volvo 110s saildrive seal

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musarkie

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I have a Volvo MD11c with 110s saildrive. The round rubber diaphragm appears to be in very good condition when inspected on the inside of the boat. It has not been changed for at least 7 years. The boat is out of the water 6 months a year.
Does anyone know how long they last?
 
I've heard the figure of 10 years mentioned, but you need an accurate figure from Volvo, it's not something to get wrong !

I suspect the criteria is age, so how much time the boat is in the water may not be that relevant.
 
I changed the 120SD diaphragm on a [new to me] boat a couple of years back. I was at the 11 year mark.

Visibly from inside the boat it looked no different to the new. Once out however you could tell that the new was so much more flexible and was actually quite a few mm thicker..

It's not a tricky job if you have space to move the engine forwards 3-4 inches... and sounds like you have time on your hands as well!

With a bright lamp (and if it was mounted a thoughtful way round), you should be able to make out the year of manufacture stamped into the surface of the rubber from inside the boat.
 
Mine is OK after 25 years - the boat is out of the water, like yours for six months every winter.
I would add that the boat is used on the Norfolk Broads and therefore does not go to sea.
 
Easticks28 said:
Mine is OK after 25 years - the boat is out of the water, like yours for six months every winter.
I would add that the boat is used on the Norfolk Broads and therefore does not go to sea.
Click to expand...

Damn! You beat me! When I changed mine it was 19 years old. Perfect.

Just remember a boat which is out of the water 6 months every year and has not had the seal changed for, say, 10 years, only actually has 5 years of use.
 
galadriel said:
Damn! You beat me! When I changed mine it was 19 years old. Perfect.

Just remember a boat which is out of the water 6 months every year and has not had the seal changed for, say, 10 years, only actually has 5 years of use.
Click to expand...

Galadriel,

I had a boat with a saildrive, but fortunately not for long enough to have to change the seal; I'd have thought replacement time is due to 'age hardening'
effect on the rubber, rather than something mechanical like vibration, torque, water flow etc ?
 
Seajet said:
Galadriel,

I had a boat with a saildrive, but fortunately not for long enough to have to change the seal; I'd have thought replacement time is due to 'age hardening'
effect on the rubber, rather than something mechanical like vibration, torque, water flow etc ?
Click to expand...

Funnily enough, I would suspect that being out the water may age the rubber marginally more than being in the water as UV is the principal cause of deterioration in rubbers and plastics! However UV is not a major concern in the shade under a boat!!
 
Seajet said:
Galadriel,

I had a boat with a saildrive, but fortunately not for long enough to have to change the seal; I'd have thought replacement time is due to 'age hardening'
effect on the rubber, rather than something mechanical like vibration, torque, water flow etc ?
Click to expand...

It'll be synthetic, will sit in land fill for 1000's of years I'd expect.
 
galadriel said:
It'll be synthetic, will sit in land fill for 1000's of years I'd expect.
Click to expand...

Galadriel,

I'm sure it will, but age hardening would affect the fit and resilience in the boat I'd think.

I think research into rubber age hardening should be carried out post haste; I can think of a diver or two I could volunteer to be hung in the sun or placed underwater for 10 years to judge the effects.
 
Regarding work hardening.. The old diaphragm never really returned to the original thickness after being removed from the boat. The newer was much thicker and more supple.
 
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