T.R. Bauer
New member
Spike":1m0t5230 said:
You don't with a single, but it looks like you get that. On twins you can adjust the bracket (at least on mine) to make them so the are not perfectly parallel with one another.
Singles versus Twins
- Thread starter Stuberg
- Start date
You don't with a single, but it looks like you get that. On twins you can adjust the bracket (at least on mine) to make them so the are not perfectly parallel with one another.
lloyds":e9cxaq9p said:
The trim tabs on our boat are set at at least 20 degrees, prolly more. Don't be afraid to add another 5 or 10 degrees. You won't know unless you try. The drag imposed by that little tab is miniscule compared to drag created by having to force the boat to maintain course.
Look at the size of Doel Fin or Bennett trim tabs that some of us shove into the water in order to make our boats more efficient.
Yellowstone
New member
Just a thought. Having crossed the Pacific several times on the water and seeing ships with one propeller (although most trans- oceanic ships have twin or multiple screws) making the crossing. given the reliability of both 2 and 4 cycle motors properly maintained, the redundancy of twin motors may be more of a comfort factor than a reality one. But it really may depend on the nature of your boating. I guess I'm more confident in today's motors. Besides, twins gobble up space on the transom of a 22' complicating swim steps, steering and tabs, and simply are less economical on plane than a single engine. It is interesting to note that the Marinault is designed for a single engine; Les and his folks are comfortable with the single engine design. Then again, each person needs to scratch his fleas in his own way. John
Captains Cat
New member
Spike":1cewxjcb said:
Toe in/out is only used with twin engines. Think about feet and "pigeon toes". You can't do toe in/out with one main engine. The little trim tab under the cavitation plate is there to help offsite the single prop rotation and keep it on course at higher speeds where the tab has more effect.
Think of the front wheels of a car for toe in/out. Two wheels. If you were riding a unicycle, it would not apply.. :wink:
Charlie
Charlie
I knew that I did not need to worry about toe in or out as I have a single with a kicker. I was wondering how a person set and adjusted the toe on a twin set up.
Chester
I did not even think of the tie bar between the two motors. Next questions, Can you adjust the toe in or out force useing just the tab under the cavation plate, and do you have to adjust for toe in/out when the motors are mounted farther apart as in a Tomcat or a larger mono hull deep V where the motors may be farther apart than say a 25 or 22 CD. Thanks
I knew that I did not need to worry about toe in or out as I have a single with a kicker. I was wondering how a person set and adjusted the toe on a twin set up.
Chester
I did not even think of the tie bar between the two motors. Next questions, Can you adjust the toe in or out force useing just the tab under the cavation plate, and do you have to adjust for toe in/out when the motors are mounted farther apart as in a Tomcat or a larger mono hull deep V where the motors may be farther apart than say a 25 or 22 CD. Thanks
Spike":2lk3ituo said:
The tab is there strictly to compensate for steering torque. Toe in is the geometric relationship between the motors. Deep V hulls require more toe in than shallower hulls such as C-Dory monohulls.
I don't know how varying distance between the motors affects toe in requirements. Some race boats use toe out for certain applications but that also is above my pay grade.
One thing to clarify is the definition of toe "in" vs "out". The way I understand it is, that for toe in, you adjust the front of the outboards outwards, more away from each other, as compared to exact parallel.
This increases efficiency and provides better steering centering by aligning them with the natural direction of water flow at the stern of the boat. You want the two wakes to merge correctly at some distance behind the boat at a given speed -- I do not know that speed/distance, it would vary by the length of the boat and the distance between the engines.
Is that what others understand?
This increases efficiency and provides better steering centering by aligning them with the natural direction of water flow at the stern of the boat. You want the two wakes to merge correctly at some distance behind the boat at a given speed -- I do not know that speed/distance, it would vary by the length of the boat and the distance between the engines.
Is that what others understand?
Teleflex says:
"Toe-out = props farther apart than engine centerline (the prop is the "toe" of the foot, the engine gear housing is the heel).
Toe-in = props closer together than engine centerline (pigeon toe!).
Although I don't know the percent of single screw commercial ships--it is very high. Many of these can de-couple a cylinder and then use 11 instead of 12 (for example)--Some can be repaired under day. Most commercial fishing vessels are single screw.
"Toe-out = props farther apart than engine centerline (the prop is the "toe" of the foot, the engine gear housing is the heel).
Toe-in = props closer together than engine centerline (pigeon toe!).
Although I don't know the percent of single screw commercial ships--it is very high. Many of these can de-couple a cylinder and then use 11 instead of 12 (for example)--Some can be repaired under day. Most commercial fishing vessels are single screw.
starcrafttom
Active member
I don't think that the benefit of two motors is to off set the reliability of modern motors. Today's motors are just to good. I think the benefit of twin motors is to off set the mistakes of captains running over stuff. In which case a single with a kicker is by far the better option.. yes I am bored and decide to chum today.
starcrafttom":27rajgez said:
I agree with you Tom about the kicker, but as for today's motor's being "just too good" -- that's up for debate. Motors used to have simple carburetors, gasoline used to be gasoline (not ethanol added), and they had simple points -- everything was simple. Today's engines are highly complex and refined, and one could argue that a lot can go wrong. Perhaps they are too complex. My brother-in-law, for example, had a diesel inboard/outboard in his late model 26' boat that blew the computer three times when he tried to go from forward to reverse. Each computer cost $2,000. I was with him on one of those occasions when the engine just stopped in the middle of a channel. He got stranded two times. It's not like the old days with direct linkages of the transmission -- it's sensors everywhere: sensors to detect when the throttle is in reverse, forward or neutral, but when a sensor or a computer fails, you're up the creek without a panel. The manufacturer wouldn't do anything about it. He would have given anything for a good old fashioned direct linkage of the throttle to the transmission! I had 5 failures on the water due to an intermittent, failing wiring harness in my old boat. In another case, my engine in the old boat stalled in the middle of the river, because a black, nylon dock line in the water had wrapped around the prop. So many things can go wrong that it makes sense to have one engine free and clear of the water, and with a separate fuel supply.
Captains Cat
New member
Okay here's a new singles versus twins discussion... Had a need to remove the old osprey nest (Eagles and Canadian Geese broke it own)from the pole about 10 feet above the water and replace it with a nest about 6 feet above the water. Backed the boat up with the Twins , dropped the anchor, nestled the pole between the twins, cut it off of with an electric chainsaw. Would've been a lot more difficult with the single-engine. But not impossible.
Installed the prebuilt nest, the Male osprey arrived yesterday, he was a day early. He was very anxious and was carrying sticks all around us to start a new nest!
Will post pictures tomorrow.
Charlie
Installed the prebuilt nest, the Male osprey arrived yesterday, he was a day early. He was very anxious and was carrying sticks all around us to start a new nest!
Will post pictures tomorrow.
Charlie
potter water
New member
Running on Lake Powell this year with the predicted low water, one of, "still crazy's." twin Suzies will be up enough to make sure that only one takes a hit if some log or whale rears it's head. It is nice to know that I'll still have a 50 hp to get me home rather than 15 or less. At Powell, altitude and density altitudes, a 15 hp kicker will be down by 30% or so in hp. But, I agree with the often posted, "twins just look cooler," as the very best reason to have twins.
Oh, and don't forget my own personal favorite: Would you want to get on a commercial jet that had a big engine on one wing and a little bitty one on the other?
Oh, and don't forget my own personal favorite: Would you want to get on a commercial jet that had a big engine on one wing and a little bitty one on the other?
Oh Great ..... It's back :lol: :lol: :lol:
And what single and kicker can go from the entrance of the marina to the slip or launch ramp and never touch the steering wheel :?: :roll: :shock:
:smiled
As a couple of friends of mine used to say, "Twins are twice the fun" :thup :thup
BTW, nice job Charlie
Harvey
SleepyC:moon
And what single and kicker can go from the entrance of the marina to the slip or launch ramp and never touch the steering wheel :?: :roll: :shock:
:smiled As a couple of friends of mine used to say, "Twins are twice the fun" :thup :thup
BTW, nice job Charlie
Harvey
SleepyC:moon
starcrafttom
Active member
you know what they way in the south. "if your going to be impotent you should dress impotent.