saildrive diaphragm replacement

[sthurley]

Opinions please. If a yacht is 12 years old but has spent 2 full years on the hard and then every winter season ashore therefore only having technically 5 years of use, does the diaphragm need changed? I know it is recommended to do every 7 to 10 years (Volvo saildrive)

 

[Jabs]

Tough decision.

Opinions please. If a yacht is 12 years old but has spent 2 full years on the hard and then every winter season ashore therefore only having technically 5 years of use, does the diaphragm need changed? I know it is recommended to do every 7 to 10 years (Volvo saildrive)

Is it worth the risk?

Mine was changed last year and I still think about it!

It is probably the only single point failure that will cause the loss of the boat.

I know it costs but what price peace of mind.

Good luck with the decision!

Tony

 

[nigelmercier]

I would suggest that being out of the water could age the rubber at the same rate or even faster. No evidence for this, just a gut feeling. Set aside two days (for the first time) and two people to do it, and don't try to reduce the distance you move the engine back. Short lengths of wood are handy to use as props.

 

[Skylark]

I bought a brand new boat in August last year and did not do enough research on saildrives. They are the work of the devil. A complete abomination in my humble opinion. The seal isn't the issue, it's the lack of engineering by the boat designer to make it easy to change. Simply ridiculous that the engine has, at best to be moved and worse case has to come out, to gain acess.
I wrote to my maker to ask about the Design FMEA, about Weibull Life prediction and factors affecting life. They fobbed me off with 100% BS.
If the design life is stated to be 7 years (mine is a meagre 5), albeit without any public domani evidence to back this up, I wouldn't feel comfortable floating with a 12 year old seal in place.

 

[sailorman]

I bought a brand new boat in August last year and did not do enough research on saildrives. They are the work of the devil. A complete abomination in my humble opinion. The seal isn't the issue, it's the lack of engineering by the boat designer to make it easy to change. Simply ridiculous that the engine has, at best to be moved and worse case has to come out, to gain acess.
I wrote to my maker to ask about the Design FMEA, about Weibull Life prediction and factors affecting life. They fobbed me off with 100% BS.
If the design life is stated to be 7 years (mine is a meagre 5), albeit without any public domani evidence to back this up, I wouldn't feel comfortable floating with a 12 year old seal in place.

Its all in the name of saving money / time in construction, just as the transom is part of the deck moulding on AWBs

 

[Mrnotming]

The diaphragm in mine at 7 years was perfect upon removal.However it has a date stamp!If you can convince your insurers that it's OK to have it there for 20 years or so,this would be a good outcome?
Whilst I said that the diaphragm was good looking on removal,there was other creeping corrosion on drive parts adjacent,which needed recoating to ensure long service life.
If DIY use a camera at each sequence,and a selection of bowls to keep bits in order whilst disassembled!
Luckily for me,I only had to remove a little piece of joinery to lift the leg into the vessel.
There will be some reprints available from PBO which are helpful.
Order the various sealants in advance,they are supposedly specialised.
Seven years comes around all too quickly!
Get a pro to do it if unsure,as they do it quicker if time is an issue!?

 

[WF36]

How much have people paid to have the diaphragm changed? I've seen quotes been £650 & £1600!

 

[sailorman]

How much have people paid to have the diaphragm changed? I've seen quotes been £650 & £1600!

Thats why its better to be shafted in the first place

 

[WF36]

Thats why its better to be shafted in the first place

Reminds me of a quote from Guapa: "Prefer a saildrive any time. Seems to be a lot of snobbery about. Some people will just not accept a saildrive."

 

[strudders]

Had a Volvo MD2020 with saildrive on the last boat. We changed that at 14 years when the rubber started to show the first sign of being brittle - it goes a bit white. This was how to tell apparently as stated to me by my authorised Volvo mechanic when we first bought her second-hand, and he simply checked her every six months for us. Changing it is an expensive business, and why change it if it is not worn out? For piece of mind, we did get the professionals to do the job ( Gosport Boat Yard, who are very good at most things IMO)

 

[maby]

Had a Volvo MD2020 with saildrive on the last boat. We changed that at 14 years when the rubber started to show the first sign of being brittle - it goes a bit white. This was how to tell apparently as stated to me by my authorised Volvo mechanic when we first bought her second-hand, and he simply checked her every six months for us. Changing it is an expensive business, and why change it if it is not worn out? For piece of mind, we did get the professionals to do the job ( Gosport Boat Yard, who are very good at most things IMO)

If you are checking every six months, it will not take long before it is cheaper to replace the saildrive! A lift and hold on our boat costs hundreds of pounds - four unnecessary lifts probably costs as much as a professional diaphragm replacement.

 

[Tranona]

How much have people paid to have the diaphragm changed? I've seen quotes been £650 & £1600!

The bits are less than £300 so the variability is in labour - both the amount and the cost. The hours vary according to the ease with which the old one can be removed from the boat. Some installations require removal of bits of furniture, for example. Hourly rates depend on location and travelling time. Typical price for a straightforward change like most Bavarias is 12 hours labour, so for a yard based fitter (no travelling time) between £900-1000 including parts. Can easily be done in a working day with 2 fitters.

 

[strudders]

If you are checking every six months, it will not take long before it is cheaper to replace the saildrive! A lift and hold on our boat costs hundreds of pounds - four unnecessary lifts probably costs as much as a professional diaphragm replacement.

No we checked from inside the boat - we did not need to lift out - we could see all of the ring easily

 

[maby]

No we checked from inside the boat - we did not need to lift out - we could see all of the ring easily

Not sure that applies to a Yanmar - they have two diaphragms - the inner one is the standby designed to stop you sinking immediately when the outer fails.

 

[Tranona]

Not sure that applies to a Yanmar - they have two diaphragms - the inner one is the standby designed to stop you sinking immediately when the outer fails.

However, there seems little reliable evidence of failure of diaphragms of either make, so this is a bit of a moot point.

 

[nigelmercier]

Imagine you were the manufacturer of an item like this, whose failure could mean the loss of a boat. You did some testing and discovered they lasted X years. What figure would you publish for replacement?

My guess: X/2

I therefore replaced mine at 10 years, and will do so next time.

 

[Sans Bateau]

I would challenge anyone to find evidence of a saildrive gaiter ever catastrophically failing resulting in a boat sinking. I very much doubt you ever would.

I have replaced 2 of these now, one on our own boat at 19 years old, the previous owner of 10 years had only ever had the boat afloat from May - Sept, so similar times in service to the OP. When I changed the diaphragm the old one was as good and as supple as the new one. The second one I changed was on a 12 year old Bav 36 in the South of France, so a greater risk of UV damage, again perfect condition.

Dont let the robbers at Volvo put the fear of God in you to extract money, of course they will say it must be changed at XXXX years, they want to sell you another. However if they said it will last for ever and in the unlikely event one did fail they might be liable.

 

[Bav34]

Anybody know what happens when there is a failure?

Or not, as seems to be the case.

Does the rubber suddenly just say 'that's that' I now have the strength of a bin liner just 'because', or is it a gradual observable weakening caused by vibration, or is it the ss clamps deteriorating?

I have seen a few being changed in various boatyards and have always been told that the old one was as good as the new.

 

[maby]

Anybody know what happens when there is a failure?

Or not, as seems to be the case.

Does the rubber suddenly just say 'that's that' I now have the strength of a bin liner just 'because', or is it a gradual observable weakening caused by vibration, or is it the ss clamps deteriorating?

I have seen a few being changed in various boatyards and have always been told that the old one was as good as the new.

My guess is that the failure mode would be a sudden and catastrophic rupture - these are not thin, flexible sheets of rubber, they are thick slabs. I assume that the anticipated degradation would be a stiffening followed by a fatigue failure rather than minor puncturing. As you say, I've never heard of one actually failing, so it is presumably all pretty theoretical.

 

[Cantata]

As well as easier installation for the boat builder, there are upsides for the boat owner - lack of vibration, no propshaft or shaft seal (or P-bracket and cutless bearing on some boats).
Seems that designers of taday's boats don't necessarily worry about the guy who comes along to change the seal. I've done it on my Moody, no problem. But I helped a friend with his Bav34 and we had to take a saw to the aft bunk joinery, not too drastically though. Same applied to another pal with a Bav32.
If you have a spare £1000 to throw at an engineer, fair enough, but if you are capable of basic boat maintenance and have the time, the job is not difficult at all, as others have said. Much easier with 2 people, and we did the whole job on the Bav34 comfortably in a day.