Possible electrolysis/ dezincification on p brackets

[Restoration man]

Ok I’ve taken the p brackets off my Storebro biscay 31 as I wasn’t that happy with them and wanted to re seal everything under the water see other thread prop shaft alignment ,I’m a bit worried I might have electrolysis problem / dezincification?? The One on the left is more of a rose gold colour it’s not patchy or anything like that ,there is a little bit of surface pitting but that seems to grind / sand out, the one on the right is more of a gold bullion colour, one of them might have been replaced at some time hence the different colour ??? If I only had one I prob wouldn’t know the difference,Do any of you know if this is still safe to use ????

 

[oldgit]

To replace those will involve considerable outlay. Think Close to £1000.00
Looks like a few more years of life left there.
No obvious fatique cracks anywhere due to impact. ?
Is there a nice solid donk of metal when you hit them with hammer.
Bolt back on and make sure one bolt is grounded to anodes.
Personally think painting is waste of time, just cover with A/F .

 

[Restoration man]

To replace those will involve considerable outlay. Think Close to £1000.00
Looks like a few more years of life left there.
No obvious fatique cracks anywhere due to impact. ?
Is there a nice solid donk of metal when you hit them with hammer.
Bolt back on and make sure one bolt is grounded to anodes.
Personally think painting is waste of time, just cover with A/F .

Thanks oldgit , they look ok so far but I will have to get rest of paint off and see ,it’s just that the one looked a bit pink, hence me wondering,Also they have stainless bolts is that normal ? I heard someone say they should be bronze bolts ???

 

[oldgit]

Thanks oldgit , they look ok so far but I will have to get rest of paint off and see ,it’s just that the one looked a bit pink, hence me wondering,Also they have stainless bolts is that normal ? I heard someone say they should be bronze bolts ???

Nuts/ bolts and washers holding on my P brackets are stainless.

 

[Reality61]

My Princess had pinking of the p brackets this year when out, I have re bonded all the fittings as the connections often go green, is everything bonded ?
I also think although not sure the bolts are normally bronze as well ? mixing metals is not good the same as on skin fittings which makes them go pink.

You need to take resistance readings from every fitting to fitting .( Anode to Shaft to prop, anode to shaft to p braket, prop to anode, p bracket rudder to prop, shaft, p bracket anode so everything relates etc etc and side to side there are often plates linking the bolts inside on the p bracket these are normally double nutted ) the reading needs to be as close to 0.0 as possible dont know the upper limit allowed, but you need to checkon on this, I just happened to be there when mine was being tested. Once you find the high place you can work an earthing/bonding solution but they all should be linked, shaft is normally a problem as some of the earthing solutions need attention regularly. Antifouling rudders and p brackets can insulate them which can add to the problem. Once you find and stop it you will get many years fom your existing under water gear.
Hope you find a solution.

 

[Restoration man]

My Princess had pinking of the p brackets this year when out, I have re bonded all the fittings as the connections often go green, is everything bonded ?
I also think although not sure the bolts are normally bronze as well ? mixing metals is not good the same as on skin fittings which makes them go pink.

You need to take resistance readings from every fitting to fitting .( Anode to Shaft to prop, anode to shaft to p braket, prop to anode, p bracket rudder to prop, shaft, p bracket anode so everything relates etc etc and side to side there are often plates linking the bolts inside on the p bracket these are normally double nutted ) the reading needs to be as close to 0.0 as possible dont know the upper limit allowed, but you need to checkon on this, I just happened to be there when mine was being tested. Once you find the high place you can work an earthing/bonding solution but they all should be linked, shaft is normally a problem as some of the earthing solutions need attention regularly. Antifouling rudders and p brackets can insulate them which can add to the problem. Once you find and stop it you will get many years fom your existing under water gear.
Hope you find a solution.

thanks , I bought the boat cheap so I expected to do all this work , just want to do it right first time hence my questions,I’ve also removed all the skin fittings and ball valves and putting new ones on regardless of condition , at that point I noticed that they had attempted to earth Bond all the skin fittings as well , so one big round anode on the transom was earthing the all the skin fittings and the p brackets , there was very little wear on the anode so prob not connected to well, I’ve never had boat that’s had the skin fittings earth bonded before and I’ve done some research and concluded that dzr fittings don’t need to be bonded so just going to fit them , I’ve also got shaft anodes but don’t like the idea of those, I’ve got solid shaft coupling so will try earth the shafts and props on the hull or transom mounted anodes as I don’t like the idea of shaft anodes disrupting the flow of water to the propellers

 

[oldgit]

Chum has just put his Princess 360 on our drying blocks, not a second to late.
The merest tiny trace of zinc left on the securing bar. ?

Bottom was suprisingly clean just a light coating of slime.

 

[Wightwill]

Hi there Restoration Man,
Did you price up new P Brakets?
I'm interested in a 31 Baltic but the Port bracket has a crack in it and will have to be replaced.

 

[oldgit]

Hi there Restoration Man,
Did you price up new P Brakets?
I'm interested in a 31 Baltic but the Port bracket has a crack in it and will have to be replaced.

Having been down a "how much and how long" to fabricate a new "P" backet to replace a damaged unit would suggest that you first investigate repair if at all feasable.
Proved impossible to even identify who made the "P" brackets on my 1990 Princess and quotes of well over £1000 pounds and 2 + months to get a matching unit cast and machined.
Would have been cheaper and faster to get a stainless steel copy fabricated at local workshop.
Bet there is local engineering outfit nearbye who can weld/rebuild/ machine virtually anything and sort that bracket at fraction of the cost of a new one.
In my case the bracket was seriously bent and after some eyewatering estimates to replace, this lot, Invicta Marine | Propulsion | Propellers | Thrusters, sorted the old unit in a jiffy.

 

[Keith-i]

From a thread last year where I was enquiring about pink patches on my rudder the conclusion was that if it was going pink it must be brass rather than bronze. On that basis an anode won’t help as it’s no more noble than the zinc already in the brass.

 

[QBhoy]

Every year, I check the continuity between all the sub surface gear. So in this case, I’d have a meter onto the hull anode and the p bracket. Just to make sure the anode is doing it’s job. Check the wiring between all the gear internally too. Same with the rudders and props. Hope that helps, if it’s applicable

 

[Restoration man]

Hi there Restoration Man,
Did you price up new P Brakets?
I'm interested in a 31 Baltic but the Port bracket has a crack in it and will have to be replaced.

hi I decided just to take the chance with what I’ve got , I showed them to a propeller company ( castle marine ) and they said don’t worry about it as it’s that thick it won’t be a problem, good enough for me , a coat antifoul and I’ve forgotten about it ???? I don’t see why yours couldn’t be welded

 

[bowler]

hi I decided just to take the chance with what I’ve got , I showed them to a propeller company ( castle marine ) and they said don’t worry about it as it’s that thick it won’t be a problem, good enough for me , a coat antifoul and I’ve forgotten about it ???? I don’t see why yours couldn’t be welded

Carwyn knows his onions. His word would be good enough for me too. ?

 

[oldgit]

Went to look at mates Princess 388 up for sale last year, with a view to buying. On the hard standing . Had a walk round underneath to check sterngear/hull etc both the "P"brackets had minor pitting , the sort you see on every 30 year old boat.
Boat sold pretty quickly ,not suprising due to asking price.
While sitting on his new boat asked mate about how the sale of the P388 went.
After " the survey" , buyer chipped him for 2K because the "P" brackets urgently needed replacing.

 

[Bandit]

Both brass will de zincify if the unit is not protected, Bronze is better than brass, and stainless set bolts set in sealant can isolate the bolt from the palm of the P bracket.

The P bracket looks like it is showing signs of eleoctrolysis, but not severe damage . As said above do they ring like a bell if hit with a hammer or do they sound dull.

It is difficult to see if it is pinking but I have seen far worse.

Remount the P bracket and check with a multimeter if you have continuity, if you don't have continuity, you need to fix that. In fact check all stern gear components, skin fittings, trim tabs etc and all anodes to see what is bonded to what anodes and rectify any dodgy terminals or wiring, use tinned wire where you have wet or green connections inside the boat .

At the same time check continuity of all anodes to shafts, props, p brackets and all skin fittings, don't forget trim tabs transom plate to tab a connection can be made. Rectify any dodgy terminals or wiring, use tinned wire where you have wet or green connections inside the boat .

Edited after Tranona's comments, I must not post after a long Sunday lunch.

 

[Tranona]

If it is really bronze it cannot dezincify because bronze does not contain zinc, just copper and tin plus small amounts of other metals . That is what differentiates bronze from brass (which is copper and zinc) and gives it the strength and resistance to corrosion.

 

[limecc]

Having been down a "how much and how long" to fabricate a new "P" backet to replace a damaged unit would suggest that you first investigate repair if at all feasable.
Proved impossible to even identify who made the "P" brackets on my 1990 Princess and quotes of well over £1000 pounds and 2 + months to get a matching unit cast and machined.
Would have been cheaper and faster to get a stainless steel copy fabricated at local workshop.
Bet there is local engineering outfit nearbye who can weld/rebuild/ machine virtually anything and sort that bracket at fraction of the cost of a new one.

I found the cheapest way to get something galvanised is to find a local steel fabrication company as they send stuff to the galvanizers every week. It goes in with one of their batches for just a few quid cash in hand. Far better than going directly as you get charged the earth.

 

[Wightwill]

Having been down a "how much and how long" to fabricate a new "P" backet to replace a damaged unit would suggest that you first investigate repair if at all feasable.
Proved impossible to even identify who made the "P" brackets on my 1990 Princess and quotes of well over £1000 pounds and 2 + months to get a matching unit cast and machined.
Would have been cheaper and faster to get a stainless steel copy fabricated at local workshop.
Bet there is local engineering outfit nearbye who can weld/rebuild/ machine virtually anything and sort that bracket at fraction of the cost of a new one.
In my case the bracket was seriously bent and after some eyewatering estimates to replace, this lot, Invicta Marine | Propulsion | Propellers | Thrusters, sorted the old unit in a jiffy.

I havn't seen the offending bracket, just going by what the broker told me that the previous survey had picked up so it is possible it could be repaired or possibly replaced with these 316 Marine Grade Stainless Steel P Bracket , suitably sized of course and you would have to do both.

 

[oldgit]

All the motor boat "P" brackets have ever seen have flat plate and use 6 bolts to secure bracket to hull..That bracket looks like something a yacht would use.