Converting a petrol boat to diesel

[dignity]

I'm on the verge of selling my boat. Been looking at a couple of Carver 30's, I have been offered a real nice one at silly money because of twin Mercruiser petrols (Shafts), been pricing up new marine diesels, and it would be quite realistic to re-engine and still have a good priced boat. However there's a couple of points I'm not sure about ?

1) Can you use the same tanks?

2) How easy is it to match up with original instrumentation?

3) Obviously the props are going to need changing, is is likely that all the sterngear will need up-grading?

4) Would I get a realistic price for 2 Mercruiser 470's with gearboxes, or would they be scrap?

5) Any other downfalls?


Any information at all on this subject would be appreciated.


And finally my wife thinks I'm mad!!

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[BarryH]

Aaaaannnnnndd que Martyn.

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[BarryH]

Sorry shouldn't be flippant. Yes you can do it

1 Yes but get'em cleaned thoroughly
2 Tach will be hardest as it takes its feed form elsewhere
3 Probably not, depends on what shafts you have now
4 Yep they is scrap, I'll give you 200quid the lot
5 It will take longer than you initially think and will cost atleast 50% more than you budgeted/quoted for.

Is it woth seeing what repower packages are about. They will normally take your old engines as part payment/trade in type thing.

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[duncan]

As Barry says..........however get someone to do the whole job - fixed price and project timing - and accept the premium that goes with it.

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[Dave_Snelson]

If the engines are knackered, then go ahead with the re-power. If not...

Do you have an LPG filling capability where (or near) you keep your boat? The cost of conversion for two motors is about £5k and the price per gallon is about £1.45

Just a thought....

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[dignity]

Engines are fine but no LPG anywhere near !!

Don't mind the work anyway just don't want to out-price the boat.

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[martynwhiteley]

Sorry Barry, been doing some real work for the last hour or so!

IMHO tanks ok only if stainless, otherwise replace.

Since I'm more of an outdrive boy, this one's stretching my boundaries, however it looks a good case for a pair of Lancing marinised Fords. In fact they will give you so much good advice on all the topics, it's pointless us half guessing matters here.

I'm sure such conversions are cost effective, perticularly a) if your buying a petrol boat dirt cheap, and/or b) you keep the repowered boat for a few years.

Otherwise you'll pay the same total cost for an existing diesel version, but the diesels will be 1000 hours old, not brand newies, and when you do sell on, you'll lose a few grand more.

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[Dave_Snelson]

Yes - the purchase of a pair of diesels puts you in danger of out-pricing the boat for future sales. What HP are you looking for? Have you tried Sabre re-con & new build marine diesels? There are mixed reports about Sabre on this site - mixed meaning that some people say they're OK and others not so! There are probably a few other recon fitters out there that other forumites could point you in the direction of.

Sabre 01202 893720

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[dignity]

Looking at around 150hp. I've just finished building a dutch barge, when pricing for engines for it the price difference between a good recon and new wasn't that much. I think all the work involved it's got to be new, it's just a matter of getting a good deal .

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[BarryH]

Ah well if your only looking for 150'ish hp then I'd say yer best bet is a pair of Puma's from lancing. They'll set you back about 5 grand'ish each. So with another 10K plus on the purchase price is it still worth it.

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[martynwhiteley]

You should be able to pick up a couple of new Mercruiser D120's ex drives/gboxes, but inc. instruments for about £12K. Don't be put off by the 120 rating, they'll give any 150 rated competitors a run for their money, very quiet, no smoke, 4 gph.

Doral fit a pair in their 280, does about 40 knots.

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[BarryH]

Knew you wouldn't let us down, it was only a matter of time/forums/images/icons/wink.gif

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[tico]

Oi! time for my 2 pennorth

Tanks OK but drain first & use the opportunity to get rid of any sludge at the bottom
Prop change yes, but rest will prob be OK. See Vetus for calcs on shaft sizes.

agree with comments re total cost the same as existing diesel but engines will be brand new.
Only way to keep cost down is to do all the biz yourself. Need good engineering resources and not for the faint hearted. Tiz possible tho.

Talk to mike bellamy at Lancing he'll fill you in on all the detail.
Will prob need new gearboxes (cost) in order to match revs to suitable prop pitch.

BTW, would have thought 2x150 hp in a 30' a bit on the low side. If u are happy with that tho, he does a nice job on the Pumas.

<hr width=100% size=1>Been there, done that, got the oily T shirt

 

[barryjl]

I have investigated this thoroughly as have been thinking about converting my boat to twin diesels. Have been told that price (£23/25k) will include all new instruments and new fuel tank. Obviously, the sum to do is how long it will take to recoup that, and what extra value on the boat. My reckoning is some three years to recoup and probaly £10k/£15k on the boat, reducing recoup time down to around two years. Think my decision is to stay with what I've got and have engines totally overhauled (reliability factor) and then trade boat end of next seasom for something with twin deisels.

<hr width=100% size=1>There's no problems..just opportunities

 

[tico]

you dont need a new tank barry, Fairline fitted nice Stainless ones. Mine was good as new

<hr width=100% size=1>Been there, done that, got the oily T shirt

 

[barryjl]

Yes, spoke to you before. But if I remember rightly, you did loads of work yourself, which is just no go for me (technically/mechanically dyslexic). Have been told though of local firm of engineers who buy from Lancing Marine, then fit, guess that might be a cheaper option.

<hr width=100% size=1>There's no problems..just opportunities

 

[Andrew_Fanner]

Had it done in 2002 and still bickering about the prop that is supposed to have been fitted:-(

I bought a recon AD41 from Coastal Rides and can't fault their service. You will certainly need a new gearbox as the old petrols will rev far higher then the diesels, unless you get a fancy modern high revving job. The engine came with a complete set of instruments, calibrated to suit. I got a useful but not money spinning trade-in on the old engine and grearbox, which covered the cost of the replacement gearbox.

The work cost as much as the engine, not something that seemed apparent from the estimate. With hindsight, check what the engineer, if you use one, is doing, and what is being done by others such as a shipwright moving engine bearer pads about. We were a bit innocent and feel that our fingers, if not exactly burned, were certainly singed at the edges. The actual engine spannering part of the quote was about 1/3 of the total invoiced cost. About a week's work, which seemed to take from June to, well, until that prop is sorted I'm not convinced the job is done even now.

But it all felt worthwhile when I filled the tank and had change to go down the pub, instead of the old petrol running cost whih seemed to require three months to save up before being able to visit the pump.

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[dignity]

Having read your previous posts, who supplied your Mercruiser if you don't mind me asking.

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[martynwhiteley]

I was lucky to find a company making up inboard ribs in Norfolk, who had an order cancelled, and a D120 surplus, so got it at their cost price (about £1,800 saving on list).

Recently, a company was advertising lots of Mercruiser diesels at trade cost type prices (less than £6K for the D120 ex vat).

My local marine engineer can get good discounts, PM me if you want me to get a quote.

However I was offered a pair including outdrives from the importers for £15K (inc. vat) at SBS in 2002, so I'm sure a pair of engines only must be securable for £12K.

Since they rev to 4400, the existing GB's may be ok?

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