Shaft overheating?

Hueso · Post by **Hueso** » Oct 17th, '06, 09:43

Last week I got my B31 engines alligned. Last Sunday I cruised my 454 crusaders at 3,000 rpm for about half an hour and when I reached port, the shafts were extremely hot and doing a single beat whine. I tied my boat and clutch it and I saw the shafts "saying no". That means, they moved side to side when they rotated. Questions: is it normal for the shafts to get hot after cruising for a while? should I haul out to find out if the shafts are bent? Should I tale a look inside the coplings to see if there is any wear? Should I kill the mechanic because my shafts were not doing that before he worked on them?

Thanks in advance.

ScottD · Post by **ScottD** » Oct 17th, '06, 10:10

It's sounds like you need to loosen the packing glands, remember they have to leak to cool them.

ScottD

scot · Post by **scot** » Oct 17th, '06, 11:00

I'm not sure about the 31's log's ability to feed water to the packing. I assume this is not a problem. I have a prop pocketed inboard that requires the water injection packing system to keep it cool. When I built and launched the boat the packing/shaft temp went through the roof. I installed the water injection system and it never gets over sea water temp now.

Sounds like you have other problems. I don't recall other 31 owners talking much about this. The logs in the 31 are very traditional. The injection system is something to keep in mind. Several companies built them. I am reconfiguring a B25 to straight inboard now and will be installing the injection system.

I would agree that the first place to look is that the packing nuts are too tight.

Harry Babb · Post by **Harry Babb** » Oct 17th, '06, 11:04

I read in your post that both shafts are overheating. It sounds like you have 2 problems. First the packing is to tight and is probably ruined and should be replaced. When the packing is working correctly it should leak about a drip per minute. After installing new packing you should leave it loose and run it some. The way that I do this is to run the boat for 10 minutes or so then loosen the locknut and tighten the packing slightly and then run it again and repeat this process until I get a slight drip when the shaft is not turning. The squealing noise is dry.....no lubrication.....burned up packing

The second problem that I see is that the engines are not properly aligned or your shafts are bent or your couplings are not fitted and matched correctly to the shafts. A good mechanic should have been able to detect any of these problems during the alignment process. Properly installed shafts and aligned engines will not wobble when the transmissions are engaged.

If it were me I would unbolt the couplings from the gear and check behind this guy. Most likely you have Velvet drives and the max misalignment I think is .004" about the thickness of a piece of note book paper. If your shafts are straight and the couplings are faced true with the shaft you will be able go hold the gear coupling face in one position and rotate the shaft and any misalignment will be seen in the same position thru a complete rotation of the prop shaft. If misalignment followes the propeller shaft rotation then the problem is in the shaft or coupling.

I was almost finished and ready to submit thoughts when one more idea came to me mind. Its possible that if the engines are properly aligned and the couplings and shafts are are correct that the shafts are not centered in the shaft log and rubbing hard on the shaft log itself.

So 3 things have to happen here and in this order
1-The coupling must be correctly fitted to a straight shaft and the coupling
face must be EXACTLY square with the shaft centerline
2- the shaft must be installed in the strut and centered in the shaft log
3- the engine must be aligned to the shaft coupling while the shaft is
maintained in the center of the shaft log.
All of this is assuming that the strut is already in alignment with the shaft log. I have heard similar "Squealing" noises coming from the cutlass bearing in the strut when alignment was not correct.
Harry Babb

scot · Post by **scot** » Oct 17th, '06, 11:05

Sorry, I missed one of your comments...if you can see "run-out" i.e. side to side or woppling type movement, in your shafts, they are not aligned correctly, or they are bent. I'm surprised that you did not feel any vibrations.

I'm not sure if a hot stuffing box can bend a shaft???

IRGuy · Post by **IRGuy** » Oct 17th, '06, 11:55

Another point to consider, although I think the major ones are well explained above..

When you had your mechanic do your realignment, which I assume he did with the boat out of the water, did he make final adjustments after the boat went back into the water? My diesel guy says to always launch the boat and let it take on it's floating shape, and then make final adjustments before the alignment job is finished.

Good luck!

scot · Post by **scot** » Oct 17th, '06, 15:07

I too have always been told to do the final alignment with the boat in the water. I think this is a function of just how stiff a boat is. I built a HD stringer system in my last boat, reinforced the hull from the engine mounts to the strut, etc. and I have never had any problems with alignment jobs that I did on the bank. But my mechanic buddy swears you have to do it in the water?

It makes sense considering how much boats can flex, but are they not flexing all the time while underway? How can you tell if the shaft is aligned correctly in the strut/cutlass bearing if the boat is in the water? How can you tell if the alignment of the shaft penetrating the shaft log is centered correctly in the water?...makes my head spin.

Carl · Post by **Carl** » Oct 17th, '06, 16:32

A few cents to throw into the pot.

Keeping it real simple as you have a big problem and that makes finding it easy.

Packing- If traditional flax it should leaking a bit, if it's not it is too tight on the stuffing box. A drip every minute or so is fine. Too tight and it will make shaft hot, not wobble though.

Alignment, as you have a big issue you should be able to find answer quickly. Remove shaft/tranny coupling and pull couplings apart, does shaft and coupling easily move back into engagement with tranny coupling or do you have to heave it over into location. When they meet the faces should come together, as mentioned, but I am thinking you will see a noticable gap with the issue you are having.

If alignment is off you know where the problem lies and need to realign. I have seen several occasions where good mechanics forgot to lock the jam nuts enough and vibrations backed the adjusting nut off letting engine fall. Last time was on a 47 Buddy Davis, damm shaft nearly cut thru shaft log.

Hueso · Post by **Hueso** » Oct 17th, '06, 17:17

Thank you for all the input.................I have a dripless system.............when I returned the boat into the water after the haulout the mechanic was not present and he sent an assistant......he only tighten the stainless steel piece of the system that has 3 allen screws..........I clutched while he was in the boat and the shaft wobbled.....he said to try it and to call the mechanic to take a look at it.........I tried it and you know the story...............next saturday I'll be camping at the marina in front of the mechanic's office to force him to get into my boat and fix the damn thing....if he can't, I will throw him overboard.............just kidding, but the thought has crossed my mind a couple of times.............great input here...........thanks again guys.........keep the ideas coming so I can have all the information and possible situations before meeting with him on Saturday.........

CaptPatrick · Post by **CaptPatrick** » Oct 17th, '06, 17:21

Hueso,

Hot shafts & logs on a dripless system means that the cooling water hoses from the engine to the seals are either plugged or not hooked up properly...

Br,

Patrick

In Memory of Vicroy · Post by **In Memory of Vicroy** » Oct 17th, '06, 17:24

If you are dripless, are you sure the water line from the engine to the packing is connected and open?

UV

Hueso · Post by **Hueso** » Oct 17th, '06, 18:04

I will check on the cooling hose to see if it is jammed or clogged.....calling the mechanic tomorrow morning..........

Harry Babb · Post by **Harry Babb** » Oct 17th, '06, 19:14

This note is back to Scot..........about strut alignment and shaft log alignment.
You cannot check for strut alignment while the boat is in the water without going overboard. I always assume that the strut is correct unless it was reported that the Captian hit something.
As far as centering the shaft log I always disconnect the coupling from the gear then let it drop to lay on the bottom of the shaft log then lift it to top of the shaft log then block it up as close to the middle of the difference as I can then align the engine to the shaft.

Ha.....around here if you ask 6 different people about alignment you will get 6 different methods. Its my opinion that shaft alignment is a very systematic process and if you follow common sense you will get excellent results.

I did not realize that HUESO had the dripless system I just assumed that he was running packing.

Harry Babb

scot · Post by **scot** » Oct 17th, '06, 22:01

I have seen guys use the estimated "half way" in the middle of the stuffing box method because it works...the alignment issue is not quit as critical as folks think. Shafts under 1 1/2" will bend and flex all over the place, crap if you lean them in a corner they will bend over night.

I'm a fanatic about precision...it's in my blood, I managed a machine shop for a few years. I have tried feeler gauges, dial indicators, etc. But the "Do it by feel" is more than adequate for boat shaft alignment. Just keep moving the engine around until there is "0" gap between the flanges 360 degrees and the shaft companion flange will move easily in and out of position. Check with a feeler gauge if you like.

Here's the method I use on my boats when out of the water:
I have a split bushing/ spacer custom made for the gap between the stuffing box ID and the shaft OD. When aligning the shaft I place the 2 halves of the bushing around the shaft, secure it with a hose clamp and push it into the stuffing box from the bottom....this creates a near perfect alignment (within .005-.010). The bushing is designed to be a tight fit. When I'm finished with the trans/engine alignment I remove the clamp and the bushing. Perfect stuffing box and shaft alignment everytime. This creates a cheap radial jig custom made for your boat. In many cases a bearing shop can order you a bronze bushing to size for around $10 bucks.

Harry Babb · Post by **Harry Babb** » Oct 17th, '06, 22:23

Scot
I thought that I felt a connection to your post. I own a machine shop and we do a lot of shaft/coupling industrial work. A couple of the local boat yards use us for straightening shafts and reworking couplings. The only way to actually solved vibration problems is to simply getting in the "Precision" mode.

One of the most difficult task that I had to overcome was training the mechanics in the yards how to handle a shaft. DO NOT PICK IT UP IN THE CENTER or it will bend and when you are installing a coupling do not ues a sledge hammer.

Its really rewarding to get all of the vibration out of a drive system! !

Harry Babb

JGomber · Post by **JGomber** » Oct 18th, '06, 07:58

Harry,
Pardon the dumb question, but...
Is it really possible the bend a 1 3/8" x 72" stainless shaft by picking it up in the middle? I'd expect that it would take something big (like the log I hit) to bend that thing.

Harry Babb · Post by **Harry Babb** » Oct 18th, '06, 09:42

Hi Jerry,
Your right.........a small shaft like our boats use will not bend by picking them up in the middle. But if you store this shaft supported on the extreme ends the shaft will develop a sag over time. The 1-3/8" X 72" shaft only weighs about 30 pounds. Your not dealing with much weight vs length with these little shafts.

I was making a general statment about the mindset of some of the boatyard workers that I have come accross over the years. I have seen shafts 1-1/2" diameter 12 to 18 feet long up to 3-1/2" shaft 22 feet long. You pick these puppys up in the middle and you certainly stand a good chance of bending them.

I bent my port shaft or prop a couple of weeks ago, just idling and hit a log.......I am going to repower soon and I intend to use at least a 1-3/4 dia shaft
Harry Babb

scot · Post by **scot** » Oct 18th, '06, 10:29

Harry,

You may want to re-think the 1 3/4"...I read and article recently about small boat shafting and the article claimed that 1 1/2" is the magic number.

The guy claimed that shafts larger than 1 1/2" at these lengths do not flex enough under normal conditions and end up causing more damage to transmissions, struts, etc. Apparently it is a ratio of the diameter vs length and the bigger shafts are just too stiff for smaller boats. The article stated that the larger the shaft, the stiffer the boat needed to be and the alignment also needed to be dead on. (which you can do)

I have no first hand on this but seems logical that a very ridgid shaft in a flexing hull would put hi loads on the trans output bearing and the strut.

More than likely there are guys on this board with first hand experience on installing large dia shafts into 31s.

Scot

Harry Babb · Post by **Harry Babb** » Oct 18th, '06, 10:48

Scot,
That's interesting......I never considered things from the angle you described. I am the guy that can run over an Oak Tree 40 miles out in the Gulf and I was think more in the lines of not bending anything. What you said does make a lot of sense.
Any idea where I could get a copy of the article????
Thanks for you feedback
Harry Babb

Capt. DQ · Post by **Capt. DQ** » Oct 18th, '06, 11:15

Harry,

At 40 MPH hitting anything like a log / etc., something gonna get bent or broke period. Doesn't matter what shaft size you have.
R,
DQ

scot · Post by **scot** » Oct 18th, '06, 12:03

Harry,
The article was on line...I'll see if I can find my way back to it.

scot · Post by **scot** » Oct 18th, '06, 12:12

Harry,
Here you go...

http://yachtsurvey.com/alignment.htm

Skipper Dick · Post by **Skipper Dick** » Oct 18th, '06, 13:15

Scot,

That is an elighting David Pasco article. Thanks for bringing it to our attention. I always learn something when I read one of his articles.

Dick

Harry Babb · Post by **Harry Babb** » Oct 18th, '06, 14:55

Scot,
Thanks for the article...........Brings a new prespective to my way of thinking. Bigger is not necessarily better.
Harry Babb

Hueso · Post by **Hueso** » Oct 21st, '06, 15:47

Guys......just to let you know, checked the water injection hoses and they were clogged......really clogged..........and of course replaced.......shaft heating resolved...........thanks a lot for all your help...............On the other hand, took out the coupling and the shaft did not swing up or to the side...........therefore, I believe the shaft did not bend.......alignment seems ok......engine bushings also.............................but the wobbling continues..........plan is to haul out, insert new coupling and pray to the God of the Seas to end the problem...

Brewster Minton · Post by **Brewster Minton** » Oct 21st, '06, 17:27

make sure the plastic pieces of the dripless did not melt or deform because of the heat when it was clogged. I saw one that melted really bad so I set mine up so if one clogs the other side will feed it. This setup does little when both are clogged.

Hueso · Post by **Hueso** » Oct 22nd, '06, 21:27

today I cruised for about two hours and the shafts where not hot......thanks for the advice though......I'll see on that

Carl · Post by **Carl** » Oct 23rd, '06, 12:30

I have a shop too, its beginning to look like a Machine Shop forum here.

We tell our guys to hold shafts supporting them in aprox. thirds. Simple and easy to figure out how to hold

scot · Post by **scot** » Oct 23rd, '06, 12:44

Boats have lots of stuff that spins....if the shoe fits.

IRGuy · Post by **IRGuy** » Oct 23rd, '06, 16:09

There was an instance this spring near here where a brand new boat being taken from the factory to a boat show sank within a couple of miles of the factory while two experienced guys were operating it for the first time. Both drowned.

Reports were that one of the flexible hoses between the dripless packing gland and the shaft tube was charred and torn, letting water into the engine room and ultimately sinking the boat. From what I heard it appears to me that the cooling/lubricating water to this seal was somehow blocked. Consider the factory guys rushing to get a boat ready for a boat show, and somebody messed up installation of the dripless seal. No lubrication, no cooling, enough friction heat from the dry seal to burn the rubber tube, big leak way back in the after part of the engine room.. by the time the two guys (who were unfamiliar with the boat's normal handling characteristics) realized the boat was not handling properly she was on her way down.

I check my dripless seals regularly when underway!

Hueso · Post by **Hueso** » Oct 23rd, '06, 16:58

I don't know if I did the correct thing, but I installed the clear braided type hoses to always see if water is flowing...........what do you think guys?..........

scot · Post by **scot** » Oct 23rd, '06, 19:42

I'm going out to my boat and put some clear braided hose on the one I have for sale. That's a great idea. Just goes to show you that 300-400 heads are better than one. I really like things that can be easily monitored.

Just make sure you use a good quality ss hose clamp...nothing worst than having to go back later on a hardware store hose clamp that's rusted shut.

I like it, that's one I'll put on my new boat.

Thanks,
Scot

IRGuy · Post by **IRGuy** » Oct 23rd, '06, 21:46

Hueso...

Great idea!

Brewster Minton · Post by **Brewster Minton** » Oct 24th, '06, 07:08

The clear hose is a super idea. I am going to go and change mine out right away. Thanks!

Rawleigh · Post by **Rawleigh** » Oct 24th, '06, 08:11

That is what I have on my boat. I was worried about whether it was strong enough, but its been on for 5 years with no problem.

Tommy · Post by **Tommy** » Oct 24th, '06, 10:13

Hueso,

Thanks for the heads up on the clear hose, sounds like a great idea.

As IRGuy reported, a brand new 35' Carolina Classic sank as a result of a compromised packless seal, and two experienced delivery captains died (hypothermia). It sank about 20 miles from where I keep my boat on the Neuse River (ICW) in about 15' of water and a mile from shore. I try to check my seals and thru-hulls at least every hour while underway. It takes less than a minute to pop the four hatches, perform a visual for bilge water, and place my hand on the seal to check for excess heat.

Tommy

Hueso · Post by **Hueso** » Oct 24th, '06, 19:31

It would be great to have a clear bellow on the shaft seal.......Capt. Patrick should call them to have that done.....

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