[Alberg30] Alberg 30 center of gravity

[Bob Johns]

On Monday, April 22, 2002, at 02:42  PM, chrishardy wrote:

> I dug out my Chapell and he also has a rule of thumb for c.g. he states 
> "As a "rule of thumb" it is assumed that the center of gravity of the 
> hull structure(planking, keel, deadwood, stem, sternpost, frames, 
> floorsdeck-beams, decking, bulkheads, cabin trunk, cabin floorand cabin 
> joinerwork) is at the middle of the overall length. As a matter of fact 
> this assumption is not over an inch or two out in normal sailing 
> hulls,excepting deck-houses (such as used in motor-sailers) from 
> consideration. Since this is the case it is customary to calculate on 
> this basis and to reckon on the heavy weights, such as engines, full 
> tanks, lighting plant, batteries, icebox, stove, winches and windlass, 
> anchor, spars and large deck structures, as the items of weight 
> controlling trim which must be counterbalanced by ballast." Don't know if 
> this is a help.... but it is food for thought.  Best way is too leave the 
> trailer axels unbolted and move them until you get about 10% tongue wt... 
>    

Chris,

This makes sense to me. I also agree that the right amount of tongue 
weight is very important. I've never towed anything heavy but we used to 
tow a Mobjack (similar to a Thistle) that weighed about 500 pounds and 
loaded with camping equipment was probably around 1000 pounds. The first 
trip to Lake George it seemed to tow OK until I started to pass a car at 
highway speeds. The trailer started to fishtail violently and I almost 
lost control. After that I always checked the loading of the boat with 
bathroom scales and had no further problems. I shudder to think what 9000 
pounds plus would do if it started to fishtail like the Mobjack did.

Bob

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