sunworksco

Need information about the prop shaft seals on the WTC.
Please help.
John

subsinker

My Feedback: (61)

John,

Which kit and what exactly do you want to know? I have built the Lafayette, Gato and Typhoon class Engels. Any one of those and I may have a shot at answering your question.

Pete

sunworksco

Pete,
The one that seals at the deepest dive.
Do you have an image of the seals?
I'm mounting two motors on an aluminum screw plugon the WTCand using the outside prop bores
to mount bronze bearings/Engel Simmering seals but not sure what the Engel subs are using.
John

subsinker

My Feedback: (61)

John,

Engel uses a very simple brass tube that goes from the inside of the wtc to the outside. It is made so that the shaft will slip into it and exit the wtc. Over that is a vinyl(?) tube that fits over the shaft seal, thus encasing it in the wet space. They are specific about the length of the tubing. It is a simple but very reliable setup. I have been using them for years without any problems. Eventually, the tubing will get old and you simply cut it off and replace it with a new piece.

I have also used simmering seals on some of my subs, they work fine but are a bit more tricky to set up.

hope that helps,
Pete

sunworksco

Could you please post some images?

Taxidriver

subsinker

My Feedback: (61)

Thanks Taxi...ya beat me to the punch!

Pete

sunworksco

I'm assuming that that image is inside the wtc?What is in the smaller brass fitting right side of the coupling?
I am using the Engel coupling but do you have an image of the rubber/metal spring loaded Simmering seal installation that Engel offers?
If you can picture my two motors bolted to the aluminum screw plug on the inside of the wtc and the motor shaft bores through the thickness of the screw plug to the wet hull side with bronze bearings and the Simmering seals pressed inward from the wet hull side with two threaded o-ring cups inserted over the wet side shaft bores.

Taxidriver

No everything in the picture is on the wet side.

I tried really hard but I just cant picture that! You only need 1 seal per shaft and it need to be wet on one side I (in contact with water) or it will overheat with friction on the shaft and breakup . This goes for just about and rubber/nitrile/PVC seal.

sunworksco

The output shaft end of the motor has six threaded mounting holes for mounting to the dry side of the screw plug.
The screw plug has two shaft bores that will be slightly larger than the bolt diameter pattern for the mounting of the motors.The motors will be bolted to a thin area of aluminum flange seperating the wet side bores from the dry side of the wtc.
The inside diameter of the motorbolt patternin the bores will be female-threaded for the male-threaded bronze bearing and Simmering seal support cups with o-ring seals in between the cups and bores.
These cups will have the bearings and Simmering seals pressed in.
This will keep the water from reaching the motor that is mounted on the dry wtc side of the screw plug..

Taxidriver

If your using a Simmering seal you dont need any orings.

sunworksco

The screw plug has two 1-1/2" bores through it.There is a small bolt pattern flange on the motor mount side of the plug.To seal the bolt holes and have the bearing and Simmering seal support housing,I am machining two threaded pipe-like fittings with o-rings to seal the screw plug bores.These will be threaded into the bore holes with the o-ring in between the end of the pipe compressing against the motor flange to seal off the bolt flange.The two pipes will have the bronze bearing and Simmering seal pressed into it.There are no o-rings on the prop shaft,only the bearing/seal cups to seal off the bores.
It is similar to the image attachment.

AQUASUB

I just make my own have not replaced one yet in 25 plus years.

Taxidriver

That causes far too much resistances, and can be messy. Assuming offcause it doest leak with the Pisrton tanks the OP wats to use. Repacking it after removing or changing a shaft is going to be a pain as well. A Simmering is the way to go here, seals tighter the deaper you go too.

cyclops2

I just use SS bearings / shafts & brass tube coated on the inside with a VERY thin grease. 8' PTB has run for years with no maintaince.
Same setup for the rudder. Fine also.

I did sand down the shaft for about a .003" to .005" fit. Important to any grease / oil fit & seal.

sunworksco

Is your 8' PTB a submarine?
Only a Simmering seal is rated for a submarine propshaft seal.

cyclops2

Not yet.

AQUASUB

The stuffing boxes I make have very little resistance and can handle a tremendues amount of pressure or vacume much more than any ballast system could produce or deep the sub could ever travel.The same designe is replascing the TT s shaft seal that was not going to hold up and had no bushing witha dod bone drive,not a good designe at all as the seal would leak constantly at depth of 25 plus feet.
To repack the box just remove the shaft or install a smaller brass tube or nipple or verkfitting though I have never had to repack one in many years some of my subs are 20 plus years old and have miles on them and still go strong.

If you want a shaft seal that will never fail and can go the depth for as long as you own your boat this designe is fantastic cheap and can be made to any standard or metric shafts as bushings come in many sizes and K and S tubes also have ahuge range available.

This designe has been around for a long time and for good reason it works very well and you can make it taylord to your needs as short or as long as you need ..If its made right and its so easy the shaft will turn very smothly and i garantee it won't leak!!

I get my shafts from smallparts.com centerless stainless shafts super high quality made for fine instruments ,the cintered bushings also.The total cost is very cheap and will out last any single flexable seal out there.The prop shafts are the most used seals on a sub and must never fail so i prefer to build a quality box that I never have to worry about.

Dave

cyclops2

Aquasub.
Putting grease in it center section will just increase shaft drag. The real sealing is at the sintered bushings. I like the design.

Skip Asay

"The stuffing boxes I make have very little resistance and can handle a tremendues amount of pressure or vacume much more than any ballast system could produce or deep the sub could ever travel.The same designe is replascing the TT s shaft seal that was not going to hold up and had no bushing witha dod bone drive,not a good designe at all as the seal would leak constantly at depth of 25 plus feet."


Somehow, given your track record concerning honesty coupled with 35+ years of experience, I sincerely doubt that any of the above is true. I've tried this method myself.....yes, it works.....for a while and then the grease extrudes out into the WTC which makes an ungodly mess. And I've seen too many other guys swear by this method until the first or second time they take their boat deep. And then they start swearing AT it. Yes, this method has been around for a long time. But only the newcomers use it any more because they don't know any better.

You just can't argue with the laws of nature and physics.

And cyclops2, it works for you since your boat doesn't submerge. But I don't recommend trying it on a submarine.

Skip Asay

sunworksco

I'm in agreement with Skip.
I work with all type and size circulator pumps and pump seals and the Simmering seal is really more suitable for propshaft sealing.

cyclops2

Well all surface boats have a .......submerged prop, bearings, stuffing tube and a set of bearings near the motor. So the water pressure 4" down is the same for both sub & surface boats. That is the depth where all types of boats shaft seals spend 99 % of their time. My Gato has no leaks at 2' down running for 2 minutes. True, I do use SS sealed bearings in all boats.

The change in water pressure is very little from 4" to 5'. I can look up the pressure change fom 4" to 5' if that would help.
A sealed bearing with a low friction neoprene seal actually squeezes the shaft tighter as the outside pressure builds upon the shaft and seal face. At least mine do.

cyclops2

I could not remember the depth versus pressure changes.

Pressure increase @ 33' down is 1 atmosphere. 14.7 # increase more than surface air pressure. So we have a worst case of the seal at 33' resisting the difference of 15#. A problem may occur in the water being able and wanting to push itself into the WTC due to the compression of the 14.7#of PSI air in the chamber.

That problem in our subs is handled by a VERY VERY close fit of the shaft diameter & the stuffing tube inside diameter.
I run a few thousandths at MOST. I spin the driveshaft with a electric drill in a vise & constantly hand sand down the shaft till the shaft just slips in for the entire length. Oil works fine on 3" & longer. At 6" long & longer I switch to SS Sealed ball & thrust bearings to reduce needless shaft drag.

Rich

sunworksco

Fresh water: 0.43 psi per foot Sea water: 0.44 psi per foot.

So, for each additional 10 feet of depth, figure about 4.3 to 4.4 psi increase in pressure.

You can calculate this yourself by using the fact that fresh water weighs about 62.4 pounds per cubic foot (pcf) and sea water weighs about 64 pcf. Divide those numbers by 144 (the "footprint" of one cubic foot, 12 x 12) and there you go.

It's interesting to note that this pressure is independent of volume or expanse. i.e. the water pressure behind a fresh water dam at 100 feet deep is about 43.3 psi regardless of whether the dam's reservoir is 25 miles long or 10 feet long. Depth and density are the only relevant parameters needed to determine pressure.

Dive pressure, however, would be the water pressure of 43.3 plus the air pressure above the water. So the net pressure on your ears & body would be 43.3 plus 14.7 (one atmosphere)totalling 58 psi,or about 4 atmosphers. That's four times our normal experience. Worthy of careful consideration.

cyclops2

The good thing about our model shaft bearing areas is how...... small of a area........... is actually being in danger of deforming . On my 1/4" diameter shafts only about .030" to .060"of the circular seal face is in a "" bendable area "". The rest is pressed in place by a SS ring and much thicker.
Bearing seal faces come in all weird face shapes. Some help & others make a leak occur faster. We just have to check with the bearing mfgr. to find out.

BIG phone bills for a little detail. [:'(]

Still, the bearing tube & shaft with a few thousandths of clearence works very well.
I put Vasaline in the 1st one I did to a few thousandths. 6" long & the size 280 motor could bearly turn it at room temperatures. Would have flamed the motor easily in the water..........Oil is all that should be used in close fitting shafts & tubes.