Bronze or Stainless woodscrews

[Rum Run]

Hello All
In order to re-sheath the deck on my GRP hull + plywood deck Thompson T31 (built 1968) I am going to have to remove the toe rails and various fittings. The bungs in the toe rails are pretty good, but it looks like the screws underneath are plain steel as the heads have rusted to oblivion. The question is, should I use silicon bronze or stainless steel to replace them?
I would assume that the bronze option is better for corrosion than the stainless, but so far as I can tell at the moment, not having extracted one yet, they will be 12 gauge and 3" or more long, so the difference in price will be eyewatering i.e 27p each vs £1.15.
I am quite surprised that the original steel screws lasted this long without damaging the toe rails or even popping out all the bungs TBH

 

[ex-Gladys]

Hello All
In order to re-sheath the deck on my GRP hull + plywood deck Thompson T31 (built 1968) I am going to have to remove the toe rails and various fittings. The bungs in the toe rails are pretty good, but it looks like the screws underneath are plain steel as the heads have rusted to oblivion. The question is, should I use silicon bronze or stainless steel to replace them?
I would assume that the bronze option is better for corrosion than the stainless, but so far as I can tell at the moment, not having extracted one yet, they will be 12 gauge and 3" or more long, so the difference in price will be eyewatering i.e 27p each vs £1.15.
I am quite surprised that the original steel screws lasted this long without damaging the toe rails or even popping out all the bungs TBH

Where are you getting your quotes from? If you've got a load to buy, I would have thought you could have done much better than those prices. I've taken out brass/bronze screws from Gladys that were not much better than steel... If it was my, I'd go for stainless, as you only want to do it once!

 

[vyv_cox]

Silicon bronze would be my recommendation for below water wood screws but on deck I think you will get away with stainless steel. My toerail and hand rails are held on with stainless steel screws, have been there for 30 years. The wood around some looks a little blackened but the screws themselves come out OK.

On my 1972 motor sailer the timber strakes are attached with galvanised steel coach bolts, it is a never-ending project to replace them all, at staggered 2 inch pitch along the length of the boat, double in places, and many of them hidden behind furniture.

 

[Rum Run]

Where are you getting your quotes from? If you've got a load to buy, I would have thought you could have done much better than those prices. I've taken out brass/bronze screws from Gladys that were not much better than steel... If it was my, I'd go for stainless, as you only want to do it once!

27p for stainless at Sea Screw, £1.15 for bronze at Classic Marine. That's per each, + vat!
Actually Seaware is a bit better at a mere £1 plus the vat each
Looking at the price of phosphor bronze round bar which we use for work sometimes, I am not sure the actual price of the bronze woodscrews is very bad in fact.

 

[Rum Run]

Silicon bronze would be my recommendation for below water wood screws but on deck I think you will get away with stainless steel. My toerail and hand rails are held on with stainless steel screws, have been there for 30 years. The wood around some looks a little blackened but the screws themselves come out OK.

On my 1972 motor sailer the timber strakes are attached with galvanised steel coach bolts, it is a never-ending project to replace them all, at staggered 2 inch pitch along the length of the boat, double in places, and many of them hidden behind furniture.

You have my sympathy with the motor sailer Vyv, that sounds painful.
I will probably go with the stainless going by your experience. Did you use A2 or A4?
Also is there some magic unguent one can use to dip the screw in prior to driving or maybe pour down the hole in order to prevent / delay corrosion ? I will probably use candle wax to lubricate the driving process if there is nothing less 18th Century.

 

[DanTribe]

I replaced the toe rail on my Stella with stainless screws [A4, I think]. I had to remove a few 20 years later for a repair and they were as good as new.
As Vyv Cox says, not for use below water line. I used some to fit a rudder strap, after one seaon only the heads were left.

 

[Tranona]

You should not have any problem with corrosion with stainless, either A2 or A4 as water should not get anywhere near them if you seal the toerails etc. to the deck and then put the bungs in with epoxy. If you are buying a lot, then go to a fastening wholesaler rather than buying retail! Stainless is widely used to hold down teak decking - hundreds of them! Rarely a problem even when the deck starts leaking.

 

[tillergirl]

For goodness sake, get a quote from Anglia Stainless for both stainless and bronze. They are suppliers to most of the chandleries around here so much more reasonable.

 

[rob2]

There is a cheaper alternative. Brass screws should be adequate and have an acceptable life cycle, so long as they are well fitted. Afriend replaced the toe rails on a T24 by fitting with plain steel screws of the same pattern so as to cut the thread into the wood, then replacing each with brass before capping them off.

Incidentally, he raised the toerail on blocks to effectively create continuous scuppers. (Just an idea).

Rob.

 

[martinriches]

Screwfix will sell you 100 6x70mm a2 for £12.49

 

[Rum Run]

Screwfix will sell you 100 6x70mm a2 for £12.49

True, but the shank is thinner than a proper no.12 imperial screw, which has it's own issues if I want to use the original holes in the toe rails
I use screwfix a lot for work, but am wary of their products in a critical application eg where it would be a pain in the transome to do it again in this lifetime

 

[Rum Run]

For goodness sake, get a quote from Anglia Stainless for both stainless and bronze. They are suppliers to most of the chandleries around here so much more reasonable.

Will do. :encouragement:

 

[thinwater]

There is a cheaper alternative. Brass screws should be adequate and have an acceptable life cycle, so long as they are well fitted. Afriend replaced the toe rails on a T24 by fitting with plain steel screws of the same pattern so as to cut the thread into the wood, then replacing each with brass before capping them off.

Incidentally, he raised the toerail on blocks to effectively create continuous scuppers. (Just an idea).

Before I considered brass, I would look at 304 SS deck screws. MUCH cheaper, and I've used them a good bit on boats, including boarding ladders. No failures. Consider the vast numbers that are used on docks.

Rob.

 

[Deleted member 36384]

There is a cheaper alternative. Brass screws ...

All brass screws in my interior corroded and crumbled due to dezincification as evident in the pink metal when the screw head sheared off. The shipwright used stainless on the rebuild including on the teak cap over the gunwale. This was removed and re-bedded after various repairs.

In my opinion brass would be a very poor choice of screw. Then again, what is brass, such a variance in the material.

http://woodworkingtips.com/etips/etip63.html

https://en.wikipedia.org/wiki/Brass

The so-called dezincification resistant (DZR or DR) brasses, sometimes referred to as CR (corrosion resistant) brasses, are used where there is a large corrosion risk and where normal brasses do not meet the standards. Applications with high water temperatures, chlorides present, or deviating water qualities (soft water) play a role. DZR-brass is excellent in water boiler systems. This brass alloy must be produced with great care, with special attention placed on a balanced composition and proper production temperatures and parameters to avoid long-term failures.

 

[macd]

I've taken out brass/bronze screws from Gladys that were not much better than steel... If it was my, I'd go for stainless, as you only want to do it once!

Well, which were they: brass or bronze? And which brass or bronze? Big difference. Silicon bronze is certainly up to the job, at a price. But as said, even 304 stainless should be fine, especially if plugged and sealed as Tranona suggests.

All brass screws in my interior corroded and crumbled due to dezincification as evident in the pink metal when the screw head sheared off.
In my opinion brass would be a very poor choice of screw.

An experience shared by many of us, especially if there's the slightest dampness around.
You also link to DZR information. To the best of my knowledge there's no such thing as a DZR brass woodscrew. The alloy was developed for, and its use is (I think) confined to, pipe fittings.