shaft bearings ideas please

[whoosh]

the boat is al al, the shaft is 1 1/2 or maybe 40 2205 which is higher in tensile than 316l and more corrosion resistant
Plan is pps seal and possible Aquadrive cv in the space available
It is 2000mm shaft length
Anybody used the Vetus couplings/ which would be less costly?

[apex1]

the boat is al al, the shaft is 1 1/2 or maybe 40 2205 which is higher in tensile than 316l and more corrosion resistant
Plan is pps seal and possible Aquadrive cv in the space available
It is 2000mm shaft length
Anybody used the Vetus couplings/ which would be less costly?

We use Vetus couplings as standard.
Regards
Richard

[whoosh]

We use Vetus couplings as standard.
Regards
Richard

and alignment are you clock dialing?

[apex1]

and alignment are you clock dialing?

They use a "rotalign" called tool, pretty simple and reliable. Could´nt find out what we paid for it, but was not cheap the Prod. manager remembers. He also said "clock dialing" was the worst method he knows. Except it is done on a calibrated roller bed.
Regards
Richard

[whoosh]

Another strong point of the Bullflex coupling in the excellent alignment of hte propeller shaft. Perfect alignment of engine and propeller shaft. Perfect alignment of engine and propeller shaft often tends to be a rather time consuming affair, but the Bullflex comes to the aid of the installation engineer. Even with a misalignment of 2 degrees, the shaft will remain perfectly centered onto the flange of the reverse gearbox. On account of a special centering ring, high shaft revolutions are entirely possible and even in reverse gear, the shaft will remain perfectly centered. The non-tapered clamping hub ensures easy installation and - probably even more important: easy dismantling of the shaft assembly. This in contrast with a tapered clamping hum. Costly machining of hte shaft, such as tapering and keyway cutting is not longer required. Just cut the shaft to length, free of burrs, degrease and install.

i still prefer to clock the coupling(dial indicator) it is best practice, although not a good idea for aquadrive cv types
oh fisheries supply seattle the bullflex(vetus) 40mm 1000 usa, cheaper than anywhere else

[mydauphin]

Have similar setup. I am assuming that shaft log is aluminum and that bearings will be composite not bronze. Make sure you have constant water circulation around shaft. Isolate shaft from engine and put plenty of zincs everywhere.

Aquadrive type is best, but if alignment is less than 2 degrees then bullflex would do but I would try for dead on alignment and let bullflex take care of margin of error. That way bullflex will last longer.

They are not cheap either...and I have to buy two. I am looking for cheaper alternatives.

[whoosh]

Have similar setup. I am assuming that shaft log is aluminum and that bearings will be composite not bronze. Make sure you have constant water circulation around shaft. Isolate shaft from engine and put plenty of zincs everywhere.

Aquadrive type is best, but if alignment is less than 2 degrees then bullflex would do but I would try for dead on alignment and let bullflex take care of margin of error. That way bullflex will last longer.

They are not cheap either...and I have to buy two. I am looking for cheaper alternatives.

yes thanks, me built 32 alloy boats so far:)) so nothing is a mystery and you are right nothing is cheap
I do not OVERZINC, just dont mix metals Usually Zn in front of prop, and one on keel, thats all ever done I have found Fisheries Supply in Seattle to be cheapest The tube willl be 6080
if anyone is interested I put a piece material into end, with small hole in centre, one in other end with say 3mm hole, then I stick mig wire through it, , find centre with mig wire, cranked up tight to Centre of bearers or floor or bulkhead, that way you can keep check on alignment whilst welding

[apex1]

Here is a link to the tool we use:

http://www.pruftechnik.com/fileadmin/user_upload/COM/Alignment_Systems/Products/Shaft_Alignment/ROTALIGN_ULTRA/Brochures/ROTALIGN-Ultra_4-page-leaflet_ALI-9.843_07-08_D.pdf

see my (edited) post above.

[mydauphin]

I feel so ancient... I use feeler gauge.

[whoosh]

I feel so ancient... I use feeler gauge.

feelers and straight edge are fine, its just I got so used to clock dialing(been around as longs as metal lathes) on my 4 jaw lathe that it became simple

[mydauphin]

So we have;
Lasers
Mig wire, not sure how that works
Clock Dialing
and Feeler gauges

any other way.

[MikeJohns]

Stuart et al

On many smaller boats (<20m) with shaft RPM< 1000 we have been grease filling the tunnels and removing the water lubrication with success and even reduced bearing wear for both the hard rubber and metal bearing surfaces.

SS shaft corrosion in flooded tunnels, is a pain the water loses it’s oxygen and boats that are laid up for several months suffer from high rates of shaft crevice corrosion . Painting the shafts and tunnels is sensible but often then there is crevice corrosion on the shaft bearing surfaces. Problem boats that we shifted to grease fill are running fine. Then it's sensible to opt for non fluted bearings and grease seals .

I’d be interested in others experiences here as shaft pitting is a significant problem.

On smaller vessels unless everything is hard mounted on very rigid beds then shaft coupling alignment is hit and miss with even the most accurate equipment.
If soft mounted then misalignment is both caused and also accommodated by the mounts, and if you look at how much the engine moves just from torque and main vibration modes and you quickly see that aiming for very high accuracy at the flange faces is invalid. To properly do it you’d crank the engine over to an operating torque angle and do it there :)

Pull the shaft back into the tunnel so its supported close to the end and a dial gauge will indicate any runout on the flange face and check for any eccentricity on the rim. Check also the gearbox output flange. If anything is out remove and true the faces and surfaces.

With the shaft back in position you may need to support its weight as the shaft will sag. Recommended procedure is to align the flange edges and then go through the adjustment routine with the engine mounts for the flange gap. At the end it should pinch 3 thickness gauges, strips of paper are quite useful mylar strips are good too and this is easier and more accurate than trying to push a feeler gauge in at 3 points.

The classic over the top alignment has always been wood and GRP hulls that are a different shape on the hard if not fully blocked, then the alignment should only be done afloat. The engine installer dial gauges the whole installation and if it’s cracked apart in the water the alignment is out by a frightening amount.

[mydauphin]

Stuart et al

On many smaller boats (<20m) with shaft RPM< 1000 we have been grease filling the tunnels and removing the water lubrication with success and even reduced bearing wear for both the hard rubber and metal bearing surfaces.

SS shaft corrosion in flooded tunnels, is a pain the water loses it’s oxygen and boats that are laid up for several months suffer from high rates of shaft crevice corrosion . Painting the shafts and tunnels is sensible but often then there is crevice corrosion on the shaft bearing surfaces. Problem boats that we shifted to grease fill are running fine. Then it's sensible to opt for non fluted bearings and grease seals .

I’d be interested in others experiences here as shaft pitting is a significant problem.

.

I think people in USA are terrified of grease bearings from a environmental fine point of view. It seem to me that shaft pitting is cause by boat siting. If no water circulate around shaft or where bearing and shaft meet it will eat shaft.
That is why water circulation is crucial even when you are not using boat.

[Ad Hoc]

here are a couple of nice examples of pitting, as noted above.

One of the main reasons for this, apart that noted, is the material of the stern tube. From our experience, we now always recommend using GRP stern tubes. Have done several with GRP..after many years service...no problems at all...and shaft in excellent condition.

[MikeJohns]

I think people in USA are terrified of grease.....

Oil bath is common enough fully sealed and it is easier to seal in grease than oil, how do all the old wooden boats with their greased bronze assemblies get treated in the USA ? Even if the shaft is over-pumped you can have a relief tube into a container inside.


Interesting AdHoc that the grp tube works this way. how do you fix it within a metal construction such as Stuarts. Do you us it as a tunnel liner?

In alloy boats we have had more noticable problems with shaft pitting with uncoated tunnels it may be that the alloy surface bonds more of the oxygen from the water and depletes it faster.

[Ad Hoc]

MJ

"...Do you us it as a tunnel liner?.."

The first ones were like a liner, if i recall, for class requirements, as they were very conservative (this was well over 10 years ago now, so my memory has faded a bit). But where possible a complete tube made from GRP.

Otherwise stern tube suffers poorly too...see attached.

[MikeJohns]

Aslo why we always specified for the tube to be epoxy coated but with oil or grease filling there is no problem.

That illustrated corrosion is also very similar to the corrosion in alloy watertanks when uncoated.

[Ad Hoc]

MJ

you mean like this?

This was as a result of two aspects which are often over looked.
1)The alkaline/acidity of the fresh water
2) alloy grades

The internal stiffening was a different grade of ally to the plate. It was this, that caused simple bimetallic corrosion. Never encountered this before between two different gardes of ally, so close on the scale too. Solution, all stiffening on the outside of the tank now.

[whoosh]

all noted: and thats why 2205 is so successful, it is very corrosion resistant in salt particulary warm brackish stuff You can also reduce in size too, as I did argue successfully with NZ MARINE DEPT at time using 80mm as against 100 mm rudder stock
I AM at odds with your theory ideas on soft mts Mike, you do give the gearbox bearings a big chance by clocking shafts in
i remember years before I was into building I was a field service engineer, Cummins Eng co I went to new installation on a small trawler, down In Newcastle Well the noise from the twin disc was unbelievable, the thing was owner built and they were ready literally to beat the crap outta me, they were all drunk, I split the coupling and that shaft never came withing 2mm of kissing the gear flange Misalignment is just poor workmanship
I have mussel harverster with 20000 hrs on scaniaS with centreflex couplings still oiriginal It is just something I have always done
however on cv types like aquadrive , misaligment is advised or apparently they will wear in one spot
with greased stern tubes one must be careful that the grease is kept away from ceramic seals
in the past I have bored the tubes from solid 5083 square sections, leaving the section square too, except where it exit the hull, Reason being 5083 is not to my knowledge available in solid round or tube
ttp://www.azom.com/Details.asp?ArticleID=958#_Mechanical_Properties
The corrosion behavior of 2205 duplex stainless steel was compared with that of AISI type 316L stainless steel. The 2205 stainless steel is a potential orthodontic bracket material with low nickel content (4 to 6 wt%), whereas the 316L stainless steel (nickel content: 10 to 14 wt%) is a currently used bracket material. Both stainless steels were subjected to electrochemical and immersion (crevice) corrosion tests in 37° C, 0.9 wt% sodium chloride solution. Electrochemical testing indicates that 2205 has a longer passivation range than 316L . The corrosion rate of 2205 was 0.416 MPY (milli-inch per year), whereas 316L exhibited 0.647 MPY. When 2205 was coupled to 316L with equal surface area ratio, the corrosion rate of 2205 reduced to 0.260 MPY, indicating that 316L stainless steel behaved like a sacrificial anode. When 316L is coupled with NiTi, TMA, or stainless steel arch wire and was subjected to the immersion corrosion test, it was found that 316L suffered from crevice corrosion. On the other hand, 2205 stainless steel did not show any localized crevice corrosion, although the surface of 2205 was covered with corrosion products, formed when coupled to NiTi and stainless steel wires. This study indicates that considering corrosion resistance, 2205 duplex stainless steel is an improved alternative to 316L for orthodontic bracket fabrication when used in conjunction with titanium, its alloys, or stainless steel arch wires. (Am J Orthod Dentofac Ortop 1997;112:69-79.)

[MikeJohns]

....
I AM at odds with your theory ideas on soft mts Mike, you do give the gearbox bearings a big chance by clocking shafts in..........that shaft never came withing 2mm of kissing the gear flange Misalignment is just poor workmanship.....

2mm is still gross misalignment I just smile when I see someone chasing the last few thou on a soft mount.

I'll tell a tale as well :)

I just looked at a used boat recently purchased by a local , the gearbox output shaft bearing had failed and after a new bearing and seal, the engine was in perfect alignment BUT on low power it all sounded fine on high power it sounded harsh and horrible and he knew something was wrong. The mech he had used was obviously useless and he had replaced broken bolts on the coupling and checked the alignment again dialed the shaft to check for a bend and found nothing amiss.

I saw immediately the engine was soft mounted and there was no flexible coupling. After nearly $3k for a coupling its all sweet and the stuffing box has stopped leaking too.

Engines move on flexi mounts especially under torque and that does interesting things to alignment particulallry on the models where the mounts are off the shaft plane or a drop box changes the line.

[anotherMike]

A few notes to add to the shaft alignment discussion:
1. most of the boats we align, older boats of traditional design, don't have the clearance around the couplings or access to allow use of a dial-indicator. Feeler gauges have the advantage of being shock- and water-proof, and cheap to replace.
2. I've found that the final few thousandths are quick to achieve, by that time the system for moving the engine is perfected. Assuming there is deflection from thrust, I've always felt the total mis-alignment, and therefore stress, would be less if the starting-point is zero. I just don't feel right bolting up a coupling with a runout of more than a few thousandths.

[whoosh]

when all said and done, some of us build for a living
It is up to us to follow good and sound practice, to remove doubt when things go wronrg etc and to stop people suing when and if they go wrong
About the corrosion in the tube, shaft log, call it what you will, although tunnel is not, big ships have tunnels where the shaft spins and greasers, oiliers engineers walk, to place knowledged hands on bearing cases:)
If you pressed in , light interference fit a liner if that green eng plastic, line bored it, then that would stop any corrosion issues
Old fashioned stuffing glands had white metal bearings, the inboard end of the shaft was supported These days with dripless seals, you dont get a (free) inboard bearing
who uses what? vesconite? In NZ Chatfield eNG WILL supply the bearing machined to allow for swelling
Who can remember the recommended distance between bearing? for given shaft Dia?

[Ad Hoc]

"...Who can remember the recommended distance between bearing? for given shaft Dia?.."

You don't. It's called whirling calculations, and you have to calculate it for your own individual layout to satisfy yourself and/or class.

[MikeJohns]

Stu
OK stern tube on a smaller vessel .

Interesting on the new ships that knowledgable hand is replaced by sensors and that engineer sits in front of a computer on land and monitors the fleet with remote telemetry.

The basic procedure is to calc the critical whirling speed and change the shaft dia and bearing spacing and or shaft material until whirling will not occur.

Society rules give specific calculations that incorporate this transparent to the user.

[MikeJohns]

A few notes to add to the shaft alignment discussion:..........I've always felt the total mis-alignment, and therefore stress, would be less if the starting-point is zero. I just don't feel right bolting up a coupling with a runout of more than a few thousandths.

That's the catch, unless you are really into rotating machinery you're interest ends in doing a highly accurate static matchup and then you are out of there feeling happy.
How many go back and actually look at what the whole setup does under full power which is where you should analyse it. Just look at a soft mounted engine as its cycled through its power range and you will visually see it move with most soft mounts. Then there should really be a pre-load to account for that so some initial mis-alignment may actually be beneficial, but thats why the flexi-coupling is there.

[Ad Hoc]

"...Reason being 5083 is not to my knowledge available in solid round or tube.."

5083 is available in any form, you just have to ask for it.

I've used solid bar and tube 5083 endlessly. It is also a class requirement for inlets too...so you just need to find the mills that produce it regularly.

[whoosh]

you can NOT buy this stuff in NZ or Au, in fact I just rang the al co James, to get heavy walled tube, you need a mill run, min 500kg
nothing and I mean nothing is stocked in 6082 0r 5083 Point me to any site that will supply 2 m of this and .6m of that
even solid bar or squares are not available from which one could machine from.
there are rules thumb rgds bearing, I know in Skeins, but I can not find my Skeins
ok I found my skeins which is an old Bible trusted, argue with that, no doubt you will, the recomendation for 1 1/2 is five feet and five inches

[Ad Hoc]

I just assumed someone who has been building/working with aluminium since the 70s would know where all the mills are and how to get it by now!

Onesteel, Soon lian, Pechiney etc etc...all make/stock it...but like everything, small quantities come at a price. So, just try local mills/yards that use it regularly if no luck, be prepared to pay a premium for it.. or use a size that is not ideally suited, as would often be the case, since these are almost always in stock somewhere.

[MikeJohns]

....Skeins
ok I found my skeins which is an old Bible trusted, ...., the recomendation for 1 1/2 is five feet and five inches



To compare our requirements for survey under USL is calced:
0.142 X cube root (d squared) ...........in meters
d is dia in mm


Gives 1.6m or 5' 3 " with a recommended 12d minimum from the last bearing to the coupling.

[whoosh]

To compare our requirements for survey under USL is calced:
0.142 X cube root (d squared) ...........in meters
d is dia in mm


Gives 1.6m or 5' 3 " with a recommended 12d minimum from the last bearing to the coupling.

thanks Mike, I will up to 40mm I should just squeeze in
on the Bullflex website , the coupling speed max is halved if the misalignment is 2 degrees
40 40^(1 / 3) = 3.41995189 x.142
does not tally?

[MikeJohns]

Sorry Stu missed that, something wrong with your calculator :-)

(40^2)^(0.333.) X 0,142
=(1.6E3)^(0.333.) X 0.142
=11.70 X 0.142
=1.66 m

[whoosh]

S,all right fer you, but sci fi calculaters, I can not drive
Ah well, I have 1.6, from inboard end of bearing
I will stick number 8 coupling as for 12 would need spacer to clear pump,
Oh Fer your info
I ordered sections from China price to you::)) 5 dollars kg
It took a long time to est. trust with them but after ringing their clientele around the world I am satisfied

[Brent Swain]

20 years ago I machined a plastic drivesaver type coupling insert out of a piece of 3/4 inch poly plastic cutting board type material, and it is still there ,no problems, after cruising 11 months a year since. With the insert on one side and the projection to fit into the tranny on the other, it stays completely centred. Using my angle grinder for a lathe, I made several spares, but haven't had to use any.
I once used a poly plastic hose barb for a shaft bearing , on a direct drive , 2500 shaft RPM ,for three years with no visible wear. I've been told big ships use gumwood for shaft bearings. One couldn't ask for better lube or cooling than at the back of the stern tube.
Brent

[apex1]

Oh Fer your info
I ordered sections from China price to you:) 5 dollars kg

Stu, what are those sections? Precut ally or prefabricated (welded) structure?

Regards
Richard

[whoosh]

Stu, what are those sections? Precut ally or prefabricated (welded) structure?

Regards
Richard
one is solid railcap, the other is 16mm face belting
this company has clients all aroung the world, they built the dies for only 2200 US, and I only ordered 780kgs, enough 2 boats
the railcap is the ideal way to top a bulwark, both 6082 T6
CAN YOU READ RHINO FILES YET? OR DFX?

[MikeJohns]

20 years ago I machined a plastic drivesaver type coupling insert out of a piece of 3/4 inch poly plastic cutting board type material, and it is still there ,no problems, after cruising 11 months a year since. With the insert on one side and the projection to fit into the tranny on the other, it stays completely centred. Using my angle grinder for a lathe, I made several spares, but haven't had to use any.
I once used a poly plastic hose barb for a shaft bearing , on a direct drive , 2500 shaft RPM ,for three years with no visible wear. I've been told big ships use gumwood for shaft bearings. One couldn't ask for better lube or cooling than at the back of the stern tube.
Brent

Ships have use a variety of synthetic materials for decades now that out-perform the lignumvitae and similar oily hardwoods.

Couplings come in all shapes and sizes in industrial applications and I 've seen some very good home-brew affairs. They are much simpler and under considerably lower combined loads if a thrust bearing is fitted on the shaft.

I should also mention the other advantage of a thrust bearing when the engine is soft mounted, it prevents the fore-n-aft movement of the engine under load.
A common problem is insufficiant clearance between the prop and the cutlass bearing. It's not uncommon for the compression of the rubbers in the mounts and the coupling to cause the prop to slide foreward by half an inch ubder load. Then you see the characteristic wear rings on the hub, also it seals of the cutlass tube the end of which becomes a thrust bearing.

This movement can aslo screw up close tolerance minimum spacings to deadwood etc with higher vibration at higher power making people scratch their heads.

This foreward movement can also do nasty things to that nice computer shaft alignment :)

[whoosh]

Yes nice post mike
these days one must shop around, take into account labour times vs store bought
many of the later (softmts) are desined to take the thrust with min distortion fore and aft
I do prefer the Aquadrive, COS it does have a big thrust bearing, which one must mount upon the hull structure All very easy on a metal boat, but just another big exercise on a glass or timber boat when machines for fabricationg steel and al al are not to hand,
Nice day up here, heading for 26

[apex1]

one is solid railcap, the other is 16mm face belting
this company has clients all aroung the world, they built the dies for only 2200 US, and I only ordered 780kgs, enough 2 boats
the railcap is the ideal way to top a bulwark, both 6082 T6
CAN YOU READ RHINO FILES YET? OR DFX?

Thanks Stu, nice prices!
I always could read dxf. dwg and the like. Rhino still not. I have´nt seen my home since 11month now!! And as it seems to happen I will not for another while.

Regards
Richard

[whoosh]

to Mike in partic
you often talk of the movement , thrustwise on (soft mts) but that is nothing compared to when say a yacht drops off a 40 foot wave, or comes to a stop when she hits a solid wall of water, is it?

Considerable research and developent have gone into making these compounds super reliable, , thrust is nothing compared with such as I just described, or knockdown or even a total 360 rollover, is it?

[MikeJohns]

The compounds are excellent now, much better than 20 years ago, just the metal is often only electroplated and needs painting :-)

It's an interesting exercise to measure just how much the engine throws off with full power, most people never think of this. On some big powerful soft mounted installations there is an arm to reduce it but never on the smaller installations.

Hog and sag and wracking in a seaway are all factors in any boat for shaft alignment. How much it moves depends on the vessels design and construction.

A lot of steel vessels are quite stiff in the engine and shaft area and with well designed installation ( engine beds,decent central keel etc) you don't find that much flex from hull movement.

In contrast some light weight FRP vessels afloat at the dock, just a person walking fwd on deck can pinch the feeler gauge when doing a shaft alignment.

Larger Trad timber fishing boats bend like anything in a seaway but often massive engine beds and a rock crusher bolted hard down keep them quite rigid one way or another and then I'm never quite sure just what is supporting what.

Added a pic of trad timber fisherman which shows the Bulwark buckling as they encounter a head sea.

[whoosh]

likewise al al, no movement, fishing boats on the Au coast often have = paravane flopper stoppers, they are really hard on a timber boat
what are rental propertys like down there? cheaper? more available?

[Brent Swain]

For the last decade or two I have been using bronze oilite bushings for stern bearings. They work fine, and cost under $5.
I have seen some very expensive plastic stern bearing advertised, for around 39 cents worth of material and $70 worth of hype.
Brent