[Public-List] Dripless stuffing box (was: Standpipe exhaust)
mahseer at kos.net
mahseer at kos.net
Wed Dec 16 10:34:59 PST 2009
The dripless seal I am looking at does have a water inlet installed to
cool the surfaces at high RPM. This may not be necessary on my A4 that
runs at 1500rpm but will keep it cool. On this model there is fixed
portion attached to the stern tube within the bellows and a fixed disk (I
believe it is a carbon composite material) attached to the prop shaft.
Inside this disk are 2 "O" rings that create the water seal on the shaft.
The water inlet is on the sterntube assembly as long as there is
sufficient presure on the carbon surfaces no water will pass. I believe
this is the same principle used on some top load washing machines. I am
still not convinced to go this way but it is high on my priority list.
John Boor
MAHSEER #380
> John,
>
> I'm not sure what brand of dripless seal you are using, but here is
> what I understand:
>
> The ones I'm familiar with do want you to have a flow of cooling water
> (a small plastic PTH connector is inserted and you run a hose to it),
> but that is usually not required, flow wise, for a displacement speed
> boat. On the other hand, some people still do elect to install the
> cooling water hose in a displacement boat, because this eliminates the
> need to burp them upon launch.
>
> Not that burping is a problem, but you have to be sure that the yard
> does it.
>
> Rachel
>
> PS: I can't remember which of the two popular brands this is, but one
> of them requires a really good shaft surface for it to seal to;
> whereas the other brand uses two mating discs to seal, and thus is
> more tolerant of slight imperfections in the shaft.
>
> PPS: Don't take this as an endorsement at all. Personally, I vastly
> prefer the traditional stuffing box, with some nice gore packing.
>
> On Dec 16, 2009, at 10:17 AM, George Dinwiddie wrote:
>
>> John, I'm not a fan of the mechanical dripless stuffing boxes. And
>> I think any modification to add a valve would only let the
>> manufacturer off the hook in case of a failure. Besides, can't you
>> just pull on the accordian fold to drain the bearing?
>>
>> - George
>>
>> mahseer at kos.net wrote:
>>> When I opened up my exhaust, except the section that is above the
>>> water
>>> line that had some soot the bronze pipe was as good as the day it was
>>> made. No corosion or pitting, I am in fresh water not salt. the
>>> weak link
>>> seems to be the braise between the copper pipe and the bronze lower
>>> washer.
>>> This winter I have to remove the engine to replace the cockpit drain
>>> gate valves, while doing this I might replace the stuffing box with a
>>> dripless one. Since they need a flow of water to cool them I am
>>> thinking about useing the exhaust drain valve to do this this way
>>> there
>>> is no standing water in the pipe when the boat is not used. Any
>>> thoughs
>>> on the dripless bearing and the cooling idea.
>>> John Boor
>>> MAHSEER #380
>>>> If the joint leaks, it'll dump into the bilge, not the cylinder.
>>>> The
>>>> center pipe is continuous. Also, the old ones had a drain valve to
>>>> drain the water out for the winter.
>>>>
>>>> - George
>>>>
>>>> Peter Amos wrote:
>>>>> I had one of these on my previous boat.It was an incredibly heavy
>>>>> weight on the exhaust manifold,it leaked from a weld,out of sight
>>>>> ,and corroded an engine mount.I saw a diagram in one of Calders
>>>>> maintenance books and it looked to me that it always had water in
>>>>> it.If an interior weld leaks I think it would dump water into the
>>>>> cylinders
>>>>>
>>>>> Pete #166
>>>>>
>>>>>> Date: Tue, 15 Dec 2009 09:50:00 -0800
>>>>>> From: gwyn at beluga.phys.uvic.ca
>>>>>> To: public-list at lists.alberg30.org
>>>>>> Subject: [Public-List] Standpipe exhaust
>>>>>>
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I just had mine refurbished. It was leaking and something inside
>>>>>> was rattling. I didn't actually see the pipe disassembled, but
>>>>>> the guy made some drawings which I've reproduced and put
>>>>>> on the web at:
>>>>>> http://astrowww.phys.uvic.ca/~gwyn/pers/sailing/standpipe.gif
>>>>>> The drawing is a bit crude, and not to scale, but it gives
>>>>>> you the idea.
>>>>>>
>>>>>> The rattle was caused by the deflector cap coming loose,
>>>>>> which is what is described in the last paragraph of:
>>>>>> http://www.alberg30.org/maintenance/MechanicalPropulsion/Exhaust/standpipe.html
>>>>>> It was resoldered in place. It wasn't possible to get the top
>>>>>> cap off by melting the original solder, so it was cut off and
>>>>>> then resoldered with silver solder.
>>>>>>
>>>>>> The guy who did this (Townside Auto in Victoria BC) said the
>>>>>> pipe was copper, not bronze. He figured that to make a new one
>>>>>> would require 200$ worth of copper parts plus 3 hours shop time.
>>>>>>
>>>>>> Stephen Gwyn
>>>>>> #495 Quasar
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> ------------------------------------------------------------------
>>>>>> Stephen Gwyn | Tel: 1-250-363-3136
>>>>>> Dept. of Physics & Astronomy | Fax: 1-250-363-0045
>>>>>> Univ. of Victoria | Cell: 1-250-885-6969
>>>>>> PO Box 3055 | E-mail: gwyn at uvastro.phys.uvic.ca
>>>>>> Victoria, BC V8W 3P6 | http://orca.phys.uvic.ca/~gwyn
>>>>>> ------------------------------------------------------------------
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>>>> --
>>>>
>>>> ----------------------------------------------------------------------
>>>> When I remember bygone days George
>>>> Dinwiddie
>>>> I think how evening follows morn; gdinwiddie at alberg30.org
>>>> So many I loved were not yet dead, http://www.Alberg30.org
>>>> So many I love were not yet born. also
>>>> see:
>>>> 'The Middle' by Ogden Nash http://idiacomputing.com
>>>>
>>>> ----------------------------------------------------------------------
>>>>
>>>>
>>>>
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>> --
>> ----------------------------------------------------------------------
>> When I remember bygone days George Dinwiddie
>> I think how evening follows morn; gdinwiddie at alberg30.org
>> So many I loved were not yet dead, http://www.Alberg30.org
>> So many I love were not yet born. also see:
>> 'The Middle' by Ogden Nash http://idiacomputing.com
>> ----------------------------------------------------------------------
>>
>>
>>
>> _______________________________________________
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>> Please support them.
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>
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