Re: [Amel Yacht Owners] Re: re caulking of stanchion base


James Alton
 

Bill Kinney,

   Actually you may have done yourself a favour by using the slotted head style.  While the hex and square drive heads are really convenient since slippage of the tool is reduced, in my experience the maximum torque that you can apply to the head is not nearly as great as with the slotted head in a screw material that is not hardened.  I have driven probably upwards of 30,000 slotted bronze and stainless screws slotted screws and if the tool fits the head really well and the the screws are driven true, it is quite possible to twist the head right off of the screw if too much torque is applied, often without any damage to the slot in the head.  2 years ago, I drove 6000 square drive screws and I had to be quite careful to keep the torque down to prevent the square in the screw from beginning to yield.  I never broke off a single head due to the torque limitation and had to throw out several hundred screws that were damaged.  Future removal of those screws is very iffy IMO.  I think that the square and perhaps the hex drives are more suitable in a material where the head can be hardened such as a deck screw made of carbon steel.  I am not a fastener expert so just sharing my experiences but unless I can find a good reason to switch from the original slotted, I am going back with the original head installed by Amel.   If anyone has any information showing that a head other than hex beats the maximum torque of a slotted head, please enlighten me.

Best,

James Alton
SV Sueño
Maramu #220

On Aug 7, 2018, at 12:10 PM, mfmcgovern@... [amelyachtowners] <amelyachtowners@...> wrote:

Davi,


That screw is black oxide coated mild steel.  It will rust in no time.  You want to use 316 Stainless Steel screws whenever you can on the boat.  Certainly for anything that is exposed to salt water.  Here is a link to a 316 Stainless Steel Hex Drive Flat Head screw should work for this application:  https://www.mcmaster.com/#93395a410/=1e1x4s3

Mark McGovern
SM 440 Cara
Deale, MD USA
 


---In amelyachtowners@...,
Davi,

That doesn't look like the right screw...  I do not think it is stainless...

The best choice would be part number Grainger Item# 26LG09  But before you order them, pull out one of t he existing screws to be sure the size and length is right!  All I know is what screws were used on my boat...

I used Grainger part number 31JR46.  It has a slotted head. I ordered them before I saw Joel's excellent suggestion to use the socket head screws. Next time!
 
Compass Marine has an excellent "how-to" page on the how's and why's of using butyl tape for sealing deck hardware.  https://marinehowto.com/bed-it-tape/

Bill Kinney
SM160, Harmonie
Annapolis, MD, USA



---In amelyachtowners@...,
Bill, Hi there.... is this the screw for the job, from grainger? I think I might be needing this soon on my SM #56... Got some butyl tape ordered too...so would I unseat the stanchion, clean the rust from everything, tef gel the screws as per your instructions in this thread, then only use butyl tape to cover the whole stanchion base and rescrew everything down? 

Many thanks... 
Davi
 
 


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