In a perfectly balanced boat...

Hypothetically, If my boat is perfectly balanced side to side - say center console, gas tanks, batteries, etc. all right on the centerline - what effect will the prop have on tilting the boat to one side or the other? Will it tilt to the left side (sorry, I don't know my starboard from whatever terms)? Or will it not make a difference? Seems like it would cause some tilting.

If you know the answer to that question, how much weight would I need on the other side (about 3 feet off centerline) to offset this tilt? or is there another way to offset it? (I have a 50HP on a 16 foot V style boat)

I'm planning the boat layout now for my rebuild and just trying to get mostly equal weight on both sides and still be adapable for solo trips vs trips with a friend. I have a side console boat now. With me alone, I'd fill the livewell on the other side and it ran real nice. The plan now is to move the livewell to be across the centerline and a few feet farther forward.

Will

Theoretically the torque would bury the port rail, IOW tilt it to the left. That's why boat manufacturers have placed the steering wheel on the starboard side, most times this is unnoticeable unless you are in a really high HP low weight machine, like a bass boat. Inboard jet drives apply the torque the other direction (bury the starboard rail) which is why the steering is on the port side. again, these are high HP low weight boats (thrust to weight ratio) so it makes a big difference. For most fishing boats, especially the type we build here, you will proly not even notice it.

To answer the question of how much weight is needed is beyond my meager math capabilities. It would depend on how much ballast (weight) you have to move around and how far from centerline you could get it. The farther from centerline the less weight is needed. you said three feet from centerline but you must also consider the centerline of the ballast as well.

the best way to overcome this is using Trim Tabs (trim is what we are discussing here anyway); this way no matter what has caused the out-of-trim condition (gear, people, big fish) you can compensate for it with the press of a button.

Running a 50 HP on a 16 footer will require some lift in the stern anyway, that's a lot of weight for a 16 footer; trim tabs will take care of that.

Port and Left both have four letters.

lckstckn2smknbrls said:

Port and Left both have four letters.

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That's the only way I remember that. :mrgreen:

ACarbone624 said:

lckstckn2smknbrls said:

Port and Left both have four letters.

Click to expand...

That's the only way I remember that. :mrgreen:

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Unless you use the typical abbreviation for Starboard: Stbd :wink: .

Sorry, couldn't resist

Thanks Rat.

I guess I'll just plan on not planning for that and run with it. 8) It shouldnt matter much unless I'm going out alone or with just one of the little kids. I'll set it up with the gas tank and one battery on the 'port side' to offset my weight a bit, and then have the option of the trolling battery in one spot or the other. Just more wiring and another battery box to get. If I do it right, I could have two batties for the trolling motor and go all day long. :wink:

wasilvers said:

Thanks Rat.

I guess I'll just plan on not planning for that and run with it. 8) It shouldnt matter much unless I'm going out alone or with just one of the little kids. I'll set it up with the gas tank and one battery on the 'port side' to offset my weight a bit, and then have the option of the trolling battery in one spot or the other. Just more wiring and another battery box to get. If I do it right, I could have two batties for the trolling motor and go all day long. :wink:

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I agree, worry more about weight placement than what effect the prop rotation will have on the trim. Try to keep the heavier items along the centerline and as low as possible (batteries). This way you create a large amount of inertia to overcome and having weight outside of this 'inertial moment' will have less effect on trim. A 200 pound keel three feet below the hull bottom on a sailing vessel will offset something like 800 pounds of weight, it has to do with leverage, inertia, center of gravity and center of buoyancy. There is now way you can get weight that low, but still, keeping it centered and as low as possible will help that much more. As the hull pitches, yaws and heels your center of buoyancy will move as well, keeping everything heavy close to the center will help keep the center of buoyancy close to the center of gravity, which creates a more stable boat and one that will right itself quicker.

In my old 12 foot Jon I had no choice but to have the battery against the port side chine when single handing; to relieve my self I had to lean over the starboard side rail, if I leaned over the port side I could bury the rail under water very easy. the moment of capsize in that little boat on the port side was very short, but much better on the starboard due to the offset weight and leverage of the battery on the port side. Here's an interesting thought experiment. In the case I just related the force is a lever, the hull bottom being the lever, the battery the counterweight and me the work being moved; the fulcrum was the center of buoyancy, or the weight of the water pushing up on the hull. I could make the lever more efficient or less efficient by moving the weight (me) instead of moving the fulcrum, which is what we usually do with levers.

okay, I'm rambling...

ACarbone624 said:

lckstckn2smknbrls said:

Port and Left both have four letters.

Click to expand...

That's the only way I remember that. :mrgreen:

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Another way is that L(Left) comes before R(Right) in the alphabet so P(Port) comes before S(Starboard) in the alphabet.