Switched to Electric

Fah Kiew Tu

Curmudgeon, First Rank
10,376
3,470
Tasmania, Australia
I'm confident I can do the work myself, I would prefer to so I learn something from the process even if it'll take a lot longer than if a pro did it.

I've come across something else though; would it be best practice to gear down the motor with a belt drive and adding a thrust bearing to the motor?

You really have to have a thrust bearing in there. An electric motor isn't designed to take thrust as a rule.

If you get serious about it I can find the reference to the SKF bearing & housing I used. It's a bearing that handles both thrust and axial loads. Makes a nice setup using standard industrial stuff. ATM I'm 1000 km away from my boat and reference material though.

What you're asking about is quite do-able if you want a project and experiment with it, so you're prepared to put in the time and keep tweaking stuff. I'd not do it myself given there's a functional engine but hey, I'm not averse to going down rabbit holes either if I feel like it.

Could be a slipping transmission too, now I think on it. In your position the first thing I'd do is sort out what's going on with the current setup, then decide.

FKT
 

Tylo

Member
207
116
Sweden
You really have to have a thrust bearing in there. An electric motor isn't designed to take thrust as a rule.

If you get serious about it I can find the reference to the SKF bearing & housing I used. It's a bearing that handles both thrust and axial loads. Makes a nice setup using standard industrial stuff. ATM I'm 1000 km away from my boat and reference material though.

What you're asking about is quite do-able if you want a project and experiment with it, so you're prepared to put in the time and keep tweaking stuff. I'd not do it myself given there's a functional engine but hey, I'm not averse to going down rabbit holes either if I feel like it.

Could be a slipping transmission too, now I think on it. In your position the first thing I'd do is sort out what's going on with the current setup, then decide.

FKT
I see. That would be a very welcome piece of information if you can find it, I'd really appreciate that.

The thought of the slipping transmission has occurred to me too but if that were the case, wouldn't the engine be revving up without anything happening? The state of it now is that it just takes forever for the engine to build any revs. I've checked the oil in the transmission and it's at the correct level and looks great.

I made a new discovery about my engine yesterday though, it's leaking water from where the exhaust elbow bolts onto the cylinder head.
Hopefully the corrosion in the cylinder head isn't too bad. I noticed that cast stainless elbows are available for this engine at ~30% higher cost (an extra $100 give or take) than the cast iron ones. Would that be a good upgrade? I'm guessing it's not 316 but still, more noble than cast iron. It shouldn't turn the cylinder head into a sacrificial anode since the head has a zinc anode screwed into it, right?

thumbnail_IMG_7878.jpg
 

Zonker

Super Anarchist
10,131
6,317
Canada
I'd first change the transmission oil, no matter the appearance, unless it has been done regularly.

I would also remove the exhaust elbow and see if a new gasket fixes the issue before ordering a new one. Stainless steel and exhaust gases don't mix very well, so cast iron may well be a reasonable choice.
 

Jim in Halifax

Super Anarchist
1,787
849
Nova Scotia
That's a pretty minor leak. Try tightening the bolts a little bit and see what happens. You may need to replace the gasket. If the rest of the engine is as clean as what is in the picture, that is a good sign. As Zonker says, cast iron exhaust elbows often last better that stainless steel.

You should see if a basic diesel course (or better yet, a marine diesel course) is available at a local college - it would be very worthwhile for you. Diesels are beautifully simple and reliable engines...once you grasp the basics.
 

Tylo

Member
207
116
Sweden
Thank you for the input! I'll look up the torque specs on the bolts and see if I'm able to tighten them a little.
If not I'll remove it and replace the gasket and possibly use some liquid gasket as well if there is corrosion on the sealing face.
If it's very corroded or gunked up inside I'll replace the elbow with a new cast iron one - thank you for the input on the material choice, saved me money and having to replace it sooner in the future.

I appreciate the recommendation of a diesel course, it might be for the better.

Thanks again everyone!
 

Fah Kiew Tu

Curmudgeon, First Rank
10,376
3,470
Tasmania, Australia
I'd first change the transmission oil, no matter the appearance, unless it has been done regularly.

I would also remove the exhaust elbow and see if a new gasket fixes the issue before ordering a new one. Stainless steel and exhaust gases don't mix very well, so cast iron may well be a reasonable choice.

Agree. Cast iron is nice material for a job like that. Stainless isn't the best choice though faced with a choice between an outrageous price on an original replacement and a fabricated stainless one, I'd go for the stainless option. But I can do it myself so only material cost involved, and I'd use Schedule 80 or heavier pipe section.

This is the bearing I used. It is a SKF SR-BS2-2208-RS. I put that in because the SKF link isn't playing nicely when I look after posting this.


It was in one of these housing/carriers.


The actual part number was FC 508M.

Now I did it this way due to space considerations, a foot mounted bearing carrier would be simpler if space permits.

And obviously you'd only need a lot smaller bearing.

Those bearings come with both parallel bores and tapered bored where a wedge shaped bushing tightens down onto the shaft to hold it in place. I used the parallel bore one because it was easier for me, and as I machined my own prop shaft, coupling etc I knew what I was dealing with.

FKT
 

Ripply

Member
99
51
Homer Alaska
I'm curious if anyone has seen one of the non-propeller Fin5 electric outboards? They claim an efficiency increase to go along with the safety benefits. Can that actually be true? Or is this vaporware? It's a very cool concept if the numbers work out.

 

Tylo

Member
207
116
Sweden
Agree. Cast iron is nice material for a job like that. Stainless isn't the best choice though faced with a choice between an outrageous price on an original replacement and a fabricated stainless one, I'd go for the stainless option. But I can do it myself so only material cost involved, and I'd use Schedule 80 or heavier pipe section.

This is the bearing I used. It is a SKF SR-BS2-2208-RS. I put that in because the SKF link isn't playing nicely when I look after posting this.


It was in one of these housing/carriers.


The actual part number was FC 508M.

Now I did it this way due to space considerations, a foot mounted bearing carrier would be simpler if space permits.

And obviously you'd only need a lot smaller bearing.

Those bearings come with both parallel bores and tapered bored where a wedge shaped bushing tightens down onto the shaft to hold it in place. I used the parallel bore one because it was easier for me, and as I machined my own prop shaft, coupling etc I knew what I was dealing with.

FKT
Many thanks!
That's hugely helpful.
I think I'll follow the general advice I received and keep the diesel for a while. It's probably just a matter of getting used to the boat and how it handles, rather than immediately spending a ton of cash just because it doesn't "feel" like most other boats I've driven.

I'll have to fix the leaking exhaust but other than that I'm hoping it'll keep running nicely.

I also have a lead on a full electric setup that will come out of a boat of similar length and displacement to mine in a year or two as the owner is converting to outboard power instead. When the time comes I'll have had more time to get to know my own boat and I'll know whether an electric conversion is still something I'd like to go through with.
 

Ajax

Super Anarchist
14,999
3,281
Edgewater, MD
I had a stainless elbow once. It literally dissolved where the water ran fast. Shiny clean right up until it’s early demise.
Interesting. On the advice of this forum, I had a custom, SS elbow fabricated for my Universal 5424. Normally I'd say "I'll keep a close eye on it" but that seems pointless if there are no leading indicators of failure.
 

Jim in Halifax

Super Anarchist
1,787
849
Nova Scotia
Interesting. On the advice of this forum, I had a custom, SS elbow fabricated for my Universal 5424. Normally I'd say "I'll keep a close eye on it" but that seems pointless if there are no leading indicators of failure.
Just buy a handy-dandy UT thickness tester. Probably standard equipment if you own a steel yacht. Don't forget to buy the sensor too. Just loosen the purse strings! Or, you can probably get one on AliExpress quite a bit cheaper...
 

longy

Overlord of Anarchy
6,985
1,280
San Diego
Don't worry. Failure will show as tiny rust spots in the surface. As they progress, they will squirt either exhaust gases or salt water. I used to work a lot with welded up SS 'dry' & water jacketed systems.
 

El Borracho

Verified User
6,825
2,784
Pacific Rim
Interesting. On the advice of this forum, I had a custom, SS elbow fabricated for my Universal 5424. Normally I'd say "I'll keep a close eye on it" but that seems pointless if there are no leading indicators of failure.
Mine was fine upstream of the water injection. The aggressive erosion of the stainless was where the exhaust+seawater mixture flowed a short distance downstream. The soot layer prior to the water injection point and the dry conditions may prevent erosion. If your exhaust transitions to rubber hose immediately after water injection, as many do, you may not have an issue.
 
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longy

Overlord of Anarchy
6,985
1,280
San Diego
The combination of how exhaust gases & salt water produces sulphuric acid compounds at a high temp. This is what causes most corossion. Hot salt water isn't good, either
 

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