Outboard mounted Midships..yes /no ?

[Submarine Tom]

PB,

Is there a compromise that you could mount it just aft of centre allowing for directable thrust steering and eliminate the need for a rudder?

-Tom

[DCockey]

A motor mounted "just aft of centre" will not steer the boat effectively. In order to steer a boat, an outboard needs to be mounted away from the longitudinal center of the boat.

An outboard doesn't turn a boat by directly exerting a moment on the boat. Rather, when an outboard is turned it pushes sideways against the boat WHERE it is mounted. So if it's at the stern that causes the boat to start to move sideways. The effective center of resistance to the motion of the boat is forward of the stern. This seperation of the thrust vector of the motor from the effective center of resistance results in a moment (couple) which in turn causes the boat to turn.

[Submarine Tom]

DC,

You're so clever. I did say "compromise", not all the way to the stern and not midship. Get it?

-Tom

[DCockey]

Submarine Tom, interesting tone to you reply.

"A compromise that you could mount it just aft of centre" which provides reasonable steering control without a rudder would need to be close to the stern (or bow) and thus not close to the center.

If there was a reason steering by a center mounted outboard is needed then one way to improve the steering performance would be to add lateral resistance forward.

[troy2000]

Originally Posted by Submarine Tom

DC,

You're so clever. I did say "compromise", not all the way to the stern and not midship. Get it?

-Tom

You also said, "just aft of center."

[Submarine Tom]

I believe you have missed my point.

I tried.

-Tom

[keysdisease]

The difference between theory and practice is excersised everyday here in South Florida. The mullet skiffs I reference have their motors mounted anywhere from center under a console to forward (as the boat pictured in my earlier post) and while thay have different steering characteristics than a transom mounted powered boat under certain conditions (docking) their handling can be superior to a transom mounted powered skiff. They also plane very nicely.

These boats have been in common use as net tenders here in South Florida for 40 years.

For the intended use with the motor mounted anywhere on centerline with steering fixed straight and an appropriate sized rudder aft the vessel should steer just fine.

Steve

[David Cockey]

Do the mullet skiffs have a rudder, or are they only steered by turning the engine?

[keysdisease]

No rudder, steering is conventional push-pull teleflex style steering. These boats typically have 90HP and below.

[keysdisease]

these are also common in gulf States like LA ans AL

[Lake Trolling]

I have considered a forward mounted outboard in a rectagular well placed approximentally one third back from the bow and steered by a rear mounted rudder. The boat would be built like a shallow vee hull but with a tunnel the width of the well running to the aft through the transom. We are talking a bit less that 20 foot boat. The sides of the well would also feature dagger board that could be lowered to help hold the boad from side drift when fishing near the bank. There are other features but I will post this and wait for the responses.

[pistnbroke]

dont see any point in the tunnel unless you are trying to make a tunnel drive or unless the boat is heavy enough to totally fill the tunnel and will only go slow ie not plane ....if the prop is through the bottom and below the hull thats fine but if you fit a tunnel it would need to go forwards and backwards or the water flow would be bad and may draw in air ....

[Lake Trolling]

I know I'm not explainning this very well but from the well back there would be a six inch rise in the bottom (not a tunnel as I first indicated, bad choice of word on my part). If you could see my hands helping to discribe what I'm saying it would help. Let's look at the transom and the bottom portion would look like a W or kink of like that with the center of the W six inches tall by the width of the well and squared off on the top. The deck of the boat would be flat across the to of the what I called a tunnel without the bottom section so maybe you would call it a very deep grove. Darn it is hard to draw a mental picture of the bottom of the boat.

[pistnbroke]

yes I follow but the flow in front of the prop is as important as the flow behind and if this boat planes it could pull the prop out of the water and the tunnel pull air in at the front ....bad idea not neccessary...just make the centre line of the boat a ride pad about a foot wide and stick the motor through that ....

[Lake Trolling]

You are absolutly right and that is why the prop will drop down below the front well transom and the wake will be cleared through the hump of the hull. So when you are trolling at the slow speed you use when trolling you are not seeing much of the wake or prop wash at the stern. And when you have a hook up you are not as concerned about landing the fish and the stern mounted prop. Some of the lakes turn over in my neck of the woods and the unfouling of weeds in the prop is easier when the outboard is brought up in a well, rather than leaning over the aft of the boat and trying to clear the prop. when you are bass fishing and are in the water close to the shore it always seems that the wind is blowing you into the bank, even if it is a gentle breeze. With a dagger board set up at the sides of the well you can put down the dagger boards and help maintain position much like a sea anchor and yes an electric motor is also useful for this. Keep the thoughts coming as I do appreciate them.