Saildrive - for and against

[aluijten]

I have replaced the seal on two different Volvos now, neither had corrosion like this, in fact there was no corrosion at all.

Interesting. Which models were this?

I've had it both on a S120 as a MS25S. The latter is 10 years old and was mounted without any coating other then what came out of the box.
Most of the coating was still in very good shape but on the picture you can see not all of it. This boat was mostly kept on fresh water.

 

[the_branflake]

I've just replaced the sail drive seal on mine. I also had slight corrosion in the places shown by aluijten. Mine is a S120c. Just to add, some muppet had bypassed the negative solenoid on mine, I was lucky for once that the leg hadn't suffered.

Needless to say its now been corrected, it just needed taking apart and cleaning. You can see the two tiny wires in the picture here http://www.ybw.com/forums/showthread.php?t=310933 - no wonder it turned over slow.

 

[doris]

Picking up rubbish on the prop

Noone seems to mention the requirement for a rope cutter.
I had never had anything round a prop before I got a sail drive. Over the last 6 seasons we have picked up stuff 5 times and are very grateful for our stripper. I am very convinced that a sail drive gathers this stuff more readily that a P bracket set up. That said I am more than happy to have a sail drive and will do again, just with a stripper from the outset.

 

[jerrytug]

Exactly Doris,if you wanted to design a device to entangle semi -floating pot buoy lines,bits of net etc,it would look something like a saildrive. And if you do get entangled,aren`t saildrives too delicate to winch off the entanglement? A good cutter would be a must surely,but even then it`s an accident waiting to happen. Jerry.

 

[Sans Bateau]

Both were 120S probably C version. One on a MS2 gearbox 1993, the other a later 1999 gearbox.

 

[Sans Bateau]

Exactly Doris,if you wanted to design a device to entangle semi -floating pot buoy lines,bits of net etc,it would look something like a saildrive. And if you do get entangled,aren`t saildrives too delicate to winch off the entanglement? A good cutter would be a must surely,but even then it`s an accident waiting to happen. Jerry.

Strange that, the only time I destroyed a gearbox and P bracket when I wound a rope between P bracket and prop, this in turn tore the side out of the aluminium ZF gearbox. But its true, in the polluted in which we sail a rope cutter is advisable on any drive.

 

[fireball]

Noone seems to mention the requirement for a rope cutter.
I had never had anything round a prop before I got a sail drive. Over the last 6 seasons we have picked up stuff 5 times and are very grateful for our stripper. I am very convinced that a sail drive gathers this stuff more readily that a P bracket set up. That said I am more than happy to have a sail drive and will do again, just with a stripper from the outset.

Strange - had a boat with a shaft drive & p bracket - each year on haulout there would be remnants of line on the shaft ...

now got a boat with saildrive - no lines present .... but then we do have a cutter too ... not that I've ever noticed it do anything ...

both are two bladed fixed prop - so it's not that either ...

 

[Talbot]

Strange that, the only time I destroyed a gearbox and P bracket when I wound a rope between P bracket and prop, this in turn tore the side out of the aluminium ZF gearbox. But its true, in the polluted in which we sail a rope cutter is advisable on any drive.

A Catamaran in the far east that had no rope cutter, and was using a dyneema rope on their tender, got the rope around the prop and destroyed the engine mounts and then ripped out the gasket on one engine. This led to the boat effectively sinking. I have heard of similar problems with ropes on shaft drives.

One area that does need attention on a saildrive, is the cooling water inlet. In most designs, this is a small pipe with a gate valve on the saildrive leg. This has blocked in areas with large crustacean problems. There is a significant body of thought that believes this system needs to be disabled and a proper inlet valve (preferably marelon) fitted.

 

[Tranona]

One area that does need attention on a saildrive, is the cooling water inlet. In most designs, this is a small pipe with a gate valve on the saildrive leg. This has blocked in areas with large crustacean problems. There is a significant body of thought that believes this system needs to be disabled and a proper inlet valve (preferably marelon) fitted.

That really does depend on where you keep the boat. There is more than enough capacity in the intakes to cope with some fouling, but there are locations where small mussels grow, so if your boat is moored in one of those locations there may be benefit in having a conventional seacock in addition and connected via a Y valve to give choice. However, if it is mussels that cause the problem they can just as easily block a seacock, particularly if it has an external grid.

 

[Tintin]

That really does depend on where you keep the boat. There is more than enough capacity in the intakes to cope with some fouling, but there are locations where small mussels grow, so if your boat is moored in one of those locations there may be benefit in having a conventional seacock in addition and connected via a Y valve to give choice. However, if it is mussels that cause the problem they can just as easily block a seacock, particularly if it has an external grid.

I have this and have used it on occasions, most recently when some agricultural plastic wrapped around the leg. The prop cleared itself enough to keep going but the inlets were blocked.

The comment from the yard (as she was lifted for anti-fouling) was a reminder to remove the plastic wrapping before I played with my toys.

 

[Sans Bateau]

Getting a plastic bag or plastic around the saildrive leg is not uncommon, it has happened to us a couple of times. In both cases we eased the throttle to neutral, then carefully into reverse, once engaged plenty of revs for a few seconds has cleared the problem. I guess the plastic is blown back the way it came.

When doing this it is advisable not to run in reverse so long that you take all way off.

 

[Talbot]

One area that does need attention on a saildrive, is the cooling water inlet. In most designs, this is a small pipe with a gate valve on the saildrive leg. This has blocked in areas with large crustacean problems. There is a significant body of thought that believes this system needs to be disabled and a proper inlet valve (preferably marelon) fitted.

That really does depend on where you keep the boat. There is more than enough capacity in the intakes to cope with some fouling, but there are locations where small mussels grow, so if your boat is moored in one of those locations there may be benefit in having a conventional seacock in addition and connected via a Y valve to give choice. However, if it is mussels that cause the problem they can just as easily block a seacock, particularly if it has an external grid.

I think you must have missed my statement in the third sentence! This has blocked in areas with large crustacean problems.

 

[Tranona]

I think you must have missed my statement in the third sentence! This has blocked in areas with large crustacean problems.

Apologies - I did miss that bit - concentrated too much on the opening statement!

 

[Tranona]

Getting a plastic bag or plastic around the saildrive leg is not uncommon, it has happened to us a couple of times. In both cases we eased the throttle to neutral, then carefully into reverse, once engaged plenty of revs for a few seconds has cleared the problem. I guess the plastic is blown back the way it came.

When doing this it is advisable not to run in reverse so long that you take all way off.

Plastic bags are normally no problem and can be dealt with as you suggest - if the prop has not chewed the stuff up already. Bigger problem is heavier stuff like fertiliser sacks which can wrap round the prop blades. Happened to me before I had the rope cutter fitted. Big bang as we hit it, but a bit of in and out of gear broke it up enough to get some drive, then had a diver clear it in harbour.

 

[Halo]

Agricultural plastic bag/sheet can be a nightmare. I montered my Westerly 25 coast to coast through the Leeds Liverpool canal and got some of it round the prop half way through the Foulridge tunnel - nightmare requiring me to get in the water/ooze and free it in the dark - an actiivity which convinced me to fork out for a stripper.
Back to shaft/sail drive options not all props are compatible with sail drives e.g brunton autoprop. This would not put me off another sail drive but is worth bearing in mind

 

[rob2]

An acquaintance wrote a nice article on changing the seals on the saildrive on his boat. Being an engineer, his writing covered all the points you want to ask after reading the official text! However, after relaunching the outer/fairing seal adhesion failed (we all make mistakes) and he could barely make any weigh back to the hoist to fix it.

It reminded me of the swiming costume my mother knitted me as a child. Once in the water it was like a sea anchor around your ankles!

Rob.

 

[Tranona]

Back to shaft/sail drive options not all props are compatible with sail drives e.g brunton autoprop. This would not put me off another sail drive but is worth bearing in mind

Not so Bruntons have props to fit Volvo, Yanmar and Bukh saildrives in sizes 13-20" diameter.

Very wide range of alternate props available for saildrives, both folding and feathering. The only popular one that I knoww about that does not work is the new Featherstream, but no doubt that will come in the future.

 

[eddystone]

I have just been on a diesel maintenance course and the instructor wasn't very keen on saildrives - I think he believed that the seal was too high a risk.
That apart, as one of the boats I am looking at has a saildrive, I wondered how much difference it would make to annual servicing/winterisation routine. The course gave me the confidence to do this myself and save a fair wad of money and the only thing I can see as different is the fact the gearbox oil has to be changed when it's out of the water. However, I may have misunderstood but is the water inlet on the leg the main cooling inlet for the engine. I had intended to keep the boat in the water all year round apart from a month or so lift out for maintenance and would fill the raw water cooling system with fresh water/antifreeze mix then when I came to use the boat in winter I would reconnect the raw water inlet etc. and re-winterise when I left. If the raw water inlet is inaccessible way down in the leg, that isn't feasible.

 

[Tranona]

Yes, the water intake is in the leg, although some boats have a separate intake through a conventional valve. No need to worry about water freezing in it in our climate. Nowhere in the UK does water (particularly seawater) freeze to that depth. Nothing special required for winterising. The engine coolant has its own antifreeze/inhibitor. You cannot fill the leg water passages with antifreeze anyway as the valve is in the boat. You could drain the seawater section inside, but really is not necessary. On some models you can change the saildrive oil from inside - however oil changing is not necessary every year.

There are some people who have an irrational bias against saildrives. However they have been in use for over 30 years now and are fitted to the majority of new boats (in Europe anyway). The main diaphragm is very reliable, and although many are changed at the recommended interval, reports suggest that there is no evidence of any degradation. The seals in the bottom of the leg are more vulnerable, but fitting a rope cutter reduces the chances of anything like fishing line getting in, which is a cause of seal failure. Regular checking of oil will indicate if the seals are leaking as the oil goes milky. Changing lower seals is not a big job, obviously with the boat out of the water.

 

[Talbot]

....... I may have misunderstood but is the water inlet on the leg the main cooling inlet for the engine. I had intended to keep the boat in the water all year round apart from a month or so lift out for maintenance and would fill the raw water cooling system with fresh water/antifreeze mix then when I came to use the boat in winter I would reconnect the raw water inlet etc. and re-winterise when I left. If the raw water inlet is inaccessible way down in the leg, that isn't feasible.

If you have a sea water strainer

then you can easily change over for a flush with antifreeze.

However, the valve on the leg is easily accessible - although I really do not like the design, and have installed separate 3/4 marelon thru-hulls for the salt water cooling.