Diesel outboard motors

[sottorf]

Can anybody inform me what arethe latest developments in this area. I know there are some Chinese brands offering small 3-10HP Diesel OBMs. What size is the largest Diesel OBM currently available commercially?

I recall some years back there was a small UK based company making OBMs for military use that were diesel powered. Anybody know anything about this?

[Crag Cay]

Yanmar had a couple of models (27 and 35Hp) diesel outboards. They were horrendously expensive but there were some takers amongst the fish farming industry and mlitary for moving bridging units.

Barrus were the suppliers in the UK.

When most petrol outboards were 2 stroke, there was a market for these, but the advent of 4 stroke OB saw them off.

[CatBuilder]

I looked into this for a very long time, but those small Chinese outboards are the only diesel outboards made.

The old Yanmars are no longer produced and would be impossible to service, so not a good choice.

Your only choice for 20HP and up would be the gasoline outboards.

[sottorf]

Thanks Catbuilder. I would have thought that there is a niche market for professional boats that are deployed from larger vessels such as rescue craft, insertion craft, boarding boats etc. Diesel outboards would avoid logistics and safety requirements of carrying gasoline on board the mothership. I guess the niche is too small to warrant the development cost and most applications jsut go inboard Diesel...

[CatBuilder]

Originally Posted by sottorf

Thanks Catbuilder. I would have thought that there is a niche market for professional boats that are deployed from larger vessels such as rescue craft, insertion craft, boarding boats etc. Diesel outboards would avoid logistics and safety requirements of carrying gasoline on board the mothership. I guess the niche is too small to warrant the development cost and most applications jsut go inboard Diesel...

I think the niche (thanks to multihulls) is larger than one would imagine. If anyone made a long shaft diesel 30HP outboard, I would have bought a pair.

I know a lot of other people that prefer outboards as well. There are a lot of advantages, plus industrial use.

A diesel outboard would have enabled me to build my own fuel tanks and comply with the law. Instead, I have to purchase tanks now to comply.

I think there is a small, but worthwhile market. Unfortunately, nobody else seems to think so.

[Stumble]

The problem with them was that they were horrendously heavy, and expensive. As I remember they ran about tripple the weight and twice the price of comparable gas ones, and didn't have a log of advantages other than fuel selection.

I would be interested in seeing one, but the ones I have looked at just didn't seem to have much to recommend them.

[sottorf]

I think if Diesel outboards had enjoyed the same level of development as their gasoline counterparts we would see lighter weight models out there.

I found this link to some guys developing a large Diesel OBM but it seems they lack investment

http://www.megoutboards.com/index.php

[masalai]

The Yanmar 27 and 36hp diesel outboards, (of yesteryear if you can find any reconditioned), compared reasonably with modern equivalent sized sail-drives weight-wise BUT the OB,s had peak RPM at around 4500 - way too fast and spun the propeller too fast too - poor implementation of a potentially very useful option...

http://www.minardsdiesel.com/outboard.htm - My 20 hp nanni saildrives weigh in at 144kg each - I see the Yanmar calls it at 94kg for 27hp... I would still be tempted to change over to used and reconditioned OB diesels if gearing was better - say at max engine rpm the propeller spun at 1200rpm and I could fit a fairly large diameter propeller (18 inches diameter at 27hp from the engine would be nice)...

- The advantage being that the leg could be lifted so it was clear of the water and I would not need mini-keels - I could delight in reducing static draft from 3 ft to 2 ft or even less and ease of removal for major work and maintenance...

I would NOT need steering just careful alignment as at slow speed, - throttle is the best steering system for a catamaran and mostly cats sail so rudders are there for cruise and autopilot interface...

[Stumble]

There are a couple for sale....

Take a look at http://www.megoutboards.com/30L_vision.php they have a 150, 225, and 300hp equivalent. The 150hp weights in at 770lbs and the two larger ones at 820lbs as compared to a 300hp Yamaha at 560.

The yanmar d-36 weighed in at 270lbs dry weight compared to a Yamaha 40 at 223lbs.

There is also a company named star that sells Chinese built, Indian branded engines. http://www.goodsdirect.net/dieseloutboard.htm I have never seen one, but their weights are about double what a gas engine would be.

[DCockey]

55 HP outboard which runs on Diesel and other fuels:
http://www.evinrude.com/en-US/Engine...ENGINES/MFE_55
http://www.marineenginedigest.com/pr...vinrudemfe.htm

Weighs 10 lbs more than the gasoline only 60 HP Evinrude, but cost is considerably more.

[mydauphin]

Originally Posted by DCockey

55 HP outboard which runs on Diesel and other fuels:
http://www.evinrude.com/en-US/Engine...ENGINES/MFE_55
http://www.marineenginedigest.com/pr...vinrudemfe.htm

Weighs 10 lbs more than the gasoline only 60 HP Evinrude, but cost is considerably more.

They may run on diesel also, but the question is how well.

[CatBuilder]

Yeah, I looked at the Evinrudes but somewhere that I looked suggested they ran on a whole list of fuels, but that list didn't show diesel on it, so I kept moving.

[mydauphin]

I would love for there to be a full range of diesel outboards, 5, 10, 20, 50, 75, 150, 250. The company that made them would have trouble keeping them in stock. I don't see how they would be that much more money than a gas outboard is now. Meeting pollution standards is probably biggest problem.

[masalai]

Seems many are comparing apples with pommelos... (diesel against petrol with the only link being outboards),

BUT when diesel OB is matched against the diesel inboard or diesel sail-drive or diesel sterndrive, - THEN - the potential advantage of the few diesel outboards can be seen... Some are inspired by military need... - - - - - Weight advantage is definitely there for the few diesel outboards. - - - - - and the price is fairly competitive when compared with the other diesel options and the ease of installation of outboards...

I am sure the range could be reduced to 20, 50 with a, - - "possibly a maybe", for 100hp - - because at around 100hp the weight and low end torque may cause engineering problems as the advantage of getting the propeller out of the water and ease of removal for servicing would be negated by effectiveness of inboard mounting in a "proper engine room"...

[Richard Woods]

As Catbuilder says, this has been discussed before. I suspect the manufacturers would be looking at 100,000+ units to make it worth their while.

The diesel outboards were developed for the military, so cost was no object. One of the major causes of fire in the Falkland conflict was from exploding petrol (gas) stored on board for use in the RIBs

Having said that, I did see a number of Yanmar outboards being used by Columbian fishermen a few years ago. I have never seen a "yacht" diesel outboard, only ones suitable for workboats

Richard Woods of Woods Designs

www.sailingcatamarans.com