Do you have insight about using the Loos Guage to tension ALUMINUM, not SS shrouds. How do you adjust the suggested values in the Loos instruction sheet for aluminum or do you have to do anything at all? Plese reply to devitalis@cox.net TIA
- Status
Aluminum?
I've never heard of Aluminum for shrouds, I wouldn't have thought it would have enough tensile strength. What kind of boat do you have? In any case, I'd consult with the Loos people if you are dealing with a different metal. I would expect that it would give different reading. Chris
I've never heard of Aluminum for shrouds, I wouldn't have thought it would have enough tensile strength. What kind of boat do you have? In any case, I'd consult with the Loos people if you are dealing with a different metal. I would expect that it would give different reading. Chris
It is going to be different
The (going technical here) modulus of elasticity (E) for SS is much higher than any aluminum alloy. My structural engineering books say that SS has an E of 29-30 X 10^6 psi while aluminum's is 10X10^6 psi. So aluminum would "stretch" 3 times as much if the size of the wire and the load where identical. More seriously; the yield stress for aluminum is 20X10^3 psi while SS is 50-160X10^3 psi. So while it stretches 3 times as much it also "goes into failure" at a much lower load. Now if the cross sectional area is 3 times more on the aluminum they would stretch the same amount but the load that it would fail at would still only be at the lower end of the SS range. Since aluminum is 2.9 time lighter than SS this does not sound like there is any weight saving to be had here either. AND aluminum has a nasty habit of developing cyclic load stress fractures. which is a fancy way of saying they break after a lot fewer loadings. With that said, I've been out of the metal structures business for quite a few years and the new aluminum alloys can be made to do some pretty amazing stuff. They make air plains out of them right! What is the brand name for these shrouds?
The (going technical here) modulus of elasticity (E) for SS is much higher than any aluminum alloy. My structural engineering books say that SS has an E of 29-30 X 10^6 psi while aluminum's is 10X10^6 psi. So aluminum would "stretch" 3 times as much if the size of the wire and the load where identical. More seriously; the yield stress for aluminum is 20X10^3 psi while SS is 50-160X10^3 psi. So while it stretches 3 times as much it also "goes into failure" at a much lower load. Now if the cross sectional area is 3 times more on the aluminum they would stretch the same amount but the load that it would fail at would still only be at the lower end of the SS range. Since aluminum is 2.9 time lighter than SS this does not sound like there is any weight saving to be had here either. AND aluminum has a nasty habit of developing cyclic load stress fractures. which is a fancy way of saying they break after a lot fewer loadings. With that said, I've been out of the metal structures business for quite a few years and the new aluminum alloys can be made to do some pretty amazing stuff. They make air plains out of them right! What is the brand name for these shrouds?
Aluminum Shrouds
I AM ASKING FOR A FRIEND WHO PURCHASED HIS FIRST BOAT, A SOUTHCOAST 22, VINTAGE 1977. THIS IS AN ALBERG DESIGN AND THERE ARE BUNCHES OF THEM STILL GOING STRONG. MY FRIEND WANTED TO BORROW MY LOOS GUAGE, BUT DIRECTIOINS IN THEIR PAMPHLET ONLY RELATE TO THE BREAKING STRENGTH OF SS. I WILL LET HIM READ THIS AND POSSIBLY HE WILL WANT TO REPLACE ALUMINUM WITH SS. TKS FOR A CLEAR AND ACCURATE AND KNOWLEDGEABLE STATEMENT OF THE FACTS.
I AM ASKING FOR A FRIEND WHO PURCHASED HIS FIRST BOAT, A SOUTHCOAST 22, VINTAGE 1977. THIS IS AN ALBERG DESIGN AND THERE ARE BUNCHES OF THEM STILL GOING STRONG. MY FRIEND WANTED TO BORROW MY LOOS GUAGE, BUT DIRECTIOINS IN THEIR PAMPHLET ONLY RELATE TO THE BREAKING STRENGTH OF SS. I WILL LET HIM READ THIS AND POSSIBLY HE WILL WANT TO REPLACE ALUMINUM WITH SS. TKS FOR A CLEAR AND ACCURATE AND KNOWLEDGEABLE STATEMENT OF THE FACTS.
Aluminum Shrouds
Arturo, I've never heard of Aluminum Shrouds but if it were my boat, I'd replace them with Stainless Steel. I wouldn't trust Aluminum. If one of your stays ever broke while you were sailing on a beat with a good wind, your mast would bend in half and be in the water quicker than you could blink an eye. You'd be looking at about $3000.00 replacement costs for this damage. I'd take them off and bring them down to a rigger and have some new stainless steel shrouds made up with open turn-buckles and you'll have piece of mind in knowing that your stays are going to be good for many years. They are a little pricey, but if you had to replace a mast it would be a whole lot more expense. To my way of thinking, Aluminum seems to be so inferior when it comes to stress and corrosion tendencies. My two cents. Take it for what it's worth. Joe
Arturo, I've never heard of Aluminum Shrouds but if it were my boat, I'd replace them with Stainless Steel. I wouldn't trust Aluminum. If one of your stays ever broke while you were sailing on a beat with a good wind, your mast would bend in half and be in the water quicker than you could blink an eye. You'd be looking at about $3000.00 replacement costs for this damage. I'd take them off and bring them down to a rigger and have some new stainless steel shrouds made up with open turn-buckles and you'll have piece of mind in knowing that your stays are going to be good for many years. They are a little pricey, but if you had to replace a mast it would be a whole lot more expense. To my way of thinking, Aluminum seems to be so inferior when it comes to stress and corrosion tendencies. My two cents. Take it for what it's worth. Joe
I don't know where a person could buy aluminum
cable other than electrical cable. Galvanized steel is an acceptable choice for shrouds and stays in fresh water. I have seen bronze wire rope but I have never seen aluminum wire rope.
cable other than electrical cable. Galvanized steel is an acceptable choice for shrouds and stays in fresh water. I have seen bronze wire rope but I have never seen aluminum wire rope.
- Status