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Replacing a internal diesel engine with an outboard


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Hi, I've just bought an old Van de Stadt Privaat (Buccaneer) that has an old diesel inboard that is unreliable and leaking oil. I've got a 6hp Johnson outboard and am planning to mount it on the transom and remove the inboard diesel. I'd appreciate any advice on the best way to so this. There is a swim ladder and chainplate for the backstay in the centre so I was going to mount it to one side using a rise and fall outboard bracket. One issue is that the design of the boat means it might be quite tricky to operate the outboard from the cockpit so it might need to convert it to remote control. Another option I've been thinking of is to replace the inboard with a pod electric system but this seems quite expensive compared to just using the outboard I already have (although would be nice and quiet!).

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Outboards on the transom can work ok for manoeuvring in sheltered waters. They have some problems in a chop and pushing against wind and tide. The first is that they can lift the prop from the water if not mounted pretty low, as the ends of the boat tend to see-saw over waves. They are not rev governed  and will over rev if this happens. 
Next is prop size. A small outboard cannot spin a prop of the size that the diesel will - it simply doesn’t have the torque. Torque is what pushes thru the waves/tide/wind etc.

this is why the boat was designed for a diesel.

So, if it were me, and the diesel does not have a terminal issue (low compression, low oil pressure, anything else that would require a rebuild) I’d seriously consider fixing it. Diesels are simple, clean fuel, clean air, compression and properly timed and injected fuel, and they are extremely reliable. 
 Might be worth cleaning it, and working out where the oil is coming from, and addressing the cause of the unreliability before ditching it!

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We have some nice 5kw (replaces a 10hp diesel) electric motors going cheap ($3000) which would drop in to replace your existing diesel. Definitely the best option if you keep it in a marina where you can plug it in. On a mooring it depends how often you use it but solar panels can easily provide enough power unless you use it on consecutive cloudy days.

An outboard will get dunked under water and/or the prop will come out of the water in big waves on a lee shore, just when you really need it to perform. Inboard of any kind is much, much better.

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Thanks for all the great replies! I will see what I can do with the diesel. There is not much room in the cabin and the engine and all the bits take up quite a bit of room so would ideally like to get rid of it for that reason as well!

The inboard is a 6hp single cylinder Lister Petter AC1W.

The 'drop in' electric alternative sounds good (I'd love the idea of quietly motoring around on a still day) but my investigation was that it might be very expensive with the cost of the battery etc. I'd need solar panels as on a pile mooring. Also not sure how it would work with an old-fashioned stuffing box and potential for water in the bilge... @syohana - can you send me a link to more info? I was thinking if I did electric I would seal everything up (no holes in the hull...) and put a pod drive on the bottom.

 

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OK, I suggest using the outboard while you do a good assessment on the Lister.  This way, the worst case is you have an outboard bracket mounted that you can use later if needed.

If the Lister is starting ok and not making wild knocking noises its possible that an oil leak is something relatively minor - rocker cover gasket, rear main seal or similar.  Over time small diesel leaks can accumulate to make it look like a major when in reality some new crush washers and 500ml of engine degreaser resolves the problem.  The collection of cable ties, different hose types and crimp connectors tells me the engine hasn't had love for a while - like all of us, they respond well to the occasional cuddle...

A really good clean around it removing any oil and dirt will help identify where the leak is which then gives you a good idea of what is needed to solve it.

 

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Sounds like a good plan. I think the leak is fairly major as the previous owner said it was spraying oil around as it dripped and hit moving parts... I think a temporary outboard solution sounds best with the aim to get the diesel going at some point if possible. It will mostly be used for getting in and out of the marina and will just be doing a bit of sailing in the harbour on quiet days with no waves to start with.

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1 hour ago, Tigermoth said:

The 'drop in' electric alternative sounds good (I'd love the idea of quietly motoring around on a still day) but my investigation was that it might be very expensive with the cost of the battery etc. I'd need solar panels as on a pile mooring. Also not sure how it would work with an old-fashioned stuffing box and potential for water in the bilge... @syohana - can you send me a link to more info? I was thinking if I did electric I would seal everything up (no holes in the hull...) and put a pod drive on the bottom.

Yes, a pod drive and seal everything up is the best solution and we can supply those too but.... A pod is two to four times more expensive for a bit less power. If you didn't already have a prop and shaft then a pod is certainly best but you can save a fortune by using what you've got. Stuffing box is fine as long as you remember to stuff it. Our oldest electric boat has one (35 years on electric power and still going strong). She goes out on hire every day, nothing wrong with a good old fashioned shaft drive but a pod is simpler, slightly more efficient and even quieter if it's a direct drive model.

If you're not racing, don't mind the weight and don't need huge range then old fashioned lead acid batteries are fine, don't cost much. Use them as ballast. Used ones come up once in a while, can save a lot of money if you know their history (ex cellphone mast or data centre backup batteries are a great option, kept like new, quality brands and replaced every few years).

You can see more about the 5kw inboard motors on electricboat.co.nz under "shop" then "inboard motors".

 

 

 

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27 minutes ago, Tigermoth said:

I think the leak is fairly major

There is an old saying in the engineering (and possibly medical) business - "A pint of oil, blood or whiskey looks like a gallon when its on the floor".  I'm sure you get the meaning.

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1 hour ago, waikiore said:

I hope that is not a straight 'T' upstream of the water pump -or you run the very real risk of the raw water pump sucking air instead of water....

I noticed that too and wondered what it was. Looked like a cockpit drain or something. Surely thats going to suck air into the system causing overheating. 

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[quote] 2 hours ago, waikiore said:

I hope that is not a straight 'T' upstream of the water pump -or you run the very real risk of the raw water pump sucking air instead of water....

I noticed that too and wondered what it was. Looked like a cockpit drain or something. Surely thats going to suck air into the system causing overheating. 

[/quote]

Agreed. And the impeller appears to be on the wrong side of the water filter. The filter is supposed to protect the impeller but the impeller is connected directly to the seacock and what looks like a filter is on the outlet of the impeller.

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13 minutes ago, syohana said:

[quote] 2 hours ago, waikiore said:

I hope that is not a straight 'T' upstream of the water pump -or you run the very real risk of the raw water pump sucking air instead of water....

I noticed that too and wondered what it was. Looked like a cockpit drain or something. Surely thats going to suck air into the system causing overheating. 

[/quote]

Agreed. And the impeller appears to be on the wrong side of the water filter. The filter is supposed to protect the impeller but the impeller is connected directly to the seacock and what looks like a filter is on the outlet of the impeller.

 The filter if we are looking at the same thing is actually  the engine water heat exchanger, the engine must be freshwater cooled. Must be a header tank somewhere close by. Petters go forever given a modicum of TLC. Parts will most probably be available, it is probably original to the boat, so will have been acceptable to all its previous owners.

 

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Thanks for the replies. Some more photos showing where that vertical hose goes to. Also close up of where the oil leak(s) look like they are coming from.

I had it started today and it ran for about 30 seconds and then died. Some water started squirting out of the back of the water pump - it is very corroded if you look at one of the attached photos. I can't see a filter between the stop cock and the water pump.

Looks like they might have added an extra heat exchanger on as well? (That is really in the way of one of the berths!).

Any idea what that coolant is doing?

@syohana, I'm tempted to try out the electric motor you have. Can you message me the install instructions?

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Looks like the hose going up from the tee might be an improvised anti-siphon device.  It would have been added because the water pump is leaking. As long as the valve at the top is closed, the water pump will work OK but it will leak. If you open the valve at the top then it will let air into the top of the loop and that might stop water siphoning in and leaking out of the water pump, so it might stop it sinking the boat. It should never be opened when the engine is running. Just a guess.

If the tee is below the waterline then either it isn't that, or it is that but it doesn't work.

Email me through the contact page at electricboat.co.nz and I can tell you more about the electric drive.

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