To Bond Or Not To Bond

[fstbttms]

Not specifically related to trawlers, but I know the level of expertise here is high, so I'll post this question anyway:

I have a new customer with a Prestige 560. The boat has a factory-installed H+B Technics tender lift mounted on the stern. While the lift has multiple anodes mounted on it, Prestige chose not to bond the lift to the large plate anodes on the transom that protect the transmissions and pod drives despite the fact that the H+B Technics manual specifically requires that the lift be connected to the boat's bonding system. Prestige does not include a boat-wide bonding system beyond the transom anode arrangement.

The question the boat captain has is; should the lift be connected to these transom anodes? Is there a downside to doing this? The lift has previously suffered some corrosion issues, which is why the question came up.

 

[psneeld]

For the money we are talking here...I would hire an ABYC corrosion certified tech and have him\her do an analysis and report.

I hate spending money as much as the next guy but it would come in handy when discussing with both the lift and boat manufacturers if there is no consensus.

My gut and experience would say bond to the plates, there are those that say not everything on a boat needs bonding...I lean towards the bond the large metal masses group....small distant seacocks and fittings less so.

 

[O C Diver]

Is the water the boat is in Salt, Brackish, or Fresh? If Brackish and some of the anodes are aluminum, bonding everything together can lead to faster deterioration of the aluminum anodes with the zinc basically not being used. This is also true if all the anodes are the same basic material such as zinc, with the most sacrificial one being eaten first. Agree with Psneeld that it would be advisable to check with a corrosion tech if for no other reason than liability. If bonding everything together is choosen, encourage the owner to have more frequent anode inspections done until the deterioration pattern is determined. Even if everything is tied to a large transom plate anode, there will be one or two smaller ones that dissolve much more quickly. At least that's what happens on my boat.

Ted

 

[fstbttms]

Is the water the boat is in Salt, Brackish, or Fresh?

The boat lives in saltwater and all anodes are zinc.

 

[O C Diver]

The boat lives in saltwater and all anodes are zinc.

Ok, that makes it easier if all the anodes are zinc. What you will find is that all the zincs aren't exactly the same material composition, so some make go faster than others.

As a side note, Side Power bow thrusters now come only with aluminum anodes. While they aren't usually tied to the bonding system, it could pose a problem if they were. As some manufacturers now choose aluminum instead of zinc, bonding may accelerate anode deterioration.

Ted