

Originally Posted by sabray

Huh 304 has a a higher strength 316L is more corrosion resistant. When using/ replacing 304 materials it is common to upsize to compensate for the slight strength loss with the added benefit of better corrosion resistance. I have never heard otherwise till now.

no matter what is used, one must realize that these components need to be constantly checked and inspected and every 20 years REPLACED. and when replacing the chain plates, might as well replace the tangs.

BANG is not a noise you wish to hear at sea.

[NeptunesTrident]

Originally Posted by sabray

Huh 304 has a a higher strength 316L is more corrosion resistant. When using/ replacing 304 materials it is common to upsize to compensate for the slight strength loss with the added benefit of better corrosion resistance. I have never heard otherwise till now.

304L and 316L have the same strength. 304 and 316 have the same strength. 75k psi. That is tensil strength. The difference between 304 and 316 is 316 is more corrorsion resistant. Molybdenum is the reason for this. It is also the reason 316 is more sensitive to cold working.

Bottom line, even if you have a steel or aluminum boat, the stainless fittings you use are stronger than the hull material. Any of it is fine, except the 400 and 200 series.

[NeptunesTrident]

Originally Posted by zeehag

no matter what is used, one must realize that these components need to be constantly checked and inspected and every 20 years REPLACED. and when replacing the chain plates, might as well replace the tangs.

BANG is not a noise you wish to hear at sea.

Can I get an A-MEN?!