Is this true for all aluminum boats?

[CWCW]

I just viewed a video off of the Stratos website that compared the hull stability and balance in water compared to the Stratos fiberglass boats. The two guys on the aluminum boat (both on one side of the boat) really leans to that side but this doesnt happen on the fiberglass Stratos boat. I think the aluminum boat being compared is a Tracker. Is this unstable "rock" to one side or the other common for all aluminum boats or is it just common for this Tracker being shown? Watch the video. http://www.stratosboats.com/vi...e.flv

 

[KCook]

Re: Is this true for all aluminum boats?

On my lame dialup connection I'm not spending all day downloading a video. However I can tell you that my Tracker aluminum bass boat had no side-to-side rocking issue. Whether any boat rocks is mainly a matter of beam, deadrise, and displacement, not material. If you want absolute minimum rocking, then get a pontoon.

Kelly

 

[tashasdaddy]

Re: Is this true for all aluminum boats?

link does not work. i have had both, and yes my aluminum was more prone to weight movement.

 

[jay_merrill]

Re: Is this true for all aluminum boats?

I disagree with the premise that displacement, etc. makes all hulls of a given shape the same. Here's how I understand the issue:

Any hull has a center of bouyancy and a center of gravity. The difference between the two is the "righting arm." When you shift the center of gravity from the center of bouyancy laterally, you create a "negative righting moment" and the effect of the weight that is moved in the boat is going to be affected by the overall weight of the boat. The higher your weight as a proportion of the overall boat weight, the more of a negative moment your body will make.

 

[Chris1956]

Re: Is this true for all aluminum boats?

CWCW, The stability of the hull is based upon design of the hull. The weight (heavy F/G vs light aluminum) will have a small effect, ie in two identical hull designs the F/G will be a bit less tippy than the aluminum hull.

Now the tricky thing is that at drift a flat bottom craft is very stable, however, at planing speed a v-hull is best for rough water. Like most things in life, a compromise is what you want. Flat bottom for stability at drift and top speed, v- hull for comfort at speed. Pick a shallow vee or flat bottom for lakes, deeper vee for bays, and deep vee for ocean or rough water.

 

[JB]

Re: Is this true for all aluminum boats?

Reread Jay's explanation, CWCW. I agree with him.

If you move 300# to the edge of a 800# boat it will tip a lot more than the same shaped hull that weighs 1000#.

Think about that. Seems to me that the aluminum boat, being lighter, has an advantage that Stratos didn't intend to demonstrate. Yes, it tipped more, but I bet it is faster and easier on fuel, all other things being equal.

I guess my point is that each design and each material offer features that appeal to different boaters for different reasons.

 

[steelespike]

Re: Is this true for all aluminum boats?

Lone Stars from the 50s were very prone to tipping if you got to far to one side in the forward third of the boat if you stepped on the gunwale or extreme end of the front seat (had a 40" front deck)it would tip very quickly
and I'm convinced it was the shape of the bottom flare to the bow.It had a nice flat run aft.Had a crestliner the same year that reacted little with the same treartment.
By the way the St Lawrence rowing/sailing skiff of the late 1800s 18 to 22 ft long and about 38 inches wide, gently rounded bottom.An average size man could stand on the gunwale and not tip over.