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Saturday, December 31, 2011

Proper Electrical Connections

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   These are something that has no place on a boat - wire nuts.
On Board with Mark Corke shows us the correct way for wire terminals. He says....
I recently surveyed a power cruiser which had lots of alterations to the electrical system, not only were many of the connections made with wire nuts the cable was solid core rather than multi strand tinned boat cable, both of which are a big no-no on a boat. Wire nuts are not moisture resistant and cable with a solid core is susceptible to vibration and fatigue eventually leading to failure.
For the complete step by step guide to making proper electrical connections continue reading ..

Wiring on a boat leads a hard life; corrosion, vibration and chafe all conspire against your boats electrical system to bring it to a premature end. Bad connections are to blame for many problems and knowing how to make proper crimped terminals will go a long way to avoiding problems. Simply twisting wire together, using wire nuts or wrapping it round a terminal screw simply will not do. Proper crimped terminals are neat, allow the free movement of electricity and prevent short circuits. It is a good idea to have some practice runs on some spare bits of cable so that you are able to make perfect joints every time. Tug on the connector to test the integrity of the completed joint; if there is any movement or the terminal comes off you need to cut back the cable and start afresh. Terminals and cables come in a variety of sizes measured by what is called gauge; the smaller the number the larger the cross sectional area of the cable conductor and therefore it’s ability to carry higher electrical loads. Always make sure that you use the correct size cable for the maximum amount of the current that the cable will have to handle. Finally only ever use tinned marine cable on a boat. Untinned cable is cheaper but is very susceptible to corrosion.



Tools and materials needed
Cable
Crimping terminals
Heat shrink the same color as the cable
Crimping pliers
Wire strippers
Heat gun

Tip
Making proper terminal connections is very straight forward and easy but it pays to have a trial run with some scrap cable to get the feel for how things should go.



Wire1
1. Cut back any suspect and ragged ends using a pair of side cutters or the cutters built into the crimping tool. This is especially important if the wire is at all corroded. You can skip this step if using fresh new cable from a drum.

Wire2
2. Strip off the insulation from the wire being careful to cut only through the sheathing and not into the actual wire. Remove only sufficient insulation to allow the wire to be entered fully into the terminal with no bare wire visible.
Wire3
3. Grasp the wire in one hand and with the other twist the strands together between thumb and forefinger.  This binds the strands tightly together which makes pushing the cable end into the terminal easier.

Wire4
4. Cut a length of heat shrink about an inch long the same color as the cable insulation and slip this onto the wire.
Wire5
5. Slide on a terminal connector to the end of the cable and after ensuring that it is pushed fully home use the crimping pliers and squeeze it onto the wire. Note that the crimping jaws are color-coded. The colored dot on the plier jaws must correspond with the color of the terminal.
Wire6
6. Slide the heat shrink back up the cable so that it covers the crimp completely then use a hot air gun or a match shrink it into place. Do not apply too much heat; warm it just sufficiently to shrink it to the cable.
Wire7
7. The completed job. A perfect electrical connection, which should give years of trouble free service.

Friday, December 30, 2011

Propellor Clearance

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It is essential to have the correct amount of tip clearance between the end of the propeller blades and the hull. The recognised minimum clearance  should be between one sixth and one fifth of the total prop diameter. Therefore with a 16 inch blade like the one in the picture we should be looking for about a 2 and half inch clearance at least What there is in fact is so little room that it was impossible to get even the end of my pen between the underside of the hull and the blade tip. The way that a prop works is fairly complex and it creates lift and thus drives the boat forward. When the tip clearance is compromised two things happen; the first is that the water flow is interrupted and the blade will not be anything like as efficient and secondly the water is 'trapped' between the rotating prop and the hull. With each revolution this slap will be felt inside the boat as added vibration. The only way around this problem in this particular case would be to either have a slightly longer shaft to move the prop away from the boat a little but even that I doubt would not be enough or secondly would be to go for a different prop of perhaps a smaller diameter but with a slightly increased pitch.
As a footnote the generally accepted practice is that the shaft should project no more than one and a half times it's diameter past the end of the cutless bearing.

Thursday, December 29, 2011

Fuel Filter Indicator

Fuel filter service ind
 One of the issues with any fuel filtration system is that you never know exactly when the filters need replacing or are restricted in some way. One method is to install a drag gauge into the system which will show just how much 'suck' there is in the vacuum side of the pump, the greater the drag, the higher the reading and thus more the fuel fuel flow and filters are clogged. It is a great system but comes at a price and complications which many recreational boat owners can do without. A simpler solution is the fuel flow service indicator from Racor. Essentially this simple but effective bit of kit is teed into the fuel line on the vacuum side of the line between the filter and the pump. As the vacuum increases a yellow disc is sucked down in the clear bowl. While the disc is in the green sector all is well but as the pump has to suck harder as the fuel filter becomes blocked it enters the red sector indicating the need for a filter change. I should add that the disc stays at the highest setting achieved even after the engine is shut down so it is possible to monitor the performance of the filters even when the engine is off and cold. Once filters have been changed the operator merely has to press the button on the top of the unit and the disc resets. The cost is a very sensible $60 and can be had from West Marine and other such suppliers.

Wednesday, December 28, 2011

Tuesday, December 27, 2011

PYI Mini Floor Anchors

Mark Corke has this to say about the PYI Mini Floor Anchors. An excellent web site from Mark; and a useful  product. He says.......


  I wrote some time back about PYI anchors and indeed installed some on my own boat to hold the cabin sole in position so was excited to learn that my good friends at PYI have come out with a new product called the mini anchor which is aimed primarily at the OEM market. The basic principles are the same as the original product but instead of having the bayonet style latch the smaller anchors screw together and need to be undone with a screw driver rather then using a quarter dollar coin as it is possible to do with the larger versions.

As I was unfamiliar with the new anchors I thought it best to have a trial run so that next time when I want to use them I have the confidence to install them without fear of messing things up. You don't need a lot of tools but you do need to be careful in your marking out or the parts won't line up and the results could be disappointing this could be especially frustrating if you are using them on expensive teak and holly sole plywood.
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The anchor consists of three parts The screw part that is held in place in the sole or other panel and actually screws into the bottom half, that,s the larger of the two bits that you can see in the picture and finally the flat locking nut that you only need if you attach the female part to something like an aluminum floor member. Lastly the other bit is the tool that you need to screw the female part into the boat. As this was a trial run I was able to do this at the work bench and therefore use a pillar drill. A hand held electric or rechargeable drill work just as well but be sure to keep in perpendicular to the surface.
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The next step is to mark out where you want the anchors to be placed. This is definitely one of those time that you should check twice and drill once. Aim not only for a neat appearance but try to ensure that you will not be placing the anchors too close to an edge or worse still be drilling into a cable or pipe hidden from view. This was just a trial for me so I did not have any of those worries, but be neat. Mark the drilling centers with a crisp pencil mark, if installing into a pre finished cabin sole then I would have stuck a piece of masking tape down and made a mark on that.
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The male part of the anchor is retained within a sunk cup and this needs to be a good fit as the anchor is simply a push fit. A 9/16th bit is exactly the right size I found. A Forster bit would have been better but I did not have one of the of the correct size so I want ahead and used a standard twist bit which I made sure was sharp. I used some tape to mark the depth that I needed which is the depth of the cut and no more, refer tot he drawing and you will see how this insets into the cabin sole.
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This shows the completed counterbore for the cup.
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Next using a 10mm bit I drilled a clearance hole for the screw part the remainder of the way through the panel. Note that I am using a ½ inch ply here which is ideal, thinner ply stock could be more of a problem as the cup will be very close to the underside surface of the panel.
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Here is the completed hole as I insert the male part of the anchor into place. The 9/16th hole is snug fit and required the use of a few hammer taps to seat the anchor correctly flush with the surface. A scarp bit of wood between the anchor and hammer will protect the chrome finish.
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How it should look when it is correctly installed.
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I used the same 10mm drill to bore for the female part of the anchor. I was only drilling into softwood which has some 'give' when screwing in the anchor if boring into something tough like teak then a 10.5 mm drill would be a better bet. Make sure that you drill deep enough so that the anchor won't 'bottom out' before it is fully screwed in.

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Chucking the insertion tool into a cordless drill I drove the anchor into the wood.
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The female part of the anchor in place. It is very snug in the wood but you could use a little dab of epoxy if you were ever worried about it coming out, but I did not think this necessary.

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The two parts can then be fixed together using a small screwdriver.
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The completed anchor which is very neat and rattle free. If I were doing this for proper on a sole a little piece of strategically placed hatch tape under the board may be a good idea to prevent any squeaks.

TIP
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If after marking out the sole drilling through with a 1/16th bit will mark both the sole itself and provide a guide for the where to drill into the supporting structure.