Outboard cost vs Diesel Sterndrive cost

thejonesey

thejonesey

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Without wanting to start any arguments … I was wondering whether a petrol outboard (around 300hp) would cost more or less than a VP D4 260 in a typical 50 hour season on an 8m sports boat. (Thinking Finnmaster T8 vs Leader 8) Servicing costs for the outboard would be less but fuel costs must be more as petrol is more pricy and drinks more? Ignoring different price, depreciation or which boat is ‘better’😁
 
That is an interesting question to which i needed to google a few things. From what i read ...
The vp-d4260 uses 54l/h at wide open throttle.
A 300hp outboard uses 60.5l/h at 5000 rpm.
Change the 300 to a 350 and at the same speed as the 300 is 1000rpm less and 45l/h !
A 300hp outboard and the VP are a similar price to buy new .The outboard is half the weight of the diesel maybe saving even more fuel ?
 
Assuming nothing breaks on either boat, I'd think the overall cost will be about the same. The vp d4 and dph outdrive will cost more to service than the mercury 300, but the mercury 300 will cost more in fuel.

Where the mercury will ultimately win though is in the longer term, it'll be less likely to break than the d4 +dph drive and when it does break the parts costs will be way less.

The vP d4 and dph drive is a relatively complex setup compared to the merc outboard, ie vp d4 has supercharger, turbo charger, intercooler, charge cooler etc. Steering rams submerged in water, outdrive submerged in water etc. With the merc it's just a big naturally aspirated petrol engine, no turbo, no supercharger, no submerged steering parts, no rubber bellows, less moving parts etc, can be raised fully out of the water when left etc.

My current boat has a mercury 300 V8 outboard, my previous boat had a vp d4 260 with dph outdrive.

The d4 engined boat would use about 25to 30 litres of diesel per hour at 25 knots, the merc uses about 45 to 50 litres of petrol at the same speed.

So far the outboard boat has been way cheaper to run overall, but it is much newer, so I guess less likely to break just by virtue of being newer
 
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julians said:
Assuming nothing breaks on either boat, I'd think the overall cost will be about the same. The vp d4 and dph outdrive will cost more to service than the mercury 300, but the mercury 300 will cost more in fuel.

Where the mercury will ultimately win though is in the longer term, it'll be less likely to break than the d4 +dph drive and when it does break the parts costs will be way less.

The vP d4 and dph drive is a relatively complex setup compared to the merc outboard, ie vp d4 has supercharger, turbo charger, intercooler, charge cooler etc. Steering rams submerged in water, outdrive submerged in water etc. With the merc it's just a big naturally aspirated petrol engine, no turbo, no supercharger, no submerged steering parts, no rubber bellows, less moving parts etc, can be raised fully out of the water when left etc.

My current boat has a mercury 300 V8 outboard, my previous boat had a vp d4 260 with dph outdrive.

The d4 engined boat would use about 25to 30 litres of diesel per hour at 25 knots, the merc uses about 45 to 50 litres of petrol at the same speed.

So far the outboard boat has been way cheaper to run overall, but it is much newer, so I guess less likely to break just by virtue of being newer
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Thanks for this. Yes, taking all other costs out I thought it would be similar in running costs but hadn’t considered the potential expensive repairs. It seems like the world is switching to outboards on smaller boats/medium sized boats which says something.

Seastoke, fuel availability not an issue where I boat and nor is safety as long as you are sensible (in my opinion although I accept the greater risk!)
 
julians said:
So far the outboard boat has been way cheaper to run overall, but it is much newer, so I guess less likely to break just by virtue of being newer
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Putting aside the fuel cost what was it on the diesels that cost so much more?
 
I believe
Momac said:
Putting aside the fuel cost what was it on the diesels that cost so much more?
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I believe that it is Cash Flow with boat manufactures why they love to put Outboards on boats, When a boat is being built if they are fitting a Diesel the boat manufacturer has to buy the engine to install it within the boat more or less at the start of production whereas with an outboard when the boat is completed it could go in the manufacturers boat park for 6 months, and only when they have dealer it is going to will the outboard be fitted, and perhaps if its made in France and shipped to the UK it may only be fitted when they have a buyer,
Plus what is the position with using Red Diesel these days. I know I can still buy it from my local Massey Ferguson dealer.
 
Jim@sea said:
I believe that it is Cash Flow with boat manufactures why they love to put Outboards on boats, When a boat is being built if they are fitting a Diesel the boat manufacturer has to buy the engine to install it within the boat more or less at the start of production whereas with an outboard when the boat is completed it could go in the manufacturers boat park for 6 months, and only when they have dealer it is going to will the outboard be fitted, and perhaps if its made in France and shipped to the UK it may only be fitted when they have a buyer,
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It is running costs that I am asking about.
 
Momac said:
Putting aside the fuel cost what was it on the diesels that cost so much more?
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Servicing was more costly because of the reasons I list below and replacement parts from vp when things break are very expensive compared to spare parts from Mercury.

Reasons for more expsnive servicing:-

The Outdrive needs the bellows replacing every other year, there are no bellows on outboard.

The diesel needed the heat exchangers/cooling system cleaning every couple of years, no heat exchangers on outboard, no cleaning needed, just flush with fresh water at the end of a weekend.

The outdrive steering rams failed every few years because they were submerged in water,there are no submerged rams on the outboard.

Ultimately the outboard is a much simpler system with less to be serviced/go wrong compared to the vp d4 combination of supercharged/turbo charged diesel and out drive. And that simplicity results in less likelihood of failure(and less to fail) plus lower service costs.

If you're doing bigger hours then the diesel might work out cheaper because the fuel costs are lower on the diesel?
 
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Like with like, an outboard petrol vs diesel sterndrive, the first usually consumes about 25/30% more fuel.
This case is not like with like, the Jeanneau Leader 8 being both bigger and heavier to the Finnmaster T8, 2200kg vs 3000.
If it was like with like it will take about 20 hours to offset the cost of the stern drive service into fuel saving and break even.
 
davidej said:
Maybe but you are still required to pay duty on it,
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I didn't intend to suggest otherwise.
Diesel at the marina even with the 60/40 duty split applied is at less cost per litre than petrol . Or at least it is at the marina where I keep my boat which sells both petrol and diesel.

For me there is an lack of petrol available at the waterside at any location coastal side of the marina where I keep my boat for a distance greater than the range of most if not all motorboats which effectively prohibits any significant coastal trip without lugging petrol in jerry cans from a road fuel station.. While diesel is available at the waterside sufficiently comfortable intervals to be no worry .

By the way I don't doubt petrol outboards could be overall potentially cheaper to run for the reasons given as a response to my earlier question. I must have been lucky as I have been spared some of the expenses listed but I accept they are risk items.
 
Outboards have so many advantages over inboards with stern drives.

Minimal corrosion, easy access for the limited maintenance. Long life circa 5,000 hours if maintained correctly.

I suspect man maths comes into play as those with sterndrives play down the costs.

Eventually high hours in any year will tip the financials towards diesel/sterndrives but for most leisure users petrol outboards win hands down.

In my experience (and I spend too much time looking) secondhand prices for sports cuddys with modern 4 stroke outboards are higher than inboard stern drives.
 
Hot Property said:
Minimal corrosion, easy access for the limited maintenance. Long life circa 5,000 hours if maintained correctly.

In my experience (and I spend too much time looking) secondhand prices for sports cuddys with modern 4 stroke outboards are higher than inboard stern drives.
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5k is really a rare number in 4st outboards.

Average hours before full outboard change is 1500 hours. Those that stretch it do 2k or a bit more. I know many diesels with 5k or more.
 
Also if designed properly for an outboard there should be a lot more cabin space - but the designers a lazy so this does not seem to happen in practice.

In the med petrol is everywhere. There are lots of outboard ( small) boats and tenders that need petrol also. No petrol seems a uniquely U.K. thing.
 
You have to take in consideration ,of danger of outboard prop also the lack of decent bathing platform .
 
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