convert gas to diesel boat

jpoch

Recruit
Joined
Nov 30, 2003
Messages
1
Forgive this ignorant question. I have found a 22' downeast Sisu with a gas outboard. The boat meets most of my needs except it using gas. I am trying to fit a diesel boat to demonstrate the usefulness of biodiesel(environmentally clean, domestically grown, diesel alternative). <br /><br />With Yanmar's withdrawal of their diesel outboard, it appears there are no diesel outboards in the market. Is there anyway to convert a gas outboard boat to diesel? Can you integrate I/O into an outboard boat? Any thoughts? JP :(
 

snapperbait

Vice Admiral
Joined
Aug 20, 2002
Messages
5,754
Re: convert gas to diesel boat

If you can't wait or have already purchased the boat then re-fitting to an I/O or even a straight inboard would probably be the best route... It is "do-able"... <br /><br />If you can wait, keep looking because a diesel I/O or inboard is bound to pop up sooner or later..<br /><br />I seem to recall, just recently, someone talking about a new diesel outboard being manufactured, but for the life of me, I can't remember the who, what, or where...
 

peterbo3

Petty Officer 3rd Class
Joined
Mar 8, 2003
Messages
79
Re: convert gas to diesel boat

Hi jpoch,<br />Volvo manufacture a diesel I/O & it is possible to rebuild your transom & reinforce your hull to accept such a motor. Merc legs also take oilburners. But how deep are your pockets?<br />By the time you rewire, replumb, reupholster & re anything else that needs doing, you will have used up more resources than a small town will use in a year ;) ;) ;) <br />Unless you are going to use this boat for 500 hours a year you will probably create a monster that justs eats money.<br />If you really want to cut down your engine emissions then perhaps a four stroke would be the go. It will be way cheaper than a diesel conversion.<br />Regards,<br />Peter
 

sloopy

Captain
Joined
Jul 12, 2002
Messages
3,000
Re: convert gas to diesel boat

kw196_01L.jpg
<br />Beauty is in the eye of the beholder...
 

snapperbait

Vice Admiral
Joined
Aug 20, 2002
Messages
5,754
Re: convert gas to diesel boat

Jet Pac looks neat untill i read the part about it weighing 940 lbs... :eek: Thats like twin 200hp four stroke weight...
 

kd6nem

Chief Petty Officer
Joined
Jul 25, 2003
Messages
576
Re: convert gas to diesel boat

And the Coventry Climax unit looks pretty slick too, but better be ready for small motor performance (25 HP) and big motor price tag and weight.
 

kd6nem

Chief Petty Officer
Joined
Jul 25, 2003
Messages
576
Re: convert gas to diesel boat

I'm actually dead serious here, (believe it or not) but I don't know why someone doesn't come out with a wankel rotary powered outboard. Would run fine on diesel if so desired, though it would still have spark plugs. And would be about as light as a two stroke, small or smaller power head for the power. Would hardly ever need heavy maintenance, more reliable than anything going at present. (way fewer parts moving = less complex and more reliable) Overhauls should cost half what a new motor would cost to overhaul, typically just gaskets and seals. Would certainly have better fuel economy than any older two stroke motor, very competitive with any new motor. Smoother and low vibration too.<br /><br />Are you listening, OMC/Bombardier, Merc, Honda, Yamaha, etc.? I'd pay good money for that kind of motor. That technology has come of age, finally. Check out Mazda's RX-8 motor. Goes against the grain of tradition, I suppose, but then again so did jet airplanes at first.
 

JasonJ

Rear Admiral
Joined
Aug 20, 2001
Messages
4,163
Re: convert gas to diesel boat

They already tried a rotary outboard, didn't work too well, had a lot of issues with its seals. With todays technology they probably could make it work better, but there is a reason why the rotary isn't used that often in the automotive world, and I bet that same reason is why it isn't being used in mainstream marine applications. We have a local company that builds small rotary powered jet boats that tear arse all over my lake, but they are one-off custom jobs...
 

BRIAN03

Petty Officer 1st Class
Joined
Oct 17, 2003
Messages
284
Re: convert gas to diesel boat

I grew up working on that 22 sisu I think its a great hull. The best power we did in that boat was a inboard v-6 with a borgwarner 1 to 1 ratio. It went great and was awsome on fuel. That boat does need a set of small trim tabs. We used saddle fuel tanks and made the keel semi wet.
 

kd6nem

Chief Petty Officer
Joined
Jul 25, 2003
Messages
576
Re: convert gas to diesel boat

Jason, you're right there is a reason- in the past is was as you say- problems with seals and such. Today, the reason is marketing forces and tradition. Nothing else. And no, I am not a piston hater. I just think it a shame that the marketers and publicizers tend to focus on whatever seems popular, ensuring it stays that way. The public wants what it can see, and marketers show what they think will sell, creating a cycle. Once in the while good things get overlooked because of that. Of course not everything "new" ends up being good. But in this instance, there is a whole lot of good, sound, and now technically proven engineering getting overlooked. Comparitively it is quite simple mechanically next to the current state of the art outboards of today. There are a handful of various boat motors, virtually all inboard, using this now with good success. Few seem to be paying attention at present. Rotary is beginning to catch on in the world of light aviation, though. There are certified multi fuel airplane rotary engines being flown in Europe right now, gaining rapidly in popularity because of the difficulty in getting AvGas over their. They work just fine with the much less expensive jet fuel, unlike other gas engines. And homebuilders here are starting to install RX-7 engines in their airplanes because of their low maintenance expense and great reliability. What other liquid cooled engine will still get you home despite losing cooling and can be deliberately run way too lean without fear of catastrophe? Looking at the diesel outboard options, I'm thinking how much more elegant it could be done by breaking out of the box. IMHO, looking at the extremes the outboard manufacturers are going to improve their very high tech (and expensive)engines, it might actually be a lot easier to think outside the box rather than stay inside. Pistons may well continue to dominate, but it will be solely because of preference, not for any mechanical reasons.
 

sloopy

Captain
Joined
Jul 12, 2002
Messages
3,000
Re: convert gas to diesel boat

You could always go with oars...<br /><br />Or a turbine!<br />Or how about a Radial engine!<br />Its all been done.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: convert gas to diesel boat

wow!!! radial turbine oars:) :) . great for the smaller lakes. comes in left and right turn models :) hahahah you guys are killing me:). the three major drawbacks of the early years of the mazda rotory was the seals let go at inoppertune moments, the fuel economy sucked and people did not like trhe fact that they had to burn crankcase oil to live and third for marine use the heat exchaner for the exhaust was rather difficult to cool. I always wanted to try one and maybe oneday I will, rotary power rocks. we raced against a guy that left the line atr 11 grand and shifted at about 16 grand. if the gearbox lived he whaled our 427 canmero.a little rx3 that sounded like a souped up weed wacker :) :) . but with todays seal technology I think a small rotary would work well. but the guys that manufacture pistons,cranks and blocks would wail.<br /> good luck and keep posting
 

sloopy

Captain
Joined
Jul 12, 2002
Messages
3,000
Re: convert gas to diesel boat

There has also been outboards with; steam power, sterling engines, hydrogen, multi fuel, electric, pulse jets, etc ect... although all of those use some sort of piston...
 

kd6nem

Chief Petty Officer
Joined
Jul 25, 2003
Messages
576
Re: convert gas to diesel boat

I suppose I have a sort of passion for technology, but whatever works is also OK. In fact, I am rather fond of solar powered boating, also. Been around almost as long as paddles and oars. Sun heats earth, earth heats air & makes wind, wind fills sails......<br /><br />Back to the original thoughts of this thread, the bio-diesel is an interesting concept. I just saw a car on our rural highway which had this bio-diesel sign on it. Never encountered that before.
 

KM2

Chief Petty Officer
Joined
Oct 15, 2003
Messages
556
Re: convert gas to diesel boat

Is this some gradaute school engineering project? Sounds interesting. I think you need to find a diesel outboard first and get it running on bio fuel and then find the right boat to fit the hp output. Why not buy a boat that is already a diesel? If that can't be done, getting a inboard or I/O and replacing the v-8 with a GM Diesel doesn't seem like that would be impossible. A 6.5 GM Diesel should be easy to find and parts should be easy to get to. Keep us posted on what you decide and how it goes.
 

ted655

Petty Officer 1st Class
Joined
Oct 21, 2003
Messages
252
Re: convert gas to diesel boat

You can't convert, the parts won't stand the extra compression stress. Yamaha still makes diesel outboards.<br />The weight of the JetPak is offset by the bouency of its floating case. In the water it will weigh less than an outboard. Trailering it??? That's different, SNAP goes the transom!!<br /> I have seen a steam powered outboard. Now we have mentioned all the possibilities, except the "Electric Wheel" an electric motor designed specificly for transom instalation on sailboats.
 
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