Cutlass bearing temporary fix

[GuidoY]

Recently found there to be a dangerous (visible) amount of wobble in the prop shaft when in gear. Just going from neutral to fwd causes wobble, without giving any extra throttle.

Was planning on hauling for paint next month anyway but getting to the yard involves quite a bit of motoring through channels, which is now an obstacle.

Anyone have a suggestion on how to stabilize the shaft long enough to get me through a 1 hour motor inland? This is a direct drive a4 on a tartan 30, so about 4-5 ft shaft, no strut.

Many thanks!

[DougR]

Hello GuidoY,

It may be that the cutlass bearing is shot and causing the shaft vibration in gear, but it is just as likely, and maybe more likely, that the pillow block bearing in the center of the shaft is worn out. As you probably know the T30 was fitted with a Babbitt pillow block bearing in the center of the shaft to stabilize the long unsupported shaft. The bearing was equipped with a grease cup that was supposed to be turned down a bit every couple of hours when underway to lube the bearing, but most owners forgot all about it until there came a knocking from beneath the floor boards, and by that time the Babbitt bearing was a goner.

The fix that I used on both of the T30s that I had over 20 years was to replace the Babbitt pillow block with the same size ball bearing block. These usually come with a zerk grease fitting, but I replaced that with the original grease cup and used water pump grease in the cup. Even with non sealed bearings I never had a problem with rust from bilge water, as the grease does a good job of protecting the bearing. The ball bearing won't ever wear out as the shaft speed is low and the load on the bearing is almost non-existent. Just a twist of the grease cup occasionally will keep it going forever.

Meanwhile, to move the boat in the short term, look into this...
My recollection is that the pillow block bearings were the split type, with a removable cap. If that's the case, remove the cap from the bearing and judiciously use emery cloth on the mating surface between the upper and lower half of the bearing. Put the cap on a sheet of fine emery on a flat surface like a table saw table or a piece of glass and remove a bit of material. Check the clearance on the shaft frequently to avoid removing too much material. This should allow you to tighten up the bearing clearance enough to get where you are going without problems.
In the event that the problem is really the cutlass bearing, ask one of your buddies to give you a tow, because that could be difficult to change in the water.
DougR

[GuidoY]

Doug,

Thank you for the detailed response. Good to hear from another T30 owner. In this case there is no pillow bearing. There was none equipped when I bought the boat. On one forum (maybe this one) I read that having a 1" SS shaft, opposed to bronze, makes it unnecessary. I had considered installing a temporary pillow bearing if possible. But the cutlass bearing is definitely shot. So the answer may be a tow, or lash a dinghy to the stern quarter. Not ideal but will have to do. Maybe I will install a pillow/ball bearing set up when I haul her. Seems like it could be a good feature.

All the Best

[chris95040]

Originally Posted by GuidoY

Doug,

Thank you for the detailed response. Good to hear from another T30 owner. In this case there is no pillow bearing. There was none equipped when I bought the boat. On one forum (maybe this one) I read that having a 1" SS shaft, opposed to bronze, makes it unnecessary. I had considered installing a temporary pillow bearing if possible. But the cutlass bearing is definitely shot. So the answer may be a tow, or lash a dinghy to the stern quarter. Not ideal but will have to do. Maybe I will install a pillow/ball bearing set up when I haul her. Seems like it could be a good feature.

All the Best

If you rev up a bit does it stabilize enough to feel comfortable? Usually idle is where everything is shaking like crazy.

If you've got a dink with an outboard, I think that's your best option, particularly for an inland tow of just an hour. I did that with a 20,000 lb 40 footer, with a 6HP kicker on an 8 foot dink. Just lashed to the stern quarter and away we went. Made it right into our pole-berth.

[Cheechako]

Find a smooth low-ish RPM and go for it I think. Having the dink ready to tie along side probably good.

[DougR]

Interesting that there is no support bearing on the shaft. I had a 1971 model with a bronze shaft and also a 1973 model with a stainless shaft, both 1 inch shafts and both of them had support bearings. I tried to run the stainless shaft without the bearing briefly, but by half throttle the shaft looked like a jump rope trying to get out of the boat.

The way Tartan installed the bearing was to weld two SS bolts to a piece of 1/4" X 1" stainless steel and mount this on a block of mahogany with the bolts coming up thru the wood block from underneath. Then they bolted the pillow block bearing to the top of the wood block. They slid the bearing onto the propshaft and positioned it about 15 or 18 inches from the coupling, which is right near where the shaft lies close to the port side inner bilge wall. After centering and shimming the shaft within the shaft log they glassed the mahogany block to the hull and then aligned the engine to the shaft. It's something you might consider for a smoother running shaft.

DougR

[Cheechako]

OP: If your version is the one with the engine just aft of the mast... wow.. there ought to be a support bearing in there. That shaft must be more than 5 ft long....?

[model 10]

Originally Posted by Cheechako

Find a smooth low-ish RPM and go for it I think. Having the dink ready to tie along side probably good.

Yeah, I bet there is an rpm where it will smooth out enough to go that far. You may need to approach your next stop way to fast as it may be a bit more than just "low-ish" and you don't want to go far with it banging at low rpm.

[GuidoY]

Originally Posted by chris95040

If you rev up a bit does it stabilize enough to feel comfortable? Usually idle is where everything is shaking like crazy.

This might be the case. I didn't really push it though, so will give it a shot when I run it next. Hopefully that will get me to the yard, but "hope" is not to be relied on. Hope does not float. (dink will be in tow)

DougR, this is a '79 so not sure if they did away with that feature. I wish they hadn't as it would take a variable out of engine alignment.
I'll look closer to see if there's a remnant. Seems like construction was sturdy enough to discourage removal by a DIYer, but who knows.

It had run fine, and true enough until the cutlass bearing failed. It felt like a bogged engine or dragging the keel through mud, as near I can tell.

Thanks all for the input.

[a64pilot]

Do you happen to be a Sea Tow member?

[pcmm]

On a T30 you could (if really neccessary) replace the cutlass bearing while in the water, you just have to remove the prop and get the cutlass out of the strut. Its much easier to do on land though. If there is wobble at the strut, just replace the cutlass bearing, its pretty easy to do. Others mentioned a pillow block bearing but the T30 doesn't have one, the shaft isn't long enough to need one.

T30's are really nice boats, too bad they only made a few of them!

Just realized the Original poster was talking about a tartan not a T30!