Diesel outboard motors?

 Hi everyone,

 

A topic was mentioned with a mate of mine over the weekend who is looking to purchase a new large boat. He is looking to get diesel inboards however the other person who is buying with him wants supercharged outboards (like a Mercury Verado's)

 

then em after a few more beers we all agreed that the ultimate would be if they made modern technology (common rail injected) diesel outboard motors. Super efficient and would have great engine life for years of use.

 

The only main reason I can think of for them not being made and developed much would be due to emissions? And from what I have seen in the past most inboard diesels release the exhaust gas above the normal water line not below it? 

 

I did so e quick google searching to see if there was such a thing as a diesel outboard and there is, however they only seem to be small horsepower engines and of cheaper brands and quality to what is commonly used on most boats. If anyone has some more info on diesel outboards and their likelihood on being developed or their availability I would love to hear more.

 

scamo

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tim-o's picture

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Date Joined: 24/05/11

My quick thoughts to why

Mon, 2014-03-17 21:49

My quick thoughts to why there isnt is, weight (diesels generally heavier), noisy (not really a factor considering bloody 2 strokes), reqs turbo for any efficiency or power for that matter, which would be impractical in an outboard but not impossible, and a water to air intercooler could be used, but why bother and emissions, cant see a DPF been squeezed in there either lol. Bloody carbon oozing shits of things diesels are

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I am, as I've said, merely competent. But in an age of incompetence, that makes me extraordinary.

Josh's picture

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Date Joined: 14/09/10

 there is a multi fuel etec,

Mon, 2014-03-17 21:45

 there is a multi fuel etec, designed for the military, it'sbeen a while sin ce I read up on it, but itccouldrun on a varie ty of fuel 

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Date Joined: 18/01/12

Yanmar used to make a 35 and

Mon, 2014-03-17 22:18

Yanmar used to make a 35 and 45hp, not sure if they still do

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big blue's picture

Posts: 57

Date Joined: 25/03/10

 More to it than just

Mon, 2014-03-17 22:35

 More to it than just diesel/petrol ....

old mate is right , currently, diesel construction inherently is physically bigger/ heavier , & that is that, also they struggle with acceleration,transmissions & shafts would need to be considerably larger/heavier again adding weight, would also probably need to see some really crazy prop pitches to run them, & if you get past that then the cost would probably be close to double on initial purchase ... Same debate over diesel vs petrol cars . I struggle with how anyone justifies the purchase of a new diesel vehicle over petrol , just on initial purchase petrol is far more cost effective than diesel over the lifetime of the vehicle

when you move into boats that are big enough for diesels then the comparisons on costs come closer together

there are a couple of options for small boats if you really want a diesel , Mercury have some small Cummins powered units,Yanmar do small 2 or 3 cylinder turbo/inter cooled units these are the only ones that would really be appropriate in a trailer boat category

Some might say that if they can engineer smaller diesels for cars then why not an O/B first rule with Marine engines is they run 90% of the time @ 90% load cars run 90% @ 20% load, no doubt in years to come we'll see some changes in marine propulsion ,some of the larger ships run pod drives that are electric .... You know what they say, never say never

cheers 

carnarvonite's picture

Posts: 8671

Date Joined: 24/07/07

Diesels

Tue, 2014-03-18 06:22

I go for diesel inboards and stick a jet on the back. Less moving parts [lower maintenance] and better fuel consumption.

Castoldi do various sizes that bolt on the stern as against Hamilton jets that require cutting in to the bottom of the hull.

Brucesta's picture

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Date Joined: 29/05/09

Cost must be the big killer,

Tue, 2014-03-18 09:35

Cost must be the big killer, there is enough small diesel engines out there now and with all the tech around direct injection and turbo's i'm sure a 150hp diesel motor wouldn't be too hard, i would have thought the load issue would be fine considering diesels seem to like being under load. I'd seriously look at a diesel inboard for my next boat if the chance came.

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quadfisher's picture

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Date Joined: 28/09/10

Tow your hundi to ramp with a hundi?

Tue, 2014-03-18 12:02

 
The S250 Hyundai SeasAll marine diesel powers the 720 Pro Sport to 37 knots @3800rpm and using just 37.8L/H. At a trolling speed of around 6.5knots @1000rpm, the S250 Hyundai SeasAll consumes 2.5L/H of diesel.

The Hyundai SeasAll S250, is a 3.0L V6 Common Rail diesel and produces 250hp @3800rpm and 490nm of torque @ 2500rpm. On the 720 Pro Sport it is coupled with a MerCruiser Bravo III sternleg.

read about this ages ago , mmm a nice 7 metre WA plate boat , like a westy or coraline with a s250 , trolling at 2.5l/ph , holly economys batman!

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Bodie's picture

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Date Joined: 05/11/07

The mate of our's who is

Tue, 2014-03-18 10:07

The mate of our's who is looking at a new boat is looking at something like a 10m Niad. But wanting to keep as much deck space as possible.

He is keen on diesel inboards but the other interested party likes outboard (Keeps the deck free).

So the boat isn't a small boat (Not trailable) and they are probably looking at 300+ hp per engine at that size.

Be interested to know those who run inboards w hat the maintenance is like cost and frequency?

carnarvonite's picture

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Date Joined: 24/07/07

Twin 300 Yammies

Tue, 2014-03-18 18:33

We are running twin 3oo Yamahas on our 10 metre Naiad rescue boat, cruising at 25 knots it uses around 70-75 litres an hour, full noise at 47 knots try 235 litres an hour.

 

Saw a report recently that Kirby had built a 10 metre one with twin diesels in it , performance was about the same as the outboard version but forget what the fuel usage was., if you gave them a ring they would tell you all the details on it.

Bodie's picture

Posts: 3758

Date Joined: 05/11/07

youtube clip from 2009. Looks

Tue, 2014-03-18 10:13

youtube clip from 2009. Looks big and noisy

http://www.youtube.com/watch?v=-MUeWgGATSM

sstevee's picture

Posts: 472

Date Joined: 15/11/11

 Hmmm but that sound... Watch

Tue, 2014-03-18 10:53

 Hmmm but that sound... Watch from 9:01

http://youtu.be/0IZwQhNZJEU