saildrive diaphragm replacement

[maby]

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).
....

... and don't underestimate the pain that a P-bracket can be - some friends of ours got a rope round the shaft of their boat, the rope cutter failed to chop it and the force of the engine stalling ripped the P-bracket out - fortunately, they were close to the boat yard because the resulting leak was more than their bilge pumps could cope with and they could easily have lost the boat if they had not managed to get an emergency lift.

 

[Bav34]

I helped a friend with his Bav34 and we had to take a saw to the aft bunk joinery

Good grief!

Why?

 

[Cantata]

Good grief!

Why?

Because underneath that nice bit of veneered stuff in the foreground was a strut which prevented the leg from being lifted inside, that's why. Perhaps different on yours, I expect they change from year to year.

 

[Bav34]

So, did you saw through the strut? Any idea what it did?

 

[Cantata]

So, did you saw through the strut? Any idea what it did?

Supported the joinery I presume. He who owned it replaced it.

 

[Sans Bateau]

On the other hand the Bav 36 gaiter change was extremely easy, loads of good access.

 

[Bav34]

Interesting thanks. Off to the Bavaria forum to find out more.

 

[nigelmercier]

Interesting thanks. Off to the Bavaria forum to find out more.

Good idea ...

 

[Bav34]

Good idea ...

Yes well I'm very lost.

Sawing through joinery that's apparently a replaceable wooden strut that isn't on my boat nor seems necessary as the wood you can see in my photo seems substantial AND its the same on a 32 .

Perhaps PhotoDog could have a look on his 32.

 

[Cantata]

Yes well I'm very lost.

Sawing through joinery that's apparently a replaceable wooden strut that isn't on my boat nor seems necessary as the wood you can see in my photo seems substantial AND its the same on a 32 .

Perhaps PhotoDog could have a look on his 32.

I don't know why you should be lost. As I said earlier, "Perhaps different on yours, I expect they change from year to year." I expect by the time yours was built someone had noticed that strut was a bad idea. It really wasn't a big deal at the time.

 

[nigelmercier]

Sawing through joinery ...

If I had had a chainsaw at the time, I might have been tempted; but I got past the obstacle in the end. My first mistake was trying to cheat, and only shifting the engine a little bit. Just follow the instructions to the letter.

 

[2Tizwoz]

Has anyone cut one to see what its made of? Isn't there some fabric reinforcement which wouldn't see the light of day until the rubber was cracked?

 

[scottie]

When vp introduced their sail drive there was a lot of head shaking and gloom predictors however in all the time I was working I only heard of one diaphragm failing and ghost was in a boat used in the Red Sea and it had lost its external flap
The cause was determined to be UV rays ( try leaving a pair of wellies in a hot house)
I do know of several boats that have been lifted with a sling round the sail drive shaft without wrecking the diaphragm
Yanmar etc had apparently made such case against the sail drive that when they started marketing them they had to build in the gap and water sensor as I heard it.

 

[maby]

When vp introduced their sail drive there was a lot of head shaking and gloom predictors however in all the time I was working I only heard of one diaphragm failing and ghost was in a boat used in the Red Sea and it had lost its external flap
The cause was determined to be UV rays ( try leaving a pair of wellies in a hot house)
I do know of several boats that have been lifted with a sling round the sail drive shaft without wrecking the diaphragm
Yanmar etc had apparently made such case against the sail drive that when they started marketing them they had to build in the gap and water sensor as I heard it.

How do you get UV around the sail drive?

 

[Sans Bateau]

How do you get UV around the sail drive?

reflection off a sandy bottom perhaps. I have heard before that the external fairing is for UV protection as much as anything.

 

[philwebb]

Saildrive diaphragm

reflection off a sandy bottom perhaps. I have heard before that the external fairing is for UV protection as much as anything.

I would have thought that sea water absorbed UV. Re saildrive diaphragms, I have one on my boat. With the original engine (MD5) installed I
changed the diaphragm easily with help (one person) in a day. I think that it was original to the boat and was therefore around 20 years old.
It was still in serviceable condition, but the top clamp ring was quite rusty due to a sea water leak from the exhaust.
I have personally seen a boat lifted by a crane with one of the slings under the sail drive. It did not spring a leak afterwards-
the rubber must be really tough! The saildrive arrangement comes into its own when you need to manoeuvre in a tight space- it really
is great compared to shaft drive. Reversing in a straight line is equally possible.

 

[Dipper]

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.

When I cut through my old one, it appeared to have a similar construction to a fan belt. There was a mix of rubber and a cloth like material so they may give some indication of leakage before failing completely.

I have never heard of one failing and neither had the Volvo engineer I bought my first replacement seal from. On the other hand, I have heard of failures of shaft seals and P brackets.

I believe saildrives are fitted to most if not all round the world race yachts. Of course they will be new but they must take a hammering in the Southern Ocean.

 

[Sans Bateau]

Scare stories about saildrives are put about mainly by people not lucky to have one.

 

[Skylark]

I'm surprised to read the willingness many forum members seem to have to tear their boat apart (to gain access). I don't have an issue with the seal per se, I do, however, resent the very thought of the work required and the potential for damage, however minor, to accomplish the task. Very poor engineering, imho, and a demonstration of lack of interest by the boat manufacture in the costs and ease of maintenance for the owner.

 

[Sans Bateau]

I'm surprised to read the willingness many forum members seem to have to tear their boat apart (to gain access). I don't have an issue with the seal per se, I do, however, resent the very thought of the work required and the potential for damage, however minor, to accomplish the task. Very poor engineering, imho, and a demonstration of lack of interest by the boat manufacture in the costs and ease of maintenance for the owner.

Its not restricted to the boat building industry, cars are probably worse, some of the huge maintenance costs are down to having to do things like remove the engine to replace a service part (cam belt).