Prop Fell Off! Help!

[SeaKing]

Ex-Cali, if you look closely the bolts that hold the zinc on are sticking out. There is no Zinc on that one and it was on a boat my wife looked at 3 years ago. She took a bunch of photos for me to see. The boat was in Puerto Rico, she flew down for the first look. We wound up buying another boat nearly identical. We have a galley up and that one was galley down.

Geoff, I will have to look to see if I have a photo of the bent washer. All you do after tightening the cone is replace the allen head bolt with a hex head bolt with a flat washer under the head of the bolt, then bend an edge of the washer up against one side of the hex head bolt. that will lock the bolt.

I had put the two props on myself the previous winter. No loctite on the allen head bolt on the lost prop with cone nut.

[Therapy]

Originally Posted by SeaKing

Geoff, I will have to look to see if I have a photo of the bent washer. All you do after tightening the cone is replace the allen head bolt with a hex head bolt with a flat washer under the head of the bolt, then bend an edge of the washer up against one side of the hex head bolt. that will lock the bolt.

.

If the bolt starts to turn, could the washer just turn with it?
Does it need to be keyed some how?

[SeaKing]

good point Therapy. Also the shaft has splines on it, so the prop can't turn against the nut unless it is slipping on the rubber hub. That shouldn't happen unless you hit something or "gear stop" the prop shaft. I guess that helps my theory of the cone nut has more surface area contacting the prop. But the standard nut only contacts the metal center hub on the splines. So if the prop spins on the hub it can turn the cone nut but it does not contact the regular style nut so it really can't back it off.

[Ex-Calif]

Originally Posted by SeaKing

Ex-Cali, if you look closely the bolts that hold the zinc on are sticking out. There is no Zinc on that one and it was on a boat my wife looked at 3 years ago. .

Are you sure? I marked the photo up.

On the Volvo drive the red arrow points out the zinc mounting bolt.
The yellow arrow is pointing at the zinc split line to the saildrive leg.

The zinc on the Volvo is circular with 2 allen bolts holding it on.

[josef]

Originally Posted by Alan Wheeler

Because no one on earth (in their right mind)would give a warranty or be expected to cover a failure with SST, in saltwater, in a high stress use situation. This fault has nothing to do with a product failure due to poor design, maybe lack of maintenance on behalf of the owner. But mostly, that is the risk you take with using SST shaft in the hard working environment you use it in.
How often do you inspect your prop shaft?? I bet never. Have you had the other shaft inspected seeing as you have already had one failure?? Your shaft and drive system should be visually inspected with every annual haul out. At the point of severe wear on the bearing, the shaft should be replaced, not sleeved as I know of the odd few that have. Of course, that is my opinion of SST. Some do sleeve and get away with it. But I feel it is way too mission critical for that. But anyway, your failure is afact of life using SST. Sadly we don't have a lot of alternatives, and as long as you are using the correct grade, which would have bee done, there is little more that can be done, economically at least.

Thanks Alan Wheeler but if you assert it was not a design fault and merely "lack of maintenance" why then have Yanmar now confirmed to me that they had a design change in the prop shaft of the SD 20? My post was initiated by a desire to find out whether or not other users of this forum had had similar problems and specifically with BROKEN shafts. http://shearwater-sailing it transpires have and this is well documented. They have subsequently received compensation.Age of the boat is immaterial.If it is a design fault potentially putting crew and boat at risk then the onus is on Yanmar to inform and recall.Did they at the time?? Think you are wrong to claim it has nothing to do with product failure.

[Alan Wheeler]

A design change does not support a theory of a design fault. If there was a design fault, you would have seen failures in 6 months to a year and you would be seeing recalls made. Failures 10yrs later hardly constitutes a design fault. A poor design maybe, but that is not a fault. A fault would be if if say, the shaft was too small for the Hp provided and in normal use, the shaft would break in many unit's and the break would be the same place all the time and by the thousands and within the normal warranty period. With the hundreds of thousands of these things out there, the issues seen are really very small. And 10yrs is a long time in a marine environment.
The system Yanmar has been used by other manufacturers for years with no issues. The fact that they have changed the system may only mean they see a better way. Better could mean many things.
By the look of the drive in the picture, I would say a lot of the issues are due to poor service and when serviced, I would like to know if certain components like the lock nuts etc were replaced if they looked tired. My big question is why has this waited 10yrs before it failed. I really would suggest poor maintenance and the use of components that should have been inspected and replaced.
By the way, I couldn't get your link to open.

[MidLandOne]

It has struck me that most (all?) of the responses reporting problems with the drive are from multihull owners. Which has raised the question with me as to if the real problem is due to intentional or accidental groundings (and one poster has acknowledged groundings), especially on multihulls which have no or little keel to keep the leg off the bottom, and also greater exposure to flotsam.

Generally keels need to be quite deep to prevent a leg sinking into soft bottoms and skegs, in the same circumstance, provide no protection at all.

It may be that these drives were mostly fitted to multihulls due to their low power output and that accounts for the apparant imbalance towards multihulls experiencing problems with them, I don't know, but I would have assumed that there would be plenty of smaller monos with similar power drives.

If this is so, then whether the damage would be counted as due to abuse or not by drive manufacturers I would not know. But from my own point of view I would regard it as from abuse (which for a second hand boat may be that by the previous owner) apart from the rare occasion af genuine accident.

[ssullivan]

My problems were caused by stupidity, not a manufacturer's defect or something to do with multihulls...?? (lol)

Mine fell off because neither I nor the previous owner used Locktite to keep the bolts in place that hold the prop cone assembly on. This is imperative in order to make sure it can't come unwound when you use reverse thrust or have a great sailing day.

Now, to the multi specific stuff:

The saildrives have low power output? How so? The saildrive puts out the HP of my engine (30hp) through a 16", 11 pitch, two bladed prop at exactly parallel to the waterline. I'm pretty sure this is more power (in the correct direction, not downward) than a standard prop shaft on an angle puts out.
Grounding?? I'd have to smash about 20 inches of my hulls out and break off my skegs and rudders by the same amount in order to even touch the prop blade to the ground.

Sorry... not trying to be confrontational.... just not understanding these comments about grounding and less power coming from saildrives. Also, not understanding what this could have to do with multi vs mono.

Originally Posted by MidLandOne

It has struck me that most (all?) of the responses reporting problems with the drive are from multihull owners. Which has raised the question with me as to if the real problem is due to intentional or accidental groundings (and one poster has acknowledged groundings), especially on multihulls which have no or little keel to keep the leg off the bottom, and also greater exposure to flotsam.

Generally keels need to be quite deep to prevent a leg sinking into soft bottoms and skegs, in the same circumstance, provide no protection at all.

It may be that these drives were mostly fitted to multihulls due to their low power output and that accounts for the apparant imbalance towards multihulls experiencing problems with them, I don't know, but I would have assumed that there would be plenty of smaller monos with similar power drives.

If this is so, then whether the damage would be counted as due to abuse or not by drive manufacturers I would not know. But from my own point of view I would regard it as from abuse (which for a second hand boat may be that by the previous owner) apart from the rare occasion af genuine accident.

[Steve Rust]

MidLandOne
The saildrive is more common on multihulls though it is a used often in Europe on monohulls. I have to echo Sean's point. I think you are just jumping to the wrong conclusions. On my boat the minikeel and rudder skeg are deeper than the the drive and prop. I would suspect something similar on most boats whether it's the hull or keel. To have your drive leg as the deepest part of the boat would be pretty foolhardy. Many problems may stem from new owners being unfamiliar with the unit. I had my own learning curve with mine though it produced no ill effect's like Sean's.

[MidLandOne]

Originally Posted by ssullivan

The saildrives have low power output? How so? The saildrive puts out the HP of my engine (30hp) through a 16", 11 pitch, two bladed prop at exactly parallel to the waterline. I'm pretty sure this is more power (in the correct direction, not downward) than a standard prop shaft on an angle puts out.

I think you have misinterpreted me - I was referring to the low power requirements of the drives in cats compared to monos (if only because there are often two drives in a cat) and that perhaps meaning that more of these drives would be fitted to cats and that explain the apparant imbalance of experiences. As far as I can find these (SD 20) drives were only made up to 30 hp and in my book those then all count as low powered drives.

So nothing to do with shaft versus saildrives.

Originally Posted by ssullivan

Also, not understanding what this could have to do with multi vs mono.

I think any connotation that my post was oriented to being "multi vs mono" is purely a figment of your imagination. It certainly was not intended so but was purely offered as a possible explanation as to why most (all?) of the unfortunate experiences related in the thread seem to be to do with cats - that offering in part based on my quite wide experience with power cats (some of which in out of the way places commercial ones are intentionally grounded for maintenance).

If you cannot accept the postings of others as genuinely based offerings then it becomes clear as to why you are inclined to make comments such as -

Originally Posted by ssullivan

Sigh... this is why I have another forum now to discuss this stuff.

It sometimes seems is a very strange world we live in when some appear to construe every comment possible as being confrontational.

[MidLandOne]

I accept your comments from your experience Steve.

Originally Posted by Steve Rust

On my boat the minikeel and rudder skeg are deeper than the the drive and prop. I would suspect something similar on most boats whether it's the hull or keel. To have your drive leg as the deepest part of the boat would be pretty foolhardy.

I was not inferring that the drive would extend below a keel or skeg, as you say that would be pretty foolhardy (especially in the case of an intentional grounding). Just was based on my observations that on soft bottoms (so meaning soft muds) a keel will sink quite a surprising depth (even when underway and grounding) and a skeg will be of no use at all.

The above was based on experiences and observations with powered vessels (including power cats) not sailing cats but assumed a similarity. As another indication, for fin keeled monos (and I rush to point out that this is not meant to be confrontational, despite not knowing myself how it could be so taken ) and which are of course usually very much heavier than cats we use a berth quite regularly where on low lows we bottom and have sunk at least half a metre into the bottom, stopping when the tide turned. We have also pushed through some unknown depth of mud getting to the berth on one (unexpected) occasion. I have been on an eighty something foot mono in the same berth and she went in at least a metre, again stopping when the tide turned.

By the way, I have a soft spot for tris as when just a kid a tri was the first ever "big" boat I set foot on. That was Arthur Piver's own Lodestar and the man himself was aboard - also some family friends about that time were building one of his Victresses (which they completed and cruised). Unfortunately he didn't take me for a sail, possibly thought it was not worth it as I was just a little tyke but is a visit I always remember. Must have been around 1963'ish so not very many years before he was lost at sea.

[Alan Wheeler]

Midlandone has made some good points. I have often noted even on Mono's when a saildrive is fitted, the prop does indeed seem very unprotected. They tend to exit the hull someway aft of the keel and often the rudder or skeg is someway aft of the drive. leaving it very exposed.

Sean, I really have grown tired of your snipy little comments. What you stated was completely wrong and out of line. I have removed your remark.

[GordMay]

Originally Posted by josef

... (sic: if) it was not a design fault and merely "lack of maintenance" why then have Yanmar now confirmed to me that they had a design change in the prop shaft of the SD 20? ...

Every Manufacturer reserves the right to make changes in their products, in order to improve design, performance, reliability, and etc., as part of their continuous process of product and service improvement, or to improve product availability.
Most make written disclaimers to this effect.
Such improvements do not constitute reparation of a fault or failure, which are usually dealt with through a cautionary bulletin or recall.

[josef]

Thanks Alan Wheeler and GordMay.A grey area certainly with potential disastrous consequences .The link should be http://www.cruisersforum.com/forums/f1 14/prop-fell-off-help-15371.html#post169282

[Steve Rust]

MidLandOne
I think I get where you are coming from. On a mono you usually have a deeper keel so there is more distance between the bottom of the keel and the prop. Most multi's having the shallower hull form this distance will be less so less margin for error. I had an experience with my tri in the Erie Canal with a less experienced helmsman that went under a bridge in the wrong place. We hit a rock ledge that must have been a few inches too shallow. The keel slide over with a bang then nothing from the prop but when the skeg hit the stern jumped up a few inches with a nice loud bang. I was down below and it sounded pretty bad but no leaks developed and when I hauled out that fall the only damage was some gouges in the bottom of the minikeel. My underwater profile would be very similar to a mono with a moderately long fin keel and skeg rudder though not as deep of course. The drive is closer to the skeg than keel.

The saildrives used to be limited in engine size but now I see Yanmar has a few different models that can be used up to 75 hp.

There at the dawn of history. Maybe you met a young Jim Brown as he was with Piver at that time.