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capperbar
03-11-2003, 12:01 AM
I need some tips on replacing the shafts and rebushing the 6-8" sheaves on some blocks from a 127 feet gaff rigged schooner. I have begun by replacing the bronze bushing in a bronze sheave and making a new shaft from 7/8ths oil hardening drill rod. Several questions, Best shaft clearance in bushing? Best grease? Best shaft material? Why not some kind of stainless with the bronze bushings? Would it be reasonable to bronze bush the cast iron sheaves that run in steel shafts. Oil impregnated bushings? Also any suggestions for best wood to replace the cheeks? Any obvious question I missed? These blocks are all torn down annually and regreased. By the way,the Captian says they have the most problems with the new ones they have bought. Best count is about 60 blocks. Sorry for so many questions?
Thanks Sav

wierdscience
03-11-2003, 12:12 AM
Regardless of the grease I would recomend 316s/s shafts also I have had excellent results in doing away with the bronze bushings and replacing them with full compliment s/s needle bearings and inner races.Then use bronze flat washers on either side for the thrust /side loadThey will carry more load and will require less maitainance.As for the wood Teak would be ideal but the new stuff you get now a days is plantation grown.The best qualities to look for is a heavy dense wood that is also oily so it will hold up to the weather with out checking badly.I have used Purple Heart before with good results,Lignum Vitae is ideal as well but is very expensive at this moment it is selling for $6 a pound and it is heavy

Thrud
03-11-2003, 12:50 AM
Sav

A good water resistant grease such as Amsoils GWR or their High temp Synthetic Food Grade grease (Check with their technical department www.amsoil.com (http://www.amsoil.com) tell them if it is being used in salt water or fresh) should do the trick - good stuff.

capperbar
03-11-2003, 11:45 PM
Wierdscience,
Thanks for the stainless number, I will use it next. Probably stick to the Bronze bushings for now.
Thrud,
Glad your feeling better. I will look into the AMSOIL.

Any idea if going to the oil impregnated bronze would help.

Thanks Sav

wierdscience
03-12-2003, 12:08 AM
Yes it probibly will I have seen the sae 932 bronze cut soft shafts before as well as plain brass.

Uncle Dunc
03-12-2003, 06:32 AM
>> ... but the new stuff you get now a days is plantation grown.

Why is that a problem?

Forrest Addy
03-12-2003, 09:44 AM
Is this a salt water vessel or some weenie inland toy?

Stainless and coller alloys don't get alont in the presence of strong electrolytes like salt water. Stainless against bronze forms a galvanic couple.

For salt water, I'd reccommend silicon bronze pins and oilite or bearing grade plastic bushings. This combination would be galvanically neutral.

capperbar
03-12-2003, 11:29 AM
<font face="Verdana, Arial" size="2">Originally posted by Forrest Addy:
Is this a salt water vessel or some weenie inland toy?

Stainless and coller alloys don't get alont in the presence of strong electrolytes like salt water. Stainless against bronze forms a galvanic couple.

For salt water, I'd reccommend silicon bronze pins and oilite or bearing grade plastic bushings. This combination would be galvanically neutral.</font>

capperbar
03-12-2003, 11:40 AM
Forrest,
It is for the 127ft schooner Zodiac in Lake Union(Seattle)now. She is on saltwater most of the season and may go to Portland Oregon this year and was part of the Tall ships last year in San Francisco last summer.I think she is the largest sailing wooden vessel on the west coast.

For the short term would drill rod be better or worse than stainless?
Thanks, Sav in Seattle

QUOTE]Originally posted by Forrest Addy:
Is this a salt water vessel or some weenie inland toy?

Stainless and coller alloys don't get alont in the presence of strong electrolytes like salt water. Stainless against bronze forms a galvanic couple.

For salt water, I'd reccommend silicon bronze pins and oilite or bearing grade plastic bushings. This combination would be galvanically neutral.[/QUOTE]

Forrest Addy
03-12-2003, 02:01 PM
Definitely not drill rod. Tool steel rusts freely. salt water rust swell to 2 1/2 times its original volume. Use stainless or silicon bronze pins preferably silicon bronze (everdur). It won't be that much more expensive than drill rod

KACHINKOO
03-12-2003, 06:24 PM
capperbar, I have quite a few marine catalogs dating back to 1935 that sold blocks with bronze sheaves and stainless clevis pins. Edson, a well known company today will cast and machine any size bronze sheave you want. They recomend 316 stainless as the clevis because of the track record the two metals have in the salt enviornment. We have quite a few classic yachts at our boat yard with this same combination of metals. Some of the gear is 50 years+ with little corrosion, other boats have corroded extensivly. It's all in the maintenance and upkeep. As for the wood used for the cheeks, lignum vitae was used until it got to sparse, then teak till it got to expensive. White oak has been used extensivly with very good results. Small time operators today use teak or oak for custom blocks with bronze sheaves and s.s. cleves pins. Are these blocks for halyards, sheets, steering , or what? Dave

capperbar
03-12-2003, 09:26 PM
Kachinko,
The blocks(about 60) are for everything except steering. All sail handling is done by hand ie no power blocks. I believe all the blocks are old except a few, some date from 1927 when the boat was built and have been collected wherever possible and may be much older. The Gatlin blocks at the mast heads are new due to liablity reasons as they lift people.
www.schoonerzodiac.com (http://www.schoonerzodiac.com)
Try this link to see the sail plan.

Sounds like I need to get 316 stainless shafting to fit in bronze bushings for the bronze sheaves. Then should I use stainless clevis for the iron sheaves and would I be ok to bush them with bronze? All the blocks are torn down at the end of the season for repair and lubrication. The idea is to not just keep them going but upgrade them gradually. I will track down Edson. I have yet to explore the pile of dead blocks to see what can be salvaged.
Thanks for the help.
Sav
capperbar, I have quite a few marine catalogs dating back to 1935 that sold blocks with bronze sheaves and stainless clevis pins. Edson, a well known company today will cast and machine any size bronze sheave you want. They recomend 316 stainless as the clevis because of the track record the two metals have in the salt enviornment. We have quite a few classic yachts at our boat yard with this same combination of metals. Some of the gear is 50 years+ with little corrosion, other boats have corroded extensivly. It's all in the maintenance and upkeep. As for the wood used for the cheeks, lignum vitae was used until it got to sparse, then teak till it got to expensive. White oak has been used extensivly with very good results. Small time operators today use teak or oak for custom blocks with bronze sheaves and s.s. cleves pins. Are these blocks for halyards, sheets, steering , or what? Dave[/b]

wierdscience
03-12-2003, 09:50 PM
932 bronze works well with the stainless I wouldn't use oilite because it can be fairly brittle as it is sintered,as for the plantation grown Teak I like it ok for furniture but not for hardware the new stuff grows a lot faster than the old growth stuff and seems to have less oil.I have seen the white oak used after being soaked for a month in parafin wax cut 50/50 in kerosene.

Dave Opincarne
03-13-2003, 12:01 AM
SH*T the Zodiac? Realy? I'll help! Thats a historicly significant vesal, by all means do your research and keep the materials as close to authentic as possible. Call the people at Alaskan Copper and get their input. Also, is there anyone at CWB who has any ideas.

x39
03-13-2003, 01:37 PM
<font face="Verdana, Arial" size="2">Originally posted by wierdscience:
I wouldn't use oilite because it can be fairly brittle </font>

I agree with this, stick to a tougher grade of bronze. I have rebuilt quite a few towing blocks for commercial fishing vessels, and have had good luck using 4140HT for the shafts. Rust is generally not an issue, since they are kept well greased.

[This message has been edited by x39 (edited 03-13-2003).]

x39
03-13-2003, 06:45 PM
Sorry, double post.

[This message has been edited by x39 (edited 03-13-2003).]