Gas power for sail

[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]

Originally Posted by SuperPiper

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.

[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.

[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".