Twins? Should I be intimidated by twin engines?

smitty477 said:

Curious how many folks have really owned and/or spent large amounts of time with both a twin and single engine?

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Good point. We ran our first larger boat, a single, for about five years. After that, twins. I'd go back to a single in a heartbeat... if that suited the boat, and our goals, at the time.

But I can't argue one or the other is better; pros and cons with each.

BandB said:

Charter fishing boats in most areas are primarily twins. We just had someone here go fishing out of Westport WA. Tons of charter fishing boats there and nearly all are twin diesels.

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That's interesting. I think most (almost all?) of the charter boats around here are singles, mostly diesel these days but many gassers are still in operation.

-Chris

Britannia said:

Can't you just put the non functioning engine in gear? That's what I used to do on my sailboat - lock the transmission in reverse to prevent freewheeling while sailing.

Richard

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Most all the transmissions used on our type of trawlers use oil pressure created on a pump attached to the input shaft (which connects to the engine) within the transmission to lock up clutch packs. (There are a few exceptions) If the engine isn't running, no oil pressure - shifting has no effect at all.

Ken

If I had a twin, I'd never consider running them singly. If the boat was "right," there's little excuse to run only one unless the other was broken.

I have twins in my 52 ft OA. Wonderful. Many times two engines were a savior.

markpierce said:

If I had a twin, I'd never consider running them singly. If the boat was "right," there's little excuse to run only one unless the other was broken.

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Mark,
It's just to burn less fuel. And if you need to go to that extreme to save small amounts of fuel you've got ... the wrong boat.

Once again nearsighted responses from lack of variety in boats and opareas.

There are places some twin engine boats can hardly go slow enough on one engine even in idle.

My last boat I trolled for fish all day long switching between engines one at a time just to keep them in operating temps and keep the hours down.

I thought that I would do the same through the endless no wake or slow speed zones encountered along the ACIW.

Another example where there are totally different requirements depending where you boat.

psneeld said:

Once again nearsighted responses from lack of variety in boats and opareas.

There are places some twin engine boats can hardly go slow enough on one engine even in idle.

My last boat I trolled for fish all day long switching between engines one at a time just to keep them in operating temps and keep the hours down.

I thought that I would do the same through the endless no wake or slow speed zones encountered along the ACIW.

Another example where there are totally different requirements depending where you boat.

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The AICW no wake zones are easy compared to the Erie Canal. 4.3 knots is impossible with two engines in gear. However, as soon as we escaped the canals, speed was nice to have.

BandB said:

The AICW no wake zones are easy compared to the Erie Canal. 4.3 knots is impossible with two engines in gear. However, as soon as we escaped the canals, speed was nice to have.

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We have no problem going 4 knots on two engines. But then we have a purpose designed trawler.

psneeld said:

My last boat I trolled for fish all day long switching between engines one at a time just to keep them in operating temps and keep the hours down.

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Did the same thing fishing inshore frequently on a twin engine sportfish without trolling valves, would occasionally have to switch engines just to make a turn but it worked fine. Fished on another boat for 1 day with twin I/O's and didn't think to check which engine ran the power steering pump and as luck would have it I shut down the wrong one. No harm or foul but it took me a couple of seconds to realize what I had done.

markpierce said:

If I had a twin, I'd never consider running them singly. If the boat was "right," there's little excuse to run only one unless the other was broken.

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Nomad Willy said:

Mark,
It's just to burn less fuel. And if you need to go to that extreme to save small amounts of fuel you've got ... the wrong boat.

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Sometimes I get the feeling that both of you guys are blinded by your own perspectives. There are many legitimate reasons to run a twin on single engine. You just need to be able to see past your own blinders.

No sense beating a dead horse, though...only to be told I'm wrong or have the wrong boat.

I have trouble going below about 6 kts at idle of about 800. No trolling valves. Cummins idle specs are 750-900 and anything below about 775 gets rough. I just just bump in and out of gear as required. PITA, but I'm getting used to it. I don't know what I would do if I had to operate regularly in extended no-wake zones though. Change prop$ . . . .

]And the Dismal and the....etc...etc...etc...

Just some have never operated these type vessels and have nothing going to use as examples.

Some crew boats are so ridiculously overpowered and with the huge props can be a handful in idle with both engines in gear in slow speed areas....really fun when you can run them to their potential.

If, mah distinguished colleagues, by twins you are referring to the safety and maneuvering factors that protect our wives and children, provide for a better nights sleep, and cause an older gentleman to feel secure, then by all means I'm for them. But, if by twins you mean the diesel/gas guzzling, double every expense, knuckle busting repairs, and all things evil , then I am firmly against them - that is mah stand, and I stand firm

LarryM said:

I have trouble going below about 6 kts at idle of about 800. No trolling valves. Cummins idle specs are 750-900 and anything below about 775 gets rough. I just just bump in and out of gear as required. PITA, but I'm getting used to it. I don't know what I would do if I had to operate regularly in extended no-wake zones though. Change prop$ . . . .

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We can do no wake zones with no problem. It's the 4.3 knot speed limit at sections of the canal where we did just as you describe.

FWIW... most no wake zones are "minimal" wake and for most boats, 5 knots is fine...and some can go faster with minimal wake depending on hull design. It's wake, not speed.

As for the benefit of twins this will be argued forever without a solution. Mostly opinion and rarely fact.

The only thing that's fact is that the twins are more maneuverable, however, not significant. Even the argument that twins cost a lot more is just not true.

If you're over propped you'll never be able to go slow in the harbor.

Seevee said:

FWIW... most no wake zones are "minimal" wake and for most boats, 5 knots is fine...and some can go faster with minimal wake depending on hull design. It's wake, not speed.

As for the benefit of twins this will be argued forever without a solution. Mostly opinion and rarely fact.

The only thing that's fact is that the twins are more maneuverable, however, not significant. Even the argument that twins cost a lot more is just not true.

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Erie Canal is speeds though, nothing to do with wakes.

Florida has two type of wake zones.

Idle Speed-No Wake. The minimum speed necessary to maintain steerage. No wake expected.

Slow Speed-Minimum Wake. Very small wake. Bow can not be even slightly elevated.

Florida also has 25 mph, 30 mph, and 35 mph speed zones.

"If you're over propped you'll never be able to go slow in the harbor."

Many transmissions are now fitted with a neutral position.

FF said:

Many transmissions are now fitted with a neutral position.

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Aren't they all..?

FF said:

"If you're over propped you'll never be able to go slow in the harbor."

Many transmissions are now fitted with a neutral position.

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That was just so amusing this morning!

FF said:

"If you're over propped you'll never be able to go slow in the harbor."

Many transmissions are now fitted with a neutral position.

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Opps,
May have deserved that to some degree. I promised Fred I was'nt going to argue w him about overpropping.
This is kind-of a side issue. And frequently shifting in and out of gear won't hurt the clutches or gears .. that I know of. So Fred's comment is not only justified but correct.
I mention it as a downside as others have complained about it in the past.

Larry,
Looks like you've found RT's bag of tricks.

Peter B said:

Aren't they all..?

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A few, not many, are only a "in or out" clutch, not a true
marine transmission.

Ted

Nice to see you Ted,
Perhaps I spoke too soon. Cone clutches may be problematic w heavy concentrated use. I don't think any clutches are allergic to lots of use as long as people shift and get it over with. And do it at low speed.

Hi Eric,

I don't know if they are cone clutches or multiple plates held together
under pressure, or if I'm describing and naming the same thing.

The one I had was a power-takeoff unit on a DD3-53 driving a
freezer unit. I think it may have been a Rockford? Manual lever to
engage.

The relevent ones I have seen are on the aft end of a pair of
DD6-71 s , again manual lever to engage.

I would think it should be possible to arrange a remote method
to shift these in or out of action.

Ted

FlyWright said:

No matter which you pick, you'll eventually wish you had the other when:

with a single, your engine fails

or

with a twin, you foul your running gear on an underwater obstruction.

To me, the perfect world would be twins with full prop protection (bilge keels), but I suffer on through my boating life with a less-than-perfect boat. Woe is me...

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Agreed!

Also, Don't forget regarding human capabilities and mechanisms: Redundancy is what we [our bodies] are made of for propulsion, handling and seeing where we're going. I.e. - Two legs with feet. Two arms with hands. And two eyes to see where our feet can take us with hands to make sure we get there. Just saying!

Art said:

Agreed!

Also, Don't forget regarding human capabilities and mechanisms: Redundancy is what we [our bodies] are made of for propulsion, handling and seeing where we're going. I.e. - Two legs with feet. Two arms with hands. And two eyes to see where our feet can take us with hands to make sure we get there. Just saying!

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And two kidneys, two lungs, two ovaries, two testicles, and yet some folks have 1/2 a brain. Weird.:lol:

One heart, one brain....

And one colon...and we all know who rules when the colon doesnt work.....

So I guess like the human body, maybe the Butts on here rule.....

As a pilot, I learned to live by and love redundancy after many years operating single engine airplanes. Both have their place, but given the chance, a twin is my choice.

In fact, I enjoy redundancy in significant capabilities on my boat that make a difference to me besides propulsion. Lighting, heat, ventilation, coffee-making, refrigeration, entertainment, Wifi, and navigation to name a few that immediately come to mind. For others, I try to carry a spare part that may make a difference someday.

Knowing this crowd, I'm betting there are many boats here that can say the same. Gotta love redundancy...

I've learned the hard way to have a second pair of shoes, especially at boat shows.