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Replacing Shaft Packing

3/10/2011

1 Comment

 
Dan asks:

"I'm about to replace my shaft packing... any hints?"

Scott answers:

I have three comments. I'd love to take credit for them, but I picked them up watching Jesse at Nanaimo Shipyard replacing the packing on Island Eagle. My shaft is 3 1/2" in diameter, and the packing is 3/4", so it was a fairly tough job. He passed on three tips:

First, cutting the packing to length by wrapping it around the shaft is the way to do it. However, Jessee cut the ends on a 45 degree angle, so they would overlap slightly instead of butt up against each other. This allows a bit of slop in the length. Plus it will seal better.

Second, in many cases the shaft will droop slightly, making the space of the packing on the bottom of the shaft smaller than the space at the top (sounds like you have this problem). You can check the space using various sized sockets as feeler gauges. Use wedges or a rope to (gently) lift the shaft if required (in my case the shaft weighs several hundred pounds so we used a small jack).

Finally, the packing is often a bit oversized. Jesse's trick was to use a hammer and slightly squish the packing by pounding gently on it. This broke down the flax just a bit and allowed the packing to fit in better.

Hope this helps,

P.S. Here's a video showing replacing packing on a 5" shaft WHILE THE BOAT IS IN THE WATER!!! (done by Nanaimo Shipyard). He flattens the flax at about 0:46 of the video.
http://www.youtube.com/profile?user=captmikemaurice#p/u/3/lECeFrm4Khw
1 Comment

Battery Cables & Lugs

3/10/2011

0 Comments

 
Tom asks:

"I'm replacing the battery cables on all the batteries. What would be the recommendation, soldered or crimped terminals?"

Scott answers:


On Island Eagle, I ran A LOT of #2/0, #2 and #8 cable. Probably 200 lugs in all. Here's what I would do if I were you:

1) Do not even think of soldering. It's very hard to get a good solder job, and even if you can it will cause hard points. Plus it will burn the insulation.

2) Use high quality tinned lugs. Pico sells the exact same ones as Ancor, at half the price. Don't forget that you need to size the lugs to the studs as well as the wire.

3) You need a high-quality crimper. I used the Ancor hammer-style one for about a dozen crimps, but the quality of the crimps was marginal (and BTW, if you HAVE to use this, use a vise to squeeze it, not a c-clamp or hammer). You can usually borrow or rent a good crimper, or for a big job you can even buy one. Try your local pawn shops and used tool stores, you can sometimes get good deals. In my case I borrowed a great pair from a friend who was a linesman for the local utility. Also, better marine shops usually have one, and if you buy the wire from them they will sometimes let you borrow their crimper overnight.

4) You will also need a pair of high-quality large-diameter wire cutters. Get Greenlee Model 727. They will cost you about $50. Keep them in a safe place an DON'T use them to cut anything but copper cable.

5) Once the lugs are crimped on, cover them with adhesive-lined heat-shrink. You will need a good, hot heat gun to shrink this stuff, it's pretty hefty. This will ensure that the joint stays corrosion-free.

I found it easiest to cut all of the cable at once and then set up a bit of a production line to do all of the lugs.

One other hint, a lot of stores have random lengths of wire that have been miscut or are end-of-the-roll. You can often get a good deal. Remember, you can always go up in size. For example, I got 27 feet of black #3/0 for less than 25 feet of #2/0, just because the 3/0 was a misorder and had been sitting on the shelf for a year. So now I have #3/0 running to the starter instead of #2/0  :-)
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Heating & Ventilation

3/10/2011

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Eric asks:

"Why is the inside of my boat (20 foot wooden powerboat) so damp?"

Scott answers:


After spending 5 years working on a boat in the arctic and substantial time living in a tent in below-freezing conditions, I can understand and sympathize with your situation. There are three fundamental problems:

1) Every time you cook with propane, you are pumping water vapour into the cabin. A pound of propane is going to produce about a pound and a half of water vapour, and that's a lot. Plus, every time you exhale you are also emitting water vapour. The result is that the air in the cabin is saturated with water vapour.

2) In cooler weather there are many objects on the boat that are below the dew point of this saturated air. Windows are the obvious culprit, because they are at roughly the same temperature as the outside air. But cabin sides, dishes, metal objects, clothes, etc. can also be cold. When these objects cool the moist air below its dew point, the moisture condenses out of the air as water, settling on the cool object. The result is that everything on the boat feels damp and clammy, because it is in fact slowly getting covered with water.

3) This is exacerbated because you have no source of heat that will raise the dew point of the air.

The solutions are actually pretty simple.

1) You need to make sure that you control the sources of water vapour. The best way to do this is to put a ventilation fan in above the stove. Use a computer fan and a Nicro-fico fitting. This will move a ton of air and should be run whenever the stove is burning. I know that it's a bit counter-intuitive, that running a vent fan will make you "feel" warmer, but it's true. I have 4 of these fans on the boat, I leave them running 7X24 when I am at the dock. Keeps the boat fresh-smelling. I have three exhaust fans (vented to the outside), one in the shop, one in the forward head, and one over the stove. I also have two solar vent fans, one in the lazarette and one in the mid head. I also have one that draws from the shaft alley into the engineroom, which has several vents.

Nicro Fico makes a bunch of vents. See http://www.marinco.com/brand/nicro . You can buy one with a 12 volt fan if you want, or you can buy the unpowered one (model 500). If you buy a 3 inch computer fan (less than $10) you can glue it on to the inside and it will work like a charm. Make sure you get a quiet fan. You can also add a 100 ohm rheostat for variable speed control.

2) It's pretty hard to add insulation to the boat after the fact, especially to windows. Probably not worth it unless you live aboard. Even then don't replace the windows, just use the clear insulating heat-shrink film (eg http://www.amazon.com/Window-Insulation-Plastic-Windows-Weathersealing/dp/B002WCJA46). This works surprisingly well.

3) The real solution is to provide a source of DRY heat inside the cabin. Candles, hurricane lanterns, catalytic heaters, etc. are all useless, because they just dump water vapour into the cabin atmosphere. There are only two possibilities on your boat. At the bock you can use electric, but that's not too practical when you are away from the dock. You can also use some form of vented heater, such as a wood-burning fireplace or a diesel stove. But by far your best solution is a direct-vented propane heater like this one:  http://www.dickinsonmarine.com/propane.php This draws combustion air from the outside and then returns the products of combustion back out through the same pipe. This has the dual benefit of reducing the water vapour and also keeping the warm air inside the cabin (it's safer too).

So, here's the bottom line: put in a vent fan over the stove, and a propane heater on the aft bulkhead. Figure out how to wedge a 20 lb propane tank into a seat locker so you don't run out of propane. And cruise to your heart's content. If you do decide to head up to Princess Louisa for Christmas, consider plastic film on the windows. And run the fan when you are not at the dock, the draw is about 2 watts.
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Air horns?

3/9/2011

0 Comments

 
Ross asks:

"Trying to find a good electronic horn for the trawler - thinking about an actual air horn - little compressor size of a beer can - are they more reliable than straight electric?"


Scott replies:

Check out http://www.hornblasters.com/

I installed one of these, and also a Kahlenberg horn that I got off of eBay. A few notes:

1) Depending on your boat, you may just want to install a standard 110 VAC air compressor in the engine room and use that to power the horn. I put in an inexpensive Porter Cable pancake-style compressor, and use it for a all kinds of things. Runs just fine off the inverter when underway.

2) The first horn I installed (one of the train horns) uses a solenoid. It's easy to install, but has the disadvantage that the only volume is LOUD. For the Kahlenberg, I installed a train air valve, like this: http://www.hornblasters.com/products/details.php?i=half-inch-manual-train-horn-valve This is much more practical because you have a lot of control over the volume.

3) I discovered after the fact that boat horns are actually tuned, and according to the Colregs you are supposed to use a particular frequency based on the length of your vessel. Train horns, while fun and loud, do not necessarily meet the specifications. Here's a link: http://www.kahlenberg.com/imo.html My Kahlenberg, I discovered, is only supposed to be installed on a vessel over 75 metres (about 150 ft). Oh well!

Scott Welch
Island Eagle
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    About Scott

    I'v been boating since I was 6 years old, and I'm passionate about doing things the right way. Hopefully you'll find these posts useful, and if you disagree with then, I'm always ready to learn new things, feel free to comment or email me.

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