Hi All, Amother mast question here: I have external haylards right now and I am converting my arrangement to run the halyards inside the mast. My masthead casting is sealed at the top - I have 4 working halyard sheeves - 2 for the main and 2 for the headsail arranged on 2 SS pins...they are mouted 2 per pin side-by-side. I am planning on buying 2 ball-bearing sheeves (1 main/ 2 head sail) - then I plan on drilling a 3/4" hole directly under the sheeve (where the line rounds out) in the masthead casting to allow the halyard to run down through the mast...what do you guys think of that? How big of a hole do I need for 3/8" halyrd? Then, should I center the single ball-bearing sheeve and make some type of sleeve to hold each centered? Or use one of the old sheevs as a dummy and off-center the hole. Hope this makes sense....thx! Rob
Masthead Casting - Running Halyards Internal
- Thread starter Rob19574
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Not sure I understand. Most masthead sheeves allow the halyard to run straight down inside the mast. If you are adding external sheeves, then the halyard can enter the mast a couple of feet below the block. You will need to install an exit plate to minimize chafe. The exit plate will determine the size of the hole that you will cut.
masthead casting
Do you have the old casting off the mast? Is the splitter part of the casting or is it a separate plate?
Do you have the old casting off the mast? Is the splitter part of the casting or is it a separate plate?
Casting is off
The masthead casting is off. It is one solid piece but seems to perhaps have some type of casting-line down the center of it (from bow to stern). Maybe it was a weld but it is a very clean line (if it was welded). As mentioned, the masthead casting is sealed along the top and the old sheeves allowed the halyards to run up, over and back down the opposite side of the mast....4 sheeves for 2 halyards. I want to convert to 1 sheeve per halyard and have the line route over and then DOWN into the mast. Thanks - Rob
The masthead casting is off. It is one solid piece but seems to perhaps have some type of casting-line down the center of it (from bow to stern). Maybe it was a weld but it is a very clean line (if it was welded). As mentioned, the masthead casting is sealed along the top and the old sheeves allowed the halyards to run up, over and back down the opposite side of the mast....4 sheeves for 2 halyards. I want to convert to 1 sheeve per halyard and have the line route over and then DOWN into the mast. Thanks - Rob
Ball bearing sheaves not a good idea.
Rob: I spoke with a couple of hardware companies and they did not recommend using ball bearing sheaves in the mast. Their reasoning was because of the high load on a device that was typically in a static position. This is different than a deck organizer that has lighter loads and is constantly being adjusted. I would also be conserned about drilling a casting and possibility of weaking or cracking the casting. Have you considered trying to purchase the correct casting for the mast head?
Rob: I spoke with a couple of hardware companies and they did not recommend using ball bearing sheaves in the mast. Their reasoning was because of the high load on a device that was typically in a static position. This is different than a deck organizer that has lighter loads and is constantly being adjusted. I would also be conserned about drilling a casting and possibility of weaking or cracking the casting. Have you considered trying to purchase the correct casting for the mast head?
Catalina Direct
The masthead truck is $203 The Sheaves are $50 Catalina Direct are good folk to deal with.
The masthead truck is $203 The Sheaves are $50 Catalina Direct are good folk to deal with.
Masthead thoughts
Many masthead castings are open at the bottom, and it is common for the halyards to pass over a single sheave and run down inside the mast, so I cannot see how drilling an oversized hole for your halyards will compromise the strength of the casting. There is not much stress on its base, except for the area around the flange. In fact, you may want to drill additional holes where the other sheaves are in case you want to run more lines internally in the future. I would chamfer, smooth, and polish the holes. Centering everything will be more work, won't gain much advantage, and will lose the potential of putting the other sheaves to work in the future. Plus, with the jib and main sheaves off center, they will tend to run a little more fair of each other. Steve makes a good point about the bearings - in fact, you could drill out or replace the sheaves so that oversize pins could be used. It would also be a good idea to put a small amount of good synthetic grease on the bearing surfaces. Use top notch materials and of course check everything closely whenever the mast is down.
Many masthead castings are open at the bottom, and it is common for the halyards to pass over a single sheave and run down inside the mast, so I cannot see how drilling an oversized hole for your halyards will compromise the strength of the casting. There is not much stress on its base, except for the area around the flange. In fact, you may want to drill additional holes where the other sheaves are in case you want to run more lines internally in the future. I would chamfer, smooth, and polish the holes. Centering everything will be more work, won't gain much advantage, and will lose the potential of putting the other sheaves to work in the future. Plus, with the jib and main sheaves off center, they will tend to run a little more fair of each other. Steve makes a good point about the bearings - in fact, you could drill out or replace the sheaves so that oversize pins could be used. It would also be a good idea to put a small amount of good synthetic grease on the bearing surfaces. Use top notch materials and of course check everything closely whenever the mast is down.
Mast Trucks
On mast trucks that were not designed for internal halyards the base that fits the mast section has no holes. This keeps water out of the mast and forms the bottom of the load carrying beam. The rigging loads transfer from the sides that hold the sheaves to the mast through the base. The top of the truck and the base form the top and bottom sides of a beam. The rigging loads from the forestay and backstay put the top of the truck in tension and the base in compression. The sides that hold the sheaves are the sides of the box section beam. When you cut a big assed hole in one side of the beam the loads have to transfer somewhere. The sides have to be thicker to compensate for the lost compression area of the bottom of the beam. You have two choices. 1. Bet that the truck was so over-engineered that cutting a hole in the base for halyards won't cause a failure. Further bet that the hole won't cause a local stress riser that will cause the truck to fail. 2. Change the truck for one that was designed for internal halyards (or have one built). Cat 30's use 1/2" diameter pins for the sheaves as well as the forestay and backstay pins. No way in a halyard going to stress a pin more than the rig. The 30 year old sheaves show no wear or signs of failure. Chances are that the truck won't fail after the centre is hogged out for the halyards ... but ... if the mast does come down and the truck is broken, what chance is there that your insurance adjuster won't point to the modified truck and deny the claim? $203 for a new truck vs DIY engineering is a no brainer for me. Not spending $150 for BB sheaves you don't need makes the cost of the truck $53.
On mast trucks that were not designed for internal halyards the base that fits the mast section has no holes. This keeps water out of the mast and forms the bottom of the load carrying beam. The rigging loads transfer from the sides that hold the sheaves to the mast through the base. The top of the truck and the base form the top and bottom sides of a beam. The rigging loads from the forestay and backstay put the top of the truck in tension and the base in compression. The sides that hold the sheaves are the sides of the box section beam. When you cut a big assed hole in one side of the beam the loads have to transfer somewhere. The sides have to be thicker to compensate for the lost compression area of the bottom of the beam. You have two choices. 1. Bet that the truck was so over-engineered that cutting a hole in the base for halyards won't cause a failure. Further bet that the hole won't cause a local stress riser that will cause the truck to fail. 2. Change the truck for one that was designed for internal halyards (or have one built). Cat 30's use 1/2" diameter pins for the sheaves as well as the forestay and backstay pins. No way in a halyard going to stress a pin more than the rig. The 30 year old sheaves show no wear or signs of failure. Chances are that the truck won't fail after the centre is hogged out for the halyards ... but ... if the mast does come down and the truck is broken, what chance is there that your insurance adjuster won't point to the modified truck and deny the claim? $203 for a new truck vs DIY engineering is a no brainer for me. Not spending $150 for BB sheaves you don't need makes the cost of the truck $53.
a little more info would help
rob; i moved all my halyards internal. O'Day 30, 1979 model. what model are we talking about here? a picture would help.
rob; i moved all my halyards internal. O'Day 30, 1979 model. what model are we talking about here? a picture would help.
mast on 30 catalina probably similar to o'day
as i recall mast on catalina is similar in that they are both mast hd rigs and the size of tele poles. mine had four sheaves that were mounted in the mast head fitting . the halyards at the time were run over two sheaves. one to the head sail and the other to the main. it sounds as though your set up is similar to the setups on older C&C's. i would be leary about cutting into mast head fitting. either buy the proper mast head fitting or do the alternative of getting mast entry fittings from harken. mine is set up now with 5 halyards 2 mains, 2 headsail and spinaker. since the spin is external on a ring like fitting on the front of the mast fitting i cut a slot for the entry into the mast about 18" below top of mast. this fitting has 2 sheaves one on top and one on bottom. top sheave guides halyard into mast and lower guides it down inside. fitting is about 25 bucks or so. older c&c's had all halyards set up in this manner.harken specs will tell you the correct size fitting to use for a given line size.one caviet to keep in mind when putting halyards into mast is to be sure lines inside don't get crossed or cross over thru bolt at spreader incorrectly. if they do, then some binding may occur. you will also have to cut slots in lower end of mast for exit plates. these all need to be staggered so as not to weaken lower end of mast. i would'nt recommend entry plates for the top. i looked in west catalog and numbers are harken #089 and #134. i would'nt consider non ball bearing sheaves because of added friction.
as i recall mast on catalina is similar in that they are both mast hd rigs and the size of tele poles. mine had four sheaves that were mounted in the mast head fitting . the halyards at the time were run over two sheaves. one to the head sail and the other to the main. it sounds as though your set up is similar to the setups on older C&C's. i would be leary about cutting into mast head fitting. either buy the proper mast head fitting or do the alternative of getting mast entry fittings from harken. mine is set up now with 5 halyards 2 mains, 2 headsail and spinaker. since the spin is external on a ring like fitting on the front of the mast fitting i cut a slot for the entry into the mast about 18" below top of mast. this fitting has 2 sheaves one on top and one on bottom. top sheave guides halyard into mast and lower guides it down inside. fitting is about 25 bucks or so. older c&c's had all halyards set up in this manner.harken specs will tell you the correct size fitting to use for a given line size.one caviet to keep in mind when putting halyards into mast is to be sure lines inside don't get crossed or cross over thru bolt at spreader incorrectly. if they do, then some binding may occur. you will also have to cut slots in lower end of mast for exit plates. these all need to be staggered so as not to weaken lower end of mast. i would'nt recommend entry plates for the top. i looked in west catalog and numbers are harken #089 and #134. i would'nt consider non ball bearing sheaves because of added friction.
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