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Sheave material
I need to replace some old plastic sheaves, and I have the option of sheaves
made of Delrin, acetal, or glass filled nylon. (I have learned that delrin is acetal, but don't know if all acetal sheaves are delrin). So what are the relative attributes of acetal and glass filled nylon sheaves? I read somewhere that GFN might be more abrasive on the pin, but I assume that it is stronger. Ronstan sells both, but their website doesn't solicit questions. |
Sheave material
On Sat, 31 Jan 2009 09:35:42 -0500, "Garland Gray"
wrote: I need to replace some old plastic sheaves, and I have the option of sheaves made of Delrin, acetal, or glass filled nylon. (I have learned that delrin is acetal, but don't know if all acetal sheaves are delrin). So what are the relative attributes of acetal and glass filled nylon sheaves? I read somewhere that GFN might be more abrasive on the pin, but I assume that it is stronger. Ronstan sells both, but their website doesn't solicit questions. Why not give Ronstan or your local rigger a call and find out the pros and cons of each? |
Sheave material
Frankly, I thought I'd get a better answer here.
It's really moot now, because I have a choice of GFN for only one size sheave(I need 3 different sheaves) . I'll probably get it and try it because the size might be better than the closest acetal sheave. "Wayne.B" wrote in message ... On Sat, 31 Jan 2009 09:35:42 -0500, "Garland Gray" wrote: I need to replace some old plastic sheaves, and I have the option of sheaves made of Delrin, acetal, or glass filled nylon. (I have learned that delrin is acetal, but don't know if all acetal sheaves are delrin). So what are the relative attributes of acetal and glass filled nylon sheaves? I read somewhere that GFN might be more abrasive on the pin, but I assume that it is stronger. Ronstan sells both, but their website doesn't solicit questions. Why not give Ronstan or your local rigger a call and find out the pros and cons of each? |
Sheave material
"Garland Gray" wrote in message ... Frankly, I thought I'd get a better answer here. It's really moot now, because I have a choice of GFN for only one size sheave(I need 3 different sheaves) . I'll probably get it and try it because the size might be better than the closest acetal sheave. My most humble apologies for not being able to give you the answer you sought. Seriously, this is one of those, "You pays your money, you takes your chances," sort of decisions that nobody else can really make for you. I thought the suggestion from someone else to talk to your rigger about it was spot on. For my own part, I don't like putting plastic parts anyplace where I can't inspect them on a regular basis, and would always choose metal sheaves if at all possible. |
Sheave material
Perhaps I didn't state that clearly. I place a high value on serious replies
here. I wasn't complaining over just one response, or the quality of it. I'm not asking others to make my decision for me; but why try to reinvent the wheel ? The idea of newsgroups is to share experience, I assume. "KLC Lewis" wrote in message et... "Garland Gray" wrote in message ... Frankly, I thought I'd get a better answer here. It's really moot now, because I have a choice of GFN for only one size sheave(I need 3 different sheaves) . I'll probably get it and try it because the size might be better than the closest acetal sheave. My most humble apologies for not being able to give you the answer you sought. Seriously, this is one of those, "You pays your money, you takes your chances," sort of decisions that nobody else can really make for you. I thought the suggestion from someone else to talk to your rigger about it was spot on. For my own part, I don't like putting plastic parts anyplace where I can't inspect them on a regular basis, and would always choose metal sheaves if at all possible. |
Sheave material
On Tue, 3 Feb 2009 20:35:39 -0500, "Garland Gray"
wrote: The idea of newsgroups is to share experience, I assume. In a way, that is what I was doing. Perhaps I'm fortunate to have a really good rigger that has given me a *lot* of incredibly good advice over the years. He sees hundreds of different boats and rigging issues every year, getting far more experience with such things than I ever will. He also has a direct pipeline to all of the engineering folks behind the different products that he services. |
Sheave material
On Tue, 3 Feb 2009 20:35:39 -0500, "Garland Gray"
wrote: The idea of newsgroups is to share experience, I assume. In a way, that is what I was doing. Perhaps I'm fortunate to have a really good rigger that has given me a *lot* of incredibly good advice over the years. He sees hundreds of different boats and rigging issues every year, getting far more experience with such things than I ever will. He also has a direct pipeline to all of the engineering folks behind the different products that he services. |
Sheave material
"Garland Gray" wrote in message ... Perhaps I didn't state that clearly. I place a high value on serious replies here. I wasn't complaining over just one response, or the quality of it. I'm not asking others to make my decision for me; but why try to reinvent the wheel ? The idea of newsgroups is to share experience, I assume. Well, FWIW Harken uses Delrin sheaves in most, if not all, of their midrange and smaller blocks, and at least many of their Big Boat range as well. I'm not sure if they use metal sheaves at all any more. I've used their blocks for the past fifteen years and have never had one fail on me. The delrin cheeks will discolor over time, going from black to dark grey, but it doesn't seem to harm them. I like Garhauer for their "all metal" policy, but I have bought quite a few Harkens over the years and have never regretted it. You can get them about anywhere there's boats, and there's a lot to be said for that convenience. |
Sheave material
On Tue, 3 Feb 2009 22:15:06 -0600, "KLC Lewis"
wrote: I'm not asking others to make my decision for me; but why try to reinvent the wheel ? The idea of newsgroups is to share experience, I assume. Well, FWIW Harken uses Delrin sheaves in most, if not all, of their midrange and smaller blocks, and at least many of their Big Boat range as well. I'm not sure if they use metal sheaves at all any more. I've used their blocks for the past fifteen years and have never had one fail on me. The delrin cheeks will discolor over time, going from black to dark grey, but it doesn't seem to harm them. I like Garhauer for their "all metal" policy, but I have bought quite a few Harkens over the years and have never regretted it. You can get them about anywhere there's boats, and there's a lot to be said for that convenience. When I was racing on big boats (50+ ft) most of the sheets and guys had wire tails. With wire a metal sheave is absolutely necessary. |
Sheave material
"Wayne.B" wrote in message ... When I was racing on big boats (50+ ft) most of the sheets and guys had wire tails. With wire a metal sheave is absolutely necessary. Wire tails on sheets have to be hard on the hands. But you're right, they'd destroy plastic in short order. |
Sheave material
On Jan 31, 9:35*am, "Garland Gray" wrote:
I need to replace some old plastic sheaves, and I have the option of sheaves made of Delrin, acetal, or glass filled nylon. (I have learned that delrin is acetal, *but don't know if all acetal sheaves are delrin). So what are the relative attributes of acetal and glass filled nylon sheaves? I read somewhere that GFN might be more abrasive on the pin, but I assume that it is stronger. Ronstan sells both, but their website doesn't solicit questions. Nylon is very susceptible to UV degradation, but low friction. Don't use it unless the part is both shielded from sunlight, and gets a lot of running wear. Acetal is somewhat harder, better at resisting UV, slightly higher friction, costs more. It seems likely to me that a drop-in replacement for a specific sheave will only be available in the material that specific mfg'r choses. Fresh Breezes- Doug King |
Sheave material
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Sheave material
"KLC Lewis" wrote in message
et... "Wayne.B" wrote in message ... When I was racing on big boats (50+ ft) most of the sheets and guys had wire tails. With wire a metal sheave is absolutely necessary. Wire tails on sheets have to be hard on the hands. But you're right, they'd destroy plastic in short order. I remember long ago, when I re-rigged by Cal 20 it had sheaves specifically for wire. I switched to spectra and switched the sheaves to Delrin, which I took to be the standard. I recall there are also aluminim sheaves that accept both line and wire. Delrins are injection molded, so I'd think that there might be some inconsistencies in them from time to time. I believe the GFN sheaves are also injection molded but stronger. Looks like there are also Delrin GFNs... :-) http://www.jacoproducts.com/materials/thermoplastic.htm -- "j" ganz @@ www.sailnow.com |
Sheave material
"Capt. JG" wrote in message .. . I remember long ago, when I re-rigged by Cal 20 it had sheaves specifically for wire. I switched to spectra and switched the sheaves to Delrin, which I took to be the standard. I recall there are also aluminim sheaves that accept both line and wire. Delrins are injection molded, so I'd think that there might be some inconsistencies in them from time to time. I believe the GFN sheaves are also injection molded but stronger. Looks like there are also Delrin GFNs... :-) http://www.jacoproducts.com/materials/thermoplastic.htm -- "j" ganz @@ www.sailnow.com Both my CT-41 (first boat) and my Rawson 30 (current boat) had wire crab winches for the main and jib halyards when I bought them. The first thing I did was to replace those wrist-breakers and get rid of all those fish hooks. Now with the ultra-low-stretch super-strong lines being available in small diameter, I have to wonder whether wire tails couldn't be replaced with the new technology. No fish hooks, anyway. But I still loath crab winches. |
Sheave material
"KLC Lewis" wrote in message
et... "Capt. JG" wrote in message .. . I remember long ago, when I re-rigged by Cal 20 it had sheaves specifically for wire. I switched to spectra and switched the sheaves to Delrin, which I took to be the standard. I recall there are also aluminim sheaves that accept both line and wire. Delrins are injection molded, so I'd think that there might be some inconsistencies in them from time to time. I believe the GFN sheaves are also injection molded but stronger. Looks like there are also Delrin GFNs... :-) http://www.jacoproducts.com/materials/thermoplastic.htm -- "j" ganz @@ www.sailnow.com Both my CT-41 (first boat) and my Rawson 30 (current boat) had wire crab winches for the main and jib halyards when I bought them. The first thing I did was to replace those wrist-breakers and get rid of all those fish hooks. Now with the ultra-low-stretch super-strong lines being available in small diameter, I have to wonder whether wire tails couldn't be replaced with the new technology. No fish hooks, anyway. But I still loath crab winches. I was fortunate that the previous owner of the Sabre dealt with those sorts of issues. How did you like the CT? I had a very pleasant trip on a slightly larger version (48) some years ago. Didn't much like the hydraulic steering, but other than that, it was a nice boat. -- "j" ganz @@ www.sailnow.com |
Sheave material
"Capt. JG" wrote in message easolutions... I was fortunate that the previous owner of the Sabre dealt with those sorts of issues. How did you like the CT? I had a very pleasant trip on a slightly larger version (48) some years ago. Didn't much like the hydraulic steering, but other than that, it was a nice boat. -- "j" ganz @@ www.sailnow.com We had the pilothouse version, ketch rigged (I'm a dyed-in-the-wool ketchie), 1972 model IIRC. It sailed very well, very seakindly and no bad habits. Full keel, of course, very thick and heavy glass, displaced about 28,000 dry and empty. It had Edison quadrant steering, not hydraulic, and rudder feel was adequate although I still prefer a tiller. If I had it all to do over again, I wouldn't go pilothouse as it gives up entirely too much living space for the inside helm which is of questionable value. The pilothouse version also puts the engine under the saloon sole, which is raised to accomodate it, which is the primary cause of the reduced living space. And I would seriously inspect that puppy, looking for any dryrot in the deck core and house -- ours was in bad shape and we had to completely rebuild the deckhouse. But it's hard to beat a William Garden design for good sailing. Kind of a handful for single-handing, though, as she was rigged. But that could be fixed easily enough. |
Sheave material
KLC Lewis wrote:
"Capt. JG" wrote in message easolutions... I was fortunate that the previous owner of the Sabre dealt with those sorts of issues. How did you like the CT? I had a very pleasant trip on a slightly larger version (48) some years ago. Didn't much like the hydraulic steering, but other than that, it was a nice boat. -- "j" ganz @@ www.sailnow.com We had the pilothouse version, ketch rigged (I'm a dyed-in-the-wool ketchie), 1972 model IIRC. You know what they say about ketches. Once you've owned one, you'll never own another one! Heh heh Gordon, P365 ketch |
Sheave material
KLC Lewis wrote:
"Garland Gray" wrote in message ... Perhaps I didn't state that clearly. I place a high value on serious replies here. I wasn't complaining over just one response, or the quality of it. I'm not asking others to make my decision for me; but why try to reinvent the wheel ? The idea of newsgroups is to share experience, I assume. From Brion Toss's book Loads on the sheave itself are not so concentrated as those on the bearing, but sheave material can be important relative to cost, weight, and stability under load. Nylon, for instance, is very cheap and light but can distort under heavy load. Worse, it swells when wet, increasing sidewall friction. Delrin sheaves are more stable and nearly as cheap, making a good medium duty sheave. Bronze, stainless, and aluminum sheaves are heavy and expensive, but will stand up to extremes. On sheave shape Sheave score profile, Semicircular for three strand and common braid. Flat bottomed for kevlar V grooved or semicircular with a notch for wire and rope Gordon |
Sheave material
"KLC Lewis" wrote in message
et... "Capt. JG" wrote in message easolutions... I was fortunate that the previous owner of the Sabre dealt with those sorts of issues. How did you like the CT? I had a very pleasant trip on a slightly larger version (48) some years ago. Didn't much like the hydraulic steering, but other than that, it was a nice boat. -- "j" ganz @@ www.sailnow.com We had the pilothouse version, ketch rigged (I'm a dyed-in-the-wool ketchie), 1972 model IIRC. It sailed very well, very seakindly and no bad habits. Full keel, of course, very thick and heavy glass, displaced about 28,000 dry and empty. It had Edison quadrant steering, not hydraulic, and rudder feel was adequate although I still prefer a tiller. If I had it all to do over again, I wouldn't go pilothouse as it gives up entirely too much living space for the inside helm which is of questionable value. The pilothouse version also puts the engine under the saloon sole, which is raised to accomodate it, which is the primary cause of the reduced living space. And I would seriously inspect that puppy, looking for any dryrot in the deck core and house -- ours was in bad shape and we had to completely rebuild the deckhouse. But it's hard to beat a William Garden design for good sailing. Kind of a handful for single-handing, though, as she was rigged. But that could be fixed easily enough. I like the ketch model also... almost bought a Pearson 356. -- "j" ganz @@ www.sailnow.com |
Sheave material
"Gordon" wrote in message m... You know what they say about ketches. Once you've owned one, you'll never own another one! Heh heh Gordon, P365 ketch Ya, it's a "Ketch as ketch can" situation. lol |
Sheave material
Thanks all.
I will be trying the GFN for one sheave anyway, but will get a delrin alternate as well . Size may determine which ends up being used, as they bracket the original sheave in diameter. "Garland Gray" wrote in message ... Frankly, I thought I'd get a better answer here. It's really moot now, because I have a choice of GFN for only one size sheave(I need 3 different sheaves) . I'll probably get it and try it because the size might be better than the closest acetal sheave. "Wayne.B" wrote in message ... On Sat, 31 Jan 2009 09:35:42 -0500, "Garland Gray" wrote: I need to replace some old plastic sheaves, and I have the option of sheaves made of Delrin, acetal, or glass filled nylon. (I have learned that delrin is acetal, but don't know if all acetal sheaves are delrin). So what are the relative attributes of acetal and glass filled nylon sheaves? I read somewhere that GFN might be more abrasive on the pin, but I assume that it is stronger. Ronstan sells both, but their website doesn't solicit questions. Why not give Ronstan or your local rigger a call and find out the pros and cons of each? |
Sheave material
Garland Gray wrote:
Thanks all. I will be trying the GFN for one sheave anyway, but will get a delrin alternate as well . Size may determine which ends up being used, as they bracket the original sheave in diameter. Garland, do you have a machinist friend, or maybe a hobbiest friend with a lathe? Making a sheave from a chunk of Delrin is trivial, or aluminum, or brass, stainless is a bit trickier, not to mention expensive. Cheers Martin (have lathe, will travel) |
Sheave material
Well, I do have access to "country" machine shop that is reasonble, but I
think I can find a stock size close enough, maybe even be more suitable than the original. "Marty" wrote in message ... Garland Gray wrote: Thanks all. I will be trying the GFN for one sheave anyway, but will get a delrin alternate as well . Size may determine which ends up being used, as they bracket the original sheave in diameter. Garland, do you have a machinist friend, or maybe a hobbiest friend with a lathe? Making a sheave from a chunk of Delrin is trivial, or aluminum, or brass, stainless is a bit trickier, not to mention expensive. Cheers Martin (have lathe, will travel) |
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