Replacing an engine: your thoughts on what unit to choose?

[MisterBaxter]

The outboard option has been ruled out already but just to add that there is one situation in which it would be worthwhile, which would be if the owner wanted a big reduction in weight and bulk, and was happy with the reduction in power. A friend once replaced a 15hp inboard with a 6hp outboard and was broadly happy - he raced a bit and when cruising he was obsessive about sailing whenever possible. The benefits to sailing performance were apparently dramatic.

 

[LONG_KEELER]

I would council against an outboard option anyway due to security and fuel costs perhaps 2 or 3 times an inboard

After 20 years of inboard diesels I switched to outboards in a well (last four yachts) . With modern 4 strokes I would put diesel and petrol about the same. I noticed yesterday at filling stations a difference of 25 pence per litre between petrol and diesel at the moment. I know that the idea of petrol on a boat is not for everyone but you don't hear much about problems and fires like there used to be. I'm guessing that most of the problems were inboard petrol engines ?

 

[john_morris_uk]

I’m trying to work out why any thread on engines on the forum brings out a lot of sycophantic remarks about Beta engines?
Lots of pointing out how easy spares are because it’s a Kubota engine that’s been marinised. The fact that exactly the same thing is true for Nanni marine diesels is never mentioned.
I appreciate that Beta are usually pretty good with their support and will (at a price) offer alternative engine bearers that might fit your existing beds etc, But my experience is that they’re equally capable of suggesting that you go to your local steel fabricator.
And I speak as one who has recently bought and installed a Beta 38 to replace a Volvo 2040.

The OP doesn’t have a Beta agent nearby. He needs an engine to suit HIS boat in HIS location. I’m sure lots of forumites have had good experiences with Beta but other engines are available that are equally good and may be a much better choice for him.

 

[oldmanofthehills]

How often are those distances done in one voyage though? I've done ferry trips between Ireland and Scotland for yachting events, longest distance being ~150 miles, rarely will there be no time under sail and only once did we have to motor the whole way due to no wind. Regardless of wind or no wind, those distances in coastal pilotage are no fun, only undertaken to get the boat where it needs to be and contingency allowed for(i.e. +24hrs for weather diversion, mechanical failure, etc). Cruising is a different kettle of fish, most people like to stop for the night. South of Ardnamurchan you could cruise the west coast of Scotland with an electric auxiliary as described without difficulty. North of there marina berths are fewer and farther between, but with planning it could be done.

I go at least once a year on long journeys where power might be useful for over 60 miles. I didnt expect to need a 400 mile range under power recently but was rather pleased I could call into obscure irish and n irish harbours with no fueling facilities as I travelled north. And no fuel or electric on most of the Small Islands either. And theres the rub. Unless one has marina facilities at under 50 mile range, electric is a waste of time unless one always stays in port awaiting perfect winds

 

[LONG_KEELER]

I go at least once a year on long journeys where power might be useful for over 60 miles. I didnt expect to need a 400 mile range under power recently but was rather pleased I could call into obscure irish and n irish harbours with no fueling facilities as I travelled north. And no fuel or electric on most of the Small Islands either. And theres the rub. Unless one has marina facilities at under 50 mile range, electric is a waste of time unless one always stays in port awaiting perfect winds

Whilst cruising I have never had a problem finding some kind soul , shore based , to run me there and back to a filling station . The local car owners have to get their fuel from somewhere.

Depending on the size of boat though , you will need a large size/quantity of jerry cans spare to travel any serious distance. Mr Concerto didn't seem to have any fuel problems with his Round Britain trip this year though.

 

[Praxinoscope]

#43, I just wonder if a lot of the ‘sycophantic remarks’ about Beta engines, comes from the amazing situation that for once there is a British company actually proving to be a success, good at what they do and treating their customers like human beings, OK the base engine is Japanese ( it would be nice if we could build engines like this in the U.K., but we don’t).
Of course the Nanni engines use the same base engines, but as Beta are marinised in the U.K., and the majority of ybw posts seem to originate in the U.K. there probably is a bias towards Beta simply for ease of access to spares and advice, not to mention competitive pricing.
I think the OP is based in NZ so it may well be that other engines/suppliers may well suit better, as most small yacht diesels are now based around various Japanese base engines it is more a case of cost, will it fit (or made to fit), how good thé marinisation is and local services, than which engine is quieter, smoother or more reliable.

 

[penfold]

Kubota engines are ubiquitous in small industrial machines and agricultural machinery, much like Perkins were 50 years ago, so spares can be found nearly anywhere; I doubt NZ is any different. Naturally it's quite sensible to consider whatever franchise the local marine engineer(if any) holds, but it shouldn't be the only consideration.

 

[oldmanofthehills]

Whilst cruising I have never had a problem finding some kind soul , shore based , to run me there and back to a filling station . The local car owners have to get their fuel from somewhere.

Depending on the size of boat though , you will need a large size/quantity of jerry cans spare to travel any serious distance. Mr Concerto didn't seem to have any fuel problems with his Round Britain trip this year though.

A few years ago I cruised s ireland. Lifts from tractors and the use of folding barrows sorted out fuel, and fairly used to that in English Bristol Channel as no fuel Weston, Clevedon, Watermouth, Porlock or indeed most places except ilfracombe and padstow and it is extravagent to make 100 round trip to fuel up at pontoon so very appreciative of newer engines miserly use of diesel.

Heaven help us if we were still at WSM and wanted electric as nearest electric point would be in Wales at Cardiff and thus overnight trip to charge. Electric van owner complained of similar issue for commercial usage

 

[nestawayboats]

I did say electric wouldn't suit everybody. But that if it does, it has advantages which nobody ever seems to weigh up against "range". A range which is already enough for a lot of people, most of the time.

Almost no noise or vibration, zero exhaust fumes, zero oil or fuel smells/leaks inside boat. No servicing. Motorsailing becomes pleasant. And so on.

So if we want an electric propulsion system how could we solve "range issue" for the few occasions we might need to?

We do actually get some regen under sail, but it's only really effective above 5.5 knots, which is not unusual but towards the higher end of Sadler 29 sailing speeds. Solar panels and wind generators are also options, but relatively slow compared to the size of the battery bank (a couple of days at anchor between passages would definitely help, but a couple of hours won't notice).

Ignoring cost and sticking with all electric, we could easily add 50% to current capacity, by adding a 3rd 9kWh capacity battery within old engine bay. Or double it, by adding a 4th where the fuel tank used to be (and still not taking as much room). So 120nm range at 4 knots on battery only is feasible.... or ~80nm at 5 knots. But we have just added £8k more cost in batteries...

Much cheaper than more batteries, we could carry a 2kW petrol "suitcase" generator (Honda EU22i etc). The only time I can imagine needing more than the current battery capacity - let alone if we doubled it - whilst on passage, is in an absolute flat calm. So it could come out on deck solving the ventilation/exhaust issues. Not ideal from a noise point of view, but this is a backup. 1.5kW pushes the boat along nicely, so range would then be as much petrol as we could carry. And at a push, much as I object to generators at anchor, it could in the right (or wrong) situation charge batteries when moored away from shorepower.

Not something I've looked at much, but you could consider fuel cells, likely running most of the time but at lower output power (than a generator). Silent, compact, and safer fuel than a generator.

If I were fortunate enough to be speccing a new boat ie from scratch, and had long distance potentially motoring passages in mind, a built-in (and larger capacity) diesel generator would accumulate charge more quickly and at a greater rate than that needed for propulsion. If that diesel generator were specified correctly and charging a relatively large battery bank it would make very efficient use of diesel, so you'd actually need less diesel per mile of range. Most of the time you'd be using electric propulsion. At a certain level of battery depletion the generator would kick in, and charge batteries whilst the boat is still being driven electrically. And a generator can be noise and vibration insulated from the boat more effectively than a propulsion engine, so you have less noise/vibration too (which is one of the delightful features of electric). With a large and charged bank you can live for several days at anchor without worrying about charging, even if it's flat calm and foggy. When you do eventually need to recharge you're not knackering a diesel engine that was designed for propulsion by running it to spin an alternator.

But I appreciate that last paragraph has moved some way from the OP's question.

Ian, Nestaway Boats

 

[wombat88]

I’m trying to work out why any thread on engines on the forum brings out a lot of sycophantic remarks about Beta engines?

Because they are red.

 

[Tranona]

This neatly illustrates the current position. at the "ends" of the size continuum for sailing yacht auxiliaries electric or diesel/electric is viable. So you can get a choice with, say a Cornish Shrimper and once you get above 45' or so, perhaps less with a catamaran diesel electric becomes viable. Indeed many have already tried to market such combinations, although with limited success primarily because of cost. Nigel Calder's research project 10 years or so ago is still worth looking at. There also the recent move to all electric performance sailboats such as the Salona 46 where the typical sailing speed is high enough to make regeneration worthwhile.

However these are all niche sectors of the market. The bulk of the market whether it be new boats or replacement is the 25-50' sailing boat where the cost and range constraints of electric are just too great. Most of the improvement in IC for yachts has come from the automotive and industrial sectors, but there is little in electric propulsion for automotive that is relevant to boat propulsion so difficult to see much changing the basics in the foreseeable future .

 

[MisterBaxter]

The only real issue with electric power for boats seems to me to be battery price. If batteries could be had for half or a third the current price it would start to look very viable. I suppose this might happen in due course.

 

[oldmanofthehills]

The only real issue with electric power for boats seems to me to be battery price. If batteries could be had for half or a third the current price it would start to look very viable. I suppose this might happen in due course.

I suspect the ecological, financial and weight penalties of batteries will make them a greenwashing dead end. For instance the mandatory electric drive with battery in the scooter collection van in bristol reduces load capacity to 0.250 tons with a 3.5 ton van, and the driver spending maybe an hour a day looking for charge point and then charging

Fuel cells might however make electric propulsion viable

 

[LONG_KEELER]

I suspect the ecological, financial and weight penalties of batteries will make them a greenwashing dead end. For instance the mandatory electric drive with battery in the scooter collection van in bristol reduces load capacity to 0.250 tons with a 3.5 ton van, and the driver spending maybe an hour a day looking for charge point and then charging

Fuel cells might however make electric propulsion viable

If not self generated, the power for cars and boats will require massive amounts from power stations to make up the gap between petrol / diesel currently being used. AFAIK there are hardly and new projects in the UK to generate this new demand. It's likely that the power would have to be purchased from overseas which is already under pressure.

 

[penfold]

The only practical limiting factor for 99% of leisure yachting is cost; battery electric wins in every other respect. Your anecdote does not change facts.

I suspect the ecological, financial and weight penalties of batteries will make them a greenwashing dead end. For instance the mandatory electric drive with battery in the scooter collection van in bristol reduces load capacity to 0.250 tons with a 3.5 ton van, and the driver spending maybe an hour a day looking for charge point and then charging

Fuel cells might however make electric propulsion viable

 

[oldmanofthehills]

The only practical limiting factor for 99% of leisure yachting is cost; battery electric wins in every other respect. Your anecdote does not change facts.

Yes but if is not actually green, which batteries are not - and there is no great need to restrict local pollution, which is a non issue for sea going small liesure boats - and electric generation is heavily dependant on fossil fuels, which it will be until new nuclear comes on after the normal 25years -then the only motive to change to battery electric seems to be a quieter drive train

Added to that electric is essentially more vulnerable to sea atmosphere damage than the humble diesel and seems to cost twice as much for less capability

Striving for less bangs for your buck??

 

[nestawayboats]

This neatly illustrates the current position. at the "ends" of the size continuum for sailing yacht auxiliaries electric or diesel/electric is viable. So you can get a choice with, say a Cornish Shrimper and once you get above 45' or so, perhaps less with a catamaran diesel electric becomes viable. Indeed many have already tried to market such combinations, although with limited success primarily because of cost. Nigel Calder's research project 10 years or so ago is still worth looking at. There also the recent move to all electric performance sailboats such as the Salona 46 where the typical sailing speed is high enough to make regeneration worthwhile.

However these are all niche sectors of the market. The bulk of the market whether it be new boats or replacement is the 25-50' sailing boat where the cost and range constraints of electric are just too great. Most of the improvement in IC for yachts has come from the automotive and industrial sectors, but there is little in electric propulsion for automotive that is relevant to boat propulsion so difficult to see much changing the basics in the foreseeable future .

I don't agree about diesel electric not being viable below 45' in monohulls.

If we started again - with diesel electric as opposed to all battery in mind - then on the Sadler 29 we could fit a 4kW DC diesel-powered generator and at least one 9kWh battery where the Bukh diesel engine used to be. We could fit a smaller diesel tank to reflect the greater efficiency of the whole system, and then another 9kWh battery in the space saved there. Weight-wise that would be about neutral, and that's before we decide to bin the 2x12V domestic batteries (say 50kg) and run that load off a DC to DC converter. We might have got rid of two gas bottles too, if going for an electric galley.

There is at least one Cornish Crabber Pilot Cutter 30 with a diesel-battery-electric pod drive installation. It was at Southampton boat show and not built on spec, ie belongs to an actual customer.

It is definitely possible, just depends if you want it and can afford it. It won't make financial sense on an elderly boat, but often a new diesel engine doesn't either.

A diesel electric system would actually have more range per litre too... if you keep the same size diesel tank it's a way to get more range than a straightforward replacement diesel. And most of the time you'll be motoring around in silent, vibration and fume-free bliss. Even when the generator is running it's likely to be quieter than a diesel propulsion system, and not mechanically connected to drivetrain (soundproof box, soft mounts).

Electric motors are not the problem, they already exist in suitable sizes for powering yachts. Batteries are getting better but still nowhere near the energy density of fossil fuels, particularly if you want LifePo4 (which is the safest chemistry). The energy density issue is not quite as dire as it first seems, because electric motors convert electricity into propulsion much more efficiently than small diesel engines do (heat, noise etc are all waste products but nonetheless represent energy consumed). But still you get a lot more miles from a kilo of diesel than a kilo of battery.

I remain in agreement that it wouldn't suit everybody but price apart either "all-battery" or "diesel-large battery-electric drive" can be made to work in most scenarios.

The pollution point. Yes you could argue that chucking out carbon monoxide, nitrogen oxide and particulates (soot) from a not very efficient (by modern automotive standards) diesel engine doesn't really matter at sea, especially in the context of oil tankers and container ships. But it's still harmful to the marine environment, and also those on board if you're motoring downwind. And we are non-essential leisure users... sooner or later there will be tighter legislation, for new boats at least.

Ian, Nestaway Boats

 

[MisterBaxter]

Thinking outside the box here, how about a single massive lead acid battery instead of a keel??

 

[nestawayboats]

You could definitely replace some ballast with batteries if designed in from the start, but unlikely to be as low as you'd like. A slightly fatter than usual central part of saloon table could hold quite a lot of battery capacity, and still keep them out of bilges, with the weight relatively low and central in boat.

 

[LONG_KEELER]

I do like the idea of semi electric sailing. i.e. if you could only sail at say 2kn , having quiet electric power added to make 4 kn overall would probably be acceptable to most yachtsman depending on where you want to go. You would of course need to run the diesel generator at some time for recovery, but you could still keep things quiet if you hook up to power in a marina . I'm not sure if the amperage would be high enough in most marinas at present.