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Old 08-06-2023, 18:26   #1
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Skeg blocks prop shaft

On my 45í Roberts sloop the skeg is in the way to pull out the shaft.
Is this a common issue with skeg hung rudders?

Do you install the shaft at an angle to get it past the skeg?

At the moment it seems the only way to get the shaft out is lifting the engine enough to pull out the shaft through the inside.
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Old 08-06-2023, 18:49   #2
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Skeg blocks prop shaft

Quote:
Originally Posted by hzcruiser View Post
On my 45í Roberts sloop the skeg is in the way to pull out the shaft.

Is this a common issue with skeg hung rudders?



Do you install the shaft at an angle to get it past the skeg?



At the moment it seems the only way to get the shaft out is lifting the engine enough to pull out the shaft through the inside.


Yes, itís quite a common problem. Sometimes itís possible to get the shaft out after the bearing is extracted but that can be another problem in itself. If you can get the bearing out with the shaft in place, the reverse process needs to be applied for refitting the bearing..... shaft in first and then knock in the bearing. Even lifting the engine doesnít guarantee success unless there are no bulkheads or obstructions to block the shaft in the engine room and I tís no fun working under an engine suspended from the underside of a cockpit floor .....I suspect your engine is no lightweight.
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Old 08-06-2023, 18:55   #3
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Re: Skeg blocks prop shaft

It's a stupid/ignorant/insidious design flaw that's all to common.
Sometimes I think that many (so called,) Naval Architects got their degree out of a cereal box.
Perhaps if you remove the coupling and remove the packing gland and its hose there will be enough angular "slack" to slide the shaft past the skeg.
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Old 08-06-2023, 19:26   #4
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Re: Skeg blocks prop shaft

I agree, just the stupidest laziness on the builder. It's not limited to skeg rudders either, lots of spade rudders give you a choice of dropping the rudder or lifting the engine. It costs no more to install the engine JUST akimbo enough to clear the steering gear, it's just sloppy building without thinking. And it sometimes happens from designers and builders who REALLY should know better.

Another option that is sometimes available is to take out the cutless bearing. It's not always possible with the shaft in place, but if you can work out a way, it might give you JUST enough wiggle room.

The only thing worse in this vein I have ever seen was a boat where there was insufficient clearance behind the prop in the prop aperture. The only way to remove the prop was to lift the engine and slide the shaft forward. Dumb and dumber.
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Old 08-06-2023, 19:43   #5
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Re: Skeg blocks prop shaft

On some older powerboats I've seen a hole in the rudder so you can turn it and then remove the shaft through the hole. No reason this couldn't be done with a removable plug on a sailboat rudder.
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Old 08-06-2023, 20:39   #6
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Re: Skeg blocks prop shaft

If you have a "V" drive transmission you can extract the shaft from inside the boat. That is my situation.
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Old 13-06-2023, 05:37   #7
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Re: Skeg blocks prop shaft

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Originally Posted by skipperpete View Post
Yes, itís quite a common problem. Sometimes itís possible to get the shaft out after the bearing is extracted but that can be another problem in itself. If you can get the bearing out with the shaft in place, the reverse process needs to be applied for refitting the bearing..... shaft in first and then knock in the bearing. Even lifting the engine doesnít guarantee success unless there are no bulkheads or obstructions to block the shaft in the engine room and I tís no fun working under an engine suspended from the underside of a cockpit floor .....I suspect your engine is no lightweight.

Sorry for the late reply, we had a long weekend here in Oz which meant more boat work...

The bearing can be taken out but it doesn't help pulling out the shaft. Unless the shaft is split in several places inside the tube which I doubt.

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Yes, the engine is heavy, a Perkins 4.236.
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Old 13-06-2023, 05:46   #8
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Re: Skeg blocks prop shaft

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Originally Posted by hzcruiser View Post
Yes, the engine is heavy, a Perkins 4.236.
Then you're doomed

With the prop off how close to going past the skeg is it?

Without the prop ours takes the paint off the skeg and rudder, but is just manageable.

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Old 13-06-2023, 05:55   #9
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Re: Skeg blocks prop shaft

Once in a while you see a setup where the shaft is offset just enough to get it out past the skeg or rudder. That few degrees of offset shouldn't cause a noticeable "pull" right or left, at least in forward with the rudder there to counteract. On my twin screw motor yacht, the rudders are offset slightly and the shafts slide right out once the props are removed.
Just like cars and most other manufactured products, most production boats are engineered for quick and easy assembly with no thought of repair later on. The Roberts is not a production boat, it's either a pro built one off or a home build. They could have though this out a little better.
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Old 13-06-2023, 05:55   #10
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Re: Skeg blocks prop shaft

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Originally Posted by Bowdrie View Post
It's a stupid/ignorant/insidious design flaw that's all to common.
Sometimes I think that many (so called,) Naval Architects got their degree out of a cereal box.
Perhaps if you remove the coupling and remove the packing gland and its hose there will be enough angular "slack" to slide the shaft past the skeg.
The cutless bearing is deep inside the stern tube, we have never been able to get it out in previous haul-outs.

Since the stern tube wall seems to be very thin due to rust the next attempt in a few weeks will be to cut out the stern tube altogether and install a new one.

Also, the shaft appears to have been broken (yes, unheard of, everyone tells me) before I got the boat. It was repaired with what seems like a sleeve with grub screws which eventually gave way.

A few years ago that fix also gave way motoring at 4 kn and was repaired again, this time with a bolt that was welded onto the sleeve. That concoction now needs to come out and the whole shaft needs to be replaced as there is a grinding noise coming from the stern tube and with its thin wall I don't want to risk it breaking apart.
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Old 13-06-2023, 06:01   #11
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Re: Skeg blocks prop shaft

Well since you have to replace the shaft anyway, the preferred tool taking it is a sawzall. Just cut it. That won't help getting the new one back in though. The sleeve with grub screws is called a muff coupler. They're not was strong as a one piece shaft but might enable you to get a new shaft back in.
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Old 13-06-2023, 06:04   #12
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Re: Skeg blocks prop shaft

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Originally Posted by SailingHarmonie View Post
I agree, just the stupidest laziness on the builder. It's not limited to skeg rudders either, lots of spade rudders give you a choice of dropping the rudder or lifting the engine. It costs no more to install the engine JUST akimbo enough to clear the steering gear, it's just sloppy building without thinking. And it sometimes happens from designers and builders who REALLY should know better.

Another option that is sometimes available is to take out the cutless bearing. It's not always possible with the shaft in place, but if you can work out a way, it might give you JUST enough wiggle room.

The only thing worse in this vein I have ever seen was a boat where there was insufficient clearance behind the prop in the prop aperture. The only way to remove the prop was to lift the engine and slide the shaft forward. Dumb and dumber.
Dropping the rudder is easy, but the skeg is in the way first. The cutless bearing is buried too deep to take it out with the shaft in place. There is about 3 feet or one metre between the prop and the skeg.

Lifting the engine would be a huge task and there still might not be enough clearance as the engine can't be taken up all the way due to the wheel house floor. Unless we cut that open as well...

One suggestion by the yard is to cut off the skeg and add a tube to it big enough to slide the old shaft out and the new shaft in, with the rudder dropped.

That's a big job as well, though.
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Old 13-06-2023, 06:06   #13
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Re: Skeg blocks prop shaft

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Originally Posted by capt jgw View Post
Once in a while you see a setup where the shaft is offset just enough to get it out past the skeg or rudder. That few degrees of offset shouldn't cause a noticeable "pull" right or left, at least in forward with the rudder there to counteract. On my twin screw motor yacht, the rudders are offset slightly and the shafts slide right out once the props are removed.
Just like cars and most other manufactured products, most production boats are engineered for quick and easy assembly with no thought of repair later on. The Roberts is not a production boat, it's either a pro built one off or a home build. They could have though this out a little better.
Yes, offsetting the engine by a few degrees was also mentioned by the yard and might be a better option than welding a big pipe into the skeg?
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Old 13-06-2023, 06:07   #14
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Re: Skeg blocks prop shaft

A lot of steel work boats have a hole in the rudder for that. Turn the rudder to 90deg and the shaft slides right through. It's a lot more work putting a hole in the skeg, but probably doable. I don't think you'd have to remove the skeg first, just do it on the boat. If the shaft is thicker than the skeg you'd have to built it up wider on the area. It would look funny but wouldn't hurt anything.
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Old 13-06-2023, 06:09   #15
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Re: Skeg blocks prop shaft

Check the skeg to see if the lower section can detach from the upper. That's the way my new to me boat is setup to remove the shaft. You have to drop the rudder, grind off fairing material and remove some bolts to remove the lower section of the skeg. The process takes some hours but at least you can do it.
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