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post #426 of Old 08-06-2013
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Re: Pros and cons of steel sailboats

Originally Posted by smackdaddy View Post
Do any of those boats actually float or sail? Or are they just always banging on hard stuff?

I think there were some of the photos that were floating, but of course I could not see the keel on those.

I just keep going over the stress loads on that keel at impact, the question in my mind is why is the hull not thicker, especially in light of the fact that the boat is frameless, the impact stress is going to be high, especially since as I understand it from Brent's earlier post that the keel is filled solid with lead. My thinking is that this would make the keel a little too rigid, meaning that it would concentrate the point loads on the thin hull plating which should be far thicker than 3/16" along the keel area for the entire length of the boat.

I am still trying to get my head around the way this design is supposed to look, and why it would not have a thicker plate in this critical area. My instincts tell me the design is flawed on several levels, and only good fortune and the short length of the vessels has prevented issues that would show up if there were more than 50 of them built and actually sailing. I know that in some cases as much as 1/16" of that 3/16" hull thickness will be lost to corrosion, and even though the owner might paint on the hull coating thick as can be, which I also think is a poor design idea, heavy coating should not be considered a part of the vessels normal hull conditions. It should be coated appropriately, and done very well, but not put on extremely thick because thick hull paint will actually not last as long as properly applied coating will last. The paint that is super thick as Brent has described will actually be subject to damage due to the weight of the coating itself pulling the coating loose from the steel.

So, a thicker hull along the keel load areas for the length of the boat with frames to spread the moment. A hollow keel with heavy walled pipe to reinforce the leading and trailing edges, and lead or cast iron bulb at the base. A very well prepared and properly coated hull with a better finish and proper thickness of ablative hull paint for the bottom, and you are starting to get a better boat, but you still do not need to grind it on reefs, crash it into cargo ships, or any of the other abusive treatment Brent's clients seem prone to do so often.

As I read Brent's answer one more time I see he thickened up his keel to 1/4" in his last post, but I am still thinking that is very thin for the keel area. I do agree with Jeff H about columnar failure being an issue with the frameless design, make that boat 50' long and you have a boat with huge issues hogging and sagging, and you would have to stiffen it with a lot of bar stock welded longitudinally and frame it to keep it from warping the deck upwards and downwards like an accordion bellows, I guess you could use that for ventilation, the boat that breathes. When you factor in the mast weight flexing one way, the keel weight flexing it the other way, this design is going to beat the everliving crap out of you in short period waves.

It is good to learn from your mistakes, but much better to learn from the mistakes of others...
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