Recondition, rebuild, re-engine, or just patch it up?

[Danny Jo]

Freestyle is approaching the end of her nineteenth year with her original Perkins M30 (29 HP 3 cylinder diesel, believed to have been manufactured by Kubota) having done something in excess of 6000 hours. I say "in excess of" because when I acquired her 12 months ago she had 6300 hours on a meter (one that is driven by engine vibrations) that had ceased to work. In other respects, the two previous owners have evidently not neglected the engine, it was recently fitted with a new gear box and it starts like a dream. I may be a little underpowered for the Menai Strait, getting 5 knots at around 2100 revs and, flat out, just over 6 knots flat plus a lot of black smoke. Fuel consumption is a modest 2.3 l per hour at 5 knots. After 150 hours use last summer the engine has started losing fresh water coolant, probably but not definitely from the fresh water pump. The engine has two fairly substantial design glitches: (1) It is all but impossible to tighten the alternator bolts after fitting a new alternator/impellor belt, because you cannot get a socket onto the nut and there isn't enough room to swing a spanner more than about 5 degrees; (2) The manual fuel lift pump works only with the engine at top dead centre (according to the blurb), and I've yet to find top dead centre.

OK, the engine is good for a few hundred hours more, but I reckon I am going to have to do something fairly major at some stage, and if I am going to fit a new engine, shouldn't I do it sooner rather than later so that I, rather than any future owner, get most of the benefit of the investment?

I've tried googling the question, with little success bar a reference to a previous thread on the PBO forum last year. Can anyone point me to a website which does engine and prop size calculations? Or two possible sources of expert advice in the North Wales/North West England areas?

Finally, some questions:

 

[MoodySabre]

A few years ago I spent £2000 having the existing petrol engine rebuilt (the crankshaft had broken!). It never was trustworthy and two seasons later we gave up on it after calling for a tow into the marina and bit the bullet. In my book, spending money botching up an old engine (particularly if you are not thrilled with its performance) is a waste of money if you are going to keep the boat. There's no substitute for knowing that it is going to start and run for ever and punch a strong tide and wind.

When I sold the boat two years later the value of the boat had increased by about half the cost of the new engine.

An alternative might be to buy a reconditioned engine if the price of a new one is too frightening.

 

[FullCircle]

The engine has performed to what was installed for at the time. Modern cruisers have a much higher power rating than was standard years ago.
At 38 feet and I guess about 10 tons, you ought to be closer to 50-60 hp or more.

The engine has done approx 7000 hours and would cost between 1-2k to overhaul, or probably 750 quid to 'fix'. Life could be said to be approx 10000 hours as a rule of thumb.
A new installation will be much quieter, probably smaller, more economical and you will have the ear of your local dealer for at least a couple of years on the warranty if required.

If you intend to keep the boat for more than say 3 seasons, I would replace the current unit altogether. It will fetch a good price anyway.

My vote is on Yanmar as my 29HP 3YM30 is a revelation, but others will be along to recommend Nanni, Beta and others. /forums/images/graemlins/smirk.gif

 

[Birdseye]

Sounds to me as if you are creating an issue which doesnt exist. If the water leak is only the pump, sort that out and you have a perfectly working engine. If it were worn you would be having oil pressure / oil consumption problems.

Sounds like you are over propped. Black smoke is unburnt diesel and happens because the engine is getting more fuel than it needs for the revs it is doing - the revs control the air flow. Could also be a very dirty hull.

There are no such things as "marine diesels" with the exception of things like old Bukhs and Sabbs. The volumes required for economic manufacture are far greater than the boat market can sustain so you find Yanmars for example in cement mixers and earthmoving kit.

Forget the engine. Spend the spare money on women and booze instead. /forums/images/graemlins/grin.gif

 

[doris]

Absolutely agree about the Yanmar. Steer clear of the current 30hp Volvo. I have 30 hp in 39 feet and about 9 tons all up, works fine but am medium displacement. Go for a new motor, the long term cost isn't that high after a bit of amortisation!! Best of luck

 

[Kawasaki]

It would be nice to have a bit more poke whilst negotiating The Straits.
Especially if You hit The Swellies a bit wrong as You know! /forums/images/graemlins/blush.gif

Do you know Jonathan Evans, Siliwen boat yard?
Semi retired virtually but a fountain of knowledge, if caught on the right day!
Plus there are a few other characters knocking about His shed from time to time,
who may have some sage advice.

Where is the vessel right now?
I don't mind having a look at it for You.
Things to consider like how much room you've got to play with.
Shaft dimension etc etc if You are going to re-engine.
Engine/hull/prop type diameter/pitch etc "Harry Propellors" Castle marine Caernarfon is on the doorstep too.
Anyway if You would like second opinion and some more local bod's contacted details gis a PM.
Must warn You though. Advice of this nature usually has a price.
In this case a poke aroung Your engine and pointing You in the direction of Local Experts.



MMM Packet of Fags and a Pint of Guinness sounds about right! /forums/images/graemlins/grin.gif

 

[Danny Jo]

Many thanks for this and the other thoughtful and helpful contributions.

Picking up on a couple of the points raised, I guess Freestyle would be described as medium displacement. The design displacement is 7340 kilos, but I tend to carry another 700 kg of water and fuel, not to mention a month's supply of tinned food, spares etc, so I guess I'm nearer 8.5 tons all up. The cast iron keel weighs 3 tons, about 60% of which is in the wing. The waterline length is 10 m.

I take the point about being overpropped, but looking at my rather spindly two bladed folding prop, I'm somewhat surprised. It is described as 18" x 13". The open diameter is about 18", but I've no idea what the 13" refers to. The engine is supposed to develop its rated maximum output at 3500 revs, which it doesn't reach at full throttle, so I take it that the consequences of being overpropped is that at full throttle I am wasting fuel, and I am not getting the power the engine is capable of. It uses about 0.5 l of oil in 24 hours. The engine is located in the saloon, with the 50mm diameter exhaust running under the floor at the bottom of the companionway steps, then along under the cockpit floor to a water trap behind a panel in the aft cabin/ This poses something of an obstacle to moving to a larger engine, because I would almost certainly need a larger exhaust.

My questions were prompted by the need to sort out the water leak. If it is just the water pump, great. But I've had a a difficult time with my 14 year old car, which had the same problem. It wasn't until I'd replaced the head gasket and almost every rubber hose over an 18 month period, with at least 10 days off the road that a garage mechanic finally spotted the crack in a steel pipe under the engine.

I shall be pursuing Kawasaki's kind offer, and would add that I, Scuttlebutt posts notwithstanding, I certainly don't expect to be able to access expert advice for nothing. People moan about the cost of professional advice, but 5 - 15% of the cost of a project is a small sum to pay if it makes the difference between a good result and c**p result.

Thanks again, everyone.

 

[tcm]

another vote for yanmar here, which seems to be displacing volvo as original equipment amongst french builders who i suppose would be attractd to cheap yet-reliable options.

 

[Birdseye]

The 13 inch is the pitch. Imagine the prop as a form of screw - the 13 inch is how far it would screw into something in a full revolution.

Gieven that you have said about cruising and max rev/speed I would have little doubt that the boat is overpropped. Maybe you have one of the props where this is easily adjusted? This site gives a pitch calculator http://www.castlemarine.co.uk/

The .5 litre per 24 hours would concern me and is an indication of wear. Certainly I agree with the others - its likely to be better to re-engine than to repair. Probably not a lot different in cost terms either but dont underestimate either route which is why my vote would be for struggling on until you have to do something.

For example, its not just a matter of exhaust size, but which side of the engine it comes from. How you adjust the mounts to match up with the existing shaft etc

Engine speed is nice but not vital. For many years all people had was an unreliable small 2 stroke fit only to get them through the harbour gates. Its is a sailing boats after all!

 

[Kawasaki]

Yep pitch is the theoretical distance of travel per revolution.
A months supply of foodstuffs etc.
Crikey that's another ton or two on My Boat!
I understand ,taint speed You are looking for but the ability to punch a bit of tide reliably. Which is paramount locally.
Noticed it is a job to "Sail" between the Bridges!
The water loss problem needs to be understood before radical decsicions about motor swaps take place methinks.
From My understanding of Saily boats and displacement Motor Boats skiing and stuff like that aint gonna happen, 8kts is it+ a tad more and that's Your lot!
As mentioned I would go Jap more than green. Could be the Motorbike background or all the crap I have experienced with Volvo marine stuff!