Boat Handling / twin or single outboard

Fishhawk · Posted: Fri Jun 26, 2009 10:43 am Post subject:

O.K. Snal,

Osprey's props are stock Honda Cx11.1x13"s.

There seems to be a lot of doubt out there with this issue so the next time out I will run another test and report RPM as well. Since she does come out on plane I suspect I will see quite a few more RRR"s than the others are turning.

It may not be important but Osprey has no bottom paint and is always freshly waxed.

I am also now wondering if the water chemistry/quality has anything to do with this. It is very surprising to me that so many other 22's can't get up with a single 40-50 hp engine.

Cosmic C · Posted: Fri Jun 26, 2009 10:48 am Post subject:

Captain Matt, if you had had only one engine you need not have aborted your approach. Engine to neutral, hard over to starboard, quick burst of power (enough to give a little rearward motion and swing bow to port), neutral again, hard to port, modulated power to maintain bow swing.... Since the turning center of a C Dory is pretty far aft, one can pivot the boat quite well with one engine with only a little fore and aft motion on the water. Takes more effort than with two engines, but it can be done.

snal · Posted: Fri Jun 26, 2009 11:00 am Post subject:

matt_unique · Posted: Fri Jun 26, 2009 11:15 am Post subject: Single

Cosmic C · Posted: Fri Jun 26, 2009 12:25 pm Post subject:

I'm sorry I didn't make myself clearer, Captain Matt. I was thinking single engine C Dory versus a twin C Dory or Tomcat, not a Tomcat running on one engine (which I would think would be a handful in adverse conditions). While I agree that having two engines on any boat does make manoeuvering easier, my point is that there are techniques which allow one to manoeuver a single engine boat as well as a twin under most circumstances, even if they do sometimes require some quick helm and throttle changes. By the way, after 10,000 miles in my faithful CD25, I can still say that the only boat I lust after is a TC255 (but not because it has two engines!).

starcrafttom · Posted: Tue Jul 21, 2009 12:37 pm Post subject:

some thing I have noticed on several boats with twins. Its easier to turn on twins in a tight space if you just use the engines forward and reverse and not the steering wheel. if you want to turn left then forward on the left motor and reverse on the right WITHOUT turning the wheel.

Sea Angel · Posted: Tue Jul 21, 2009 4:01 pm Post subject:

The one drawback to the twin setup I see on my CD25 is that there
is not a counter rotating OB below 135hp. The 90hps are both CW and the
turning response is greatly influenced. As much as I practice and add to
my experience, I will get caught by the preverbial cross current &
opposing wind situation. I just plan for worst case and approach
accordingly... very slowly.

Art

tpbrady · Posted: Tue Jul 21, 2009 8:50 pm Post subject:

Starcraft

Don't you mean reverse on the left and forward on the right to rotate to the left. I've never had twins to work with but that would seem to be the way.

starcrafttom · Posted: Tue Jul 21, 2009 8:56 pm Post subject:

from one tom to another "thank you" . Got my right wrong that time. Embarassed

hardee · Posted: Wed Jul 22, 2009 10:44 pm Post subject: just like to look around

Tom and Tom,

It'll work both ways, in doing it the first way, you will get to see the surroundings in a 450 degree turn

, taking in all the sights. In the second, you will only spin 90 degrees Clock

, but will miss all that scenery Cry

Sometimes I just like to look around Wink

,

Harvey
SleepyC

Fishhawk

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!!! Laughing

Regards,

Capt Dan

Don and Brenda · Posted: Tue Aug 11, 2009 11:50 am Post subject:

Capt Dan

That is still pretty impressive with the load and maintaining 16mph, I assume you were on plane with that speed

Fishhawk · Posted: Tue Aug 11, 2009 1:33 pm Post subject:

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

Sarge · Posted: Tue Aug 11, 2009 1:51 pm Post subject:

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

drdosmith@aol.com · Posted: Sat Sep 08, 2018 6:27 am Post subject:

I like twin engines. They look great. Sort of like a truck with big knobby tires.