Just slipped my boat to antifoul and replace the rubber diaphragm that seals around the saildrive leg.

Volvo recommend replacement of the diaphragm every 7 years which I've read is very conservative.
Thinking mine would have been replaced in 2001 when the motor was changed by the previous owner I thought 13 years was about the right time to replace it.
When I removed it I found the date stamp indicating it was manufactured in 1993 and installed in 1994 when the yacht was built, so it was in service for 20 years old. ( first 7 years it's a charter yacht)

As the photos indicate the inter rubber ring had deteriorated significantly.

I wouldn't suggest you wait 20 years to replace but 7 is certainly very conservative, maybe in between would be about right.

very interesting!
I have a Bukh sail drive and I suspect ours would have to be original 1984, so possibly 30 years old.
I would hope it would start with a slow leak if it was going to give up the ghost ;)
great photos by the way!

Is yours a double membrane?
The Bukh one says it has a double membrane with sensor in between.

I did a story last year in the forum on this very subject.
The lowdown is that if you do not replace this item within say the permitted time frame, the insurance companies will take the opportunity to refuse a claim should there be an issue. The seal in ours upon removal showed some early signs of perishing. Yours looks like time is up as well.
The Volvo setup differs somewhat from the Bukh and Yanmar whereby they only have the one layer of rubber.
A bugger of a job and my mate viewing from the cockpit above likened me to a 'Huntsman spider stuck in a Matchbox!' while working under the floor.
I had the captive steel ring sandblasted and then epoxy powdercoated ready for re-use.
When bedding down the new rubber and all the bits you have to make sure the gearbox shaft locates back onto the engine spline properly and none of the rubber gets pinched up, which is easy to do(took us 3 go's) . Finally Volvo says that no sealants are to be applied and the seal relies on clamping pressure only. All the hold down bolts need to be tightened evenly and finished off with a torque wrench.

You can pm me if more info needed.
Best of British, or should I say 'Swedish'!

C.R.

Select to expand quote

CoolRunnings said...
I did a story last year in the forum on this very subject.
The lowdown is that if you do not replace this item within say the permitted time frame, the insurance companies will take the opportunity to refuse a claim should there be an issue. The seal in ours upon removal showed some early signs of perishing. Yours looks like time is up as well.
The Volvo setup differs somewhat from the Bukh and Yanmar whereby they only have the one layer of rubber.
A bugger of a job and my mate viewing from the cockpit above likened me to a 'Huntsman spider stuck in a Matchbox!' while working under the floor.
I had the captive steel ring sandblasted and then epoxy powdercoated ready for re-use.
When bedding down the new rubber and all the bits you have to make sure the gearbox shaft locates back onto the engine spline properly and none of the rubber gets pinched up, which is easy to do(took us 3 go's) . Finally Volvo says that no sealants are to be applied and the seal relies on clamping pressure only. All the hold down bolts need to be tightened evenly and finished off with a torque wrench.

You can pm me if more info needed.
Best of British, or should I say 'Swedish'!

C.R.

heh CR, do you have a link to the thread done on this topic, could'nt seem to find it.

I replaced it last weekend the only difficult bit was disconnecting the many items off the motor to move it forward by 300mm to allow the saildrive to be lifted back up into the boat.

When refitting the saildrive I found using a acrow prop to hold the leg at the right height was of great assistance to align the motor drive shaft.

It all went back together without any problems and no leaks!!

I could not locate that thread neither, but suspect it was in reply to somebody's request sometime back.
Your saildrive seal should not be too difficult to replace Keen.Being a single cylinder engine makes it lighter and easier to move around. Seabird's tip on using an Acrow to hold the leg makes sense and easy to adjust for height where required.

There are a lot of repowered engines carried out with the vessel left still in the water. My thinking is that if you are going to the trouble of replacing the motor, then why on earth would you not service/overhaul the saildrive or shaft components.

In our case, we replaced seals and bearings, cleared out all the crap inside the leg and checked all the workings.
The Volvo had a plastic seawater inlet valve located at the top of the leg. I was always a bit nervous that this may break off and so replaced with a stainless ball valve, being careful to isolate the thread to the alloy.
After it was all together and on relaunching back in the water, we left the boat sitting in the crane slings for a while to check for any leaks and make sure everything had taken up. That way if any problems,you can easily lift out again while still attached.
Not much fun watching your yacht sink, which happened with my old wooden boat-but that's another story!

C.R.

Maybe this was the thread that CoolRunnings recalls: www.seabreeze.com.au/forums/Sailing/General/Best-sealantadhesive-for-rubber-saildrive-flange/?SearchTerms=saildrive

Select to expand quote

Gravy7 said...
Maybe this was the thread that CoolRunnings recalls: www.seabreeze.com.au/forums/Sailing/General/Best-sealantadhesive-for-rubber-saildrive-flange/?SearchTerms=saildrive

Well done Gravy 7! That did talk a little bit about the subject.

I thought I'd put something together a bit more expanded on Saildrives/Seals on Seabreeze once.
It could well have been for the local yacht club newsletter.

Regardless, it is a key point not to forget about these hidden items shoved down at the back of the engine.
When you look at the diaphragm with the engine at idle or underway, they get quite a workout in terms of movement and vibration transferred from the motor. It stands to reason that they will wear and deteriorate over time.