[Amel Yacht Owners] Keel bolt bonding strap


alainfeuillet@...
 

dear alal,
I recently had to change also my bondoing strap. Pilgrim is hull N°26 and this is the second time it broke. Therefore I had some thoughts about copper and inoix in a salty environnment. I think it was a mistake from Amel, it may happen, to have copper on inox in the bilge. Therefore I changed for an inox strap and linked the inox strap to the copper bonding at the top, out of water. I used the sketch of Bill for the dimensions, just changed the material.
I believe this will brake after the boat is out of service...
Hope it helps
Wish you fair winds from Poros isalnd (Greeceà


Andrew & Kate Lamb
 

I think that is an interesting thought – I have not changed the bonding strap yet but I wonder about inox although I think copper is around 40 times more conductive that stainless steel so maybe that is a consideration?

 

Andrew

 

 

Ronpische

SM2k 472

Canet en Roussillion, France

 

 

 

From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Monday, March 09, 2015 8:47 AM
To: amelyachtowners@...
Subject: Re: [Amel Yacht Owners] Keel bolt bonding strap

 

 

dear alal,
I recently had to change also my bondoing strap. Pilgrim is hull N°26 and this is the second time it broke. Therefore I had some thoughts about copper and inoix in a salty environnment. I think it was a mistake from Amel, it may happen, to have copper on inox in the bilge. Therefore I changed for an inox strap and linked the inox strap to the copper bonding at the top, out of water. I used the sketch of Bill for the dimensions, just changed the material.
I believe this will brake after the boat is out of service...
Hope it helps
Wish you fair winds from Poros isalnd (Greeceà


Alan Leslie
 

And maybe the design is for copper because the copper will corrode before the keel bolt does (like zinc does), but maybe the keel bolt would corrode before the stainless (inox) strap ?? which would not be the best situation to be in !

I replaced mine with 1/4" x 1 1/2" copper......

Cheers
Alan
SV Elyse SM437   


alainfeuillet@...
 

Andrew, you are right; when replacing something, and even more considering Amel design,  all must be very carefully considered. As far as I know, this strap is only in place to carry eventual low currents in order to protect our iron cast queel from electrolysis. It is not designed to carry high currents such as lightning currents. If a thunderstrike had to take this way I would fear for my queel bolt and consequently for the whole boat.
Therefore inox seems to me good enough.
To be even more complete I used a 0,7mm inox sheet. The only available in this area in Greece.
Other comments would be welcome.
Alain


alainfeuillet@...
 

Alan,
per design the keel bolts shall be linked to the rudder zincs through the bonding strap and grounding lines (green and yellow color cables). The intent is to loose neither iron cast (keel), nor inox (keel bolt), nor copper (strap), but zinc.
I observe that when I removed the debris, the copper was destroyed few centimeters away from the nut. Copper was intact near the inox nut. If there had been electrolysis, copper would have been attacked preferably at the contact; therefore we may assume that the copper has been destroyed by what we throw with water in the bilge ie cleaning agents and chloride. It looks like chemical attack and not electrolysis.
As bolt and nuts were like new after 25 years, I expect my inox strap will follow the same way. Inox/inox contact seems to me the less risky assembly against electrolysis and nothing better than inox against chemicals.
Hope it helps to make our mind
Alain (S/V Pilgrim)


jjjk12s@...
 

I suppose technically the best to protect the strap would be a small zinc anode on it as the bilge water is not in the same water body as the rudder anode (unless you have a very big problem!). I would guess the copper is acting in a sacrificial way.

John, Maramu #91 Popeye




Andrew & Kate Lamb
 

I think an anode would need to be installed low down to be effective and would likely be harder to change than the copper strap in the first place, which probably brings the argument full circle I think. Difficult one I suspect a stainless steel strap is probably ok but …

 

Andrew

 

Ronpische

SM2k 472

Canet en Roussillion, France

 

 

From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Tuesday, March 10, 2015 8:24 AM
To: amelyachtowners@...
Subject: RE: [Amel Yacht Owners] Keel bolt bonding strap

 

 

I suppose technically the best to protect the strap would be a small zinc anode on it as the bilge water is not in the same water body as the rudder anode (unless you have a very big problem!). I would guess the copper is acting in a sacrificial way.

 

John, Maramu #91 Popeye