bilge keel stability / enhancement of keels?

[rustybouy]

i was wondering if extending my wooden bilge keels with steel would improve my stability? am i right in primarily thinking that bilge keels are for my boat to rest on when the tides out........but they must double as rolling chocks and give some resistance when rolling? here's a pic of someone else's mitchell 23 day angler with what looks like some steelwork added to the bilge keels, i was thinking along the same lines but maybe a little larger with no gaps, looks like this guys done it to protect his keels rather than anything stability orientated,what's the consensus?

View attachment 28504

Pete

 

[Rossynant]

Wouldn't bother, personally.
Stability depends on weight an the 'righting arm". Adding weight to boat you will get some more stability, but also more drag. Not much improvement with righting arm here, as weight will not be deep below. Same will be obtained with any other weight (unless placed high) - for instance heavier engine...
Roll damping will be better if area of those keels is increased, but also more drag will result.
All in all you will create slower boat, even if more stable.
I'd guess one on pic has keels extended so to sit level on hard - bilge keels look shallower than main keel.

 

[rustybouy]

thanks for the reply, i am looking to re-power my boat with a little more "ooomf" if i can - so extra drag might not be a problem, im with you on the stability thing, iv'e got her ballasted pretty well for a slightly "stiff" motion, wish i had a bit more under her to work with, i notice the amount to make the bilge keels as long as the main keel is a fair bit, thanks again for your input.

Pete