Gas power for sail

[ErikG]

Well perhaps gasoline is not the ultimate powersource for longrange cruisers... But diesels are heavy and expensive. And for boats that race a lot but still want the increased efficiency in a seaway with an inboard but cant pay for a diesel or a Honda, it looks like a nice idea.

Sportboatz.com [aus] sells a modified tohatsu (if I remeber correctly) that is used on the Thompson 870. It is a "powerhead" direcly connected to a small saildrive. Sounds like an inexpensive and clever solution at a low price. But Spoboatz are in Aus and it wont make any sense shipping one to sweden as guarantees and such will probably be useless, so...

Anyone have any kind of idea what kind of saildrive that they are using and who might make it?
I know its a bit smaller than most saildrives.

I know diesel is safer but I have an outboard with a standard plastic tank today so it won't be worse than that anyhow.

A sibling to it seems to be the more widely used Honda derivative http://www.saildrive280.com, but it's to big and way more expensive than the aus version.
Maybe I should start bringing the aus ones to sweden...

[maggot909]

try one of these http://www.yanmar.com.au/marine/sail_series/sail_series.htm#

[FAST FRED]

A standard stuffing box and prop are far less costly than any leg deive , and will be far more reliable.

For engines a yard rototiller engine may have a 4-1 or more usual 6-1 gear reduction built in.Rated for cont duty it should push a 20 ft boat to hull speed very inexpensivly.

For more push the Onan opposed twins are rated at 18 hp and could probably do 10 to 12hp (one Gal per hour ) "for ever".

The Wisconson V twins are good for 25hp rated and will run 20, 2gph for "ever".

That would be enough to get a 30ft wl to speed.

The Onan & Wisconson will need a chain or belt reduction, one wide V belt can handle about 10 hp each, so 3 would be really low maint.

FAST FRED

[MikeJohns]

I'm with Fred
Sail drives are a poor option. An outboard well is a better option.

Petroleum/Gas powered boats are safe if installed properly and everything is rated accordingly, and kept well maintained.

[Peter sk]

I have had nothing but trouble from sail drives over the years, corrosion is one big problem, collision damage is another . Mike Johns opinion on the outboard well being better I would concur with.

I have had a petrol engine on a sailboat and had no problems but the tanks were large outboard tanks and we had them in special lockers in the cockpit. Then we had a bilge blower/sucker and a gas alarm. The range was not so great but if its only an auxiliary.

[FAST FRED]

IF someone is willing to accept the added expense and complexity , an outboard in a well answers most inexpensive propulsion problems.

Stored mounted inside , ready to use after opening lower doors , it would be easy to maintain , not pitch out of the water in rough going , and be easily replaceable or repairable at a shop.Lobster pot lines would be no problem to clear!

Might not be best choice for Round the World cruiser , but should be fine for costal work.

FAST FRED

[SeaDrive]

IF someone is willing to accept the added expense and complexity , an outboard in a well answers most inexpensive propulsion problems.

I think I detect a contradiction here.

However, I agree that if an outboard will serve, it will probably be the cheapest, unless you are your own installer/mechanic. Unfortunately, most sailboats rigged for outboards either have them on the transom, or in a well where they cannot be retracted. A good transom well, e.g. Pearson 26, seems like the best solution to me. If the ob can retract in the hull, the well takes a lot of space. The Seafarer 29, for example, is really more like a long-tailed 27. Nothing wrong with that, execpt it leads to invidious comparisons.

Transom mounted outboards drive the boat pretty well, but are ugly and can be awkward to use. On many boats, the bracket has to hold them aft from the transom a little way to give room to swing the rudder.

By the way, if anyone knows a good way to put power on an H-boat, I would interested to hear.

[ErikG]

Yes an outboard is a good choice on the right boat. I have one on mine as I race, and the boat itself is only 26ft.

But there are a number of advantages with small lightweigt cheap gaspowered inboard engines in my mind.

its cheaper to buy AND service than a diesel, but it costs more to run.
Its lighter than a diesel
Any inboard will make any sailboat look better than with an ob.
Using a well is no fun as it eats up the preciuos space that is already quite limited onboard a small sailingyacht and the lid in the bottom has not worked well on any boat i've seen.
Manouvering in bad wether will be improved quite a lot.
Otoh. manouvering in tight spots in marinas will be worse than with an ob

Im not advocting against using ob mind you, i'm just curious about finding any alterntives and comparing them.

Erik

-------------------
A friend of mine just past away a week ago at the age of 32, stress causing heartfailure. Take it easy and try to think of sailing, that should calm you down a a bit at work I hope.

[ebb]

Hello ErikG,
One of your countrymen designed a number of wonderful small boats with incredibly beautyful underbodies beginning in the late '50s in the USA. In 1964 my Pearson Ariel #338 was born in Rhode Island and ended up in San Francisco Bay after many adventures where I bought her a few years ago.

I've spent much time and effort to integrate a modern 4 stroke into the OB well that was designed into this boat. I call the area between the transom and the cockpit the bustle - on Alberg boats they often have a very large hatch over the locker the Outboard sits in in the bustle.

As to your first point above, the moter is unseen in this position, while in those models of this boat with the Atomic 4 there are a couple ugly exhaust ports in the shapely transom. Not pretty.

As to another point: If your auxillary system lives in the bustle, then you have liberated a large space under the cockpit. I would say therefor that more precious space is created than lost with an OB. And more precious because it is absent of noise and smell an inboard would impose in the living area below.

As to your last points I believe an OB that is itself still maneuverable on the clamp, as it is on 338, with practice will aid in backing and in adverse conditions in tight quarters - doing it better than an inboard.

On Pearson Ariel 338 the OB will be tilted up to get the prop out of the water and nearly sealed off from following seas. The well seal for when the OB is thus shipped is made so that the weight of the motor contributes to the fairing 'lid' being kept in place. There is however a problem (unknown as yet) with a stern that squats and the water welling up in the well. And there is the subjective opinion as to whether Carl Alberg's really nice transom is spoiled by it being split to allow the shaft of the motor to tilt. When up, only the lower cavitation plate and the prop are seen just under the taff rail.

An 8/4 Yamaha on paper weighs 110#. 2 stroke motors that were in use when Carl designed the well were 40 to 50# - easy to lift out when underway. Still done during regattas. Modern regs mandate cleaner motors, that's why 338 has this monster AND why it can be electrically tilted in place because there is no way it can be unshipped while underway.

Altho 338 is not yet active the work in progress can be viewed at http://pearsonariel.org
Look for the Gallery forum after hitting the "discussion plank", scroll to Ebb's photo etc and check out pages 3,4,9,10,11. Any constructive comments gratefully received! Everybody says this will not work on an offshore cruiser! "Better with a BETA!"

[mattotoole]

Some good points have been made here.

I've always hated outboards, but I must admit the latest 4 stroke Hondas, etc., are pretty darned good. I love diesels but they're expensive and heavy for small boats. That small Honda saildrive looks neat, but it's pricey too, compared to an equivalent outboard. Not to mention the hassle of anything that goes through the hull and into the water. It's probably similar in weight, but the outboard wins in drag, because you can pull it out of the water while sailing. Plus you can take it off the boat and into the shop for maintenance, instead of standing on your head in the bilge, while breathing gasoline fumes. The space under the cockpit is a significant issue for a small sailboat too.

What I'd really like to see are small diesel outboards, right down to 2 HP for dinghies. It seems stupid to have to track down gasoline for the dinghy when there's a couple hundred gallons of diesel in the bilge! The safer fuel and lower operating costs would be great for small sailboats too.

Finally, I liked the new Etap 24(?) featured in Sail magazine recently, with the twin rudders on either side of the outboard. With the outboard in the middle like that it can be a lot more accessible than hanging off a bracket, with no need for a well.

[usa2]

Gasoline engines are not something you want to have on a sailboat in general.

[ebb]

Why? Atomic 4s have been around forever. Some folks live with gasoline just fine. And propane, there is another explosive fuel that folks or fashion find convenient to have on board a sailboat - requiring numerous safequards. And still leading to some fine explosions every year. Personally won't have either aboard mine, but will have gas OUTSIDE in the back! I'm looking for a hydrogen fuel OB. :cool:

[usa2]

i guess it is a matter of opinion. I dont support the idea of having someting so explosive on board a boat

[mattotoole]

Why? Atomic 4s have been around forever. Some folks live with gasoline just fine. And propane, there is another explosive fuel that folks or fashion find convenient to have on board a sailboat - requiring numerous safequards. And still leading to some fine explosions every year. Personally won't have either aboard mine, but will have gas OUTSIDE in the back! I'm looking for a hydrogen fuel OB. :cool:

I don't like the idea of gasoline aboard either, but how many boat explosions do we hear about, and how many are due to gasoline (or propane)? The few explosions I've been around over the years were fueled by solvents.

[woodboat]

Here is a 4 hp diesel outboard :)
http://www.hardydiesel.com/mrn/diesel_outboard.htm

[yokebutt]

The question to ask is really what kind of boatowner you are. If you inspect and service your engine regularly, replace fuel line parts when they look suspect, always run the blower and sniff the bilge before starting, then you'll be alright with a gasoline inboard. But if you're a complete yahoo, then stick with diesel.

(that diesel outboard looks a bit ag, it would probably make a great roto-tiller too!)

Yokebutt.

[marshmat]

It's a matter of simple chemistry that lighter-weight fuels, being more volatile, are more likely to lead to fume explosions.
Having said that, if your system is properly installed and maintained, any of diesel, gas, propane, CNG, etcetera are safe. The key point is PROPERLY INSTALLED AND MAINTAINED.
Hydrogen as a fuel brings with it a whole set of benefits and problems not seen with fossil fuels. If anyone's interested in starting up a new thread somewhere for that topic, by all means do.

[SuperPiper]

The fact that a 4-stroke outboard is heavier than a 2-stroke is a bummer for those looking to upgrade.

But, was there not an industry-wide move years ago to rate outboard horsepower at the prop rather than at the flywheel? So, my old 5Hp 2-stroke could be replaced with a 4Hp 4-stroke.

[ebb]

'Lo folks,
Modern 4 stroke OBs have twice the push of a comproble 2 stroke. Exhaust goes thru the prop aiding in the reverse mode. The Yamaha on my sailboat is a sailboat motor, born to push things thru the water like fish boats and barges all over the world. On a small sailboat a four stroke is a heavy price to pay. The tradeoffs are mostly subjective.

[mattotoole]

The fact that a 4-stroke outboard is heavier than a 2-stroke is a bummer for those looking to upgrade.

Except for ultra lightweights like Seagulls, most of the new 4 strokes I've seen are much lighter than the 2 strokes they replaced, at least in the low HP range we're talking about. In theory a 2 stroke can be lighter, but in practice they're not. Remember the motor itself is just a fraction of the overall unit. There's a lot of metal underneath it. Now that the whole unit has been redesigned, the 4 strokes are actually lighter.

Outboard makers had been selling basically the same old crap for 40 years. The new environmental regs were the kick in the pants the industry needed to finally redesign everything. The new motors are much improved in every way, including weight. Unfortunately, the American manufacturers tried to fight progress, while forward thinking companies like Honda ate their lunch.

[mackid068]

What about 2 outboards? That may help power-wise.

[marshmat]

For a powerboat I'd definitely want twins if I could afford it, despite the fact that two engines are less efficient than a single of the same total power. With small outboards like you find on a sailboat, I'd think the extra weight would be a big factor- a single 30hp is far lighter than two 15s.

The 4-stroke will have higher torque at low RPM than the equivalent two-stroke. On a sailboat this translates to being able to run the motor at lower rpm (and lower noise, and lower gas consumption) than the two-stroke. Where the two-stroke has the upper hand is when you want your planing powerboat to accelerate quickly, like in little sport boats, or when money is in very short supply. The fuel efficiency, quietness and higher torque of the 4 make it preferred for almost all other applications.

[PowerTech]

when I open the hatches on a old atomic 4 powered sail boats the smell is frightening.It smells like it could explode at any minute. :eek:

[mackid068]

I realize hat 2 is heavier, but 2 15 hp engines offers safety and same power (less efficiency but that's a tradeoff).

[FAST FRED]

"i guess it is a matter of opinion. I dont support the idea of having someting so explosive on board a boat"

How long does it take to get that Coal stove lit for a cup of coffee?

Safety has to do with maint, operating methods and personal responsability , not with the fuel used.

FAST FRED

[marshmat]

Exactly, Fred. Propane, naptha, CNG, gas, diesel- it's all safe IF USED PROPERLY. Key point being that you do not do anything dumb with it, and that all fuel systems are properly built and maintained.

[mackid068]

Still, everyone will do SOMETHING dumb at least once. So, protect yourself from that ONE time. Get diesel and don't drink it, folks.

[PowerTech]

there is nothing wrong with a outbord motor on the back of small sail boat like 25 foot or so.Or any little day sailer.There are plenty of advantages to a throw away 2000 dollar outbords that will last you 10 years with hardly no care or more with love.You need to run the gas out of the carb ,fresh water flush it ,oil it doun.thats it.a impelor a few times.But for a more serious boat there are inbord diesels.What is the question.You would like a 4 stroke so you aint got to mix the oil and it dont stink.About the weight I dont think it is a big deal unless you are weak or something What the hell could a 9.9 weigh any way.If it cost to mutch for you, get a 2 stroke or used 4 stroke.I have seen them old blue and white 4 stroke hondas and them white 4 stroke yamahas for ever puting around just fine even before 4 stroke was invoge.But for a larger boat you would be out of your damn mind to put in a gas inbord these days. :confused:

[mackid068]

Well, yes, on a small boat, gas is ok, but certainly not optimal!

[PowerTech]

I dont think a outbord motor hanging off the back of anything is very elegant.I would like a little 1GM yanmar tucked neatly away inside.But a outbord is cheap man.And allmost any idiot can keep one alive or just buy a new one.And that might be optimal for some weekend wariors who have never seen a diesel before and have no respect for maintenace and cannot believe a $1000+ repiar bill for something that "ran good yesterday".

[mackid068]

PowerTech, don't ever underestimate the weekend warrior. He or she can do more than we all think :)

[ErikG]

We and they can do a LOT, But our funds are limited, that was one of my reasons to look into this from the start.

[mackid068]

Ah, then a small diesel or a small outboard at 2-3 hp/2,000 lbs is perfect unless you have some sort of speed machine or are a "sailor" who buys a sailboat and only uses it for motoring around (I think you're not, hopefully.)

[mackid068]

(I may be reiterating what someone else said, but here it goes) In the short term, a gas inboard is cheaper than a diesel, yes, but in the long term, a diesel is MUCH MUCH cheaper than a gas. Simple math: if c=cost of engine (2 seperate equations, 1 for diesel and 1 for gas) and x=cost of diesel or gasoline per liter or gallon (I assume you'd use metric, but go along with gallons for now) (depending on equation), then (figure out how much gas/diesel you'd use in an average length trip, for your boat and put that as x's coefficient)
(Sample Diesel equation, engine price is $4000 and per gallon is $2.25) Total cost after 250 gallons=4000+(250*2.25)
(Sample Gas Equation, engine price is $2500 and per gallon is $2.50) Total cost after 250 gallons=2500+(250*2.50)
Simple, especially if you remember your Algebra 1...

[Raggi_Thor]

If you are a sailer, it goes like this:
The gas engine costs 1000$ while the diesel engine costs 2000 or more.
The interest, 5% of the difference (1000), 50$ is much, much more than you spend on gas the whole summer!

[ErikG]

I never mmeant for this to become a gas vs diesel disscussion...

We all know the benefits and drawbacks for each system.
I got a quote from NZ on a complete Tohatsu (gas ob) powerhead that they have converted to go with a small saildrive. The price IIRC was around one quarter of a diesel (import tax and freight not included though).

Most relattively small racers dont use their engines for other than relatively short transports. Why spend all that money on a diesel.

But comparing the concepts of gas vs diesel is not what I asked for initially. I know I can't control the discussion, it leads it's own life... :)

So I restate the oroginal basic question:
Sportboatz.com [aus] sells a modified tohatsu (if I remeber correctly) that is used on the Thompson 870. It is a "powerhead" direcly connected to a small saildrive. Sounds like an inexpensive and clever solution at a low price. But Spoboatz are in Aus and it wont make any sense shipping one to sweden as guarantees and such will probably be useless, so...

Anyone have any kind of idea what kind of saildrive that they are using and who might make it?
I know its a bit smaller than most saildrives.

I know diesel is safer but I have an outboard with a standard plastic tank today so it won't be worse than that anyhow.

A sibling to it seems to be the more widely used Honda derivative http://www.saildrive280.com, but it's to big and way more expensive than the aus version.
Maybe I should start bringing the aus ones to sweden...

So I'm looking for SMALL saildrives that could be used to do this.

To again commment on the gas vs diesel debate :rolleyes: :
Outboard engines are WAY cheaper than diesels, and I use perhaps 30 (tops) litres of gas in a summer. Price difference between gas and diesel in scandinavia is tiny, so with a summers use of gas I'd pay a few dollars more than I would have if I had a diesel.

Not even during the full servicelife of that engine would I have to spend as much as I'd have to do initially on a diesel.

Also, service would be dead simple, just dismount from the saildrive leg, and bring it to your ob service dude. Try doing that with a diesel...

[mackid068]

There are lots of small saildrives available.

[Raggi_Thor]

Erik, I agree with you, I think :-)
Never put an expensive heavy diesel in a small light sailboat, use a converted outboard, if you think www.saildrive.se is to costly, make your own with tha smallest engine you can find....

[Raggi_Thor]

And of course, we have electric outboards....

[ErikG]

Sigh... http://boatdesign.net/forums/images/smilies/rolleyes.gif http://boatdesign.net/forums/images/smilies/smile.gif
Well That IS the point!

WHO makes small sleek saildrives that are (semi) affordable?
Dont say VP and the other big name brands, there has to be others as well, I'm looking for thoose :-)

[mackid068]

http://www.sillette.co.uk/first.htm, seems relatively inexpensive. http://www.saildrive280.com/ (has Honda motor, seems nice but is $6,300 USD). http://www.yanmar.com.au/marine/sail_series/sail_series.htm (Yanmar Diesel saildrives, a 14 hp is available). Otherwise, Google works wonders, folks.

[ErikG]

sheez anyone can google... but heck first hand knowledge and personal contacts beat google hands down every time.

Thanks for the links though.
Anyone else?

[Raggi_Thor]

Do you know the swdish Z31?
www.Z31.se
It has a Honda 10-15HP, is that a saildrive280 or a "custom conversion"?

[Raggi_Thor]

http://www.ybw.com/forums/showflat.php/Cat/0/Number/336727/an/0/page/19
on the bottom of the page:
"Beware of the fact that in official Volvo stocks wordwide there are only a mere 300 rubber rings for the saildrive available. These 300 will became very rare quickly, because in scandinavia, there is some guy tat converts Modern Honda outboards to saildrive engines. And he also buys from the same 300 rings stock!!"

[mackid068]

What in hell? 300 rubber rings for saildrives IN THE WORLD? That's a scary thought...though I'm not in favor of saildrives.

[Raggi_Thor]

John Welsford (New Zealand Backyard boatbuilder) has done a conversion,
http://www.jwboatdesigns.co.nz/projects/kane/roger.htm

I think you have to go for some lifting mechanism and closing the well with a smooth fitting hatch, that is so much cheaper than a folding propeller...

[ErikG]

you might be right, but with a well you still have the storage issue, and to me that's a big issue on a small boat.

[Raggi_Thor]

Well, then, how much extra drag will a standard outboard propeller unit make, compared to a saildrive with a folding propeller? The converted outboard can be placed directly behind the keel and will probably be in teh wake.
I am thinking of a converted outboard, but with the original propeller...

[ErikG]

Just my kind of thougt Raggi Thor.
Well I've got a few ideas, I'm going to search for a scrapped engine, ripp it apart and see how and where a leg can be made shorter.
I'll need to team up with a mechanic eventually as I'm no good at making metal stuff myself.

[Raggi_Thor]

Erik, are you sure you want a gas (petrol/benzin) engine?
What about an electric engine and a movable battery pack?
here is a danish description of an el engine in a Granada 23:
http://www.granada23.dk/b%C3%A5dregister/123-mani/el%20motor%20installation.htm

[ErikG]

I've studied the eletric option a bit yes. But as a dad with three kids I'm not in a position where I can let myself be dependent on sun or wind to get to shore in an emergency.

Besides a decent sized batterybank weighs quite a bit...

[mackid068]

Electric is not the best option in this day and age, unfortunately. Small gas outboard or small diesel inboard is the best option.

[ErikG]

However it will start o get interesting as the fuelcells get into commercial production. Problem is getting the gas i guess...

[mackid068]

Well, it's either that, or "row, row, row your boat."

[ErikG]

Rowing... Hmm, maybe I should try to put oarlocks onto my 26 footer?

I one had to paddel it 100m to shore as I didnt have a spare "breaking pin" for the outboard (it broke as I engaged the gear), and there was absolutely no wind what so ever.

Took me quite a while...

[chandler]

Aren't you from the land of Saab? They make several marine diesels and they aren't as heavy as they used to be.

[mattotoole]

Electric is not the best option in this day and age, unfortunately. Small gas outboard or small diesel inboard is the best option.

Well, that depends on what your requirements are. If you need your engine mainly for getting in and out of harbors, electric power may be perfect. Think Harbor 20 but bigger. You can also have built-in regeneration under sail.

[mackid068]

Well, maybe. Land of Saab, Volvo and safety innovations. Regarding rowing, it COULD work :D.

[Raggi_Thor]

SAAB = Svensk Aero AB , Swedish Aero "AB"= AksjeBolag ="LTD", they make very fine cars, but are owned by GM, I think.

SABB is a Norwegian manufacturer of marine diesel engines. The old ones have a very nice sound and are heavy, the new ones are marinized versions of some kind. Is it "Iveco"? Is that really a Ford engine?

[Stuart C]

Ihave recently acquired at870 with this motor option you are talking about.It is a tohatsu 9.8 hp which has been modifyed.Basically there is ali plate glassed into the boat the original out board leg is used with fins removed and a geared prop installed,the gearbox is bolted to plate from bottomwith rubber boot around,on the inside the gear spindle protrudes through the plate with impellor,the powerhead sits on top with 4 bolts secured.there is an a ali box in between with the water devision inside, really quite simple and light 20kg.it is not saildrive leg but the original leg from outboard.

[ErikG]

Thanks Stuart!

Any close up pics or additional info?

So, showing my ignorance in the coice of props and powering them.
The gearbox is used to bing down the revs and bigger prop for thrust and folding I guess...
What kind of gearbox?

This actually sound pretty simple... Maybe I should try to find an old cheap outboard to try it with. The really cheapass version would obviously be to use the existing prop as well, and just create a watertight seal... Though a bit draggy... But could be done just to test it.

Winter project if I can find a cheapass engine.

[ErikG]

BTW

If anyone happens to be in posession of a service manual for a smallish (4-10hp) outboard I'd be happy to get one :) Brand i irrelevant, just need to get a few ideas of how to do this.

[Skippy]

Is it possible to hook a small gas engine onto a standard straight prop shaft? That sounds ideal in terms of weight and CG, and better than a saildrive for simplicity.

[water addict]

off the track a bit, but has anyone heard of rotary engine use on sailboats? The rotary's power to weight and power to size is unbelievable compared to typical gas and diesel auxiliaries. I wonder why no-one has developed it for the marine market - or maybe it has been done and is not a good solution? just curious.

[gmiller]

Has anyone tried to adapt the hole for saildrive as a well for outboard? I have just made a bid for an etap with no engine and would like to put that expense off for a while , the saildrive is still there but condition is unknown . and i don 't want to mess with the transom. Thanks for any advice Geo.

[cyclops]

The Mazda's are in boats with inboard shaft drives. I have seen several in Clayton , N Y.

[mackid068]

Really? Mazda rotaries? How fast do you think a rotary of equivalent power to a gas would get the boat to hull speed?

[cyclops]

You have to remember 1 very important thing about small ( cubic inches ), light weight, high horsepower engines. They can NOT move any real boats up to speed quickly. They are more like a 3 point racing hydroplane. Lots of scream and slow acceleration. Cubic inches throw boats up to speed quickly and maintain planing speed in turns.

[Vega]

Diesel-electric propulsion???
From the Malo site:

"Why is Nigel Calder’s new boat for sale?
...
The primary reason is that in the three years it has taken to design and
build ‘Nada’, two technologies that have the potential to create the
greatest changes in boat systems in more than 30 years have more-or-less
matured. These technologies are diesel-electric propulsion and distributed power systems. ..... For research and development purposes Nigel and Malo Yachts would now like the opportunity to build the same boat, including all the modifications made to ‘Nada’, but incorporating these new technologies.
This would make it technologically the most advanced cruising boat in the
world......"

What are they talking about? What is a Diesel-electric propulsion and a distributed power system? why are they such a big deal?

http://www.maloyachts.se/

[cyclops]

Malo quality is all hype according to boat owners who have to close water cocks on the port side to prevent flooding in hard turns. Old recurring problem. And they are going to Diesel - Electric power???? Wear rubber boots in the heads.

[marshmat]

Skippy- Yes, it is possible to do straight shaft with a small gas motor. Practical Boat Owner had an article on how to do it in issue 398 about 5 years ago, you might be able to find it at http://pbo.co.uk/pbo/home.htm It's generally superior to a kicker outboard, but not as good as a larger inboard for motorsailing. (I'm assuming we're still on displacement sailboats here?) There are still a few small, but beefy, low-hp marine petrol engines available that work well for this. Low-displacement 'lawn tractor' motors don't fare so well though.

Wateraddict- Yes, Wankel rotaries can be and have been used in boats. There are a few companies that do Mazda conversions or new builds for marine use. They're only suitable for high-speed applications though; the engine architecture encourages a very high RPM and so they have very little torque at low speed. They behave much like turbines, and nothing at all like piston motors. A Renesis 654cc twin-rotor, for instance, needs to turn 5,000 RPM before you get substantial torque out of it- but from there, it pulls hard up to around 9,000. So you end up needing about triple the gearing as you would with an equivalent diesel if you're using it in a boat. Great if you want to run 60 all day but miserable when puttering around at 8kts.

Vega- by "diesel electric" he is referring to a multi-part powertrain, where you have a diesel engine spinning a generator, an electric motor on the propshaft, and a bank of batteries and controllers between them. You can thus putter around on batteries alone in the harbour, or cruise on the diesel; you also have the battery as backup when the engine craps out. Also, you get a shallower shaft angle and more advantageous engine placement. The greatly enhanced versatility comes at the expense of a bit more weight, a fair lot more money, and about 5-7% in peak efficiency. I can't figure out what he means by "distributed power", unless he's thinking of something like a solar array/diesel hybrid.

[Vega]

Vega- by "diesel electric" he is referring to a multi-part powertrain, where you have a diesel engine spinning a generator, an electric motor on the propshaft, and a bank of batteries and controllers between them. You can thus putter around on batteries alone in the harbour, or cruise on the diesel; you also have the battery as backup when the engine craps out. Also, you get a shallower shaft angle and more advantageous engine placement. The greatly enhanced versatility comes at the expense of a bit more weight, a fair lot more money, and about 5-7% in peak efficiency. .

That's interesting. It looks like the hybrid motor technology developed first by Toyota in cars. Nobody has believed that at first, but they are obtaining some net results. So net that now they are preparing to put almost all their cars with that kind of motors, even the sport roadster MR2. And they manage to increase horsepower too, (both motors can work at the same time delivering more power) without significatively increasing weight. They manage to lower cosumption by 30%. In a boat it looks even more promising, because a boat uses a lot more electricity than a car and authonomy is much more important.
It looks like distributed power will be the distribution of the electric power generated by the diesel motor to where it is more needed : To charge the two different set of batteries (boat and motor), to be used directly for running at the same time the electric and the diesel power and certainly for a lot of other situations.

Nice move.:)

[mackid068]

Diesel-Electric? Aren't those often used in cruise ships and large vessels?

[marshmat]

Almost all cruise ships are powered this way, only they don't usually have the battery bank that is common in smaller vessels. The majority of the world's midsize submarines also use variations of the system.

[mackid068]

Midsize-like the Russian Kilo class, I assume? They're diesel electric.

[yokebutt]

Diesel-electric and gasoline-electric is nothing new, locomotives and submarines being good cases in point. Running the propulsion, thrusters, winches, radars, canting keels, big-screen TV:s, blenders, the wifes vibrator, and the like off of one central power source does make a lot of sense.

The latest and greatest in this area (as far as I know) are the external combustion Stirling-electric units used in some submarines.

Yoke.

P.S. See kockums.se for info on Stirling engines.

[presuming ed]

What is a Diesel-electric propulsion and a distributed power system? why are they such a big deal?

There are articles about distributed power in both this month's Yachting Monthly and Yachting World. Basically, instead of running individual power cables to each device from the control panel, you have a power bus which you tap off from for each device. Each device is controlled by a digital switch at the point of connection between it and the bus. Control of the switches is remote from their physical location - from the control panel as before. Google EmpirBus