2 engines or 1

[Mollers]

[QUOTE=willk;310514] And back on topic:



My Redbay will plane at about 20kts on one motor at WOT (with the dead stick in the water). It IS overpropped for single engine use (19 pitch) and has to be coaxed out of the water and she isn't making her normal revs either. I wouldn't fancy trying to maintain plane in short lumpy water.



Surely that blows away one of the main planks of the twin argument?

[jwalker]

For emergency services, i reckon two motors is a sensible way to go. Because of their operating conditions, a motor stoppage is not so likely to have a similar cause to a cruising or day boat. I can quite imagine being is shitty conditions trying to rescue someone from rocks or under a pier and a total engine stoppage would be unacceptable, whereas a single engine stop would at least leave some means of control.

I've had twins, triples and singles and for everyday use it's hard to beat a good single and good aux. Only on one occasion did I need the aux and it was a good number of years ago.

Something I've might mention about multi engine installations; it's often tricky to get both engines permanently is sync regards running speed. They drift in and out of sync for a number of reasons and the beat caused by them being slightly out of sync can be very wearying. And LOUD...

Now Mr Willk, wot do you consider to be, "... a nice tidy solution for mounting an auxie on a single diesel outdrive rig....".

[willk]

Originally Posted by Mollers

.
Surely that blows away one of the main planks of the twin argument?

As arguments go, it certainly does have it's fair share of planks. Hopefully my observation provides more insight to one strand of the debate.

Half of a pair of twins will never give a RIB it's optimum performance but I'd say that making 20kts in a homeward direction in most seas is a plus in comparison to:
1. Hanging over the stern, massaging an expired single.
2. Deploying a hernia, sry, auxie and hanging over the transom trying to navigate by proxy.
3. Calling for a tow.

To add to your excitement I can report that I have heard of a recent local incident where BOTH twins passed away, under way, same way. Poor guy had sludge in his tank and didn't have "proper" sight glass filters fitted. But then, anyone can make that mistake .

And I suspect that you and I may have somewhat different definitions of "short lumpy water"

[willk]

Originally Posted by jwalker

Now Mr Willk, wot do you consider to be, "... a nice tidy solution for mounting an auxie on a single diesel outdrive rig....".

I really don't know My (original) comment to Rupert was simple and sincere. The next rib will be bigger and will either have to have twins or a readily deployable, securely stowed 15 - 20hp auxie. So much of the fancy kit for hard boats wouldn't last a season on a rib used to it's full potential

[Mollers]

Originally Posted by willk

As arguments go, it certainly does have it's fair share of planks. Hopefully my observation provides more insight to one strand of the debate.

Half of a pair of twins will never give a RIB it's optimum performance but I'd say that making 20kts in a homeward direction in most seas is a plus in comparison to:
1. Hanging over the stern, massaging an expired single.
2. Deploying a hernia, sry, auxie and hanging over the transom trying to navigate by proxy.
3. Calling for a tow.

To add to your excitement I can report that I have heard of a recent local incident where BOTH twins passed away, under way, same way. Poor guy had sludge in his tank and didn't have "proper" sight glass filters fitted. But then, anyone can make that mistake .

And I suspect that you and I may have somewhat different definitions of "short lumpy water"

Yeah, yeah, yeah, but are we now of the thinking that single with a sensibly hp'd aux is the way to go?

[cuttlefish]

My wife implies that I imply all the time. However, I subscribe to your last comments. A good aux. well fitted, not that I have a completely clear idea as to what this means or how it should be done.

[cuttlefish]

You wrote: "are we now of the thinking that single with a sensibly hp'd aux is the way to go?"

Yes.

[willk]

Originally Posted by Mollers

Yeah, yeah, yeah, but are we now of the thinking that single with a sensibly hp'd aux is the way to go?

Well, actually "we" are thinking that a twin diesel installation is the way to go

But there's a recession on here for the next decade or so

[jwalker]

Originally Posted by rupert

My wife implies that I imply all the time.

Don't they all?

However, I subscribe to your last comments. A good aux. well fitted, not that I have a completely clear idea as to what this means or how it should be done.

Ah, more swatting for you then, cos there's plenty written about it on Ribnet if you go asearching.

[cuttlefish]

Ah, more swatting for you then, cos there's plenty written about it on Ribnet if you go asearching.
__________
Just as well I like swatting, at least, I do so long as the argument interests me. Time is still on my side. I have sold my previous boat, and have the cash for the new rib burning a hole in my pocket. So long as I don't spend it, I can swat for hours and hours and hours. When I have spent it, there is little point in swatting, unless I made the wrong decision. And that would be cold sweat swatting - not pleasant!

[Bigmuz7]

And this is where I lament the passing of 2 strokes, having settled with the concept of main plus aux for many years, the choice of aux is the next big one. Whilst tech might be improving 4 stroke aux's still weigh a ton and the ones that are usable power are barely liftable. Depending on your cruising ranges and locales,.. another dilemma beckons

[cuttlefish]

You are right. So, which aux? 9HP? 20? diesel? 2 stroke? 4 stroke?

[jwalker]

oops...accident

[jwalker]

Originally Posted by rupert

You are right. So, which aux? 9HP? 20? diesel? 2 stroke? 4 stroke?

Go with the same fuel type as your main engine. Since you're gonna use it never, provided it starts every time and has enough power any type will do.
It's a Sod's law thing really; if you don't have it, you'll need it, if you do have it, you'll never need it. Second option is best.

[Poly]

Originally Posted by jwalker

Go with the same fuel type as your main engine.

But if the main engine is diesel (he's looking at Redbay's so thats quite plausible) then a Diesel outboard will not only be like hens teeth but also cost him about the same as going with twins!

[jwalker]

Yanmars are available secondhand if you keep yer eyes peeled. Mine was a reconditioned (FYM) fish farm engine somewhere less than 4K. Can't exactly remember.
It's remarkable, starts on the button every time. I bought it early in the build and it lay for 2 years before first starting. Primed it, turned key, ran.

[chewy]

What abut an inbard wing engine?

[willk]

Originally Posted by chewy

What abut an inbard wing engine?

Damn you chewy, I wrote that post and deleted it as pure fantasy.

The one with the diesel donkey engine with the folding prop and the deployable rudder.

Stop doing that....

[jwalker]

Well, funny you should say that, a good while ago I had a conversation with Alan Priddy and he reckoned a water jet/engine as used on jet skis would be a possibility.

[Channel Ribs]

Originally Posted by jwalker

Well, funny you should say that, a good while ago I had a conversation with Alan Priddy and he reckoned a water jet/engine as used on jet skis would be a possibility.

A couple of companies make a maneuvering water jet system, with one powerplant and dour nozels. No reason why this could not be used in a cabin RIB to provide auxilliary propulsion as well as acting as a bow thruster?



(Of course I would want a hose connector on deck so I could return fire when the lifeboat crew are "testing" their fire hose!)