moody 44 1995 Keel Bolts

[winckyst]

Dear all!
The keel bolts, nuts and plates in my new (old!)moody 44 are all badly corroded. bilge was floated cause of flair of hot water system but now very very dry!
First thought was to drop down keel and make it all new but after deep search (mainly via Moody owner association web site) we understood there is a big chance that bolts are ok and they are bad looking only from the upper side (the part you see in the bildge).
1/ do you have any relevant info about it?
2/ in case I need to replace the bolts+nuts+plates: do you recommend me to use S/S bolts or to stick to moody plane and use mild steel?
3/ according to your advice, where can I get all the 14 nuts and what will be the price for them?
similar issue(not my moody)in this kink:[URL="http://www.moa.myzen.co.uk/cgi-bin/discus/board-auth.cgi?lm=1231606798&file=/1159/10047.html."]
attached few photos.
we would like to start rift in 2 weeks time in Almerimar (Spain) ship yard.
thanks alot for any help!!!

[neilpride]

Looks really corroded, keel is lead? iron?
Im not sure about the bolts and nuts , but the backing plate can be SS made it in a local shop, and the bolts and nuts need to be with the builder specifications in terms of loads , elongation , shear , etc.. is not a simple hardware store bolt, if you can contact Moody about bolts specification can be a bonus.

The bolts at the picture looks very bad but you can try to do this test, take a wire brush or a circular wire brush and clean the top of the bolts , see if there is still healty thread around and clean all the loose scale , cut just a 1 mm on top of the bolts , if you get a bright and clean cut and the corrosion is just superficial and the thread is ok there is a chance to save the bolts, this is just in case you are determined to not drop the keel and do the whole thing new.

Btw, SS is the way to go, but need to be with the same strenght as the Mild steel bolts.
Good luck!!

[neilpride]

This 2 pics come from a guy with the same problem, boat is a moody 44 to.

1. PIC SHOW corrosion and rust
2. Pic after cleaning and brushing all the corrsion.

[seahag]

Hard to imagine Moody doesn't use ss bolts with their attention to quality. Makes me wonder because it seems like a no brainer.

[winckyst]

do you have is mail or link where i can contact the guy?
thanks!!!

[winckyst]

true
many moodies got the same problem.
keel is clast iron by the way

[neilpride]

Originally Posted by winckyst

do you have is mail or link where i can contact the guy?
thanks!!!

Hee no, i stole the pics from another forum , Ybw ...
But look, steel when rust and corroded looks pretty ugly, sometimes you still have healty material after a good cleaning process.

[noelex 77]

It's very hard to determine the condition of the keel bolts looking at the bits you can see. Steel is not a great material for these bolts, but not quite as stupid as you would imagine as the ordinary 304 or 316 SS suffers crevice corrosion if there is any moisture in the joint.
I don't understand why manufacturers do not specify some of the exotic SS that are resistant to crevice corosion, bronze or titanium depending on the keel material. The cost of dropping the keel to inspect the bolts is much more than using the best material for the job in the first place.

[bstreep]

We are looking at a similar issue - just no where near that bad! The nuts can be cut off using a nut splitter. You can then put new ones on. You should replace them with the SAME type nuts. Steel is much stronger than stainless - so unless someone tells you it's OK, don't just replace carbon steel with stainless steel.

[noelex 77]

Originally Posted by bstreep

We are looking at a similar issue - just no where near that bad! The nuts can be cut off using a nut splitter. You can then put new ones on. You should replace them with the SAME type nuts. Steel is much stronger than stainless - so unless someone tells you it's OK, don't just replace carbon steel with stainless steel.

The tensile and yield strength of steel and stainless steel is generally resonably similar, but does vary considerably with the different grades.
Keel bolts are generally massively over specified, but it doesn't take much corosion to make them marginal. Avoiding corrosion is the key to keeping your keel attached.

[Stumble]

I am actually in the process of working with some keel and boat manufacturers to switch from steel or 316 over to titanium. Both of these typical metals have real problems being used as keel bolts, and honestly I wouldn't recommend either. As pictured steel rusts from the top down, and is terrible in applications subject to salt water intrusion. 316 while much more corrosion resistant suffers from crevice corrosion and frankly a bilge is about the worst place in a boat for crevice corrosion to start and propagate.

By comparison Grade 5 titanium is about 2.5 times stronger than 316, and roughly 1.5 times the tensile strength of most mild steel and compares reasonably with all but the highest tensile strength steels. It also is completely non-corrosive in salt water environments (at tempratures below 215F). It does cost a little more at the front end, but since it is a permanent solution, it is gaining traction in the keel industry.

It you decide to replace them, Mars Keels has a nice guide to how to do it for lead keels. It is a pretty major project, and requires melting lead, but doable.

[Stumble]

Originally Posted by noelex 77

The tensile and yield strength of steel and stainless steel is generally resonably similar, but does vary considerably with the different grades.

Noelex,

This isn't really true. Here are some numbers...

........................Tensile............yield

316.....................84ksi...............30ksi
Grade 5 Titanium.130ksi.............120ksi
Aqualoy..............100ksi..............37ksi
C65500................92ksi..............55ksi
2205 duplex.........90ksi...............60ksi

So while the tensile strength is similar for 316 as compared to the 2205, the yield strength (the point at which it distorts) is not. On a highly engineered part, the only reasonable thing is to only replace a part with something that is either identacle to what was there, something better in all significant ways, or to reengineer the part to ensure it will withstand the loads.

[noelex 77]

Originally Posted by Stumble

Noelex,

This isn't really true. Here are some numbers...

........................Tensile............yield

316.....................84ksi...............30ksi
Grade 5 Titanium.130ksi.............120ksi
Aqualoy..............100ksi..............37ksi
C65500................92ksi..............55ksi
2205 duplex.........90ksi...............60ksi

So while the tensile strength is similar for 316 as compared to the 2205, the yield strength (the point at which it distorts) is not. On a highly engineered part, the only reasonable thing is to only replace a part with something that is either identacle to what was there, something better in all significant ways, or to reengineer the part to ensure it will withstand the loads.

I think you are misreading my post.
I was comparing carbon steel with stainless steel in response to bstreep comments that SS is not as strong as carbon steel.
You have quoted the tensile and yield strength of various stainless steels, titanium and bronze

Anyway it's great to see your company is providing engineering advice to replace 316 and 304 stainless steel with something that will last the life of the boat. For just a few dollars more boat manufacturers could do this in the first place.

[barnakiel]

I had a piece of corroded chain here. Very, very corroded. 10 mm material.

I had to cut it. Grabbed an angle grinder ... Inside, the material was pristine - full 9.99 mm of it.

I assume there is some time-exposure related factor in how much such steel corrodes. The cleaned part looks actually - clean.

I would undo some of the nuts while on dry and see how things look like around there.

b.

[minaret]

You can use ultrasound, x-ray radiography, or magnetic particle flaw detection to check the condition of keel bolts without removing them. This will tell you if you have corrosion anywhere in the bolts that you can't see. For a bigger boat it is much cheaper than dropping the keel for visual inspection, and more reliable.