restoring old wooden sailboat(refastening)

[CRS]

this boat is about 26' on deck w- full keel and needs a lot of restoration work on the topsides the hull is in fair condition but I would like to replace the screws on the planking what is a good way to do this ? Some I see are rusty so they may have been galvanized but over time ...

[gonzo]

Does it have electrolitic corrosion around the fasteners? How about the frames and other structural timbers?

[PAR]

The problem with fastener removal is the amount of damage that can happen removing the screws. The least damaging way and easiest to insure the fastener will come out clean is to drill the heads and use an "easy-out" bolt extractor.

This assumes the planking stock and framing is in good enough shape to be re-fastened. If you have iron sickness (mild steel screws) then the fastener holes should be considered suspect at least. This can lead to a bunch of unseen issues cropping up. A very complete inspection or survey is in order to insure you don't waste time, money and materials doing something before knowing what's really going on.

[gonzo]

ditto

[Dr. J]

crs, assuming that your boat is structurally sound (free of decay), the hull sides have retained their lines, and the faying surfaces between the planking and frames remain tight, then changing the fastenings is a relatively straightforward task. Removing the seam caulking (cotton/oakum) is your first priority before considering any refastening.This ensures that your planks will return to their original place. I always use a bit and brace when removing counter sunk screws. This affords you a sense of feel when backing the screw out. You must take care when doing this because the head will invariably snag up on the wood and create tear out. Then you will have to use a larger countersink at best, or repair the split surface at worst. Try tightening the fastening very slightly prior to backing it out. Once the fastening is removed, I would suggest installing a tapered plug in the hole before refastening. I use air dried edge grain red cedar shaped to a long taper, lightly tapped with a small mallet over the length and gently tapped into place until snug. Use care in tapping over the plug's surface so that you don't fracture it.You are only trying to soften the outer surface so that it will swell in the hole. In addition, do not drive the plug in too far or you will split the planking.If possible, using a heavier scheduled fastening will also ensure an acceptable fit. As previously stated by PAR, those areas that exhibit rust stains, can be a source of concern. Seek advice from your local shipyard if you cannot afford to have a surveyor or shipwright inspect it. Attempting to remove a rusted out screw is never an easy prospect. Usually the area of greatest corrosion is at the faying surface between the frame and plank. Therefore you face the prospect of a broken fastening because the fastening must travel several turns before coming free. If you are unable to remove a fastening that is exhibiting signs of rust, then I suggest removing as much rust as possible from the head and coating the fastening with blue steel prior to replugging /bunging the hole. This will help stop the staining and slow the corrosion process .Perhaps you could install a new fastening beside or between the old fastenings. Just remember to place it on a different grain line on your frame (it will help avoid splitting the frame).Then simply sand and fair the surface, undercoat and paint over. One should be aware, however, that any signs of rust (corrosion) are an indication of moisture. Eliminate the source first or your troubles have just begun.

[GDE]

Can't disagree with anything anyone has said so far, but the material the woodscrews are made of is pretty critical.

Mild steel can't cope with any moisture, brass is not strong enough in most structural settings, stainless steel 304 is OK but will weep, stain the timber and it work hardens, pretty much the same story with 316 - (it stays shinier longer).

The two materials preferred are Silicon-Bronze and Monel Metal. With Monel winning hand down in performance - the strength of high tensile steel, extreme malleability and no corrosion at all - ever.

I know you can get Silicon Bronze in the US, not so sure about Monel - both will be more expensive than stainless equivalents.

Regards,
Gordon

Bronze 1" X #8 17.14/ 100 SS= 11.80/ 100 Are they fair prices

[PAR]

#8 of what? Wood screws? Flat, pan, oval, rolled or cut threads?

The stainless prices seems retail, the bronze price seems very retail (high) but I'm getting my stuff wholesale, so it's tough to compare.

Try a company called "FastenAll"

Thank you very much for the pricing guide and the supplier. Rich

[gonzo]

Stainless steel should never be used below the waterline.

[Dutch Peter]

Originally Posted by gonzo

Stainless steel should never be used below the waterline.

Please explain Gonzo??

To my knowledge it shouldn't be a problem, provided you don't use other metals below the waterline!

[gonzo]

Stainless steel needs oxigen to create a protective barrier. Below the waterline it doesn't happen so there is crevice corrosion. At the contact surface between the metal and the hull, electrolisis scavenges the iron atoms. It creates microscopic tunnels that weaken the material and eventually make it fail.

[PAR]

Gonzo is correct in that the free oxygen found in the air,protects the steel from oxidation, but in the water oxygen is captured with hydrogen and can't protect the steel.

Completely entombed fasteners in true encapsulated epoxy construction methods, should keep your fasteners okay. Very few backyard builders are capable of true epoxy encapsulation construction and the fasteners ultimately end up living in wet wood and bilges, where corrosion and electrolysis will occur.

Use bronze. If there are fasteners other then bronze in your boat, they'll need be replaced with bronze also.

[Dutch Peter]

Thanks for the explanation, I now remember I read this somewhere before. Maybe an other thread?
Isn't it so that you can use st.st when the heads are countersunk and covered with a wooden plug?

Regards

[PAR]

Dutch Peter, in short, no. In theory yes, but speaking from the experience of having to remove what's left of the damn things after someone has been talked into to it, NO. The wood is going to get wet. This can't be prevented on any boat not stored in a museum. Any service at all will bring dings, scratches and other forms of breaches in the protective moisture barrier. Once the water gets in, it's just a mater of time, much faster in some types of woods, like white oak, for example.