Lightweight diesel engines

[longjonsilver]

i am looking at a trimaran with a 9.9hp outboard. What lightweight diesels are there on the market? The beta 14 is 90kg. What else is there?
jon

[tkeithlu]

I'm not going to answer your question. I'm going to enquire as to your goal. Is it to replace the outboard with a diesel inboard engine? That's a pretty extensive project, with finding an appropriate engine being the easy part. How about making your goal clear? There might be a path to it, perhaps through a saildrive.

By the way, from the perspective of being a retired scientist, your tag line really isn't logical. In one case you are talking about a product of the technology of a complex organism (an encoded signal), and in the other, how the organism itself became complex.

[Sand crab]

Yup, and astronomy doesn't say we'll find a coded signal from space. They "hope" to find a coded signal from space. Big difference.

[longjonsilver]

Originally Posted by tkeithlu

By the way, from the perspective of being a retired scientist, your tag line really isn't logical. In one case you are talking about a product of the technology of a complex organism (an encoded signal), and in the other, how the organism itself became complex.

As a retired scientist you should realize that the POINT of the whole line is that it is not logical.

jon

[DefinitelyMe]

Originally Posted by longjonsilver

i am looking at a trimaran with a 9.9hp outboard. What lightweight diesels are there on the market? The beta 14 is 90kg. What else is there?
jon

A lot of the racing boats use Yanmars because of their power:weight ratio. Of course, if you really want to optimise it go for a jetski engine or marinize a motorcycle engine. :-)

[tkeithlu]

This may not be the place for a discourse on the philosophy of science, but you are claiming that two related elements are not logically congruent when they are actually not related at all. There is no reason that they should be congruent.

[Westcliffe01]

Depending on the target range for the application, the weight difference of the engine would quickly be overtaken by the difference in the fuel weight as the range increased. And diesel is a considerably safer fuel to keep aboard.


If you could avoid the weight of a heat exchanger and water pump">raw water pump by using some sort of keel cooling, that all helps, but means you would need a dry stack and muffler.... The Kubota Z482 is 53kg dry weight (including flywheel and starter but no bell housing). I got one of those in exchange for a bolt action 22 mag rifle, so the equivalent of $400.

[longjonsilver]

Originally Posted by Westcliffe01

If you could avoid the weight of a heat exchanger and raw water pump by using some sort of keel cooling, that all helps, but means you would need a dry stack and muffler.... The Kubota Z482 is 53kg dry weight (including flywheel and starter but no bell housing). I got one of those in exchange for a bolt action 22 mag rifle, so the equivalent of $400.

So probably by the time that the transmission is added and the heat exchanger and raw water pump, the weight might be comparable to that of the Beta 14 at 90kg

Originally Posted by DefinitelyMe

A lot of the racing boats use Yanmars because of their power:weight ratio. Of course, if you really want to optimise it go for a jetski engine or marinize a motorcycle engine. :-)

Thanks, thats a good place to start.

Originally Posted by tkeithlu

This may not be the place for a discourse on the philosophy of science, but you are claiming that two related elements are not logically congruent when they are actually not related at all. There is no reason that they should be congruent.

Here is how they are related: one group of scientists claim that coded messages point to a creative intelligence and the other group of scientists claim that coded messages don't point to an intelligence. They are related in that they are both scientists - and they come to opposite conclusions on the meaning of coded messages.

This is because of an overarching theological viewpoint that both of them share - that the universe created itself; that there is no god that created the universe.

[longjonsilver]

Yanmar sells this 9hp one lunger at 71kg.

[Pete7]

Originally Posted by longjonsilver

i am looking at a trimaran with a 9.9hp outboard. What lightweight diesels are there on the market? The beta 14 is 90kg. What else is there?
jon

So how about a diesel generator that weighs 51kgs and produces 2KVA say 1.6Kw, This powers an electric motor or the house bank etc for £4000? Electric heating and cooking thrown in for free and no gas to worry about

That should give you roughly 3 to 4 knots cruising speed depending on the tri.


https://www.advanceyacht.co.uk/marin...ro/paguro-2000

[Westcliffe01]

It looks like a 9.9 Tohatsu outboard is 43kg dry in the lightest version. So not a huge difference in weight. The size of the tri is not stated. Unless you go air cooled, cant see it getting lighter. Air cooled boat motors make about as much sense as air cooled submarines... I only mentioned the Kubota Z482 because of the prices asked for the small diesels. Outrageous is all I can say. Outboards are also expensive for what they are but the inboards kick it up a couple of orders of magnitude. I do get the impression that people pay less for their diesels in other part of the world than the USA, cheaper even in the UK.

[longjonsilver]

Originally Posted by Westcliffe01

It looks like a 9.9 Tohatsu outboard is 43kg dry in the lightest version. So not a huge difference in weight. The size of the tri is not stated.

i am looking at a 32' 4500 lb empty, 6000lb full trimaran.

Originally Posted by Westcliffe01

I only mentioned the Kubota Z482 because of the prices asked for the small diesels. Outrageous is all I can say. Outboards are also expensive for what they are but the inboards kick it up a couple of orders of magnitude. I do get the impression that people pay less for their diesels in other part of the world than the USA, cheaper even in the UK.

i am sure that i can put it in myself. i am currently putting a different motor in my car that requires welding, electric modification, using parts off the shelf.....And yes, i have seen that diesels in n America are probably the most expensive in the world, but not secondhand.....

[NevilleCat]

The baby Lombardini 502 SD has an alloy block and weighs about 108 kg including the sail drive.

[Westcliffe01]

The TMC-40P gear box is 8.8kg dry and it only uses a little oil. Would still need an adapter plate, coupling etc. Its the transmission used on the smaller Beta engines, if one could find a used transmission it would reduce the cost. Do you think a dry stack is an option at all ? That option can save a lot of weight compared to a wet exhaust and means the engine could run on regular antifreeze with a lot fewer failure points.

[longjonsilver]

Originally Posted by NevilleCat

The baby Lombardini 502 SD has an alloy block and weighs about 108 kg including the sail drive.

A saildrive is out (pun not in 10 did) for a variety of reasons.

Originally Posted by Westcliffe01

The TMC-40P gear box is 8.8kg dry and it only uses a little oil. Would still need an adapter plate, coupling etc. Its the transmission used on the smaller Beta engines, if one could find a used transmission it would reduce the cost. Do you think a dry stack is an option at all ? That option can save a lot of weight compared to a wet exhaust and means the engine could run on regular antifreeze with a lot fewer failure points.

i don't see any reason a dry stack couldn't be used. i don't understand how they work, but i have researched keel coolers. Thanks much for all your help.

jon