Changing engine

[robertt]

Can anyone give me a very rough idea of how much money (and hassle) it would cost to switch engines from petrol to diesel. I mean for a roughly 25 foot sports cruiser with an outdrive going from single petrol to single diesel (any decent engine will do)?
The reason I ask is I want a boat for coastal use but all of the boats I like the look of locally are petrols. They otherwise tick all the right boxes for me but I have convinced myself that diesel is the way to go, and I'm beginning to wonder if it might be worth the extra cost of a new engine to get the kind of boat I like.
In saying that I have no concept of what's involved in changing engine in terms of cost or work involved, or what else might need to be done to facilitate this.
Which is why I would be very grateful for any advice
Thanks

 

[PCUK]

Very straightforward on an outdrive boat. We'll now get all the doom and gloom merchants saying don't use a marinised engine. Well, that's the way forward to keep costs down. A properly marinised engine is equally as good as a supposedly proper "marine" engine and don't let anyone persuade you differently!
An ex vehicle engine converted and ready to fit will cost in the region of £2500. About £500 for fitting if you can't do it yourself. A secondhand "marine" engine will cost a little more and a new engine of say 200hp will cost up to £10,000 but possibly much less as you don't need a drive or gearbox..
You must be sure the outdrive is strong enough to take the diesel torque before you buy the boat that you want to convert.

 

[[2068]]

It almost never makes financial sense to convert. But, if it's the perfect boat otherwise, and you don't mind sinking £10k into it and getting £4k back out...

Have you checked out Neale's diesel boat for sale?

http://bayliner2450.moonfruit.com/#

 

[miket]

Start with diesel.

It is usually cheaper to buy with diesel to start with.
I assume you are talking 2nd hand?
If you intend doing the work yourself, it may make more sense and try and stick with a known make of engine.
I suspect smaller sports cruisers with oddball diesel engines are not worth a lot more than their petrol equivalent.
Sorry for the gloomy info'.

 

[BartW]

some years ago I made a similar thread to asc opinions about replacing a petrol engine by diesel in a 25ft boat.
general advice and conclusion was: find another boat with diesel,
unless you can find a petrol boat with a broken pertrol engine at a bargain price

 

[alb40]

Im currently replacing a petrol with diesel in friend's boat, which is a 26ft Fairline on a single outdrive. As said by others, an outdrive boat is possibly the easiest to convert but its not likely to make sense financially. In the case of our conversion, the original petrol engine was beyond economical repair - it still ran but it wasnt the most reliable and it needed a small fortune spent on it (e.g. manifolds, carb, transom shield bearings etc).

We opted for a second hand volvo diesel because it would link to the existing drive and would cost less than a new block and parts for the old petrol. Its less powerfull than the old engine (130hp vs 260hp) but the boat is mainly used on the medway where there is a 5 knot speed limit. The engine still has a bit of power in reserve for tidal crusing occassionally but it certainly wont be anywhere near as fast as the old petrol.

The total cost of the conversion is likely to be around £6k, including purchase of the second hand engine, replacing some drive parts, transom repairs, glassing in engine mounts and all the plumbing. This does not include any labour as we are doing the work ourselves and there will probably be little increase in the value of the boat, but it will return it to running order and allow it to be enjoyed again.

If we had opted for new engines, a 145hp engine from lancing marine would be in the region of £9k, linking to the existing volvo drive. You dont wanna know how much a new volvo would have been (as a new drive would be needed too).

If you can source a cheap boat, with a broken engine and get a second hand engine in good order, and fit it yourself, then its viable technically (but not nessessarily financially). Otherwise my advice would be dont bother - find one thats already done.

 

[ARA]

Robertt,

what age boat are you thinking about buying? If it is over 10 years old then there is a large risk that the engines & outdrives are not good or will develop problems. Petrol boats are a lot cheaper than diesels so if you did have to re engine some of the costs would actually go towards the selling price of the boat.
Running costs will be a lot cheaper. I am at present doing exactly this & should have a superb boat at the end of it, but it does cost a lot to do & you will never get your money back.
From petrol to diesel look at the additional costs of re-engineing as 1/3 fuel savings over 4 years, 1/3 of the price increasing the value of the boat & 1/3 total loss. (making the assumption that the re-engineing is a new marine engine & not one out of a Transit van.)

 

[robertt]

Thanks to all for great advice, it really makes you wonder! If it were £3 to £5K or thereabouts I wd poss think about it but beyond that it doesn't seem viable to change. I'm looking at used boats in the £20K bracket, there just aren't that many diesels around locally and the boats I like the look of are all petrol. I have time on my side however as I wouldn't be buying right now in any case.
Thanks again

 

[neale]

It almost never makes financial sense to convert. But, if it's the perfect boat otherwise, and you don't mind sinking £10k into it and getting £4k back out...

Have you checked out Neale's diesel boat for sale?

http://bayliner2450.moonfruit.com/#

Thanks for the plug

I'll back up the 'it doesn't make financial sense' argument. I converted with a brand new engine and drive in 2006 and the amount it cost is pretty much what I am going to get back on the whole boat now.

If you can get a GOOD secondhand engine and drive it may just about make sense. Unfortunately a GOOD secondhand package is as rare as rocking horse poo.

One big consideration is which drive you start with and which you end up with. The transom holes are often diffferent sizes. I went from OMC to Volvo which was OK cos the Volvo was bigger so the hole could be made bigger. If you were to go from Volvo to Mercruiser for exapmle, the transom would need to have some serious work becuse you'd need a smaller hole that you start with.

If you want to use the existing drive there are often gear ratio issues as petrol engines tend to rev much higher than diesels. You may be able to ofset some of the difference with a prop change but that alone may not be enough.

WIth regards to marinising a car engine, you would need to select the engine carefully. You will need at least 150hp, if not more, in a 25ft boat if you want it to go at a decent speed. Many car engines that are commonly marinised are much smaller than this such as the 4 cylinder ford.

Lancing Marine is a good company to talk to about marinising.