Saildrive - for and against

ghostlymoron

ghostlymoron

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Sorry if this topic has already been aired to death but I just can't use the forum search facility.
Anyway. I have no experience of this set up but have seen boat with it which seems to fit my spec in every other respect.
Are they safe? Unlikely to fail in a spectacular way.
Thanks
 
I had a Carter 30 with a Volvo saildrive.

I've read on these forums that saildrives are mainly for the convenience of the boatbuilder, and reckon that's probably true.

I've never heard of the big seal letting go on anyone, but it is a worry and cost every 10 years or so.

I found the core plugs on my Volvo rusting through, but that was probably just an anode issue with the boat before I got her, frankly too late !

The boss holding the folding prop' cracked, when I had access to all the various welding & sorting dept's of BAe Kingston - a lot of expertise & high tech' kit - I was told it was such **** nasty zinc metal nothing could be done with it so had to buy new; £480 in 1990...

If I was ever looking at a boat with an inboard again I'd prefer a traditional shaft drive ( though that's not without snags ) but if I set my heart on a wonderful boat I wouldn't let a saildrive put me off.
 
I've never heard them described as unsafe and I've never heard of "spectacular" failures. Don't have one personally - not usually fitted on boats in the 33 foot range. I think the claim is that they are less subject to prop walk and they permit better use of space since there is no prop shaft occupying space under the aft cabin. They certainly are more complex than a simple shaft drive and maintenance is higher.
 
I've got an elderly saildrive.

No problems.

No glands to pack.

No drive shafts to vibrate and go out of alignment.

No weeps.

Don't fret if the boat ticks all other boxes.
 
Quieter. Can only change oil out the water. Big rubber seal needs changing every seven years (in theory) and its a biggish/expensive job.
Prop tends to be more central so no prop walk, so a long way from rudder so no prop wash.
 
You will be ok if it is an LM. They have saildrives - but within a watertight engine compartment under the cockpit sole.

All may not be lost if the seal fails (apart from the engine - that is :eek:).
 
Comrade Red said:
I've got an elderly saildrive.

No problems.

No glands to pack.

No drive shafts to vibrate and go out of alignment.

No weeps.

Don't fret if the boat ticks all other boxes.
Click to expand...

last repacked the stern gland 11 yrs ago
no alignment probs
no drips
no aluminium leg
no big seal to leak or remove the gearbox / leg to replace it
 
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Comrade Red said:
On that last point, does anyone know of anyone who has had their main saildrive rubber seal leak or fail?
Click to expand...

I've known a few leak - they have a finite life expectancy. So do seals on shaft drives - the difference is that a shaft drive seal is typically a lot cheaper and easier to replace.

The bottom line is that saildrives are a fact of life on modern larger boats - from the owner's point of view, they have a few advantages over shaft drive - though nothing major. They are a bit more complicated and expensive on maintenance - but not ruinously so. If the boat that you want has saildrive, that is not a reason to not buy it, but budget a bit more for maintenance.
 
tom52 said:
Quieter. Can only change oil out the water. Big rubber seal needs changing every seven years (in theory) and its a biggish/expensive job.
Prop tends to be more central so no prop walk, so a long way from rudder so no prop wash.
Click to expand...

I have a saildrive on a 33 foot boat. When i engage reverse there is a marked movement to starboard. Is this prop walk? Find it quite useful.
 
ghostlymoron said:
Sorry if this topic has already been aired to death but I just can't use the forum search facility.
Anyway. I have no experience of this set up but have seen boat with it which seems to fit my spec in every other respect.
Are they safe? Unlikely to fail in a spectacular way.
Thanks
Click to expand...

Yes, it has been done to death. Saildrives have been in use for over 30 years and arguably now dominate the new boat market, with more builders progressively moving towards them. This is partly because of the increase in size of boats, but mainly because of the benefits they offer. It is a fallacy that they are significantly cheaper or necessarily easier to install for the builder, but they do offer benefits of better space utilisation.

The major benefits for users are generally smoother and quieter installations, thrust parallel to water line and reduced prop walk. No stern tube to seal so no drips, so more compatible with today's bilgeless boats.

Things to watch out for are seals in the bottom of the leg, anode wear and problems if the wrong paint is used on the leg housing. The seal does in theory need regular replacement, but they do not systematically fail. Most people who have replaced seals report the old one was just fine. Latest designs have much larger anodes and the drive oil can be changed from inside, both of which are improvements. Biggest potential downside is the high cost of replacing the drive if it fails (rare) but when you actually cost it not that much more than gearbox and stern gear replacement of a shaft drive.

More important things to worry about when buying a boat than the drive system - except that with many desirable boats you don't have a choice!
 
When I bought my first diaphragm from the Volvo agent he said he had never heard of one fail apart from a brand new one that the owner had lubricated so it slipped in place easily. It also slipped out easily! They are relatively easy to replace by a competent DIYer but expensive (c£170 for the 120S kit). The only difficulty I have had with mine is very limited access to the back of the engine.

All the round the world racing yachts seem to have saildrives and they survive the Southern Ocean. I've heard of more problems with shafts falling out of boats.
 
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mdonnelly said:
I have a saildrive on a 33 foot boat. When i engage reverse there is a marked movement to starboard. Is this prop walk? Find it quite useful.
Click to expand...

Yes, that's prop walk. Strangely, the sailing community seems completely polarised on the issue - if your boat has it, it is useful, if your boart doesn't, it's a liability. Our boat has virtually no prop walk and I'm very pleased that it doesn't.
 
maby said:
Yes, that's prop walk. Strangely, the sailing community seems completely polarised on the issue - if your boat has it, it is useful, if your boart doesn't, it's a liability. Our boat has virtually no prop walk and I'm very pleased that it doesn't.
Click to expand...

I have saildrive and I miss prop walk.

I suppose if your saildrive is near the stern then you can have saildrive and prop walk.
 
The recent discussion on prop walk here turned into another marathon! I know the theory and even used it on our previous boat which had a viscious kick in reverse. Our current boat has virtually none and I far prefer it like this - OK, there are tight turns I cannot make any more so I avoid circumstances where I need to make them. On the plus side, when I need to stop quickly, I know I can do so without having to fend off from the boat next to me... I got fed up with ending up parked at right angles across the lock after having to come in with a moderate tail wind! :)
 
Recently moved from shaft to saildrive. No regrets other than more maintanance as discussed by others and need for prop to have an anti vibtration feature.
Handling is great, it seems smoother than a long whirling shaft and I am confident that I can run the engine with more revs without doing damage to the flexible anti vibration coupling.
Boat layout could not be as good with shaft - I expatct this is main reason they are selected by boat builders
Having gone this way I would not let the presence or absence of a sail drive layout sway a boat purchase one way or the other.
 
maby said:
They are a bit more complicated and expensive on maintenance - but not ruinously so. If the boat that you want has saildrive, that is not a reason to not buy it, but budget a bit more for maintenance.
Click to expand...

Just for interest, how much is "a bit more" per year, typically?
 
EugeneR said:
Just for interest, how much is "a bit more" per year, typically?
Click to expand...

Never actually owned one myself - just sailed friends boats with saildrive - so I'll defer to someone that has actually had to pay the bills. As I understand it, you are looking at an extra thing to oil-change each service plus a gasket change every five to ten years. It's the gasket change that can get expensive depending on the model of boat - in some cases it requires significant dismantling.
 
I changed my saildrive seal last year, it was 17 years old and looked as good as the new one that replaced it. I changed the seal on a friends boat in Feb, took a day and a half. They are no big deal, dont let club bar stories scare you.
 
galadriel said:
I changed my saildrive seal last year, it was 17 years old and looked as good as the new one that replaced it. I changed the seal on a friends boat in Feb, took a day and a half. They are no big deal, dont let club bar stories scare you.
Click to expand...

That does assume that you do it yourself - a day and a half labour in a half-decent boatyard is a significant cost!
 
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