Direct Injection versus 4 stroke

[Owly055]

     Two cycle engines have an inherent weight advantage over 4 cycle engines, but that is quickly eaten up by the increased amount of fuel they burn.   The Optimax and Etech engines attempt to achieve both fuel efficiency and light weight, at the cost of some pretty high technology.  These engines have intrigued me since Mercury came out with the original Optimax, which was less than perfect, but quite impressive.   
     The little yanmar putting away below decks is a nice solution, but it introduces some issues.   First a shaft and gland, and a propeller that is a permanent drag.... or a folding prop, which is not particularly efficient.  also the need to bring  sea water into the engine and to exhaust it, and to exhaust air, all through through hull fittings, all potential maintenance points and potential leaks.  I frankly see no reason to have ANY through hulls.   On the Searunner 31, the space is limited, and weight is critical, and a diesel really is not suitable as far as I'm concerned, and that means an outboard.  Virtually all of these use outboards for that reason.    A 15HP outboard would be pretty ideal.
     The inboard offers the potential of operating things like a larger generator / alternator, and even directly operating a refrigeration compressor efficiently, and having a way to make ice on a voyage would be useful.... or at least pleasant and convenient......But again it's a system that requires weight and maintenance. 

     I've flown hundreds of trouble free hours with Rotax power (Bombadier), and for that reason the E-tech appeals to me, but I don't know if shaft extensions are available for the 15HP Etech..... presumably they are.    The E-tech also has a charging system with about double the capacity of most outboards, though I cannot see using the outboard just for charging.  Solar panels are so cheap these days........

     These days most sailboats are motorsailors.  Most people never sail upwind beyond perhaps a close reach, if that.    Even the Hiscocks in their last boat often motored for many hours, even days, but they always seemed to be breaking that cardinal rule about not having a schedule.   Motoring into a port, or through a pass into an atoll, or help beating off a lee shore when you've gotten yourself into a situation, or moving you along when your bad judgment placed you in a dangerous situation, a motor can be a life saver, and while I would not dream of saying that it is categorically foolish to voyage without a motor, I will say that it would be foolish for me.    Motor sailing however is another matter.  It's usually a matter of impatience, or of trying to meet a schedule.   The weight of an outboard, 181 pounds for the 15 HP Etech, it makes good sense to me.   The wide open throttle fuel consumption of the 130 HP version is the only data I can find, and that is 12 gallons per hour.    That equates to 72 pounds of fuel per hour, or about .55 pounds per horsepower hour.   Typical 4 cycle efficiency runs about .5 pounds per horsepower hour for an efficient engine (honest horsepower measurement).  That makes this a very impressive 2 cycle engine.   Diesels go as high as .35.  Different web sites provide different figures, and unfortunately much of the published data is not "honest".    To be honest, an accurate dyno much be linked to accurate fuel flow data.  Unfortunately there are many ways manufacturers "fudge" numbers.   Honesty unfortunately is in very short supply these days.   Lycoming for example lists fuel consumption for their O-235 engine at something near .4 pounds per hour......... but this is based not on 115 horsepower (rated output), but on cruise settings, which are far lower output.  Ford claims 20% better economy for the Ecoboost series engines, but nobody is seeing it.    In aviation, I've long been frustrated by the patently absurd power claims of various alternative engines.    Evenrude's claim about fuel consumption at WOT is based on what actual horsepower output?   The diameter and pitch of the prop will change this.........
     In the end we have to rely on the very subjective observations of owners, because manufacturers are interested in selling products, not in supplying good data.

                                  H.W.

                                               

                                                                               

[lance on cloud nine]

interesting! as diesels have gotten lighter...I have day dreamed of a small diesel outboard with an access hole through the top of the cowling to accept a p.t.o. shaft of a small clamp on generator. Just for when stopped.

[Owly055]

     I've had a fascination with the barrel engine design with swash plates.  My favorite was built by Sterling many years ago, and was a two cycle.   The cylinders were in an arrangement like a revolver barrel.  Each cylinder had two pistons, one at each end, converging in the center.  Needless to say the engine had no head as we know it.  The two pistons came close together at the center, and the fuel was injected into the combustion chamber formed by this space.   It was a two cycle engine, and the air was pumped in through ports in one end, and the exhaust exited the other end, so one piston covered the intake port and the other the exhaust port.   An elegant and simple design that has the potential of making a lightweight high powered efficient diesel engine.   No cams, no valves, minimal parts.   Unlike a conventional two cycle where the piston goes down and opens the exhaust port, and later the intake port, and when the piston goes up, the exhaust port closes after the intake port, causing loss of air/fuel out the exhaust, this engine has a flow from one end of the cylinder the other, with the exhaust opening first of course, and the intake charge (air only) driving it on out the port so that there is little exhaust mixing with the air charge, and no fuel escaping.   The same design could be used with gas, and a timed injector at the intake port so that no fuel was lost.   
     I can see this same design being used for outboard diesels.  It's so simple and obvious.

     Traditional two cycle gas engines are so inefficient that on a sailboat, they would be useful ONLY for motoring in port.  And really for a cruising sailboat, this is perhaps the way it should be.    I noted in Hiscock's books that once they built Wanderer IV, with it's nice Ford Diesel, they motored quite a lot, but most modern sailors do......

                                      H.W.

interesting! as diesels have gotten lighter...I have day dreamed of a small diesel outboard with an access hole through the top of the cowling to accept a p.t.o. shaft of a small clamp on generator. Just for when stopped.

[SailorTom]

I'm happy with my 4hp 4cycle outboard on my Pearson Triton. If the wind is blowing I sail, if the current is contrary I anchor if I need to dock where they freak out over sailing I pull the starting cord and putter.
At home in Maine I heat the house with wood. I split the wood with an axe. Wood is awesome it heats you twice! Inboard engines make me ...well... like heat pumps in homes
     Simplicity is Bliss.

[Godot]

I gotta say, I really love the Diesel. Except when I hate it.

I had a similar relationship with the outboard on my old Seafarer. It was great...when it didn't suck.

Schedules may be something that can be dropped when full time cruising; but those of us with shoreside commitments gotta make some sacrifices. I used to dream of going engineless. I sometimes still have those dreams; but now call them nightmares.

If it can be done reliably and affordably, I'm all for any kind of engine. If lifestyle and conditions allow, I'm all for no engine at all. I'm happy(ish) with diesel; but I figure something new and revolutionary is due.

[CharlieJ]

Yep- used to pride myself in anchoring and un anchoring under sail

Try running the Gulf Intercoastal waterway east OR west bound without a stone reliable engine-all 1000 miles of it.

When you can see a bridge coming for 12 miles, and falling back for 12 more

Some times ya just MUST run the engine.


Edited to correct mileage on gulf ICW :)

[Phantom Jim]

Even Lyn and Larry Pardey admitted that engines were acceptable when schedules were part of the cruising planning.  Why is the wind always on the nose when you are cruising in the ICW?  Is this just God laughing at us?

[Frank]

Old saying:

"Want to make God laugh.... Tell him your plans"


So true, and why schedules and cruising just don't work too well 😄

[Owly055]

     I regard engines on sailboats as primarily a safety device.  They will allow you to get into places where you otherwise might not due to wind and current, and to navigate among other boats in harbors with a bit more safety.   Sail power alone is not allowed in some harbors I've read.   As far as keeping a schedule......... If you need to keep to a schedule, sailing really isn't for you in my opinion....... at least not pure sailing.     

     I've not sailed the inside passage or the ICW, but I've read that it is virtually impossible to sail either without an engine for assistance.  It makes sense, as islands and land masses tend to create wind shadows.   

                                         H.W.

[CapnK]

I see 2 main key factors with engines, whether gas or diesel, or however many strokes, or whatever:

1) Gotta start with one that runs good.  8)

2) Gotta 'rub on it' real regular like, in order to make it keep doing that.  ;D

IOW - maintenance is non-optional, and the more you can do, the better.

Pretty much like everything else on the boat, eh?  ;)

Other larnin's -

I found that 6hp isn't enough to buck 25-30 kts direckly on the nose with 5k#'s of sailboat, without being able to 'tack' in that direction (yes, under power). But it'll pull you straight upwind *in reverse* at a sedate 1/4 to maybe 1/2mph. That's how I got thru the bridge...

And having the prop deep enough that it cannot breathe, that's another Good Thing. Learned that one when we almost didn't make it into the Bay, bouncing on the ebb tide waves generated at the mouth.

Last, even knowing I have a good motor - like the Johnnyrude 48 SPL on my Hobie Power Skiff, or the little Volvo in my A30 - I am always paranoid it'll quit unexpectedly, and try to stay prepared for what-to-do-now if that does happen. This includes toting extra snacks and drinks, and having a SeaTow membership.  ;D

[ralay]

I've said this before, but even if you throw out your personal schedule, sailing is inherently full of natural schedules.  Nature wants you certain places at certain times and will slap you silly for not keeping pace.

I don't ever have to be to work on Monday, but I have to be in a certain type of anchorage by the time this gale arrives.  Or through the inlet/reef before dusk.  Or through the cut with a certain current.  Or over the bar at high tide.  Or north before hurricane season...  I guess if you were going to stay safely offshore you could drift/heave to/fart around without much concern for the wind, current, light, or tide.  But then you'd just be worrying about the Water Schedule. 

Sailing is not for people without schedules.  It's for people who are bored with their current schedule and want to trade it for some new ones.    ;D

[Frank]

Relay....extremely well written! Too true!!
Grog for that!! 😄😄

[CharlieJ]

Relay....extremely well written! Too true!!
Grog for that!! 😄😄

ditto

[CapnK]

ditto

Tripto.

I guess. :)