Livin' the Dream...rudder repairs in exotic locations
- Thread starter Not My Real Name
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Fah Kiew Tu
Curmudgeon, First Rank
Here's an excerpt from https://www.parker.com/literature/Engineered Polymer Systems/5350.pdf
[SIZE=19.8058px]Engineering[/SIZE][SIZE=14.8543px]Catalog EPS 5350/USA[/SIZE][SIZE=16.4388px]2-5[/SIZE][SIZE=12.2797px]Parker Hannifin Corporation[/SIZE][SIZE=12.2797px]EPS Division[/SIZE][SIZE=12.2797px]Toll Free: (800) 233-3900[/SIZE][SIZE=14.855px]www.parker.com/eps[/SIZE]
[SIZE=16.4388px]This also means that the primary function of [/SIZE][SIZE=16.4388px]single spring-loaded designs is dependent on the[/SIZE][SIZE=16.4388px] installation direction. While the seal will perform[/SIZE][SIZE=16.4388px] both retention and exclusion functions, they are[/SIZE][SIZE=16.4388px] not performed equally. [/SIZE][SIZE=16.4388px]If the primary function is retention, the seal[/SIZE][SIZE=16.4388px] should be installed with the steep lip angle facing[/SIZE][SIZE=16.4388px] towards the lubricant. This is normally the open-[/SIZE][SIZE=16.4388px]faced side. If the primary function of the seal is to[/SIZE][SIZE=16.4388px] exclude, the steep angle needs to face toward the[/SIZE][SIZE=16.4388px] contaminant (see[/SIZE][SIZE=16.4388px] Figure 2-3[/SIZE][SIZE=16.4388px]).[/SIZE][SIZE=16.4388px] Figure 2-3. [/SIZE]
[SIZE=16.4388px]Installations Facing Lubricant and[/SIZE][SIZE=16.4388px] Contaminant[/SIZE][SIZE=16.4388px] [/SIZE]
[SIZE=16.4388px]If both retention and exclusion are critical and [/SIZE][SIZE=16.4388px]the level of contaminants is heavy, one seal should[/SIZE][SIZE=16.4388px] be used to retain the lubricant, and exclusion[/SIZE][SIZE=16.4388px] capacity should be added using another lip seal,[/SIZE][SIZE=16.4388px]auxiliary excluders or by upgrading to a bearing[/SIZE][SIZE=16.4388px] isolator (see[/SIZE][SIZE=16.4388px] Page 2-27[/SIZE][SIZE=16.4388px]).[/SIZE][SIZE=16.4388px] The purpose of the spring is to provide a[/SIZE][SIZE=16.4388px] constant, uniform load of the lip on the shaft for the [/SIZE][SIZE=16.4388px]life of the seal. The spring keeps the seal lip in[/SIZE][SIZE=16.4388px] contact with the shaft during higher shaft speeds[/SIZE][SIZE=16.4388px] and also overcomes compression set and wear of[/SIZE][SIZE=16.4388px] the lip material. Compression set of the lip [/SIZE][SIZE=16.4388px]material is normal as it is subjected to thermal[/SIZE][SIZE=16.4388px] cycles during operation.[/SIZE]
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This confirms a couple of my thoughts.
First, the bottom seal should ideally be double, one facing in and one facing out, as exclusion of seawater is (should be) a high priority. I can't see this from the drawing.
Second, and importantly, if the bottom seal *is* set in the position to best exclude seawater (open side down) then the spiral spring MUST be replaced with an O-ring. Those springs are not stainless and do not like exposure to salt water.
None of which alters what is there, but it's useful (IMO) to know how things should be designed. Wonder which way that seal is installed.....
FWIW this is how my prop shaft cutless bearing (bushing) is built. Machined from Vesconite with back to back lip seals outboard and the shaft tunnel grease filled.
Agree the oil bottle may well be intended to provide a head pressure. How effective this is would depend on how far below the WL the hull penetration is and how far above the bottle is. In theory if the head was sufficient and the bottom seal failed, oil would leak out of the seal until equilibrium was reached. If the top seal then started to fail, fluid could start escaping there.
FKT
[SIZE=19.8058px]Engineering[/SIZE][SIZE=14.8543px]Catalog EPS 5350/USA[/SIZE][SIZE=16.4388px]2-5[/SIZE][SIZE=12.2797px]Parker Hannifin Corporation[/SIZE][SIZE=12.2797px]EPS Division[/SIZE][SIZE=12.2797px]Toll Free: (800) 233-3900[/SIZE][SIZE=14.855px]www.parker.com/eps[/SIZE]
[SIZE=16.4388px]This also means that the primary function of [/SIZE][SIZE=16.4388px]single spring-loaded designs is dependent on the[/SIZE][SIZE=16.4388px] installation direction. While the seal will perform[/SIZE][SIZE=16.4388px] both retention and exclusion functions, they are[/SIZE][SIZE=16.4388px] not performed equally. [/SIZE][SIZE=16.4388px]If the primary function is retention, the seal[/SIZE][SIZE=16.4388px] should be installed with the steep lip angle facing[/SIZE][SIZE=16.4388px] towards the lubricant. This is normally the open-[/SIZE][SIZE=16.4388px]faced side. If the primary function of the seal is to[/SIZE][SIZE=16.4388px] exclude, the steep angle needs to face toward the[/SIZE][SIZE=16.4388px] contaminant (see[/SIZE][SIZE=16.4388px] Figure 2-3[/SIZE][SIZE=16.4388px]).[/SIZE][SIZE=16.4388px] Figure 2-3. [/SIZE]
[SIZE=16.4388px]Installations Facing Lubricant and[/SIZE][SIZE=16.4388px] Contaminant[/SIZE][SIZE=16.4388px] [/SIZE]
[SIZE=16.4388px]If both retention and exclusion are critical and [/SIZE][SIZE=16.4388px]the level of contaminants is heavy, one seal should[/SIZE][SIZE=16.4388px] be used to retain the lubricant, and exclusion[/SIZE][SIZE=16.4388px] capacity should be added using another lip seal,[/SIZE][SIZE=16.4388px]auxiliary excluders or by upgrading to a bearing[/SIZE][SIZE=16.4388px] isolator (see[/SIZE][SIZE=16.4388px] Page 2-27[/SIZE][SIZE=16.4388px]).[/SIZE][SIZE=16.4388px] The purpose of the spring is to provide a[/SIZE][SIZE=16.4388px] constant, uniform load of the lip on the shaft for the [/SIZE][SIZE=16.4388px]life of the seal. The spring keeps the seal lip in[/SIZE][SIZE=16.4388px] contact with the shaft during higher shaft speeds[/SIZE][SIZE=16.4388px] and also overcomes compression set and wear of[/SIZE][SIZE=16.4388px] the lip material. Compression set of the lip [/SIZE][SIZE=16.4388px]material is normal as it is subjected to thermal[/SIZE][SIZE=16.4388px] cycles during operation.[/SIZE]
-----------------
This confirms a couple of my thoughts.
First, the bottom seal should ideally be double, one facing in and one facing out, as exclusion of seawater is (should be) a high priority. I can't see this from the drawing.
Second, and importantly, if the bottom seal *is* set in the position to best exclude seawater (open side down) then the spiral spring MUST be replaced with an O-ring. Those springs are not stainless and do not like exposure to salt water.
None of which alters what is there, but it's useful (IMO) to know how things should be designed. Wonder which way that seal is installed.....
FWIW this is how my prop shaft cutless bearing (bushing) is built. Machined from Vesconite with back to back lip seals outboard and the shaft tunnel grease filled.
Agree the oil bottle may well be intended to provide a head pressure. How effective this is would depend on how far below the WL the hull penetration is and how far above the bottle is. In theory if the head was sufficient and the bottom seal failed, oil would leak out of the seal until equilibrium was reached. If the top seal then started to fail, fluid could start escaping there.
FKT
Hi Zonker; yes I'm well aware of the intention of the oil installation here. But it's only a stopgap add on not well thought through. Also for a radial lip seal the reduction in differential pressure will only make the seal less effective.
As for ships aren't you confusing oil pressure fed bearing seals with active outer seals. MARPOL changed the design of active outer seals a few years back. Good luck trying to get anything like through any class or flag authority. Pressurized air is good !
But even without MARPOL, on vertical rudder shafts where the port is subject to dynamic pressure effects well above static head, then the small amounts of water ingress that are inevitable in service in a seaway are trapped by the oil and will accumulate in the lower cavity. That's why the HR design has an open drain port, because a single lip seal in service in a seaway can pass a little water and that is not a problem, a continual stream indicates a problem.
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FKT; Yes open side down for both seals in this application on the HR (and note that you can get fully stainless seal components). If you really wanted an active pressurized oil dam as an active seal the the lower seal should be inverted.
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Not My Real Name
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Sun is shining...I it's colder though. High pressure systems, it was raining more indoors this morning than it was yesterday.
Not My Real Name
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So, this AM there is more oil. And there appears to be more water in the oil.
In spite of the increased moisture in the boat this AM, we saw no evidence of humidity or condensation in the area. No water tracks, none of the big drips that wake my ass up in the middle of the night from the window frame.
The logical conclusion is that it is coming in from the seal, ergo the bottom seal is not getting it done.
So I'm not going to fuck around with grease and stop gaps. I'm going to make arrangements to pull the boat next week down in Whangarei and drop the damned rudder and see what the hell is going on with that.
We're also probably going to to leave the boat on the hard when it's done and fly back to the US to help my parents move out of their house. The timing is right with my parents, we've got visa issues, and the 2019 tropical cruising season is pretty much shot to shit and we're sick of wiping up mildew and condensation.
The odds of us getting this repair done AND hitting a weather window before our visas expire on 7/30 are dropping dramatically. And even then, we have to fly our daughter back for college shortly after that (8/15 flight), and her 90 days is up on 8/8 so even she has visa issues. So fuckitall. If we're going to pull the boat again and drop the rudder we might as well paint the bottom, replace the cutlass bearing, and do a few other boat-out-of-water tasks.
We'll come back in the spring and cruise NZ some more when it's nicer.
In spite of the increased moisture in the boat this AM, we saw no evidence of humidity or condensation in the area. No water tracks, none of the big drips that wake my ass up in the middle of the night from the window frame.
The logical conclusion is that it is coming in from the seal, ergo the bottom seal is not getting it done.
So I'm not going to fuck around with grease and stop gaps. I'm going to make arrangements to pull the boat next week down in Whangarei and drop the damned rudder and see what the hell is going on with that.
We're also probably going to to leave the boat on the hard when it's done and fly back to the US to help my parents move out of their house. The timing is right with my parents, we've got visa issues, and the 2019 tropical cruising season is pretty much shot to shit and we're sick of wiping up mildew and condensation.
The odds of us getting this repair done AND hitting a weather window before our visas expire on 7/30 are dropping dramatically. And even then, we have to fly our daughter back for college shortly after that (8/15 flight), and her 90 days is up on 8/8 so even she has visa issues. So fuckitall. If we're going to pull the boat again and drop the rudder we might as well paint the bottom, replace the cutlass bearing, and do a few other boat-out-of-water tasks.
We'll come back in the spring and cruise NZ some more when it's nicer.
El Borracho
Barkeeper’s Friend
Wondering why the designers find it so difficult to seal a shaft. So I assume some boats, for some good reason, cannot have the rudder tube simply rise above the waterline like mine.. So a seal is needed. However, around the cabin here I have dozens of valves under much higher pressures with just a simple packing seal on their shaft. Most 50 years old. 25 to 200 feet of water pressure. Some turn often, some never. Dripping is very rare and solved with a twist of the nut. Same with older prop shafts.... Wondering...
Sorry for your bad luck B.J.
Sorry for your bad luck B.J.
olaf hart
Super Anarchist
Making the best of a bad situation BJ, sure it will work out.
My money is on the bottom seal being the wrong way round.
My money is on the bottom seal being the wrong way round.
Not My Real Name
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If it is there may be strong words.
We had a discussion about just that *before* any seals were installed!
Fah Kiew Tu
Curmudgeon, First Rank
FWIW - not much - I think that's the correct decision. Painful, but correct.
Hope it's something cheap & easy to fix.
FKT
Not My Real Name
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Cisco
Super Anarchist
Bespoke high quality yachts? Like Najad with the gooseneck blind riveted to the boom as on Neirida? Or the dodgy chainplate staples on Westerly Sealord/Oceanlords? They are pretty good... last for 20 years.... then your mast falls down.....
Me cynical? Never.....
Hope it all works out OK, BJ.
Me cynical? Never.....
Hope it all works out OK, BJ.
Not My Real Name
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Jud - s/v Sputnik
Super Anarchist
If you can afford to pull the rudder out of a HR 50+ in a yard in NZ, where you sailed to, you are indeed living the dream... 
[First World problems ]
[First World problems ]
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Not My Real Name
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Who said I could afford all this shit??If you can afford to pull the rudder out of a HR 50+ in a yard in NZ, where you sailed to, you are indeed living the dream...
h34r: Jud - s/v Sputnik
Super Anarchist
Ha! Yup, I know the feeling very well... Enjoy today, pay tomorrowWho said I could afford all this shit??
Not My Real Name
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If I were just summering or coastal cruising, perhaps my decision making would be different. But then again, so would my choice of boat.
But even a relatively short trip like New Zealand to New Caledonia you're four hundred+ miles from land. Even that isn't something to take risks with when you know there is a problem
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