My 10 year old boat is on the hard for the winter. The mast is down on saw-horses and I am replacing all the wiring and reconditioning my in-mast furler. There were some things attached to the mast and furling drum that were attached w/ aluminum rivets. I believe that if this project is ever done again (by the next owner), it would be easier if some of these parts were attached with screws rather than rivets. Is aluminum too soft to tap for screws and do I need a tap/die set or will self tapping screws thread their own holes? Also, I used pretty heavy "boat wire" for the electronics. I need to splice the common wire for the anchor light, steaming light, and deck lights together inside the mast and remove the other wires from their protective rubber casings to achieve a fit for my four wire connector through the deck. What would be the best way to establish a new protective casing for the four 16 ga. wires where they leave the mast and connect to the connector?
screws in aluminum/mast electronics
- Thread starter Bill C320 Papillon
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Screws...
assuming you mean threaded screws, not the sheet metal kind. Thick aluminum will take a tapped thread nicely. I haven't used "self-tapping" types but it seems to me that they may cause a problem if they don't thread cleanly--a tap is a sure thing. Stainless in aluminum can create galvanic reaction and deterioration (the "white powder" breakdown)--use a grease on the threads to minimize this. Also, if attaching something of stainless, go to the trouble of making a backing washer of the same size from a plastic milk or water jug to minimize any galvanic pitting as well.
assuming you mean threaded screws, not the sheet metal kind. Thick aluminum will take a tapped thread nicely. I haven't used "self-tapping" types but it seems to me that they may cause a problem if they don't thread cleanly--a tap is a sure thing. Stainless in aluminum can create galvanic reaction and deterioration (the "white powder" breakdown)--use a grease on the threads to minimize this. Also, if attaching something of stainless, go to the trouble of making a backing washer of the same size from a plastic milk or water jug to minimize any galvanic pitting as well.
Rivets ...
I'm a little surprised that you have aluminum rivets attaching things to your mast. Isn't it normal for stainless steel parts to be attached with stainless steel rivets? I am not sure that SS screws are easier to remove than rivets. It seems to me that rivets can be easily drilled out without destroying the integrity of the hole when you use the right size bit. Last year when I was removing some parts on my boom that were attached with SS screws, they were seized so tight that I snapped the heads off 2 of them. It was a real bitch drilling out the remainder of the screw and it left holes that were larger than the original which I then had to repair. Be very carefull that you don't make my mistake (use a good penetrating oil and an impact driver helps)! I think aluminum rivets are very easy to drill out and replace. I am not sure how appropriate they are for use as I think they don't have the strength needed for many applications. The aluminum wall of the mast will have no problem supporting the SS screw but I agree with Dan that the tapped hole is a sure thing as opposed to a self tapping thread. I used a few last summer that didn't tighten properly and I am going to change them out this winter.
I'm a little surprised that you have aluminum rivets attaching things to your mast. Isn't it normal for stainless steel parts to be attached with stainless steel rivets? I am not sure that SS screws are easier to remove than rivets. It seems to me that rivets can be easily drilled out without destroying the integrity of the hole when you use the right size bit. Last year when I was removing some parts on my boom that were attached with SS screws, they were seized so tight that I snapped the heads off 2 of them. It was a real bitch drilling out the remainder of the screw and it left holes that were larger than the original which I then had to repair. Be very carefull that you don't make my mistake (use a good penetrating oil and an impact driver helps)! I think aluminum rivets are very easy to drill out and replace. I am not sure how appropriate they are for use as I think they don't have the strength needed for many applications. The aluminum wall of the mast will have no problem supporting the SS screw but I agree with Dan that the tapped hole is a sure thing as opposed to a self tapping thread. I used a few last summer that didn't tighten properly and I am going to change them out this winter.
heat shrink
you could try heat shrink tubing for your wires. you can get it at any auto parts store
you could try heat shrink tubing for your wires. you can get it at any auto parts store
Happy New Year ...
1st question, how big is the boat? (Actually, how long is the mast?) Rule #1 running lights require a circuit with less than 3% voltage drop. Depending on the wattage and placement of the lights (masthead and anchor), 16 GA may not be big enough. Rule #2 running light circuits should not share a ground, least of all inside the mast. Connections are the prime source of failure, it is not good practice to place connections in hard to reach places (like inside masts). A 4 pin connector will handle two circuits, not three. *IF* the total load of all the lights creates less than a 3% voltage drop, you might be able to get a survey on the circuit with the spliced grounds, *IF* it was easy to replace the main ground from the mast to the splice. That means running a ground to the buss bar and three separate wires inside the mast. You can then make the argument that the anchor light and masthead light are not used at the same time so the single ground is okay. Voltage drop to the deck light can be 10% so the same ground for both the masthead light and the deck light is okay. Now that we have splicing the ground wires inside the mast covered, on to screws and aluminum. Aluminum rivets are great for things that do not take a load. Fixing conduit inside the mast is a perfect place for Aluminum rivets. For anything that might ever have to be removed for service, replacement, or refinishing, drill and tap. Self tapping "sheet metal" screws have no place on booms or masts, they are the mark of cost cutting factories, amateur repairs, and they snag halyards and reef lines. Placing a barrier between SS parts and the mast or boom is best practice. As is coating the threads of the fasteners with a barrier (Tef-Gel or Lanacote). the gasket of milk cartoon is a nice idea that I hadn't heard of before. May I steal it for my bag of tricks?
A single layer of electrical tape works well as does a layer of liquid neoprene. If you keep the boat another 10 years, you will be happy you did it right. If you sell the boat, you will have the satisfaction that you have not become the cursed "PO"
1st question, how big is the boat? (Actually, how long is the mast?) Rule #1 running lights require a circuit with less than 3% voltage drop. Depending on the wattage and placement of the lights (masthead and anchor), 16 GA may not be big enough. Rule #2 running light circuits should not share a ground, least of all inside the mast. Connections are the prime source of failure, it is not good practice to place connections in hard to reach places (like inside masts). A 4 pin connector will handle two circuits, not three. *IF* the total load of all the lights creates less than a 3% voltage drop, you might be able to get a survey on the circuit with the spliced grounds, *IF* it was easy to replace the main ground from the mast to the splice. That means running a ground to the buss bar and three separate wires inside the mast. You can then make the argument that the anchor light and masthead light are not used at the same time so the single ground is okay. Voltage drop to the deck light can be 10% so the same ground for both the masthead light and the deck light is okay. Now that we have splicing the ground wires inside the mast covered, on to screws and aluminum. Aluminum rivets are great for things that do not take a load. Fixing conduit inside the mast is a perfect place for Aluminum rivets. For anything that might ever have to be removed for service, replacement, or refinishing, drill and tap. Self tapping "sheet metal" screws have no place on booms or masts, they are the mark of cost cutting factories, amateur repairs, and they snag halyards and reef lines. Placing a barrier between SS parts and the mast or boom is best practice. As is coating the threads of the fasteners with a barrier (Tef-Gel or Lanacote). the gasket of milk cartoon is a nice idea that I hadn't heard of before. May I steal it for my bag of tricks?
A single layer of electrical tape works well as does a layer of liquid neoprene. If you keep the boat another 10 years, you will be happy you did it right. If you sell the boat, you will have the satisfaction that you have not become the cursed "PO" Scott
The rivets I am talking about only hold aluminum parts to aluminum surfaces. They don't function to retain any parts that have stresses applied. I agree that usually drilling out rivets, especially aluminum rivets, is pretty easy except when they are located inside the mast and the only access is through a small inspection plate. In this case, a screw driver will work much easier. I was however thinking in terms of aluminum screws and now that you mention it, I'm not sure that such a thing exists.
The rivets I am talking about only hold aluminum parts to aluminum surfaces. They don't function to retain any parts that have stresses applied. I agree that usually drilling out rivets, especially aluminum rivets, is pretty easy except when they are located inside the mast and the only access is through a small inspection plate. In this case, a screw driver will work much easier. I was however thinking in terms of aluminum screws and now that you mention it, I'm not sure that such a thing exists.
Moody
I'm obviously no whiz when it comes to electronics so you have got my attention. Let me try and provide more details and your advice will be appreciated. The boat is an Oceanis 281 and the mast is about 34'. The anchor light (Aqua Signal series 20) draws 1.5 amps. The steaming/deck light fixture (Aqua Signal series 25) is mounted about half way up the mast. If the steaming and deck lights were on at the same time, they would draw about 1 amp. There are 2 wires (a red and a black) out of the masthead anchor light and a black, red, and a blue wire for the steaming/deck fixture. The blue goes to the deck light, the red to the steaming light, and the black goes to both. All these wires appear to be 16 ga. My plan was to splice the blacks from both fixtures together with a black "pigtail" that will exit the mast along with the red,yellow, and blue wires and these four would be attached to the 4 pin connector. The splice for the blacks would be made with solder and protected with heat shrink. Granted, the splice would be inside the mast but I don't see any other way to make use of the connector. Inside the cabin, the wires from the mast connect to the original wires which run about 6' to the electrical panel. I had not planned on changing any original equipment wiring. Again any help is appreciated. Thanks Bill
I'm obviously no whiz when it comes to electronics so you have got my attention. Let me try and provide more details and your advice will be appreciated. The boat is an Oceanis 281 and the mast is about 34'. The anchor light (Aqua Signal series 20) draws 1.5 amps. The steaming/deck light fixture (Aqua Signal series 25) is mounted about half way up the mast. If the steaming and deck lights were on at the same time, they would draw about 1 amp. There are 2 wires (a red and a black) out of the masthead anchor light and a black, red, and a blue wire for the steaming/deck fixture. The blue goes to the deck light, the red to the steaming light, and the black goes to both. All these wires appear to be 16 ga. My plan was to splice the blacks from both fixtures together with a black "pigtail" that will exit the mast along with the red,yellow, and blue wires and these four would be attached to the 4 pin connector. The splice for the blacks would be made with solder and protected with heat shrink. Granted, the splice would be inside the mast but I don't see any other way to make use of the connector. Inside the cabin, the wires from the mast connect to the original wires which run about 6' to the electrical panel. I had not planned on changing any original equipment wiring. Again any help is appreciated. Thanks Bill
Bill
Moody is correct in that any nav. lighting should be wired for a < 3% voltage drop. Remember that the size of the conductor is determined by the total length of the circuit, from the source to the load AND back again. The numbers you've provided indicate a total cct. length of 80 ft± : 16 Ga. wire is OK for the feeds for the two lights but a common return (ground) should be 12 Ga to remain under the 3% margin. I can't find my WM catalogue, but I think that Ancor makes a 4 cdr cable with one of the conductors of a heavier guage: this is probably designed specifically designed for precisely the application you have in mind. I can't see any problem with tapping into the ground wire at some intermediate point provided the connection is soldered and well insulated AND all the wires inside the mast are isolated from any possible abrasion from internal halyards etc.
Moody is correct in that any nav. lighting should be wired for a < 3% voltage drop. Remember that the size of the conductor is determined by the total length of the circuit, from the source to the load AND back again. The numbers you've provided indicate a total cct. length of 80 ft± : 16 Ga. wire is OK for the feeds for the two lights but a common return (ground) should be 12 Ga to remain under the 3% margin. I can't find my WM catalogue, but I think that Ancor makes a 4 cdr cable with one of the conductors of a heavier guage: this is probably designed specifically designed for precisely the application you have in mind. I can't see any problem with tapping into the ground wire at some intermediate point provided the connection is soldered and well insulated AND all the wires inside the mast are isolated from any possible abrasion from internal halyards etc.
TTand Moody
Thanks for your help and I'm really going to show my ignorance now. I assume that the black wires I plan to connect together are what you are calling the ground. If that is the case, and the blacks coming from the fixtures are 16 ga, what do I gain by using 12 ga to connect to them? The round trip run for the steaming/deck fixture is only about 43'. Would I still need the heavier gage wire for that?
Thanks for your help and I'm really going to show my ignorance now. I assume that the black wires I plan to connect together are what you are calling the ground. If that is the case, and the blacks coming from the fixtures are 16 ga, what do I gain by using 12 ga to connect to them? The round trip run for the steaming/deck fixture is only about 43'. Would I still need the heavier gage wire for that?
what do I gain by using 12 ga to connect to them?
Remember that the combined amperage that the two 16 ga wires are carrying is being carried on the single wire to the ground.
Remember that the combined amperage that the two 16 ga wires are carrying is being carried on the single wire to the ground.
Bill
The total length of the circuit determines voltage drop. The 16GA duplex to the masthead should be fine (Thanks TT for doing the math). What you gain in using a larger ga from the panel to the splice is lower voltage drop for that section of the circuit. If no two lights are in use at the same time, it probably is not an issue. I assume that the 4 wire plug is how the boat was wired from the factory? If the boat has a single 16ga running from the panel to the mast, I have to hope that Beneteau did the math and the circuit is within spec (they are pretty good at getting it right). If, however, Beneteau ran separate ground wires to the mast for the anchor and masthead(steaming) lights, it would be prudent to splice them together at the mast to double the cross sectional area of the return circuit. IIRC the ABYC standard says something to the effect that solder alone shall not be the sole means of connection of any wire. The standard requires positive mechanical fastening. This prohibits spade connectors and non-captive fork connectors at buss bars. There is some debate over soldered connections backed up with heat-shrink. If you can show that the circuit fails in the wire and not at the solder joint you are probably okay. It seems strange, but properly applied crimp connections have proved to be more reliable than solder joints. That said, I would go ahead and make a solder joint, cover the join with dielectric grease and put Ancor (marine grade) adhesive heat shrink over the joint. I'd call the adhesive heat-shrink my mechanical connection that relives the solder joint from mechanical load. For the exit of the new harness to the deck plug, I'd use the spiral plastic harness protector and layer or two of rigging tape. I'd want the harness to be flexible so that it would not create stress in the wires. I wish every DIY sailor worried about the details as you seem to be doing. The hack jobs I've seen are bad enough to make me want to strangle some owners (I know they meant well).
The total length of the circuit determines voltage drop. The 16GA duplex to the masthead should be fine (Thanks TT for doing the math).
What you gain in using a larger ga from the panel to the splice is lower voltage drop for that section of the circuit. If no two lights are in use at the same time, it probably is not an issue. I assume that the 4 wire plug is how the boat was wired from the factory? If the boat has a single 16ga running from the panel to the mast, I have to hope that Beneteau did the math and the circuit is within spec (they are pretty good at getting it right). If, however, Beneteau ran separate ground wires to the mast for the anchor and masthead(steaming) lights, it would be prudent to splice them together at the mast to double the cross sectional area of the return circuit. IIRC the ABYC standard says something to the effect that solder alone shall not be the sole means of connection of any wire. The standard requires positive mechanical fastening. This prohibits spade connectors and non-captive fork connectors at buss bars. There is some debate over soldered connections backed up with heat-shrink. If you can show that the circuit fails in the wire and not at the solder joint you are probably okay. It seems strange, but properly applied crimp connections have proved to be more reliable than solder joints. That said, I would go ahead and make a solder joint, cover the join with dielectric grease and put Ancor (marine grade) adhesive heat shrink over the joint. I'd call the adhesive heat-shrink my mechanical connection that relives the solder joint from mechanical load. For the exit of the new harness to the deck plug, I'd use the spiral plastic harness protector and layer or two of rigging tape. I'd want the harness to be flexible so that it would not create stress in the wires. I wish every DIY sailor worried about the details as you seem to be doing. The hack jobs I've seen are bad enough to make me want to strangle some owners (I know they meant well). PS, Bill
We all seemed to get fixated on the wiring issues and ignored the other question in your post. Aluminum screws are available but I would NOT recommend using them, especially in the location you described. They are quite weak and won't take much torque, so the chances of twisting the head off or deforming the slot is high. The aluminum alloy used in masts is hard enuf to provide a good clean thread if you drill & tap for a stainless machine screw. Self-tapping screws are not something I'd want to use. To prevent stainless fasteners from "welding" themselves into the aluminum, Loctite ( Red or Blue, depending on the fastener size ) should form a barrier between the stainless and the aluminum and make any subsequent removal a lot easier.
We all seemed to get fixated on the wiring issues and ignored the other question in your post. Aluminum screws are available but I would NOT recommend using them, especially in the location you described. They are quite weak and won't take much torque, so the chances of twisting the head off or deforming the slot is high. The aluminum alloy used in masts is hard enuf to provide a good clean thread if you drill & tap for a stainless machine screw. Self-tapping screws are not something I'd want to use. To prevent stainless fasteners from "welding" themselves into the aluminum, Loctite ( Red or Blue, depending on the fastener size ) should form a barrier between the stainless and the aluminum and make any subsequent removal a lot easier.
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