On Board with Mark Corke

Weld polishing

 

 

You see all sorts of things at boat shows some good,some bad, some recherche and others, well just kind of foolish. This weld you see here is just one on a very expensive piece of kit that you bolt onto the aft end of your boat. I am not going to say any more than that as I do not want to identify the product. Suffice to say that the welds were rather poor or rather the welds were OK but they had not been ground and polished. Not only would this have made the product in question look far better but more importantly it would have made it a whole lot more durable. Contrary to what some people will tell you stainless steel can and will corrode in the right circumstances; it is especially prone to crevice corrosion wherein molecules of water become trapped and stagnate within the steel which then sets up it's insidious work of eating away at the surrounding metal. This corrosion can happen to any of the types of stainless; type 316 is probably the most corrosion resistant and is the sort most often used for keel bolts and the like. What makes this core of corrosion worse is that on the outside everything can look fine and dandy but hidden away things are going from bad to worse. It is for this very reason why you should never use stainless screws to hold planking in place for instance on a wooden boat, things can go bad very quickly. Anyway back to the item above. This was proudly on display at the Miami show for all to see and even though this was a display model the welds had started to corrode in the atmosphere so I hate to think what would happen if this bit of hardware was actually bolted to a boat and sat for months or years in a salt water environment, I doubt it would not be long before it was a rusty mess. Polishing the welds is a time consuming and dirty job which I have learned from experience but it is a necessary evil, sure it makes it look pretty but done well the weld all but disappears and the microscopic holes left on the surface of the weld are removed leaving far less cracks and crevices for crevice corrosion to start.

 

 

Proper battery charging

 

 

Back in the day on board electrical requirements were modest but as boats have become more complex their need for reliable electrical systems have increased. When I stated cruising my outboard was started by pulling on a cord, there were no navigational instruments that required electricity to function, the boat had one dome light in the cabin and a tricolor navigational light was about all that I had. Things have moved on and electricity is needed to start the engines, power up the myriad electronics and light up the cabin interior, in fact without electricity most boats are dead in the water.

Batteries are an essential part of the boat's equipment and they need to be kept properly charged. There are several ways of charging batteries but many boaters have an on board battery charger that operates from the mains when the boat is plugged in at the dock. This is a good approach and means that the batteries should be in tip top condition and fully charged when you arrive for a day on the water. To keep the batteries charged one might be tempted to nip down to the local auto parts store and pick up a cheap battery charger but this could be a big mistake. Auto store battery chargers, the type with a plug on one end and a couple of crocodile clips to connect onto the battery posts at the other are of what is known as the ferroresonant type. They are simple affairs hence the cheap price and work by putting out a large charge which diminishes as the battery comes up to charge. These chargers work great for a very occasional charge of a partially flat battery but continued use day after day will almost certainly lead to premature failure of the battery aboard your boat because unlike a more sophisticated charger the output is virtually unregulated from a cheap auto store it is possible to boil off the electrolyte from lead acid batteries.

Marine batteries are often of one of three different types, conventional flooded lead acid, like those on your car, GEL where the electrolyte is a jelly like substance and thus cannot spill and finally AGM which stands for absorbed glass mat; the electrolyte is suspended in a glass mat between the plates allowing the batteries to be mounted in any position even on their side if desired. The point of all this is that each of these different types of batteries have slightly different charging requirements which cannot be met by the cheap auto store battery chargers. For optimum charging efficiency a three step charging process is needed; bulk absorption and float which a good marine battery charger offers. Assuming that a battery is heavily discharged the charger will go into the bulk phase where a large amount of amps are input into the battery to restore the majority of it's lost capacity. As the capacity of the battery starts to reach about 90% of fully charged the charger will go into the absorption mode, this is because putting the last 10% or so of charge back into a battery is the hardest; the charger will put out less current and the micro processors in the charger monitor the battery and vary the output until the battery reaches full charge at which pint the charger will go into float mode ensuring that the battery does not self discharge and will remain completely charged almost indefinitely until the owner next turns up at the boat and unplugs the shore power cord to head off out for a cruise. Many chargers such as the Charles model shown above also have temperature sensors and as such will vary the output of the charger dependent on the ambient temperature as the cooler the battery the more readily it can tolerate a higher rate of charge. Marine battery chargers are intended to be permanently installed and connected to the batteries inside the boat, they must also be wired in correctly and although you can do this yourself is best left to marine electrician unless you are confident of your abilities.

Incidentally if your boat is not equipped with a volt meter on the electrical panel you can still check the state of charge with a cheap digital meter from an electronic store. With meter set to volts and the probes touching the battery terminals read the voltage. A fully charged battery will read about 12.75 volts, a battery that is showing 12.5 is approximately half discharged and contrary to what you might think a battery that reads 12 volts is in fact flat. Incidentally readings should be taken on the battery with the charger turned off and the battery allowed to 'rest' for at least 30 minutes.

 

Beneteau-Easy on / easy off

 

 

I had every intention of posting daily from the Miami boat show but time was very limited not just to the demands placed upon me by judging the NMMA innovation awards but also by the fact that my Verizon connection from my I pad was very spotty and in fact was not working most of the time. One of the things that I would have bought you last week was this rather novel opening transom which is an option on several of the Beneteau sailboat fleet. Before I actually saw it I was rather skeptical but having now seen it I rather like it. In the Mediterranean boats are often moored stern to in the marina or along the seawall and you therefore have to board the boat over the transom; fine if you have a large boat with a pasarelle but not so good if you have a smaller sailboat with a fixed transom. This arrangement certainly makes boarding easier and it is my guess that many of the Beneteau customers will opt for the opening transom. With the transom folded down it makes not only boarding from the dock easier but makes a great swim platform and would certainly be a safety boon if bringing a person back onto the boat from the water who was unconscious or otherwise not able to help themselves.

I like getting e mails from On Board readers it lets me know what you like and don't like and perhaps more importantly lets me know that my postings are not just disappearing into some void or black hole. However amongst those e mails have been a few queries as to why I do not post more often. The simple question to that is that I would if I had the time. I have to fit this blog around all my other commitments most notably trying to earn a living which I do by writing articles and taking photographs for magazines, writing books and surveying boats. There is a lot to fit in and although I would love to bring feature length 'how to' stories here every other day it is just not possible until I win the lottery.

Suzuki DF300AP

I have been itching to bring news of the all new DF300AP from Suzuki ever since it was unveiled to the press some time back but as they wanted to make a big announcement at the Miami boat show we were banned from releasing information to the public until now. The new motor which is currently only available as a 300hp model addresses the age old problem of counter rotating props. Until now if you had twin or triple engines on the back of the boat you had to buy at least one standard engine and another with a left hand rotating propeller. A left handed rotating engine has typically been $800 dollars more for two reasons; the manufacturers make a lot less of them and secondly the lower unit internal gearing was slightly more complex than the standard unit. With the new engine Suzuki have addressed all these problems and now the 300AP can be simply be user updated to rotate in either direction. Of course the engine does not rotate in the other direction, what happens is that essentailly the forward and reverse pinion gears are used in a different sequence. This change is acheived electronically and by simply removing the small plug connected to the wiring harness under the cowling the motor becomes a left hand turn when the shift is placed into forward gear. All the judges at the Miami innovation awards,of which I was one thought it brilliant and a deversevedly just winner of one of this years awards. The first question that anyone seeing the engine for the first time usually asked is why no one has come up with this before. This apears to be a home run for Suzuki, dealers will now only have to stock one engine which will make their inventory controls cheaper and simpler and there should be a cost savings to the customer as the only extra charge is that a left handed prop which is still slightly more expensive than standard rotation. Looking to the long term when a pair of engines get sold on the second hand market it is always the standard rotation that gets sold first and the left hand engine is more difficult to sell and is often sold at a lesser price even though it was more expensive when intially purchased. In the pictures avove you can see the small tag on the plug that is pulled to convert a the engine from left to right operation and vice versa. Brilliant!

Miami Boat show 2012

I just arrived here in Miami for the 2012 show and am looking forward to it tremendously. In addition to me being here to judge the NMMA innovation awards I have lots of great stuff to tell you about but sadly much of it is so new that it has been embargoed until later in the week. As soon as I can I will bring you all that news and more, stay tuned.
Oh and did I say that it is warm and sunny which makes a change from the cold and snowy up north.

Reading a chart and why you should.

 

In this day and age you would think that any boat owner would have little use of a paper nautical chart. But a chart is very useful and contains a wealth of information which may not be available on a chart plotter or computer display. Typically all charts will contain depth, sometimes called soundings in either feet, meters or fathoms ( one fathom equals 6 feet). Charts also show navigational markers, obstructions and other points of interest or hazards to mariners. Charts come in different scales and which is used will depend of personal preference and the area being navigated, a large scale chart for harbors and rivers and a small scale chart for passage planning or longer voyages offshore. A chart will have a scale along the top and bottom and these show latitude and longitude, horizontal along the top and bottom for longitude and vertical along the extreme left and right of the chart for latitude. Positions marked on a chart are always given as a series of numbers; degrees, minutes and seconds. It is also worth noting that one minute of arch, not to be confused with one minute of time is equal to one nautical mile with 60 seconds making up one degree. You can often find a scale elsewhere on the chart showing nautical miles and thus by opening up a pair of compasses to a desired distance measured on the scale it is possible to walk the dividers across the chart to find the distance between two objects. Assuming that we were cruising on a sailboat traveling at 5 knots and we knew where we were we could set the divers to five miles and mark our estimated position in one hours time as long as our course did not alter. Or we could find our distance off from the shore or other point by measuring the distance with the dividers and then referencing this back to the miles scale. It is also worth pointing out that latitude and longitude are measured north or south from the equator and east and west from the Greenwich meridian in London, England. For instance the position of the 59^th street harbor marina in Chicago is at 41. 47' 30” North and 87. 34'51” West. Knowing your lat and long at anytime is a good idea as it unequivocally establishes your position which can then be passed onto the coast guard if you got into trouble and needed assistance. This is much simpler and less ambiguous than just saying “about 10 miles from the big white light house”. Also charts are an important back up should your electronics fail, knowing where you are at all times is less stressful and means that you are less likely to get into trouble or make mistakes especially when you are tired. One good practice is to update your position on the chart every 30 minutes or hour, if on a longer passage, noting not only your position but the time as well in soft pencil on the chart which can later be erased when you have safely completed your voyage. In fact you can also mark favorite fishing or gunk holing spots on the chart too so that you can easily get back to them at another time. Another way that charts come into their own is on passage planning. I like to lay the chart out and study my intended route, making note of any obstructions or places that I need to avoid, sure you can do this with a chart plotter but by the time that you have zoomed out to show your starting and finishing points all detail is lost, this is especially troublesome on smaller chart plotters. Once I have done the basic planning on the chart I can then enter way points into the electronics with confidence.

If you don't keep charts on board then I strongly urge you to do so and even if you do have some aboard it may be time to pull them out dust them off, brush up on your chart work, you might be glad you did.

Nautical charts can be obtained through the NOAA website which lists all chart agents.

West Marine and other boating suppliers may also often have charts although these will often be limited to your local area.

Spar gauge

I had a long discussion the other day with a good friend of mine on the making of wooden spars. Specifically my friend Pete wanted to know the best way to turn a square lump of wood  into a svelte mast. I explained to him that the practice is not all that complicated and that the most difficult part is accurately marking out the wood to give you something to work to. When I started to talk about a spar gauge I could start to see his eyes start to glaze over.

 

 

A spar gauge is based on pythagerous'  theorem and is basically a piece of wood into which two pins are placed which rub on the outside of the square stock and inside of this are a couple of pencils. What is important is the spacing of the outside pins and pencil tips which are in the ratio  of 7-10-7. In other words the measurement between the center of the outside pin  and the point of the pencil is 7, (such as 7o mm) the measurement between the pencil points is 10 ( so assuming the first measurement is 70 mm then this will be 100mm) and finally the measure from other pencil point to center of other pin will be 70mm again. Of course you can use any measurement you like providing the ratio is correct and this will depend on the diameter of the spar that you are making with a larger spar requiring a bigger gauge obviously. What is important to note is that guage can be canted as it is run along the spar and this is shown in the illustration below which incidentally I found on the internet and is drawn much better than I could have done . I would have credited the author but I found it on several different sites so I am unsure as to the original author.

Incidentally I found a very basic step by step of the process of spar making on the Collars website which gives a great overall idea of how to go about the process.