Twin Power vs Single

[NORO LIM]

If twins are better . . .



These modest fellows were on the dinghy of a somewhat larger boat in the Petersburg, Alaska harbor this summer. There was a fishing pole in the dinghy (a 30? foot "Everglades"). Not sure about slow trolling for big Kings.

[Grumpy]

I sure would not like either the gas or routine maintenance bill for those suckers.

But let's see, doesn't routine maintenance help with reliability which is where this debate really centers??

Answer is impossible because it requires that you prove a negative. ie, what is the true cost of NOT doing maintenance. True for humans as well and mechanical systems.

Just to add a little more fuel to the flames, on another site someone recently commented ecstatically about getting fantastic economy of 10 mpg by going at hull speed and another replied by asking if he had added in the cost/hour for added maintenance on the basis that slower means more hours to get from A to B.
They had worked out that if you played by the factory rules you could be paying $4/Hr for maintenance. Now go add that to your fuel bill !!

Then you have to add in the question (do the math);- is getting 5 mpg at 4 Kts against a 3 Kt current is economical compared to 12 Kts at 2.2 mpg? (gets even better at 3 Kts against a 3 Kt current )

For me, only in a sailboat does that work.

Gotta love this never ending thread........

M

[hardee]

Really now, does it really matter? Only in your head. Which is where you are going to have the proclivity for the duplicit redundancy that the twins will offer. Yes I know, single engine, general aviation aircraft didn't even have kickers, just well maintained main (single) engines. However, I believe you will see a prevalence toward twins (or more) for off shore vessels. Yes, it is twice the maintenance (cost), but it is also twice the piece of mind.

The chance of taking them both out with a strike is there, but so is the chance that it will only be one, and yes a kicker up and out of the water is of benefit in that situation, if it runs and if it has the power to get you home.

I maneuvering in close quarters, twins will beat the pants off a single, even on a 22. And yes, they do look good

And yes, this discussion will go on forever. It's a free country, and you can have your single and I will keep my twins

my

Harvey
SleepyC

[Sea Wolf]

Good point, Harvey (!), and I admire your ZEAL, but after 10 years of discussion/debate/ listing of pros & cons (" dissuade-o-dos"), I'm going on to bed, since almost no one is ever converted from Singularity to Dualism, or vis-a'-vis! (Beautiful photo, btw.)
ZZZZZZZZZZZZZZZZZZZZ!!!

Joe.

[amy and karl]

Often left out of the debate is the twins and a kicker option. Works for us.

Karl

[BrentB]

Do the twin OBs feed from a single or dual tanks?

[amy and karl]

On our 22 they are both drawing from either the port or starboard tank, depending on which tank is selected. Our kicker runs off a portable tank.

Karl

[C-Nile]

Bob Austin made a good point with respect to the kicker, if it is intended to be used as an auxiliary motor, should have a separate fuel supply, which is something we intend to do. What happens if one's engine(s) fail due to bad fuel at a fuel dock? With respect to a separate electrical system -- if the auxiliary has a manual start (in conjunction with an electric start), that should be O.K., albeit there is always the potential, no matter how remote, that sharing a common power supply could take out the auxiliary as well as the main motor.

In my opinion, one has to look at twins as a single unit from a risk standpoint, which brings up Karl's contention that twins should have an auxiliary.

I had the honor of hearing the "Father of Disaster Recovery Planning", Mr. Edward S. Devlin, at a seminar more than 10 year's ago, and he said something that stuck with me ever since. Mr. Devlin said that everyone seems to think that Murphy never strikes, but in fact: it strikes all the time, and he went on to illustrate with specific examples, such as a town on the East Coast that was solely dependent upon a factory for its economic survival. One day, its well practiced volunteer fire department helplessly watched the factory burn to the ground, because the fire had coincided with a 500-year flood that prevented them from crossing a bridge, which spanned the waterway separating the island (upon which the factory stood) from the mainland.

One hears all of the arguments against an auxiliary: catastrophic engine failures are rare, spinning both props on a twin configuration is highly unlikely, you only need rely upon a tow service if you get in trouble -- really? Are catastrophic failures all that rare? Can you rely on a tow service when you are in peril?

Why not err on the side of being conservative?

[Will-C]

It boils down to personal preference is just my opinion. Double the maintance,on oil, plugs, lower unit oil changes, oil and fuel filters etc. Complicates things a little with the extra batteries. These days given proper maintance the newer 4 stroke and 2 stroke outboards are pretty dependable. I always liked the idea of being able to run one engine, but if you can't plane on one engine I'm not sure if I'd go that way these days. If the newer 70hp engines would have been available when I purchased I would have twins. But now I like the idea of a main and a 8 or 10 hp kicker. I have yet to add the kicker but will probably just get a basic pull start so there is no battery to maintain so it will be completely separate from the boats electrical system. I'll probably just let it pull fuel thru the same water separator etc from the boats main tanks. I would think twins with the extra drag and weight of the engines plus extra batteries rigging etc would get worse fuel economy than one single of double the power. The new Mainaut is not even equiped to handle twins I don't think. So it seems they are not big on the twin engine configuration. The same guy designed all these boats. He can't be all wrong. All bets are off if you own a TomCat. They all come with twins. If you own one or two of them you have money to burn
D.D.

[grutledge]

Thanks for all the replies. I found it much more fun reading these posts as they came in rather than searching through all the old posts (which I also did). There are many good points that were brought up that I did not think of before. As you may expect, I am not sold on one method over the other based on the discussions. More than likely, I will buy a used boat with either a single or twin based on price/location and then justify in my head that what I bought is the better option . Our brains our wonderful things!

Couple of questions/comments

C-Nile - I really appreciated your comments. Well thought out. I also love the name of your boat!

Karl - Do you have twins and a kicker on a CD22? I didn't think that would fit? Or did you attach a separate bracket?

[amy and karl]

We really do have twin 40 Suzukis with a Tohatsu 6 as a kicker on a garelick bracket. Mostly the 6 is used on the dinghy, I do not enjoy rowing. But it's nice to know it's there. We do troll for salmon with it on occasion.
Karl

[C-Nile]

Will-C,
The Marinaut was designed for only one large engine, which frees up a tremendous amount of space under the splashwell. However, we are installing an electric start, 9.8HP Tohatsu auxiliary motor on a heavy duty stern bracket. Here's a good view of the set-up.

[/url]http://www.facebook.com/photo.php?fbid=154621121292393&set=a.154621114625727.41054.139546952799810&type=1&theater

[Sea Wolf]

[amy and karl]

Here is an uglier version on our C-Dory.
http://www.c-brats.com/modules.php?full=1&set_albumName=album897&id=100_3951&op=modload&name=gallery&file=index&include=view_photo.php

[grutledge]

Thanks Karl - I was going to ask you for a picture, but I didn't want to bother you. You must have read my mind.

Glen