choice of fasteners in restoration.

hello!

I am restoring a wooden sailing boat, that has a cast iron keel. The frames are fastened to the planking with copper rivets. I have to replace all the keel bolts, and I plan to replace them with galvanized bolts of just one bigger size than earlier (24mm). Maybe one size bigger, if it is called for after the sand blasting and painting of the ballast keel.

For fastening the other elements of the backbone, can I use other rust free metals, like stainless steel or bronze? I am wondering if I am safe to use other metals as long as I am not in direct interface with the ballast keel.

So, bolting the dead wood to the wood keel, bolting the stem to the wood keel, and other back bone structures, floor timbers to the frames etc. Am I safe in using stainless or bronze?

For fastening the planking to the frames, I intend to use silicon bronze screws. Both above and below the water line. Is that ok?

I am just looking for guidelines for a good choice of metals for different fastenings.

Thanks for any suggestions.

Mohan

side note: somoene suggested to me to change the iron keel to a lead keel so I can use bronze bolts. But as I see it, the boat has managed to live 1000 years with the old ballast keel and iron bolts. That is good enough for me, and so I decided to keep things the same as much as possible.

 

Mohan:
I am only replying to your thread because no one else has... yet.
Mind you, I am not a builder or designer but, there are many around here who are and will eventually see your thread and hopefully reply.

There are a great many threads concerning the use of various different fasteners... I would suggest looking in to them and doing a little research.

As for your using GALVANIZED bolts, it is my understanding that you'll probably want to stay away from this. Someone else, possibly "Par", can give you the specifics regarding why.

As for your other elements of the backbone structure, STAINLESS STEEL is not recomended for anything BELOW THE WATERLINE. This has to do with something called "DEZINCIFICATION" and again "Par" will no doubt be able to explain this to you. See the thread "SILICONE BRONZE VS. BRASS"
http://boatdesign.net/forums/showthread.php?t=15466

Silicon Bronze is the recomended metal for fastening below the waterline.

Now, for my big question... Are you sure that your boat is 1000 years old ?

Best of luck.......................................

 

yikes!!! it 100 years old not 1000

 

I agree with everything said by Vkrue, but like him also, I am not a builder or designer- just another humble owner and learner.
The real pro's will hopefully step up.

do you have any photo's of this 100 year old wooden boat (I love wooden boats). What sort is it, what design, what construction, and what wood, etc, etc...
Being an very old wooden boat, the fasteners may be just the tip of the iceberg within your restoration. Is there any woodrot, any iron sickness etc?

Best luck.
Looking forward to seing this 'old' lady.
Hans.

 

brr.. i must be sleeping in my brain.

I asked this question almost a year back and i completely forgot about it. How forgetful is that? I am sorry if I wasted anyone's time on this

here is the previous thread that addressed the keel bolt question.

http://boatdesign.net/forums/showthread.php/t=7212

But i still wonder, if the fact that the ballast keel being iron and the keel bolts are galvanised iron, should affect my choice of fasteners above the water line, and the other bolts under the water line.

Thanks for any comments on this.

regards

Mohan

 

hi Hans and Vic...

There is a photo of the boat at http://www.pakkurti.com/maritana

Thanks for the advice.

/mohan

 

Much advise can be offered, but in regard to iron fasteners in old boats, most, myself included, will strongly recommend you make every effort to remove these types of fasteners and replace with a more noble material.

Vessels with iron fasteners generally weren't intended to live a long time. You've gotten lucky, the boat has had reasonable care, little rough use, exc. Iron fasteners were the choice in less expensive builds of that era. Bronze was (and still is) the fastener of choice when you want it to last. Iron can be had that is very good, which is clearly the case in your boat. Good fasteners like these are difficult to find. Most iron today, is not the good quality stuff, used in your boat.

Typically in a case like yours, the first thing I do is correct the boat's shape as best as possible, considering there are no plans to mold templates from. This is a long, difficult process, which involves jacking, clamping, twisting and cursing her back into shape. Several months of forcing her into shape, to remove hog, frame sag, etc. and she can be carefully disassembled to get at the now properly shaped pieces. If this isn't done, you'll remake pieces and parts of the boat to the distorted shapes and you'll have a new boat with all the ill habits and looks of a 100 year old one.

It's very likely, darn near all of her structure will need to be replaced. As these pieces come out of the boat, every attempt possible should be made to find and root out the iron fasteners. Without going into real detail, the wooden structures are suffering from "iron sickness" which is what happens to wood when it surrounds rusting iron. It dramatically weakens it, making the surrounding wood, near a fastener hole for example, useless, which compromises the remaining structure. This is why we try to get the iron out of the boats we rebuild.

Do you have specific issues you'd like to discuss?

 

...iron again

hello PAR,

Thanks for your sharing you insight into this issue of metal fasteners.

I have decided that all fasteners that do not come in direct contact with the iron keel will be replaced by a metal like marine bronze.

But, I am a little confused by your answer in terms of what to do with the keel bolts. You recommend replacing all iron fasteners with some nobler metal. In the situation, that I am in, it seems like an expensive and unnecassary distraction to make a new keel in lead so that I solve the galvanic problem with keel bolts. If I used galvanisd bolts, the bolts will probably last another 50 years, and it is up to the owner 50 years from now to deal with that

What is the most pragmatic solution to the choice of material for the keel bolt?

thanks again and warm regards

mohan