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It's a leg that pokesout the bottom of the boat with a propellor on it, quite simply (a right angle drive). My Jag 25 has one because it wasn't designed (or so I believe) to have a prop shaft i.e. an in-line drive.
Mine works a treat. Just a different was of transmitting drive from the engine to the propellor.
One debating point is the diaphragm seal that keepsyour boat water tight i.e. the seal around the leg unit. Volvo recommend you replace this every 7 years The part is a glorified piece of rubber but, phew!!, the price!!!. Add labour and you can be looking at an expensive piece of work. However, 7 years is the recommened Volvo life. In the last month there was a discussion on this forum on this very matter - have a trawl and see what you can find. Not sure what the on going maintenance with a shaft drive is.
I'm a bean counter and that's as technical as it gets!!!!!
MRM.
Mine works a treat. Just a different was of transmitting drive from the engine to the propellor.
One debating point is the diaphragm seal that keepsyour boat water tight i.e. the seal around the leg unit. Volvo recommend you replace this every 7 years The part is a glorified piece of rubber but, phew!!, the price!!!. Add labour and you can be looking at an expensive piece of work. However, 7 years is the recommened Volvo life. In the last month there was a discussion on this forum on this very matter - have a trawl and see what you can find. Not sure what the on going maintenance with a shaft drive is.
I'm a bean counter and that's as technical as it gets!!!!!
MRM.
charles_reed
Active member
Like an outdrive leg for a sailboat.
Many designs have been manufactured but the Volvo one is the best known.
Expensive to fit they are good in early life but Volvo design (like Microsoft software) has a number of basic flaws. This is not helped by the galvanic couples of the metals being used in the construction. Apart from the horrific cost of the diaphragm (if you don't change it at the recommended 7-year intervals you are probably voiding your insurance) all Volvo parts are unreasonably expensive.
I would certainly not fit one from new unless I had no alternative and would consider a serious contra-indication against purchasing a boat fitted with one.
Many designs have been manufactured but the Volvo one is the best known.
Expensive to fit they are good in early life but Volvo design (like Microsoft software) has a number of basic flaws. This is not helped by the galvanic couples of the metals being used in the construction. Apart from the horrific cost of the diaphragm (if you don't change it at the recommended 7-year intervals you are probably voiding your insurance) all Volvo parts are unreasonably expensive.
I would certainly not fit one from new unless I had no alternative and would consider a serious contra-indication against purchasing a boat fitted with one.
davidwf
Active member
On the Other hand
I accept the previous posters points re the expense of the diaphram although there are cheaper places to buy Volvo Spares rather than Volvo. Keyparts to name one.
The major plus point of the saildrive over shaft drive is the lack of vibration transmitted to the boat as the engine and drive are decoupled from the hull by their ruber mounts. Plus no stern gland to drip.
As for corrosion I agree its a problem if you fit a bronze prop; if you stick with the Alloy ones its OK. I've a bronze one and have to keep an eye on my anode consumption but normally I can go a full twelve months by just changing the anode attached to the prop.
Would I have a saildrive again, Yes quite happy thankyou.
I accept the previous posters points re the expense of the diaphram although there are cheaper places to buy Volvo Spares rather than Volvo. Keyparts to name one.
The major plus point of the saildrive over shaft drive is the lack of vibration transmitted to the boat as the engine and drive are decoupled from the hull by their ruber mounts. Plus no stern gland to drip.
As for corrosion I agree its a problem if you fit a bronze prop; if you stick with the Alloy ones its OK. I've a bronze one and have to keep an eye on my anode consumption but normally I can go a full twelve months by just changing the anode attached to the prop.
Would I have a saildrive again, Yes quite happy thankyou.
charles_reed
Active member
Re: On the Other hand
Yanmar mounts (or Halyard) and any one of the patent seals get over the two problems you mention at 1/3rd of the cost and x2 the life of a saildrive.
Once was involved with one on a Maxi 9.5, which was an awefilling lesson for me.
Yanmar mounts (or Halyard) and any one of the patent seals get over the two problems you mention at 1/3rd of the cost and x2 the life of a saildrive.
Once was involved with one on a Maxi 9.5, which was an awefilling lesson for me.
Drummond
New member
A saildrive is like an outboard leg attached through the botom of the hull to the output shaft of the gear box. They are reliable if properly maintained, but are more complicated that a traditional shaft.
In theory if the bellows that fits around the top of the leg fails the boat can sink. I have never heard of this happening. The oil should be replced ever year which requires a haul out.
In theory if the bellows that fits around the top of the leg fails the boat can sink. I have never heard of this happening. The oil should be replced ever year which requires a haul out.
extravert
New member
Re: On the Other hand
Another advantage is a much reduced stern kick in reverse, because the propellor is much closer to the centre of the boat. My X99 with a Buhk saildrive has barely no stern kick at all, and I can happily manoeuver around the place in reverse as easily as forwards.
Another advantage is a much reduced stern kick in reverse, because the propellor is much closer to the centre of the boat. My X99 with a Buhk saildrive has barely no stern kick at all, and I can happily manoeuver around the place in reverse as easily as forwards.
ccscott49
Active member
Re: On the Other hand
Stern kick is a product of propellor "walk" paddle wheel effect, I didn't think it had anything to do with where the prop was in relation to the centreline, I have learnt something, thankyou.
Stern kick is a product of propellor "walk" paddle wheel effect, I didn't think it had anything to do with where the prop was in relation to the centreline, I have learnt something, thankyou.
G
Guest
Guest
Re: On the Other hand
It's just closer to the pivot point (the keel), so there is less moment to turn the boat.
Mine's the same, does not really kick much astern - then again, it doesn't turn either! (HR-312)
I changed to the alloy prop to save problems. I also fancied that the much lighter prop was easier on all those little gears.
Most annoying thing is that it jams if you sail with it in gear in reverse.
Another thing is that the previous owner put gear oil in the gearbox, whereas the manual seems to say to use engine oil. I am currently ignoring this issue - any ideas?
It's just closer to the pivot point (the keel), so there is less moment to turn the boat.
Mine's the same, does not really kick much astern - then again, it doesn't turn either! (HR-312)
I changed to the alloy prop to save problems. I also fancied that the much lighter prop was easier on all those little gears.
Most annoying thing is that it jams if you sail with it in gear in reverse.
Another thing is that the previous owner put gear oil in the gearbox, whereas the manual seems to say to use engine oil. I am currently ignoring this issue - any ideas?
