Got to move engine forward (new shaft etc.) - any tips?

[dankilb]

After a long list of issues with our new-ish (to us) Beta 50 that was badly installed by a Beta dealer in the Med - it's become apparent that we need to move the engine around 50mm forward to allow enough clearance aft to accommodate a high rise ('crossover') exhaust elbow (which Beta have already supplied).

Every aspect of the original installation was bodged (wiring, raw water, exhaust, etc.) but the one I cannot live with - nor fix myself - is that the fall between the exhaust and the water trap is too short (based on Beta's spec) without a new exhaust elbow. The one the Beta supplied is about as compact as could be envisaged, yet it still touches the cabinetry aft of the engine.

There is plenty of space forward of the engine, in contrast. So my assumption is that the installer wanted to re-use the old shaft (they even got away with re-using 4 of the 8 mounting holes in the bearers!). The shaft is original (1989) and not in great nick. I've been worried about pitting in the region of the lip seal (although with some jiggling I think a clean area could be found).

Anyway, it looks like a new shaft will solve several problems in one go. But before I go for it, my questions include:

• Contact T Norris for the shaft, presumably?
• Is it realistic to aim just to slide the engine forward on the bearers (thick aluminium sections) using a block and tackle, say, on the mast compression post?
• Is there enough adjustment in the Beta engine mounts that I needn't stress too much about the geometry? Say, if I move it forward an accurate 50mm, presumably I can sort out alignment later?
• Anything else I should consider ahead of ordering a new shaft? We've got a fixed 3-blade prop and no rope cutter. Should I allow extra clearance for a folding prop and rope cutter in future? Is this a 'thing'?!

For context, I'm mechanically minded and we're deep into a complete refit. I wouldn't be phased pulling an engine from a car (or even measuring up for a new drive shaft). But I am distinctly phased by sliding an engine around in a confined space, surrounded by furniture, and using only other parts of the boat for purchase! Not to mention the unexpected cost of a new shaft...!

TIA

 

[jamie N]

Possibly of very slight help, but if you've the opportunity to grease the beam that it's going to be sliding on, it might just make it much easier. Oil rigs are "skidded" in this manner.

 

[rogerthebodger]

3 thinks come to mind

1) Cover the engine with blankets to protect any boat fittings.
2) Ensure that the compression post if fixed to the hull at the lowest point and rig the pull from the bottom of the compression post
3) ensure that all pipes and electrical have enough slack to move the engine or disconnect any connections that don't have slack.

How much longer will the new prop shaft be and have you considered just extending the shaft with a rigid muff coupling

If I need to remove my prop shaft I have to lift the engine vertically ot remove the prop shaft under the engine.

Its also easer that way as I only have to remove the prop and shaft anodes.

 

[Norman_E]

You usually gain some length if you fit a flexible shaft coupling. You still need to get alignment as close as possible, but a bit of flexiblity in the coupling helps with noise, so is never a bad thing. This type add around 35mm and you can always use longer bolts and a spacer to get to 50mm. R&D 4

 

[rogerthebodger]

You usually gain some length if you fit a flexible shaft coupling. You still need to get alignment as close as possible, but a bit of flexiblity in the coupling helps with noise, so is never a bad thing. This type add around 35mm and you can always use longer bolts and a spacer to get to 50mm. R&D 4

Good idea

ASPS also have prop adaptors and/or bobbins that will allow various extensions to prop shaft

Boat Propeller Shaft Couplings for Marine Prop Shafts

 

[dankilb]

Thanks everyone. All good points.

Possibly of very slight help, but if you've the opportunity to grease the beam that it's going to be sliding on, it might just make it much easier. Oil rigs are "skidded" in this manner.

Yup, sensible point, I hadn't considered that. Would seem obvious with hindsight. The beams are some sort of machined aluminium so thankfully it should slide 'like a greased weasel', if done right. As with Roger's point about rigging any tackle low on the compression post.

Thankfully the engine is already sitting completely disconnected from everything. While bemoaning the state of the previous 'installation', I like to point out that the engine has had to come back to a state where I may as well have installed it myself (minus a lift in to the boat)!

How much longer will the new prop shaft be and have you considered just extending the shaft with a rigid muff coupling

50mm give or take... so now that is an interesting proposition. It totally hadn't occurred to me to split it and extend with a coupling. That might be an appropriate solution for us as the boat only needs to make a delivery 40-odd NM around the corner. That'll get her off the hard in a drying harbour (it's a deep keel AWB!) and into a marina 5 minutes from our place, to continue the refit. In a year or so I'll have a better idea of what prop and any additional stern gear we'll run longer-term.

Right now we just need to make a delivery date pencilled in for late June and have got a lot to do, inc. filling/fairing and epoxy coating the hull, getting the engine running from its current state, replacing three rotted bulkheads and various other interior structural repairs, and a minimum refit of the running rigging and deck gear to deliver her safely on her own bottom (she's sat for 6 years now!).

So anything that defers the cost/decision on the shaft would be music to my ears! I'm googling options as I type!

You usually gain some length if you fit a flexible shaft coupling. You still need to get alignment as close as possible, but a bit of flexiblity in the coupling helps with noise, so is never a bad thing. This type add around 35mm and you can always use longer bolts and a spacer to get to 50mm. R&D 4

And this is another option I'm aware of, but hadn't yet considered as an option here. Only found out about the exhaust clearance yesterday! But the problem is, my understanding is that we cannot sensibly run a flexible coupling with our setup:

It's rigid coupling > volvo-style seal (no cutlass bearing) > P-bracket with bearing > prop (3 blade fixed, no rope cutter etc.)

Being a 42' AWB the distance between the coupling and the p-bracket is quite long. If I had to guess, I'd say it could be approaching 1000mm. So I'd worry about it shaking around. But if it was liveable-with for the delivery (say, safe cruising at 1600rpm and occasional higher bursts) I'd consider it. I could sell on the R&D coupling after and recoup a bit of the cost I'm sure.

Anyway, all food for thought. Many thanks again. Back to Google I go...!

 

[dankilb]

R&D Marine 202-169 4" Bobbin Shaft Coupling (Steel)

This is the one, surely? Might even be the right size for our Hurth box! And for just over £50, could be a 'cheap' solution - I don't think you could even make one for less (unless you had a lot of good stock lying around and even more time!).

 

[rogerthebodger]

If it only 50mm and you have a rigid coupling the easiest and cheapest way would be to fit a bobbin in between the 2 halves of the rigid coupling.

You just need to pipe flanges with a piece of pipe in between to makeup the required gap. The pipe then welded to the flanges.

I made up an extension /adaptor flange to connect my flexible coupling to the gearbox flange.

If you fit a flexible coupling yo would need to have an extra prop shaft bearing to make that rigid. It may be simpler to just fit a bobbin to extend the existing rigid coupling thus no change to the prop shaft bearings

https://www.nero.co.uk/files//e9c3aa9a-6689-4b3e-b56d-a94b00ab234f/Nero Product Catalogue.pdf

https://www.aalco.co.uk/literature/files/aalco-stainless-steel-tube-product-guide.pdf

 

[Topcat47]

You usually gain some length if you fit a flexible shaft coupling. You still need to get alignment as close as possible, but a bit of flexiblity in the coupling helps with noise, so is never a bad thing. This type add around 35mm and you can always use longer bolts and a spacer to get to 50mm. R&D 4

You might also use two flexible couplings , back to back or with a spacer. Don't forget to link the shaft coupling to the gearbox coupling electrically and don't allow too much free wire in this connection as it will no doubt stretch and snag on something if you do. If the only shaft supports are the engine and the P-Bracket bearing, I'd be a bit concerned as there's a long un-supported length of shaft in a 42'er but will also try to limit the freedom of movement of the engine. Flexible couplings aren't as free to move as a vehicle prop shaft with UJ's, so you should have no real problems using one (or two) between the shaft and gearbox couplings. The engine is likely to be flexibly mounted anyway and Beta's have four mounts, two fore and aft, which allows the engine to Shake in three dimensions. This means that the fore end of the shaft will vibrate in 3-D. It's going to be vital that the shaft is true or it will whip when rotating and knacker both the cutless bearing and the shaft seal in short order.

 

[dankilb]

You might also use two flexible couplings , back to back or with a spacer. Don't forget to link the shaft coupling to the gearbox coupling electrically and don't allow too much free wire in this connection as it will no doubt stretch and snag on something if you do. If the only shaft supports are the engine and the P-Bracket bearing, I'd be a bit concerned as there's a long un-supported length of shaft in a 42'er but will also try to limit the freedom of movement of the engine. Flexible couplings aren't as free to move as a vehicle prop shaft with UJ's, so you should have no real problems using one (or two) between the shaft and gearbox couplings. The engine is likely to be flexibly mounted anyway and Beta's have four mounts, two fore and aft, which allows the engine to Shake in three dimensions. This means that the fore end of the shaft will vibrate in 3-D. It's going to be vital that the shaft is true or it will whip when rotating and knacker both the cutless bearing and the shaft seal in short order.

Yup, it's not ideal but that's how Jeanneau set it up (originally with the Perkins M50). By using a Volvo-style seal, I understand that acts partially as a sort-of flexible bearing. Dripless face seals aren't reccomded apparently. The advice on flexible couplings also seemed ambiguous as I read it: Definitely 'no' with a dripless seal. But maybe okay with a Volvo-style lip seal. The biggest completely unsupported span is between the Volvo seal and the p-bracket.

That's good advice about the Beta feet. I will obviously do all I can to true it up on the hard, but I know it could move once in the water. If I get reasonably confident making adjustments, then hopefully we can at least motor out to deep water on the first trip, put the sails up, then I can adjust it if it's that bad. We'll have 12+ hours before we need the tide at out destination, at least.

 

[rogerthebodger]

With any stern shaft setup there can only to 2 flexible elements of the 3 elements.

You can have
1) A flexible mounted engine, flexible coupling and a rigid shaft
2) A flexible mounted engine , flexible shaft with a rigid coupling
3) A flexible shaft , a flexible coupling with a rigid mounted engine.

From your description yo have currently no 2.

I would keep the rigid coupling with the bobbin you posted in post 7.

If you do use a flexible coupling yo must either fit an extra shaft bearing to support the Volvo lip seal or rigidly mount the engine.

If you setup is different to no 2 please let me know

 

[scottie]

You usually gain some length if you fit a flexible shaft coupling. You still need to get alignment as close as possible, but a bit of flexiblity in the coupling helps with noise, so is never a bad thing. This type add around 35mm and you can always use longer bolts and a spacer to get to 50mm. R&D 4

If you have flexible mounts and a flexible stern gland it’s considered a very bad thing and to be avodied
an R&D MAY be used subject to their approval

 

[Tranona]

Can you get the shaft out of the back without dropping the rudder? If you can't then look at ways of using the existing shaft otherwise you have to lift the engine. To measure the shaft length if going for a new shaft, get the engine where you want it and measure up to the flange from the P bracket. If you are going to fit a rope cutter then you need 40mm from the back of the P bracket to the front face of the prop. It does not matter whether it is a fixed prop or folder/featherer, the front face is determined by the taper.. You will get the dimensions of the coupling - that is the race to the socket for the shaft from the spec or measuring it. measure at least twice as once it is cut you are stuck with it!

 

[jwfrary]

Bobin is a perfectly workable solution if the existing shafts in good working order

 

[ithet]

After a long list of issues with our new-ish (to us) Beta 50 that was badly installed by a Beta dealer in the Med - it's become apparent that we need to move the engine around 50mm forward to allow enough clearance aft to accommodate a high rise ('crossover') exhaust elbow (which Beta have already supplied).

Every aspect of the original installation was bodged (wiring, raw water, exhaust, etc.) but the one I cannot live with - nor fix myself - is that the fall between the exhaust and the water trap is too short (based on Beta's spec) without a new exhaust elbow. The one the Beta supplied is about as compact as could be envisaged, yet it still touches the cabinetry aft of the engine.

There is plenty of space forward of the engine, in contrast. So my assumption is that the installer wanted to re-use the old shaft (they even got away with re-using 4 of the 8 mounting holes in the bearers!). The shaft is original (1989) and not in great nick. I've been worried about pitting in the region of the lip seal (although with some jiggling I think a clean area could be found).

Anyway, it looks like a new shaft will solve several problems in one go. But before I go for it, my questions include:

• Contact T Norris for the shaft, presumably?
• Is it realistic to aim just to slide the engine forward on the bearers (thick aluminium sections) using a block and tackle, say, on the mast compression post?
• Is there enough adjustment in the Beta engine mounts that I needn't stress too much about the geometry? Say, if I move it forward an accurate 50mm, presumably I can sort out alignment later?
• Anything else I should consider ahead of ordering a new shaft? We've got a fixed 3-blade prop and no rope cutter. Should I allow extra clearance for a folding prop and rope cutter in future? Is this a 'thing'?!

For context, I'm mechanically minded and we're deep into a complete refit. I wouldn't be phased pulling an engine from a car (or even measuring up for a new drive shaft). But I am distinctly phased by sliding an engine around in a confined space, surrounded by furniture, and using only other parts of the boat for purchase! Not to mention the unexpected cost of a new shaft...!

TIA

Re moving the engine. For comparison I have with another person, slid a VP 2002 into the cabin of my previous Moody 28 just using our man power to pull/push. It was not difficult or too heavy although the gearbox was removed first, but your engine weighs 260kg against the 2002 140kg (both with GB) so some extra tackle might be required. I would not want to exert a transverse force on the compression post, it is not designed for this. Could you lead a line forward and out a fore hatch to the anchor winch (as a turning point, not to drive) then to sheet winch?

 

[jwfrary]

If I was doing it I would be undoing the foot bolts a giving each mount a tap with a rubber hammer and gradually walking the engine forward. Assuming it’s on a flat steel or grp bearer.

1200 kg engine moved the same way forward by 300mm to get a g/box out and then back again.

 

[JumbleDuck]

Every aspect of the original installation was bodged (wiring, raw water, exhaust, etc.) but the one I cannot live with - nor fix myself - is that the fall between the exhaust and the water trap is too short (based on Beta's spec) without a new exhaust elbow.

Bigger water trap?

 

[dankilb]

Bigger water trap?

No space for a Vetus plastic fantastic unfortunately - and our current s/s one is still going strong. One of the few bits of the installation I don't mind. We're at about 20cm fall whereas Beta requires 30cm. That is scarily close to the water in the trap, IMO! The high-rise exhaust gives about 35cm+.

 

[dankilb]

...but thanks all, the bobbin coupling definitely the way to go. At 87mm it's a tad longer than we need, but should think it will do just fine for a semi-jury-rigged option to safely make the delivery. It'll allow us to put the engine in the 'right' place, even if it means the prop overhangs the p-bracket a 10-20mm more than ideal. I know we could have one fabbed (or the R&D one shortened or made-to-order), but £50 for a fix is too good to turn down! I'd rather go for this, knowing the shaft needs a proper long-term solution - than risk running the engine in a setup where it could hyrdrolock at 300 hours new!

Hadn't realised that spacers for couplings were a 'thing' - let alone readily available. So another win for the Forum! Thanks again.

 

[Tranona]

Would not worry too much about shaft overhang. The rule of thumb is 1.5* shaft diameter. I assume you have a 30mm or 1 1/4" so 45mm is quite normal, buy if you look around you will see many boats running quite satisfactorily with much more than this.