Boat Handling / twin or single outboard

O.K. all,

We had Osprey out on Lake Superior yesterday evening. I ran the tests that I promised and here is what happened:
With one Honda 40 in the water, about a 3 mph tail breeze, flat 52 deg. water, 10-15 gals of fuel, 420 lbs of people, and trolling gear, by no means a heavy load, and if I am to believe my electronics, we achived 16.1 mph at 4600 rpm. WOT.

No B.S.

With both engines WOT we achived 34.5 MPH at 5500 rpm.

So there you have it. My earlier claim of 17-18 mph with one engine was either incorrect or with a lighter load.

If she is an exceptional boat, that's OK with us!!! :lol:

Regards,

Capt Dan
 
Don,

Yes, to attain that speed the boat needs to be planing or "on step" as some have said.

I have had trouble understanding why some others with 45 and 50 hp. engines are unable to do it. It has to be one of three things or a combination of them. Prop pitch, a heavier load, or no trim tabs.

I don't think there could be that much difference between the boats.

Dan
 
I have twins and one piece of advice I was given regarding rotating the boat on its axis that I found very helpful (and obvious in hindsight, but yours truly didn't figure it out) was that you need to keep the motors straight when applying forward and reverse thrust simultaneously. If you turn the motors, it throws the process out of alignment.

Yes, I'm embarrassed to admit it, but if I can help some other poor soul I'm happy to oblige.

:embarrased
 
A couple related questions regarding twin engines...

Does a dual engine setup negate the need for trim tabs?

How does a dual engine setup affect fuel economy compared to a single engine setup?

This is a very informative thread. Thanks for taking the time to share your experience.
 
I don't have dual engines, but I don't see how this would negate the need for trim tabs. In fact, it might make trim tabs more important because of the extra weight on the transom. 2 singles have to weigh more than 1 bigger engine.
 
ssobol":cs5bvadu said:
I don't have dual engines, but I don't see how this would negate the need for trim tabs. In fact, it might make trim tabs more important because of the extra weight on the transom. 2 singles have to weigh more than 1 bigger engine.
Click to expand...


If you compare various brands and hps, I think you will find that twins can be as light or lighter than a single plus a kicker (with the twins together being equivalent hp to the single). I had twin Yamaha 70s, for instance, and the weight of some 135-150 hp singles plus a kicker of any size would have been more. Whatever the case, assuming a kicker with a single main, I don't think the weight difference is llikely to be that much of a factor.

The twins can pretty much eliminate the need for trim tabs as far as port to starboard balancing goes since you can trim each engine independently. I found that Permatrims also made bow to stern trimming easy. I never had trim tabs, and never felt as though I needed them. One less system to buy and maintain. YMMV
 
Don't know about now but when our 2005 C-Dory was built twin 40/50 Hondas weighed less than a Honda 90+kicker.
I've been told having twin skegs in the water helps in rough weather especially in a following sea.
 
I guess that would depend on the kicker. The little 2.5hp Suzuki is just 30 lbs.

The 40/50 hp Hondas have weighed in at 214 lbs each. 428 lbs for both.

The 2005 Honda 90 weighs 384 lbs. The next generation EFI 90 Honda starting in 2007 weighs 359 lbs.


For comparison of other brands:

Suzuki 50 is 229 lbs. vs Suzuki 90 - 352 lbs

Tohatsu 50 is 209 lbs. vs Tohatsu 90 - 359 lbs

Yamaha 50 is 214 lbs vs Yamaha 90 - 353 lbs

Evinrude E-tec 50 is 240 lbs vs E-tec 90 - 320 lbs.
 
I've got a Honda 90 with a 9.9 kicker. I had always thought it would be nice to have twins for maneuvering, but what about this...

The Anderson Island ambulance boat has twins, but hit a bar on step and lost use of both engines. They had to paddle the big boat back. Thank goodness they didn't have a patient that was time-critical.

I tip my 9.9 up and lock in place above water when I'm cruising, and it woundn't have been damaged in the same accident scenario. If I damaged the 90, I could them put the 9.9 down and move at displacement speed.

Of course, if I only damaged one of the twins, I might still be able to get on step depending on loading, so could potentially move much faster, but I don't like the idea of being able to damage all of my motors with one miss-step.
 
"I've got a Honda 90 with a 9.9 kicker. I had always thought it would be nice to have twins for maneuvering, but what about this...

The Anderson Island ambulance boat has twins, but hit a bar on step and lost use of both engines. They had to paddle the big boat back. Thank goodness they didn't have a patient that was time-critical."
Click to expand...

They would have had the same result if running a single. The bar was on the chart, and hadn't moved in their last 20 trips. Chalk that one up to serious operator error.

Twins will out maneuver a single any time, and for ease, they can't be beat. Weight wise, depends on the mfg, and reliability depends on the maintenance.
JMHO and I might be biased :wink:

Harvey
SleepyC :moon

JC_Lately_SleepyC_Flat_Blue_055.highlight.jpg
 
Quote:
"I've got a Honda 90 with a 9.9 kicker. I had always thought it would be nice to have twins for maneuvering, but what about this...

The Anderson Island ambulance boat has twins, but hit a bar on step and lost use of both engines. They had to paddle the big boat back. Thank goodness they didn't have a patient that was time-critical."


Quote:
They would have had the same result if running a single. The bar was on the chart, and hadn't moved in their last 20 trips. Chalk that one up to serious operator error.

Twins will out maneuver a single any time, and for ease, they can't be beat. Weight wise, depends on the mfg, and reliability depends on the maintenance.
JMHO and I might be biased
Click to expand...

Well, yes the bar is on the chart, but at high tide it is way down there with our huge tidal exchange. It takes several minutes more to wind through the channel, which could be critical for am ambulance boat. I also hadn't thought about both engines being damaged at once, but there you go.

My main point was...two engines down are vulnerable to one event. A larger main down and a kicker up isn't vulnerable to a single event in the same way. A 9.9 kicker is way better than a paddle.

Yes, I have experience and I like twins over singles for maneuvering, but when I want to seriously maneuver or troll, I drop my bow-mounted trolling motor. Not sure why we don't see more of these.
 
I'll argue the difference in maneuvering between twin outboards and a single for a 22' c-dory is overstated. Only at slow speed docking in tight quarters have I noticed any difference at all, and it's pretty minor. The push the throttles in opposite directions to "turn on a dime" trick is pretty cool, but not something that is necessary for a boat this small in my opinion. The c-dory is an easily controlled boat, with either engine configuration.

Of all the reasons we've argued about which is better, I haven't seen an argument I really agree with. There's pluses and minuses on both sides. I've now spent a lot of time behind both setups and I'll state the only reason I prefer twin outboards.....

The sound while cruising. The twins have a lower pitch hum that resonate together. I got used to that sound and it just sounded right to me. The single we have now is great. It's fuel injected and efficient. Its run flawlessly so far knock on wood. But it sounds high pitch and tinny. To me it just doesn't sound right. That's my argument for twins. Also there's a coolness factor. The technical justifications don't make any sense, in my opinion.
 
ssobol":28w2se4j said:
I don't have dual engines, but I don't see how this would negate the need for trim tabs. In fact, it might make trim tabs more important because of the extra weight on the transom. 2 singles have to weigh more than 1 bigger engine.
Click to expand...

Twins would allow both fore and aft trimming and side to side trimming. That would work even better with Permatrims on the twins. Could eliminate the need (or at least lessen the significance) of trim tabs.

Paul, you are right about the difference in sound, and that is something I have noticed but never brought it up. I guess I thought it was just me thinking that.

Harvey
SleepyC :moon

JC_Lately_SleepyC_Flat_Blue_055.thumb.jpg
 
We're interested in a Venture 23. Leaning single Suzuki 140 with kicker, thanks Steve, C-Sharp:-)

I'm sure this is covered but haven't found it.

Single say 200 verse twin 90's. This is just an example.

Single 200 runs at much lower RPM than twins. Thus the engine will therotically last longer, and also be much more quiet. Higher PRM's wear an engine out more than lower RPM, or at least faster, not necessarily more. I compare this to motorcycle race engines.

Also time to plane and PRM to plane would obviously be different.

Not saying for better or worse. I like the idea and looks of twins. I also like the idea of a larger single to just chug ginghams along.

I guess it would be interesting to hear comments on sound, fuel burns and maintenance. Times to plane etc.

But I also realize this horse is beyond dead. I'll keep searching:-) If anyone can direct me that would be great. I keep searching single verse twin and it's good info but I haven't found this info.

Thanks so much,
Kirk
 
crowleykirk":xh6rg383 said:
We're interested in a Venture 23. Leaning single Suzuki 140 with kicker, thanks Steve, C-Sharp:-)
Click to expand...

Don't thank me, thank Gary & Colleen of DayBreak, of which that is the combination they have on their 23 and it sounds like a perfect set up and some great figures. They don't have trim tabs and don't even need them. You should PM them for details, but I know they are out cruising so may be delayed in getting back to you.
 
I used to fly quite a bit and my aircraft mechanic used to always say the amount of problems with twin engine aircraft is not double, it is exponentially to the power of 2.

Reliable engines well maintained are going to perform well and even with 95% reliability, 0.95 squared is still a very high number. Like it or not, having two engines long enough, the probability of one of them failing is higher than a single engine.

Note, my mechanic also said that a lot of times all that other engine can do by itself is fly the plane to the scene of the crash!
 
Doolittle":ke00f8ui said:
I used to fly quite a bit and my aircraft mechanic used to always say the amount of problems with twin engine aircraft is not double, it is exponentially to the power of 2.
Reliable engines well maintained are going to perform well and even with 95% reliability, 0.95 squared is still a very high number. Like it or not, having two engines long enough, the probability of one of them failing is higher than a single engine.
Note, my mechanic also said that a lot of times all that other engine can do by itself is fly the plane to the scene of the crash!
Click to expand...

I'm a pilot, and I totally agree - it's fact!

However, the big difference between boats and planes it that boats don't fall out of the sky! To maintain even level flight a plane needs to be at around 75% of its power output (combined even with twins), whereas a boat can limp along at very small power output and it just takes more time to get back.
 
Back
Top