thisistank

Thank you Reed. At least someone understands. I took a little sh!t for saying we turned around in a Tiger

BajaRunner

You know i was going to give you a hard time for that

StillHaulin@63

First of all, I greatly appreciate each of your suggestions and comments about running offshore. I cannot tell you how helpful sharing your own experiences has been in my gaining a better understanding of what I am doing at my own helm. Although I am fully aware that only seat-time will answer the "feel" questions relating to the fine points of pushing this speed envelope, I am equally convinced that understanding a concept is necessary before implementing it.

That being said, my last question relates to the relationship between tab and trim settings. Is one or the other dominate?
If you set the tabs at a comfortable angle for the run, do you use the drive trim for fine tuning, or visa versa?

I also agree that the center-of-gravvity (CG) has an immense bearing of the hulls attitude. Before I had my tabs repaired, I placed about 40-pounds of sand in my bow locker to try to eliminate the porposing on quiet waters I experienced when I first got the boat. The idea came to me when my hoist operator commented, "boy, is your Baja stern heavy!" It completely eliminated the porposing and made my trim control far more effective. After having the tabs repaired, I removed the sand and found the hull attitude remained the same with a very slight negative tab. But, removing the sand has changed the CG. I wonder how tab and trim settings relate to the CG?

Zudnic

I would be bet it has more effect than what most people think. I have my private pilots license so kind of consider a boat and water being much the same as planes and air. In planes the number one cause of general aviation crash's is stalls. When you stuff a boat you the cause of that is very much the same as stalling a plane. In the early eighties an MD80 passenger jet went for an icy swim in the river. The cause was ice and pilot(s) not setting the trim! Water like air for a plane does lift the boat and the reason you trim is to bring either into CG.

StillHaulin@63

Although trim and tab settings will certainly modify the hulls attitude in the water, I doesn't seem that it would have an impact on the CG. The amount of bow lift or drop from the tabs wouldn't seem to move the CG very much. Other than adding overall weight, I wonder what's the downside of adjusting the CG with strategic weight placement?

Panther

They way I think of it is the drive/tab settings manipulate the CG to a certain extent. You're changing the angle of attach wether you do it with the weight of the boat or with drives/tab.

From what I understand CG is one of the most important aspects of setting up a boat. Balance will make/break a fast boat. If the CG is off, it will ride like a turd.

If the CG is too far back the nose will be flighty, too far foward and you'll need a lot of trim to lift the bow and scrub speed. Some race boats add weights and balast tanks in the bow to change the CG on rough days.

I know someone who ran Super Cat Light and they spent many hours getting the CG right on that boat. It completely changed the way it ran in rough water and also ran its fastest with Neutral Trim and tab..

StillHaulin@63

Which do you think would be most advantageous, using weight placement to adjust the CG, or relying on trim & tab settings to modify the hulls attitude?

Remember, I'm not referring to a race setup, simply maximizing an offshore speed comfort zone!

Panther

If I were building a race boat, first I would figure out what the optimal CG was. Then I could modify from there based on the conditions on race day.

If the CG is off, it's still going to effect the way the boat rides no matter what the drive/tab settings are. CG can make the boat unpredictable, slam down hard or not fly thru the air correctly etc.

Unless your boat is really light in the bow and tends to fly away on you just leave it as it is and use the trim. If not you can always throw a sand bag up in the bow on a rough day and see if it has any effect. It's a pleasure boat though, just run it!

I'm no expert though, maybe some experts can chime in here.

thisistank

[QUOTE=SLANDREW]Its an OPINION with most of these posts [QUOTE]

That should be OSO's motto.

StillHaulin@63

My "guess" would be that an optimum CG would remain a constant, regardless of sea conditions, and that use of trim settings would be to adjust for the conditions.

But then the question arises, how do you determine an optimum CG?