Re: Pros and cons of steel sailboats
Smack doesn't like my welded down stainless handrails. He prefers the bolted down teak of his Catalina 27; thinks they are stronger and less likely to leak. I vang my mainsail to my hand rails . Try that with the teak ones on a Catalina.
He claims that 36 inches are the minimum height for lifelines. How many stock Catalina 27s have 36 inch lifelines ? How many Perry designs have 36inch lifelines? Not many. The only one I measured was 24 inches ,super thin walled stainless, cantilevered off 3 or 4 tiny bolts on the deck. Smack claims my sch 40 stainless type 316 pipe stanchions, 34 inches of the deck, supported by welding on the bottom and welded to a solid sch 40 pipe on top , supported top and bottom, are not adequate, not as adequate as his 24 inch extruded tinfoil stanchions, supported bottom only by 3 or 4 tiny bolts and plastic coated ( Crevice corrosion factory) stainless top life line!
He doesn't like my 3/8th inch pad eye on my boom bale , but prefers a block with a 3/16th shackle. He thinks the 3/16th shackle is stronger, because it has a trendy brand name on it.
And some want to rely on his judgement !
When the first issues of Sail Magazine came out, they had all kinds of tank test results, including info on rudders. A spade rudder with nothing ahead of it, had a much shallower stall angle than one with a skeg in front of it. They found that, with the bottom raked slightly forward , it was far les inclined to draw air down it, and more likely to draw water slightly up it . Extreme rake drastically reduced a rudder's effectiveness, but a slight forward rake was beneficial. Even the slightest rake aft quickly reduced the rudders effectiveness, pulling air down and causing cavitation. Donald Street wrote extensively about this . He asked many designers why they raked their rudders aft and the only answer they would give him was "It looks fast and sells boats."
Smack wants you to believe that water has changed its ways since then, in order to be "Trendy."
Smack wants you to believe that a rudder supported both ends, off a strong skeg is not stronger than a fig leaf rudder supported by the top end only!
Structural strength and hydrodynamics are not the only criteria for rudders. I have run thru some pretty heavy kelp beds in the north, which would leave Bob's fig leaf rudders carrying a huge ball of kelp, in seconds . I have ran over heavy lines, which would have left a boat with fig leaf rudder fouled and dead in the water. Try that off a lee shore on a dark night, not something anyone like Smack or Bob, with minimal cruising experience, would comprehend. A cruising boat skeg should be designed to slip over lines and kelp, with out fouling either.
A single keel gives some protection from floating debris, but with twin keels there is nothing in front of the rudder, except, hopefully, a strong skeg. Without a skeg, any hard object would wipe out a fig leaf rudder instantly.
Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"
Last edited by Brent Swain; 09-19-2013 at 09:57 PM.