Strut Failure Beneteau 325

[Clyde Sailing]

Hi Everyone
Just thought l would do my very first post , Took the boat out of the water this year and what waited for me was a snapped off prop strut , The thing is it must of been like this the whole season ! Only indication something was amiss was a slight shuddering when the boat went into reverse, but nothing really detectable. So was quoted 10K GBP for labour alone , Marine surveyor said it was due age (40 years) the process of dezincification at the bronze casting which reduces strength due to galvanic corrosion was the cause of the failure.
So this years project will be to replace the strut and all the associated work involved. Even if the boat is out for the season , means all the other jobs can now be done , In the meantime here are some pics of the damage and whilst no one should have this problem consider myself fortunate the damage was not even worse while motoring about with a snapped strut

[Rucksta]

Get more quotes.
10K is OTT

[pcmm]

Must have happened very recently you really would have noticed that if it was like that all summer! There would have been ALOT of vibration!

$10k for the repair is a bit much. this is doable DIY if you have some skills.

[Clyde Sailing]

Fellow Members,

Just to thank you all for your comments, It is a project l am keen to start over the summer, Right now it was -6 in Scotland so you have to be concerned you have enough anti-freeze coolant in the Beta Marine engine so it does not shatter the seals, Last year took out the heat exchanger and it was caked in debris from the fresh water anode that is screwed into the engine mound , Only tricky part was sliding down the battery alternator , but as advice to pass on , mark the points where the adjust bolt slides , this ensures that the belt is not too loose when you are resetting the unit and before you start get two spare set of O Ring seals in case one set is damaged when re tightening the unit back on , Whilst l had never attempted this job before it was pretty straightforward unlike trying to untighten an oil filter unit that wont budge !

[Bowdrie]

Beneteau has a 5-page service bulletin, number 3.6., dated Oct. 2005, from the "After Sales Department".
The title is "P Bracket Replacement".
Has all the step-by-step instructions and materials needed.

[Clyde Sailing]

Cheers! Just realised the importance of this forum after 1 day of joining hope when l tackle the project will provide pictures and progress for all to see, Just wish what l know now l had when l started off sailing in a Hunter 19 over 40 years ago

[barnakiel]

Normally, a fail of this kind, when running, rips the shaft out of the hull, with all the handles. You were lucky.


Any good mechanic will make / weld / a brand new strut for you that will last years. Get the old one off the shaft, get the hull part too, go to a good garage and they will make a copy.


IN EU money this looks like a 500-1000 EUR job - depending on materials used and the area one lives in.


You may also mail Bene ask if they have a spare. Sometimes they will have an old stock and will sell it off gladly.



b.

[Clyde Sailing]

Thanks for the advice , Yes l know l am lucky , Really Lucky, I am sure this strut had been damaged all season as l had mentioned when l put the boat in reverse gear there was a slight vibration , Unless it was a long withstanding stress fracture , the boat is Anti Fouled every year i would of picked it up , Anyway there are some markings under the hull made me think something like a branch got stuck under the prop shaft and was enough to lever it off. I have been out in the boat and seen parts of trees semi submerged in the Clyde off Arran one or twice with more and more storms happening now the frequency of such events is even greater, Going back to the boat tomorrow , to see if the top of the P Bracket is sitting under the fuel tank, So another job to think about will need to pump out the balance of the fuel and do some maintenance jobs on the beta engine , Thanks for all the pointers from everybody !

[Dockhead]

Originally Posted by barnakiel

Normally, a fail of this kind, when running, rips the shaft out of the hull, with all the handles. . . .

If you even notice what happened before you sink.

[GordMay]

Greetings, and welcome aboard the CF, Clyde.

I was unable to find Bowdrie's “Beneteau bulletin 3.6", P Bracket Replacement - perhaps it’s restricted to Dealers.

But, you might See:

“Replacing a P-bracket” ~ by Cox Engineering
➥ Replacing a P-bracket – Cox Engineering

“P Bracket Repair” ~ by Sailbleu, on the Jeanneau Owners Forum
➥ https://jeanneau.proboards.com/thread/1466
➥ https://www.jeanneau-owners.com/hint...ketrepair.html

[Clyde Sailing]

Latest Update

Finally managed to the boatyard to establish where the P bracket was and also to establish why there was markings under the hull, Initially l had thought the marking was from something that hit the boat but in fact the prop strut was able to freely move up and down the prop shaft and whilst rotating at speed whilst able to mark the underside of the boat.

l think this only happened when the boat was put in reverse gear hence the shuddering that was only present whilst in reverse , The cutlass bearing does not seem to of suffered any damage as it still functions on the rubber collar. Thankfully the P Bracket strut was not under the fuel tank as l am able to check if the was any cracking or movement and all seems to be as it should from a snapped bronze strut.

Maintenance today was for the Beta Marine Engine where Anti freeze coolant 50/50 mix was entered into the block after the seawater was pumped out , I checked the seawater inlet filter only to find a lot of small mussels had been caught , Probably they may of grown on the outside of the hull, Checked the anode , Air filter , Oil and water and gave the batteries a quick top up back to 14 Volts

[dlj]

Originally Posted by Clyde Sailing

Hi Everyone
Just thought l would do my very first post , Took the boat out of the water this year and what waited for me was a snapped off prop strut , The thing is it must of been like this the whole season ! Only indication something was amiss was a slight shuddering when the boat went into reverse, but nothing really detectable. So was quoted 10K GBP for labour alone , Marine surveyor said it was due age (40 years) the process of dezincification at the bronze casting which reduces strength due to galvanic corrosion was the cause of the failure.
So this years project will be to replace the strut and all the associated work involved. Even if the boat is out for the season , means all the other jobs can now be done , In the meantime here are some pics of the damage and whilst no one should have this problem consider myself fortunate the damage was not even worse while motoring about with a snapped strut

With all due respect to your marine surveyor, I don't see any evidence of dezincification. Plus, most bronze alloys don't typically have much zinc - that's found more often in brass alloys. Dezincification also tends to happen in copper based alloys containing 30% or more zinc. That being said, this may well be one of the brass alloys that are not uncommonly used for struts. However, those alloys also do not tend to dezincify.

Unfortunately, your images are not of sufficient resolution for me to see the fracture surface very well. However, one thing I do find quite interesting is the seeming lack of fatigue striations. Typically on struts that fracture after many years of service (like 40 years or more) there are fatigue striations coming in from both sides with the final fracture along a center line. This is the more common way struts break over time - from the vibrations of the prop, they are vibrating from side to side. From a curiosity point of view, I wonder if you can take a high resolution image of the fracture surface that is left in the hull. The fracture side shown in the pictures has been damaged from banging around on your hull...

Not that any of this really matters, your strut is broken and it needs to be replaced...

dj

[gonesail]

i'm guessing the estimate will include new shaft and possibly coupler.

[Clyde Sailing]

Again thank you for advice and assistance and l will endeavour to get high res pictures for you to have a look at, Initially when the boat came out of the water my first reaction was to get a quote from the yard which came in under 10k but the price did not include actual replacement parts and the bulk cost was for 125 hrs of labour , if it was found the gearbox and other components were damaged it would be added to the cost.

The information was shared with me to advise


The findings of the inspection suggest the reason for the “P” bracket becoming fractured is due to dezincification at the bronze casting, which considerably reduces strength. Galvanic corrosion over a prolonged period is considered to be the cause.

The “P” bracket has fractured directly in way of bracket to hull shell joint,

We examined the fractured faces, we noted that the fracture here had been propagating over a considerable period until failure (circled in the photo below) at the remaining part of the casting. Given the surface corrosion and staining sighted, we would estimate that this fracture has been progressing over a number of years.

Either way like you say the bracket needs to be replaced and this is a project l will take onboard over the coming months and looking forward to it

[dlj]

Originally Posted by Clyde Sailing

Again thank you for advice and assistance and l will endeavour to get high res pictures for you to have a look at, Initially when the boat came out of the water my first reaction was to get a quote from the yard which came in under 10k but the price did not include actual replacement parts and the bulk cost was for 125 hrs of labour , if it was found the gearbox and other components were damaged it would be added to the cost.

The information was shared with me to advise

For sure it's really just out of curiosity - I find often that marine surveyors look at fractures and don't really understand them. Not that it really matters - it's broken - it needs to be fixed.

Originally Posted by Clyde Sailing

The findings of the inspection suggest the reason for the “P” bracket becoming fractured is due to dezincification at the bronze casting, which considerably reduces strength. Galvanic corrosion over a prolonged period is considered to be the cause.

On the lower part, I did not see signs of dezincification. Bronze also is not usually affected by dezincification. Your strut may not be bronze. From the age of your boat, I've seen a lot of leaded naval brass used on struts. Even though these are brass alloys, they are good alloys and do not tend to dezincify. But some of them can.

I also am not seeing a clear indication of galvanic corrosion - but I would need much better images...

Originally Posted by Clyde Sailing

The “P” bracket has fractured directly in way of bracket to hull shell joint,

True statement.

Originally Posted by Clyde Sailing

We examined the fractured faces, we noted that the fracture here had been propagating over a considerable period until failure (circled in the photo below) at the remaining part of the casting. Given the surface corrosion and staining sighted, we would estimate that this fracture has been progressing over a number of years.

I also completely agree with this statement.

Originally Posted by Clyde Sailing

Either way like you say the bracket needs to be replaced and this is a project l will take onboard over the coming months and looking forward to it

It's a bit academic at this point to delve further into why it broke - however the galvanic question would be beneficial to know as it could be mitigated in your new strut, if indeed it was present.

If course it's always good to know what the actual original strut alloy was - it may well be that the replacement strut is a more appropriate alloy. I've always been a but surprised to find struts made from leaded naval brass -but hey, they do tend to last decades...

dj