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Some Quick Basics of Boat Batteries and Chargers

Here is a quick overview of an efficient, modern boat charging and battery system, with a few tips on how to wire things so you’ll know what they are and be able to work on them later.
Most pleasure boats have a 12-volt DC (direct current, the same as in a car) electrical system that powers devices, such as lights, radar, autopilot, fresh water and bilge pumps, etc., any time and a 120-volt AC (alternating current, the same as in a home), powering outlets, battery charger and high-demand devices such as microwaves, as well as tv’s and other electrical devices commonly available in 120V AC.  Grounds on both are common at some point and an isolation transformer is needed to ensure a clean AC ground, entering the boat, from the dock.
Batteries are of three basic types: Wet cell batteries are the cheapest but require regular filling with distilled water and spill if not upright, thus not suitable for sailboats, which often aren’t upright.  Sealed wet cell batteries are also inexpensive, maintainance-free but will spill if not upright.  Gel cells are maintainance-free, have a slightly lower maximum charging voltage and slightly lower cranking amperage but are more durable for deep discharging, won’t leak and are roughly 1.5 times as expensive as wet cells.  They were revolutionary when they came out in the early 1990s but are eclipsed by today’s AGM batteries.  AGM (absorbed glass mat) batteries are amazingly durable, resistant to vibration, won’t leak, can be mounted on their sides, have excellent cranking amperage, high maximum charging voltage, are durable for deep discharging and are twice as expensive as wet cells. 
Battery quality varies considerably: Buy cheap and often or buy quality and rarely.  Cheap batteries generally last two years and high-quality batteries can last a decade, if properly charged and not stressed.  Beware of house-brand batteries sold by retailers.  The best batteries have many thin, convoluted lead plates squeezed together with thin glass mat in between.  They are much heavier than normal batteries and provide greater storage as well as faster and deeper charging and discharging.  The factors in choosing a battery are their footprint (their size), amp-hours (total electrical storage), cold-cranking amps (CCA or peak discharge), warranty and cost.  I look at the size of the compartment, then the size of batteries I can fit in it and then budget and battery details.  Replacing all batteries at the same time avoids the weakest constantly draining the others and bringing newer battery lifespans to the level of the oldest. This, corroded cables and ancient/underpowered chargers are the usual reasons battery banks fail.
Battery chargers need to be set for the type of battery: Wet, Gel or AGM.  They need to be at least a three-stage charger: Flood stage, to quickly build the charge of a battery to maximum voltage; fill stage, to fill the battery at a variable amperage, while maintaining a stable amperage and a maintenance stage, which trickles small amperages and keeps the battery topped up.  Marine chargers are mandatory, as others will rust to death amazingly quickly and not being made for the marine environment, are often subject to chassis shorts and fire hazards.  They should charge at least one amp for every ten amp-hours of each battery bank they charge with each charging lead: If you have three 100 amp-hour batteries, you will need a 30-amp charger with three 10-amp charging leads or if the batteries are in one bank, a 30-amp charger with a 30-amp charging lead.  Modern marine chargers have excellent capabilities and measure the state of the batteries they charge regularly as they charge, for maximum efficiency.  They run much cooler and quieter, are smaller and charge so much better that they are well worth buying to replace chargers that are 20 years old or older: They will extend your battery life that much.

The Value of Traditional Navigation

I greatly enjoy traditional navigation. With electronic navigation (chartplotters, especially), traditional tools have lost much of their allure to most of the boating public. This is a sad state of affairs for three reasons: Lack of appreciation of the boating experience, rigidity of thought that leads to trouble and navigational danger in trouble.
When plotting is a matter of identifying landmarks, from stars with a sextant to mountains with compass, one inherently studies the environment and learns from that experience. The result is a greater sense of progress, things that aren’t going well (such as a current pushing the boat offtrack) and general connectivity with nature and the way we’re interacting with her. This, in turn, leads to better watchkeeping and therefore preventative measures and less chance of hazard. There is a profound pleasure from navigating with pencil and paper charts. I was onboard a boat in danger and the radio operator repeatedly gave our position to the Coast Guard as being at a waypoint on the chartplotter, instead of our current position. If this person would have taken sights and plotted the position, that error would never have occurred.
I’ve sailed coasts with chartplotters confidently showing the beach 2.5 miles inland (Baja Mexico comes to mind.) and have sailed past many navigational dangers not shown on paper chart or on chartplotter. The big difference here is that because of my increased awareness of my environment from taking fixes and plotting, I am much more vigilant and effective on watch: I study my environment constantly, get a superior feel for it and have an idea of the kinds of most likely dangers to look for. I remember seeing an unmarked reef 12 miles offshore and having an argument about it. I grabbed the wheel and steered us safely around the reef; the hand on watch stared incredulously as we passed what certainly would have been our doom. He relied on the chartplotter and it told him there was no danger, so what he was seeing must have been something other than dangerous.
Chartplotters are great and I often use them. It’s fun to scroll around, check engine gauges and come up with ship information of passing vessels. It’s so easy to think everything represented is factual, especially when zooming up close. It’s usually impossible to tell if electronic chart lines are interpolated or based on actual soundings and that source of error can be far greater when zooming closely than the data supports. Electronic charts are based on scanned charts, though and so much of NOAA’s budget has been moved to scanning charts from updating them that many of the charts I bought last year aren’t updated from the same charts I bought fifteen years ago: While charts are fantastic guides, that’s all they are. The focus needs to be on direct observation: Look at the color of the water for an indication of depth when close to shore, measure leeway regularly when nearing a point, etc. Direct observation includes electronic tools like depth sounder and radar. Gps-based navigation assumes accurate charts and is inherently unreliable for close maneuvering: As we near rocks with great pointy teeth, looking out for them directly becomes more important… Frequently checking other navigational aids.
The best navigators I have known delight in creatively using their navigational aids and love telling stories of… A watch, depthsounder, compass and chart finding and maintaining position in deep fog. Someone without traditional navigational skills would have been literally lost in that circumstance. It’s a matter of connectivity with environment and mastery of navigational aids.
You are the lookout and you are on watch, so do both. It’s a gas!

Jumping or Sweating Lines

Jumping or sweating a line is a technique of using your body as a fulcrum to add tension to the line and take it up with a cleat or bollard. It’s an excellent skill you’ll use frequently, once mastered and one that takes some practice.

Jump a line by grabbing (ideally about a ten foot section) it before a cleat or winch and have someone else or once you learn this trick, yourself, tail or take up the slack. At all times while jumping, the line must be strenuously tailed. This prevents the line from just being plucked like a violin string without going anywhere. Tailing keeps the line from going back out and at the end of the jump, pulls in the line gained. At no point is the line slack in this process. Here’s how to jump a line:

(1) Wrap the line with an acute angle, around the far end of a cleat or with one full wrap around a winch. Grab the tail at a comfortable place that will allow you to pull strongly throughout this procedure.
(2) Reach up or out to 45° and grab the line there.

Tailing hand is close to cleat and pulling hand is farther out, at start of the jump.

(3) Lean back, until your arm is fairly close to perpendicular to the path of the line, before you started hauling it sideways.

Pull hard with both hands, simultaneously. Don't let the rope slip around the cleat in the wrong direction!

(4) Lean towards the cleat, hauling hard, while taking up the excess you’re pulling around the cleat. When you’re done with this move, the line should be back to its original position.

As you pull towards the cleat with your forward, pulling hand, take up the slack with your tailing hand. You can see I hauled nearly a foot of line with this one jump.

(5) Lower your grip on the tail of the line and repeat, until the line is as tight as you want or can manage.

The difficult part of learning to jump a line is to take up the line after the cleat, so you’re actually making progress. Watch the line at the cleat as you jump it, so you can see when you are not pulling enough with the tail and when it goes backwards - That’s what you want to prevent. As you haul the line sideways, the line at the cleat should be stationary and as you haul it towards the cleat, you should see the line pulling around it, making the tail longer. 

If you don't have enough friction on the cleat, wrapping the line around the back of the cleat and under the other horn will greatly help.

The added friction of passing the line around the cleat is often needed when jumping lines, particularly with larger line, double braid and heavier loads.

You can jump a line to be much tighter than you could otherwise pull directly, except by a strong winch.

Jumping a line is the method used to tension a boat’s line at dock and it’s a skill you’ll enjoy using regularly. In square rigged sailing ships, this is how lines are tightened, as there are no winches. It’s also the fastest way to heave a heavy object, such as a large mainsail and this method is used on race boats on halyards, raising sails. In tall (square-rigged) ships, it’s called “sweating a line.” The large lines are the only ones sweated, as the small lines control delicate parts of the sailing gear that can be ripped by too much force. This is where the saying “Don’t sweat the small stuff” comes from.

Proper Side of the Dock for My Boat

There are some marinas with boat slips laid out cross to the prevalent breeze. Avoid them: They will always cause headaches and the leward side of your boat will constantly be scuffed and marked from rubbing. The vast majority of marinas, fortunately, are smarter than this and have their slips pointing into and away from the wind.

Because sailboats have relatively small and ineffective propellers, particularly in reverse, they need the breeze in front to stop easily at all. Similarly, their poor performance in reverse makes backing into the wind very difficult, if not impossible. Also, because sailboats’ sterns are U-shaped, their prop walk problems are enhanced, so backing into a slip is inadvisable. Therefore, sailboats need to be on the downwind side of the dock, where the breeze helps them leave and stop, when entering their slips.

Powerboats have a different set of challenges: Their engines give great mobility and control at their sterns but their light bows are highly vulnerable to being pushed around by a stiff breeze and it’s often impossible to point a powerboat into a strong wind, in harbor. Doing this in a crowded marina, particularly with average boating skills, is one of the most common causes of boat crashes at dock. Backing powerboats into slips is at least as problematic and fortunately, few recreational boaters attempt this (For those truly skilled and comfortable backing into a slip in a stiff breeze, who like their boats docked that way, the downwind side is appropriate for them.). Safe docking for powerboats in a breeze mandates their being upwind of their slip and letting their bow drop into the slip. It’s easy for a powerboat to stop their motion, so a slip on the upwind side of a dock is perfect for a powerboat.

It’s a Yin and Yang thing. Neat, eh?

Cleats Tied Right

Here’s how to correctly tie cleats and bollards. While all of us use cleats, very few use them properly, because they were never taught correctly. It’s simple and one of the things hardly anyone does right, including racers. The method I show here will allow you to quickly and easily let a line loose when it’s under tension and still keep it safely secured. It’s amazingly fast (I have to purposely tie a cleat slowly to show it on film - It’s just too fast to follow.) and easy. Learning to use bollards is important because they are on many docks. I like bollards more than cleats for docking because they’re faster, easier and give more even range of friction when jumping and snubbing.

Here’s the boat line handling skills you need to master before taking your boat out. Read the articles I’ve written for you and practice them at your slip. Please note that few boaters have mastered these skills: On almost all docks, almost all boats are tied up poorly to terribly. You’ll be glad you took the time to learn how to do these simple things in a professional, easy and safe manner.
(1) Tie a cleat to a dock
(2) Tie a cleat onboard
(3) Snub a line
(4) Jump a line
(5) Tie a boat to a dock

Cleats and their cousins, bollards, are used to both snub (slow) a line or hold it fast. Bollards are easier to use, particularly for snubbing but are larger. Cleats should be large enough for a loop of the correctly-sized line for the task to easily fit between the posts, onboard and large enough to easily fit underneath the horns, no matter what cleat it is. Dock cleats are not designed for the line to go through them, as that impedes the ability to release the line quickly. Jam cleats are of two designs: A ribbed valley and an almost normal looking cleat, with one horn having an extended base with a gap that narrows considerably, jamming the line between the horn and the base. The ribbed valley variety is quick-releasing but not suited for unattended use, as it does release on its own and is mainly used for racing sailboats.

Tying a dockline onboard:

Many boats have cleats that are too small for them. If you can not use the correctly sized line for your boat with your boat's cleats, replace them with properly sized cleats. It's frustrating that manufacturers save a few dollars, this way.

(1) Pass the spliced loop through the middle of your boat’s cleat, from the outside.

(2) Place the loop around the horns, one at a time.

(3) Pull it tight.

Cleating a dockline to a dock cleat:

(1) Approach the cleat at the side that gives an acute angle between the line and the cleat: That’s the far side.

(2) Run the line around the back, going under both horns to the front.

(3) Go over the top diagonally and under the opposite horn, coming out in front again

(4) Cross over the top again diagonally, making an X and hold the line in place with a thumb.

(5) Flip a loop of the line under (so that the end of the loop is underneath the side coming from the cleat).

(6) Place that around the horn.

(7) Pull snugly, so the top still has an X of rope. You have now locked the cleat and it is secure.

(8) If you are leaving the boat for en extended time, you can make a second locking loop on the other horn.

When you’re done, you should have a neat X on top. Starting with the acute angle not only transfers more friction initially to the cleat, giving you more control and keeping the line from initially popping off the first horn but also keeps the line more than perpendicularly off the cleat, preventing the line from rolling over and trapping itself, which can be a beast to pry loose.

Do not start with an obtuse angle because the line can pop off the cleat's horn as you're jumping the line, you are not starting with a 180° turn that gives the necessary initial friction and the line from the boat can trap the wraps, making it sometimes very difficult to undo, when leaving dock - Just when you need to quickly board your boat.  Here is what not to do:

This is what it looks like after tying the cleat, starting with the wrong side (Don't do this!):

You can see how the line to the boat traps the next cleat wrap by pulling up against it, here, when starting with the wrong side of the cleat:

There is no need to bury the cleat in loops of line – Quite the opposite, because they take so long to unwind.

When your boat is drifting in your slip as you're trying to leave, untying this mess is frustrating and can lead to problems as the boat pivots away with only one difficult to remove line holding. This means you're going to either have to jump for the boat or miss it. Neither are good choices, so prevent this problem in the first place.  Here is how to take care of the extra line: Coil it "Flemishing"

As with everything, keep it simple and utilitarian. Wise seamanship dictates work that is easily usable and looks neat because it’s easy to use and tell when something’s out of place or broken. The pile of line can also hide line that has frayed around the initial turn on the cleat and that can result in unexpected breakage and damage to the boat. A pile of line takes a minute or two to unwind, usually results in a tangle and in an emergency can cause critical delays and harm. When tied properly, a line can be released cleanly in a few seconds.

Tying a cleat (not a dockline) onboard:
Never lock a cleat by flipping the line over in a locking loop, when onboard. This is because lines onboard must be easily secured and released from cleats with one hand, as the other holds onto the boat, for safety. Here’s how to do it:
(1) Use the cleat’s horn that forms an acute angle with the line. Pass the rope under it, around the back of the cleat and under the other horn. If it’s a jam cleat that has been installed correctly, this is the jam horn.
(2) If it’s a jam cleat, after going under the jam horn, cross the center, under the first horn, in the opposite direction. Wrap the line around the base of the cleat, yanking it tight, twice. The second time, you’ll wedge the line in place. That’s it!
(3) If it’s a normal cleat, after going under the second horn, cross the center, under the first horn and cross the center again. Wrap the line around the base of the cleat, yanking it tight, twice. The second time, you’ll wedge the line in place. That’s it!
This is how to tie a cleat onboard, in pictures: