Anchor Lights and Drilling a Mast Channel

[Larry Read]

I have a question regarding anchor lights. What is the power draw for the various units? How much effect on a battery does a 25 watt bulb have verses a 10 watt? Is having the light on all night a significant power draw for either? Do you have a preference?

As a recent M owner I too was disappointed that the much advertised mast channel is available only in brochure form. I have watched this board and had many of the same thoughts regarding how to drill a 30 foot hole?

Last week at Lowes I had a MacGyver Moment. Walking down the isle there they were, four-foot long fiberglass sections used to clean out chimneys. They were on sale for about four bucks apiece so eight of these, a inch drill bit, 30 feet to PVC, and one can of Great Stuff foam later we were ready to drill the big one.

I first ground down the drill bit to fit in the female end of one of the cleaning rods. I made it a tight fit and used Elmers ultimate glue to secure it.

My wife and I tackled the project late Sunday night after most of the neighbors came by to tell us we were crazy. With the mast on the boat we removed the cap on the top and the plate from the bottom of the mast. The bottom half of the mast is empty so we assembled the first four rods and started drilling from the bottom to the top. The foam cut very easily and we did not have to pull the bit out to clear the hole. If you have a lot of foam you might have to pull the drill out every so often to clear the hole but that will be easy. As advertised in a previous post, there are three sections of foam to go through on the M. We followed the V section of the mast and gravity continually pulled the heavy drill bit into the V. The drilling process took less than ten minutes.

Next, with the rod still in place we used black tape to attach the first section of PVC to the rod. With my wife at the top of the mast pulling the rod and me at the bottom pushing the pipe we inserted the channel. We simply taped each section of new PVC together to keep it as streamlined as possible. We had to push and pull back and forth some as it was a fairly tight fit but it only took about 15 minutes and the channel was in place. I foamed the area around the top of the mast to seal it and put a small amount at the very bottom to keep it from knocking around in the hollow mast area. I havent decided whether or not to drill another hole to seal the bottom as the pipe fit fairly tight.

The entire process from beginning to end took about an hour and a half and we didnt yell at each other once. That just didnt seem right?

FYI if you feel that you need more than a 1/2 inch channel just use a one-inch bit and inch pipe or it is easy enough to run an additional inch if you need it later on.

[Paul S]

You must have a fairly new M like us. The dealers guy that did mine said he used to take several hours and a lot more pain to get the channel in on older M's (that had more foam).

He ran 3/4 PVC and it was super tight. Actually had to spray the cables (Antenna and 14/2 anchor light wire) with WD40 to give it a little lube as it went down the channel. He should have brought 1" instead.

The dealer's method it a bit more barbaric - he sharpened the end of the PVC channel and rammed it into the foam...pulled it out to clean ..and rammed it in again..twisting each time. Was pretty effective..didn't take long..then again..there was so little foam.

Still..The dealer should put the channel in (actually the factory should cast it in) before delivery..just to make life a bit easier .

While we were at it..I put a steaming / foredeck combo light on the mast. That was a piece of cake


Paul

[Chip Hindes]

The West Marine catalog publishes the watts or amps draw, sometimes both, for every light they sell.

Either way, the math is simple. If you have watts, divide by volts to get amps. So a 10 watt bulb draws .83 amps. If you have amps, multiply by volts to get watts, so a bulb that draws 2.1 amps is a 25 watter. It's easy to jump back and forth between watts and amps depending on what you want to do with the result.

In order to get total power consumption, multiply consumption in watts or amps times the length of time you'll use it. Say ten hours per night for an anchor light, so your 25 watt bulb uses 250 watt hours or 21 amp hours per night.

Nearly any battery in good condition can handle this load, but it is a substantial fraction of the total capacity of, say, a 65 amp hour "starting" type battery. Plus, you'll have to add in any other loads (running lights, radio, GPS, reading lights, pump, fan) in determining your total overnight load. Things like radios and GPS are more complicated, since they can draw considerably more power depending on the mode of operation. A radio can draw 5X or more power when transmitting than when standing by. Most of us spend about 99.9% of the time listening only, but some people never seem to shut up. They'll use more power. . The GPS draws way more with the backlight on. I leave the GPS on all night to use the anchor drag feature, but I turn the backlight off. If necessary, you can calculate a running average based on the percentage of time you transmit or use the backlight.

If you're only out for one night, no problem, but if you intend to cruise for an extended period, the next day you'll want to replenish the power you used overnight. A typical 50HP alternator is 130 watts, or 11 amps. To continue the example, if you burned only your 25 watt anchor light all night, you need to get back 21 amp hours so you'll have to run your outboard at maximum alternator power output for nearly two hours just to break even.

I believe most people would consider a 25 watt anchor light serious overkill on a 26-foot boat.

[Larry Read]

Chip

Thanks for the help. I love you guys that have electrons flowing in your veins. You make it sound so easy and you answered more questions than I even knew I had. One remains, what size wire do you recommend. Im going with the 10 watt unit to reduce the juice but it seems like a pretty fair run.

And Paul, what is the story with the wire your dealer installed? It looks to me like you could run a small city with that, then again it may be just the right size, I fell asleep in science the day they talked about electricity. Any special plans for the top?

Larry

[Paul S]

Chip

Thanks for the help. I love you guys that have electrons flowing in your veins. You make it sound so easy and you answered more questions than I even knew I had. One remains, what size wire do you recommend. Im going with the 10 watt unit to reduce the juice but it seems like a pretty fair run.

And Paul, what is the story with the wire your dealer installed? It looks to me like you could run a small city with that, then again it may be just the right size, I fell asleep in science the day they talked about electricity. Any special plans for the top?

Larry

It is 14 gauge wire. I should have run 12 gauge..but didn't think that far ahead. Most people I know run way too small gauge wire (18-22). But that is a 29' mast..probably another 10-20' inside the boat..the run is round trip..so there is a lot of potential power loss. Better to be safe than sorry....The antenna wire is RG-8U - thick expensive stuff..but there will be little signal lose for when we need it. 14 gauge is probably the right size for that application. You could get by with 16/18. But the cost difference is so slight..why not use the right size.

That was all my wire (power and antenna) that I purchased..If I left it to the dealer...I am sure it would be lampcord.

Just got an antenna and anchor light. Got a windex that mounts on the antenna, so there is not another thing mounted. Not planning on anything else at this time

Paul

[mike]

Has anyone here looked into LED anchor lights? Might be a good solution for reducing overnight consumption (they are supposed to draw much less power than regular lights).

--Mike

[Paul S]

Has anyone here looked into LED anchor lights? Might be a good solution for reducing overnight consumption (they are supposed to draw much less power than regular lights).

--Mike

I did..but for $80-$250+.... I figured a 5 watt, $20 light would be fine.

Paul

[Chip Hindes]

Still..The dealer should put the channel in (actually the factory should cast it in) before delivery..just to make life a bit easier

You guys may be missing the point of the foam. There's insufficient foam for it to provide floatation in itself. As light as it is, it's still a lot of additional weight aloft if you were to foam fill the whole mast.

The purpose is to seal the mast so that, with the air trapped in the mast, the whole mast serves as floatation. By putting a hole in it, no matter how it's done, you've destroyed a major part of its utility, safety-wise. Even with several wires partially blocking it, the flow rate through and around a piece of 3/4 or 1" conduit is substantial. If the boat goes over, it will take no more than a minute or two for water to fill the mast through the hole or conduit you've so cleverly and laboriously provided. The little bit of foam remaining at the top of the mast will provide some floatation, but not much.

There are a couple ways you can get the safety aspect back when you're done. One would be to refoam the cables and wires once you've run them. You could also get a lot of it by running the smallest diameter tubing or conduit the entire length of the mast, then foaming it in place at both ends. This is what the factory could have done, sacrificing maybe 5 or 10% of the total floatation volume of the mast. I don't know what the additional weight aloft would do to stability.

There's no excuse for saying they're going to do it in the brochure, then not doing so.

One remains, what size wire do you recommend. I’m going with the 10 watt unit to reduce the juice but it seems like a pretty fair run

The West Marine catalog (get one of these even if you don't intend to buy any of their slightly overpriced stuff) provides the data and some graphs you can use to calculate what you need. At .83 amps, with the substantial run of perhaps 70-80 feet ("round trip"), 18 gauge is close to 3% voltage drop limit recommended for running lights; keep in mind that voltage drop in the wiring is juice totally wasted. On a per foot basis, at 20 cents per foot difference, the additional cost for forty feet of 16 gauge is about $8. When I ran mine, I bought a 100 foot spool of 16 gauge. I knew I'd eventually use it elswhere, by the spool it's fifteen cents per foot cheaper, the difference between 18 and 16 gauge is only eleven cents per foot, and 16 gauge is usable in more places than 18 gauge.

[mike]

I did..but for $80-$250+.... I figured a 5 watt, $20 light would be fine.

Mine draws about 0.8 amps, so it must be a 10 watt bulb... is a 5 watt bulb bright enough to be legal?

--Mike

[Chip Hindes]

Paul S wrote:
I did..but for $80-$250+.... I figured a 5 watt, $20 light would be fine.

Mine draws about 0.8 amps, so it must be a 10 watt bulb... is a 5 watt bulb bright enough to be legal?

I'm guessing the light manufacturers go for the minimum legal light output; there's also a second thing going on here, and that's effectiveness. A five watt bulb is effectively half the light, even if it's legal the amount of light output might not be useful.

There are outfits that sell LED repleacements for standard automotive light bulbs. They're popular for taillights for the rice burner set. Some of them sell through eBay for $10-15. I know there are owners who have been happy with them as replacements for the interior light bulbs. I've intended to check out whether there are any that fit my anchor and running lights, and whether or not they compromise the effectiveness of the lights; just haven't gotten around to it yet.

[Harry van der Meer]

I have the Davis Masthead Megalight. http://www.sailnet.com/store/item.cfm?pid=11449. It draws only 0.074A. It also has a photocel which shuts the light off automatically during daylight (so I don't have to get up when sleeping in......)

[Chip Hindes]

I have the Davis Masthead Megalight.

By definition a "masthead light" is the one required by a power boat underway. On sailboats this light is rarely located at the top of the mast. On the Mac, it's the one on the forward part of the mast. I believe the term is left over from the days when tall masts were made in two pieces. The "masthead" was the connecting apparatus at the top of the lower piece, not the top of the mast.

Some people like to call the masthead light a "steaming" light to avoid confusion, but the official Coast Guard term is "Masthead Light."

A masthead light covers only 20 points or 225 degrees total. Although it's somewhat useful to have a masthead light that draws little power and turns itself off, it's not quite so useful when you're powering anyway. It's not suitable for an anchor light, which must cover all 32 points or 360 degrees.

Note as well, this one's not an LED but an incandescent; other things being equal, low watts=low light. In fact, the single review somebody wrote says exactly that, in addition noting it doesn't always turn on when it should. I also note its advertized visibility is "up to two miles". What does that mean? I wonder if it's a subtle hint that it's not actually legal. The requirement is two miles.

BTW, I checked and my anchor light is an Aqua Signal Series 20 all round, same brand and series as the other lights on the Mac, and it's 5 watts, .42 amps.

[Duane Dunn, Allegro]

When you are shopping for new lights be sure to consider the LED variety. The lower consumption is quite amazing.

Using my handy dandy Link 10 meter I can tell exactly what various load consume.

The stock mac cabin lights consume 1.3 amps each. The two cheapo cabin lights I added in the aft berth consume .6 amps in white mode and .3 amps in red mode. The halogen chart light we have for reading in the vee berth consumes .3 amps.

I recently picked up a LED cabin light from boaters world. Sea Sense #50023814. It is an 8 LED surface mount fixture, nice and small, built in switch just like the mac lights. I was surprised to find that boaters world was selling them for $19.99.

I connected it up and turned it on. The link 10 minus sign lights but the readout stays at 00.0 . This means the load is less than .1 amps. The light output is quite good, easily as much light on the surface below as the mac light puts out. It is however a different feeling type of light. It is pure white, not warm yellowish. It is directional, does not flood light all around on the ceiling and walls. While I feel it gives plenty of light where you want it, my wife says it coesn't give the cabin that warm glow so it feels too dark. I guess for now we'll stick with the mac lights that waste all those amps glowing the walls and ceiling. I am however switching out the sleeping area reading lights, where directional is OK with the admiral to the LED lights. I also picked up one of their strip LED lights to mount up under the bimini as a cockpit light.

You can now get LED running lights and all around white lights that are approved for anchor lights and you will save a lot of power.

[Paul S]

Still..The dealer should put the channel in (actually the factory should cast it in) before delivery..just to make life a bit easier

The purpose is to seal the mast so that, with the air trapped in the mast, the whole mast serves as floatation. By putting a hole in it, no matter how it's done, you've destroyed a major part of its utility, safety-wise.

There are a couple ways you can get the safety aspect back when you're done. One would be to refoam the cables and wires once you've run them. You could also get a lot of it by running the smallest diameter tubing or conduit the entire length of the mast, then foaming it in place at both ends. This is what the factory could have done, sacrificing maybe 5 or 10% of the total floatation volume of the mast. I don't know what the additional weight aloft would do to stability.

There's no excuse for saying they're going to do it in the brochure, then not doing so.

Oh I get it. Don't get me wrong. When I finish I plan on shooting some foam in the holes.

The larger question is...in between the pockets of foam..there are holes in the mast anway from the factory..would fill anyway.

The bottom 1/3 had no foam at all it is only in the top sections .

I'll do my best to seal the holes well. It won't be any worse than it was delivered.

The best way is to engineer it before hand so they don't have people hacking the mast as we are.

Paul

[Tom Spohn]

We installed a mega on our X and have been very happy with it. I threw away the bracket and drilled a hole directly into the aluminum cap on the mast. The light is inserted and held fast by a large nylon nut (and some 5200 just in case). The mega comes with two lights so if the low power one is not enough it is easy to fit the higher wattage lamp. We had no trouble seeing the light when motoring the dinghy from shore to the boat.