Tohatsu MFS9.8A3 UL 9.8HP 4STR UL (£2,141.41p) in westerly centaur with dead engine

JumbleDuck said:
Rather dodgy point that, I'm afraid. Automotive engines are generally design to run continuously at only a fraction of maximum power. My Golf has a 60bhp engine (I think) but even cruusing at 70mph on the motorway it probably only needs 15 or 20hp. The rest is for overtaking. Therefore, if you are marinising an automotive diesel and want, say, 20hp continuously out of it, you should look for something with a lot more maximum power to start with.

Remember that the BMC 1.5 litre diesel was and still is extremely popular on boats, most of which used nothing like the 40bhp it produced in taxis.
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Not dodgy at all. Read carefully what I say. There is not an automotive engine "out of a van" that could conceivably be marinised and fitted into a Centaur. There is physically not enough room for a 4 cylinder engine, nor does the boat need the sort of power they can produce. Of course larger diesels such as the BMC you refer to are used in boats - but at 30hp+ and in sailing boats in 33'+ length.

All the small engines are 1,2 or 3 cylinder and either designed specifically for boats or more likely nowadays derived from industrial power plants.

As many people have suggested there is no shortage of suitable well proven, reliable diesel engines available either new or used that will do the job for Dylan better than any outboard as shown by their almost universal use in such boats. However, dylan for his own reasons does not agree!
 
A Peugot or even a scrapped BMC Sherpa engine would do, or even a petrol engine as in ' Watermota '; water cooling is just a matter of engineering, but fresh water seems preferable to me.

While you have valid points to make - not about me ! - You seem an uneccessarily objectionable person, try to be more pleasant !
 
Tranona said:
Name me a "van" engine that can be installed in a small boat such as the one under discussion. Tell me how you are going to find the space, how you are going to keep it cool and what sort of gearbox you are going to use. Oh, and you don't have very much money to spend.
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BMC 1.5 diesel, like I said.
 
Tranona said:
Not dodgy at all. Read carefully what I say. There is not an automotive engine "out of a van" that could conceivably be marinised and fitted into a Centaur.
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Your words were "What van has a less than 20hp engine that can be marinised?" and I was pointing out, very reasonably, that marinising diesels generally means planning to run them continuously at far less than their automotive peak load. Your "less than 20hp" is therefore a red herring, because if you want to end up with a 15hp marine diesel you will start with a 40hp plus automotive one. Which is why the canals of Britain are full of boats taking 5 - 10hp out of engines originally rated at 40hp. In vans.

As for fitting to a Centaur? Have you compared the dimensions and weights?
 
JumbleDuck said:
Your words were "What van has a less than 20hp engine that can be marinised?" and I was pointing out, very reasonably, that marinising diesels generally means planning to run them continuously at far less than their automotive peak load. Your "less than 20hp" is therefore a red herring, because if you want to end up with a 15hp marine diesel you will start with a 40hp plus automotive one. Which is why the canals of Britain are full of boats taking 5 - 10hp out of engines originally rated at 40hp. In vans.

As for fitting to a Centaur? Have you compared the dimensions and weights?
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To be fair though I can't think of any modern van using a 40hp engine, 70 hp+ seems more like it. Not much point in buying an antique, even if you'd be given one for free there's still the substantial cost of converting and fitting it.
 
JumbleDuck said:
Which is why the canals of Britain are full of boats taking 5 - 10hp out of engines originally rated at 40hp. In vans.
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Well the blunt answer is that they are not (note the careful avoidance of apostrophes!)

Older ex-working boats are/were mostly fitted with two cylinder engines derived from static industrial units

The vogue in the early years of purpose built leisure narrowboats and the burgeoning hire boat industry was to fit smaller 2 and 3 cylinder often air cooled, light industrial engines (Lister SR2 and SR3, Petter etc )

There was, it is true, a period in the late 1970's and 1980's when a lot of new narrowboats were fitted with marinised versions of the BMC 1.5 and 1.8 engines and other similar automotive based engines

Then in more recent times there has been a trend back towards slower running light industrial / plant / agricultural derived engines e.g. Beta BD3 etc

Size and weight aren't a major issue when you're installing an engine into a 50' or 60' narrowboat so the 4 cylinder BMC's and their ilk were popular for a while because they were quieter running and relatively cheap. That popularity waned when people found that they were also troublesome, and sometimes expensive, to maintain compared to something like a Lister SR2 which might thank you for an oil change every decade or so but otherwise will run forever on a sniff of diesel

I have fond memories of rescuing a 60' narrowboat with a dead BMC 1.8 on the River Soar in Leicestershire. We towed her several miles upriver with our 36' Springer and her trusty SR2 and astonished the owner of the 60 footer which had never, he swore, gone as quickly! Later that evening we demonstrated what Badger could do without 60' of dead boat hanging off her stern to his even greater amazement.

Gimme a light industrial engine over an automotive engine as the base unit for marinisation every time!
 
Seajet said:
A Peugot or even a scrapped BMC Sherpa engine would do, or even a petrol engine as in ' Watermota '; water cooling is just a matter of engineering, but fresh water seems preferable to me.

While you have valid points to make - not about me ! - You seem an uneccessarily objectionable person, try to be more pleasant !
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I am being very pleasant to you. I am giving you the opportunity to explain to everybody (including dylan) how to do something that nobody else does.

Your answer so far just confirms how little you know about the subject.

Tell us all where you are going to fit the seawater pump, what heat exchanger you are going to use, how you are going to fit a watercooled exhaust manifold, what gearbox you are going to use, how you are going to attach it to the engine, and lastly where are you going to find space to fit an engine that is physically twice as big as the one normally used and how you are going to deal with twice the power (at a minimum) than is required to power the boat?

BTW Watermota gave up making petrol engine conversions nearly 40 years ago, which I guess tells you something about their suitability for the job.
 
JumbleDuck said:
Your words were "What van has a less than 20hp engine that can be marinised?" and I was pointing out, very reasonably, that marinising diesels generally means planning to run them continuously at far less than their automotive peak load. Your "less than 20hp" is therefore a red herring, because if you want to end up with a 15hp marine diesel you will start with a 40hp plus automotive one. Which is why the canals of Britain are full of boats taking 5 - 10hp out of engines originally rated at 40hp. In vans.

As for fitting to a Centaur? Have you compared the dimensions and weights?
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Afraid it does not work like you imagine it does. while it is quite possible to constrain the hp of a larger engine, there is no real need to do that. There is a vast array of mainly 2 and 3 cylinder high speed diesel engines available in capacities of 500-1000cc producing between 10 and 30 hp that form the basis of marine engines. When correctly geared and propped they use all the power available to achieve hull speed. However, as you rightly say at cruising speed they do not use all the power. So, my Volvo uses around 11/12hp approx 65% full revs) to cruise at 5.5 knots, but uses the whole 29hp to achieve the maximum of 7.3 knots. That is on a 37' boat displacing approx 6 tons. so, why is a 40hp engine needed for a 3-4 ton 26' boat?

At the other end of the spectrum it would not be sensible to have only 10hp - as has already been shown that is insufficient to achieve hull speed, even with the optimum propeller, so, as dylan will find out, he will have to run his chosen outboard at near maximum power to achieve even a modest cruising speed without having any reserve for advaerse conditions.

Not entirely sure why we are having this discussion as propulsion of displacement boats is well understood territory and you only have to look at what designers and builders specify to see that all this talk of alternative is really a waste of time.

The "ideal" auxiliary for a Centaur is a 20hp (around 700cc) 3 cylinder diesel, freshwater cooled, a 2:1 reduction gearbox and a 13*9 3 bladed prop - available from Beta, Nanni, Vetus, Volvo, Yanmar etc. Very different from anything you can get out of a scrap van!
 
Tranona said:
Afraid it does not work like you imagine it does. while it is quite possible to constrain the hp of a larger engine, there is no real need to do that. There is a vast array of mainly 2 and 3 cylinder high speed diesel engines available in capacities of 500-1000cc producing between 10 and 30 hp that form the basis of marine engines.
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My point exactly. Thank you.
 
The bottom line is that taking a random diesel van engine, with a likely capacity of at least 1600cc, marinising it, mating it to a marine gearbox, and mounting it in a little boat like a Centaur is even less economically and practically viable, and even more of a crackpot idea, than the outboard in a well option.
 
Simondjuk said:
The bottom line is that taking a random diesel van engine, with a likely capacity of at least 1600cc, marinising it, mating it to a marine gearbox, and mounting it in a little boat like a Centaur is even less economically and practically viable, and even more of a crackpot idea, than the outboard in a well option.
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lol at last someone has talked some sense.
 
Roger!

Thanks for your post at #275

I would love to wax lyrical about the noble aim of restoring a classic, but my motivation was far more base. I loved sailing (still do) but didn't have the funds to buy a sorted boat so bought a 'sailable' Hurley 22 with the intention of sailing the summer and spending my winter weekends in the yard. Not afraid of a bit of yakka after all, and not a novice either.

I just about got it back to a local yard via sea, more through the grace of God than anything else, but anyway - to cut a long story short the boat was rotten from the encapsulated keels upwards, and after 2 years in a yard and having spent far more than a decent example would have cost I realised that I was not even half way there and cut my losses. You are no doubt familiar with the issues, and the issues upon issues, that I faced, so I wont go into detail.

Sold the boat for £1. Suspect it was stripped of the expensive gear I'd put in and skipped.

I actually think that there is nothing finer than a showroom condition 30, 40, 50 or 100 year old vehicle. Any arse can buy a decent car or boat but it takes soul (and time, and money) to bring one back from the dead.

And that's it really. It's noble, but this kind of work isn't for the guy trying to saving a few quid 'cause he can't afford engine maintenance.

Internet is a funny thing. I would never comment on someone's project in real life, other than in a positive way or to say gizza shout if you need a hand or want a beer. If I saw Dylan in a yard I would not comment on his plans at all, but he has solicited opinion across multiple threads and my opinion is that his plan is nuts, but only because he is coming from the 'broke bloke wants a boat' angle

Coming at this project from a less time and financially constrained p.o.v would I think elicit a different reaction.

Anyway Roger - all the best with your boat. I enjoy your blog and was aware of it before the 'centaur outboard well' saga. I have no doubt you'll end up with a fantastic yacht.

All the best to you too Dylan. Hope your plan succeeds, or you get the boat that you want.

Jim
 
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well writtenJim,

and you are a brave fellow selling a boat for a £1

I wonder if I can find a Centaur for such a price

several have come through my inbox already so I am hopeful that I will find the right boat at the right price

I am not intending restoring anything to its former glory

just getting a boat back into sailing condition and sailing it

I am aware of the perils of boatyarditis

I experienced a small bit of it when I had Katie L at home

the idea of actually putting her in the water where she might sink and I might have to make some decisions became a little daunting

in a boat yard there are lots of little jobs that you can start and finish and get that sense of satisfaction

but a few people get distracted into seeking perfection

never been one of my faults..... perfection

I have enjoyed these threads .... or most of them

I am astonished at how they have kept going but it was a wet, horrible weekend and probbaly too horrible even to go to the boatyard so a lot of blokes sitting at their computers thinking about sailing

I do have a few more questions to ask and some maths to run past the clever blokes on here

Dylan
 
I have an outboard in a well. I use it to get from my mooring to a place where the water is deep enough to lower the keel. Then I breathe a sigh of relief when I can turn the damned thing off and start sailing! I couldn't imagine making serious passages of the sort you might make in a "proper boat" like a Centaur listening to that racket. I would say that outboards are great to get small (21ft) boats like mine on and off their moorings but not really a practical means of propulsion.
The other thing that comes to my mind is that after five years being cooled by raw seawater the outboard will be pretty worthless but a freshwater cooled Beta engine would have probably lost next to nothing. I don't know that for a fact because I've never seen a second hand one for sale, which in itself says something.
 
CreakyDecks said:
I couldn't imagine making serious passages of the sort you might make in a "proper boat" like a Centaur listening to that racket. I would say that outboards are great to get small (21ft) boats like mine on and off their moorings but not really a practical means of propulsion.
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A couple of summers ago I motored from Pwllheli to Troon as it was windless the whole way. 220 miles with only a tide stop in the North Channel for 6 hours, but my boat is not a serious boat so it couldn't have been a serious passage.

CreakyDecks said:
The other thing that comes to my mind is that after five years being cooled by raw seawater the outboard will be pretty worthless.
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My experience is otherwise. The 2 4-stroke main engines I have owned just seem to keep on going. One of them is 6 times older than your suggested life.
 
I have an outboard in a well - 4 & 5hp 2 strokes on a 22' boat - and have used them many times to motor or motorsail across the Channel, no problem especially with the later added autohelm to relieve the boredom ! :)
 
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