On Board with Mark Corke

Miami Boat show 2012

2012-02-13T19:59:37-05:00

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.

2012-02-09T18:50:43-05:00

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

2012-02-06T10:42:17-05:00

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.

Smart plug

2012-01-30T14:23:03-05:00

Any boater that has a shore power connection to their boat will be familiar with the cordset shown above. The plug goes into the shore side socket, often on the pedestal at the marina and the other end connects to the socket on the boat. These cords are in very common use but do suffer from several drawbacks; to connect them the pins have to be aligned and then twisted slightly to lock them into place. In theory this is fine but in reality the sockets wear usually at the dockside terminal and the electrical connection is far from perfect.

In an effort to address some of these concerns makers Smartplug have come up with a new kind of plug and socket. The plug is simply pushed in where it snaps into place and makes a good contact with the pins, so arcing, a common problem with the older style plugs should be eliminated. Pressing in the sprung loaded clips on either side releases the plug, which in normal operation is completely waterproof. The best bit about the new design is that the plug only fits one way round so should save lots of fiddling around in the dark when pulling into the marina at night when you can't see what you are doing.

According to the blurb from Smartplug the socket on the boat can be swapped out in about an hour or less and the mounting holes for the new socket even align with holes from most common standard twist style sockets so no extra holes or making good is required if retrofitting the Samartplug socket on a vessel. Of course this does still not help with the shore connection to which I think we shall be stuck with the old style for some time to come.

Presently the Smartplug is available in 30 and 50 amp versions with a 100 amp model due out soon.

Building the Eastport Pram

2012-01-23T12:49:03-05:00

When I was looking for a dinghy to complement my traditional gaff cutter I searched for some time until I settled on the Eastport pram from Chesapeake light craft. Pretty to look at I could build it in my spare time and it would suit the mother ship very well. Chesapeake Light Craft has been making kit boats for years so they seemed to know what they are about. One of the smallest in their range the Eastport pram seemed to offer everything that I desired. Pretty lines, good load carry ability and best of all I could add a sailing rig at some later date. In fact I have mentioned this dinghy several times before but here is a step by step series of how I set about building her.

All the parts in the Eastport pram comes as a set of precut parts. These are cut on a computer-controlled router so they are ready to go together almost straight form the box. In truth the kit came in two boxes one with all the ply parts and the other with all the necessary hardware and epoxy. In common with all the other kits in their range the Eastport pram in constructed almost entirely of marine ply but unlike some of the other kits as not parts are longer than 8 feet, the length of standard sheet of ply no scarphs are required to join lengths together.

A kit boat is good introduction to boat building, as little preparatory work is needed before construction commences. You will need some space and typically this will be the family garage but because the boat takes shape so quickly the car will not have to stay outside for more than few days.

The boat is built using what is often called the stitch and glue method, pioneered successfully many years ago by Barry Bucknell and Jack Holt in the mirror dinghy. Now however rather then using polyester resin and glass tape epoxy resin has taken over and is used both as glue and coating material.

The average reader is likely to have more than enough tools and skill to successfully build this boat but I would strongly recommend building a couple of strong sturdy saw horses on which to work. Make sure that the work area floor is level because it is all too easy to build a twist into the boat. Read the through the instructions several times before you start is a piece of advice that I should have told myself in past construction projects. Reading the plans and instructions that come with any kit will make the project go that much easier.

I mostly followed the manufacturers instructions but where I deviated I did so as either time saving method of work or because experience has taught me that their might be a better way of doing it. Next issue I will be concentrating on painting and varnishing.

Building the Eastport pram took me about 40 hours of building time and this is a reasonable estimate but expect to put as much time in again on the finishing if you want a high quality job.

Tools that you need

Pliers/wire cutters

Measuring tape

Electric drill

Abrasive paper

Clamps

Razor blades

Plane

Saw trestles

Plastic cups

Glue brushes

Squeegee

Scissors

I laid out all the parts and checked for damage that might have occurred during transit. At this stage it is hard to believe that this is a boat.

Check through the parts list is essential and helps identify each of the parts, which I marked off as I went through to make sure everything was included. The first parts needed are the lower two side panels for each side (in total there are 4 per side but you do not need to the top two just yet). Also I pulled out the bottom panel and placed this on a couple of saw horses so that it was at a convenient height.

All the panels have been cut at the factory using a computer controlled router. This makes them very accurate but sometimes there are nibs left plane off with a sharp plane. If you do not have a plane then some 80-grit paper wrapped around a block is fine too and would have worked almost as well.

The panels are temporarily stitched together with copper wire and for this 1/16^th diameter holes have to be drilled. Clamping the two lower panels together face to face and marking out for the holes at 4 inch centers and 1/2” in from the lower edge save time as I only had to do this one for each pair.

Note that the panels are rebated. The rabbet is positioned on the inside of the boat and laps over the edge of the panel immediately below it thus concealing the panel edge and allowing an area for the epoxy to bond the planks together.

Drilling tip

Although the holes maybe small I did not want to do anything that might cause wood to splinter ultimately spoiling the finish. Holding a scrap block of wood prevents breakout and gives a neat clean hole.

After separating the clamped panels I used the lower panels as a guide to mark and drill the holes in the edge of the bottom panel. Like the sides these should be drilled 1/2” from the edge and align with the 4-inch centers that you marked and drilled into the sidepieces. A weight in the middle of the bottom panel makes alignment easier and stops it from moving about.

I cut the copper wire into 3 to 4 inch lengths and bent them into a staple shape and pushed them through the holes from the inside to the outside.

Next was to twist the ends together to hold the panels. A common mistake is to over tighten which damages the wood and is likely to break the copper. You can always go back and re tighten later should that be necessary. The two lower panels are added after which the bow and stern transoms are wired in place followed by the remaining two upper panels on each side.

Fitting the bow transom

Fitting the third plank

The wires should look like this after stitching. If some parts of the hull are a little reticent to come together do not be afraid to add some additional intermediate ties but I did not find this necessary.

After finding the approximate position of the center frame I wedged it into position to help maintain the correct beam while gluing the planks. With the hull completed stitched up (it was still be a bit floppy at the stage but most certainly boat shaped) I got my wife to help turn it over in preparation for gluing.

Mixing up some epoxy and after thickening it with some Cabosil to a ketchup consistency I loaded it into a syringe and injected it into the small gap between adjacent planks. I checked under the boat occasionally to see if glue was running down inside, luckily it did not. But had it done so then I could have tightened the copper ties slightly. It is important not overfill to laps, just squirt in enough glue until it comes level with the top edge of the lower plank.

After allowing the epoxy to cure for at least overnight removed the cooper ties from the plank overlaps but left the ties holding in the transoms until later. To remove the ties snip through only one of the ‘legs’ then with a piece of cardboard under the pliers pull the complete length of copper wire out.

Turning the boat back over I once again set it level on the sawhorses. Mixing up some epoxy thickened it with wood flour to the consistency of peanut butter I used a rounded end mixing stick to spread it into the corners where to transoms met the planking and formed a smooth fillet.

This is one of those spots where I defected from the instructions that came with the boat. CLC recommends using masking tape on either side of the joint which you peel off for a neat joint. Whilst this undoubtedly works at producing a neat clean joint sticking on the tape takes time. My preferred method is to make the joint as outlined above then very carefully scrape off the excess. You need a steady hand but I find this faster than the tape method.

While I was at it I applied a smooth fillet between the bottom panel and the first plank.

After the fillets had cured I removed the copper ties for the transoms. I then vacuumed out the insides of the boat after a light sanding of the bottom panels and lay in the 6oz glass cloth. This covers the bottom panel and the no 1 planks. Using sharp scissors I cut it an inch or two oversize. There is a great temptation to drape it over the ends of the boat and cut it later but this is a mistake as the excess gets in the way and it’s weight drags the cloth from the surface.

Mix up unthickened epoxy and wet out the cloth smoothing out wrinkles as you go. This is another one of those times when I deviated from the instructions. A brush or roller as recommended in the supplied instructions tends I find to lay on too much epoxy. My preferred method is shown here. A small amount of epoxy is poured on to the dry cloth and spread with a plastic squeegee which smoothes the cloth and uniformly distributes the epoxy. Do not try to completely fill the weave of the cloth; later subsequent coats will do that.

15a

A close up of how properly wet out cloth should look; saturated but not dripping with excess epoxy. Note the visible weave.

Because the cloth only covers up to the edge of the first plank the cloth has to be trimmed with the plank edge. A sharp new razor blade and trimmed the cloth level with the edge of the plank edge in no time. If you cut too early you will drag up the cloth, too late and the epoxy will be impossible to cut easily. Wait until the epoxy is at the green or partially cured stage when it has the consistency of toffee.

Flipping over the boat once again a layer of cloth is stuck to the outside of the boat. This simply covers the bottom panel and not the planks. The squeegee comes in handy here for working the cloth well into the intersection of the bottom panel and first plank. I trimmed this back with a razor blade as soon as it reached the green stage.

While waiting for the epoxy to harden on the bottom of the boat I made up the skeg and dagger board box. The skeg helps the boat track straight when under oars or being towed behind the mother ship so it has to be straight and true. Not wanting to impart a twist into it I clamped and glued the two parts together onto a flat bench top. Note the plastic to stop the skeg from being glued to the bench.

After carefully measuring the bottom panel at either end to find the center I struck a chalk line along the bottom to aid setting out the skeg and skids.

After checking the position and placement of the skeg and skids I drilled pilot holes for bronze screws that will hold these components in place. I then had to climb under the boat and screw these components into place after coating the mating surfaces with Cabosil thickened epoxy.

Can Tip

I built the whole project on my own. The only time that I had help was when I pressed my wife into service to turn the boat over. Heavy cans are as good as a second set of hands when it comes to holding skids and skeg in position as you drive screws.

From the plans I ascertained the position of the center frame, the next component to be installed. As a reference I placed a straight edge across the gunwales to enable me to accurately mark the station mark with a pencil. I found that the frames were a sufficiently tight jam fit to hold themselves in place as the glue set. Had they been loose I would have used a few copper ties.

Here the center and seat frames are glued in place with epoxy/wood flour fillets. It is also necessary to fit the dagger board box even if you have no intention of ever sailing the boat as this supports the tongue on the forward end of the seat.

Two strips of mahogany make up the rubbing strips on each side and these were glued at this point. You need a lot of clamps!

With all the frames fitted the insides of the buoyancy tanks were coated with epoxy to seal the wood as once the seat tops, which were also coated are fitted it would be impossible to get to them later.

Transom doublers are fitted to give extra rigidity to the ends of the boat and support the weight and thrust of a small outboard. I found that a certain amount of dry fitting was necessary to get a perfect fit before gluing these in position.

With all the woodwork complete the next stage will be about 8 to 10 hours of sanding and cleaning up preparation for paint and varnish, which I covered previously here.

Joke of the day

2012-01-15T22:19:20-05:00

Did you hear about the man who fell into the upholstery machine? He is now fully recovered.

Getting started in boat building

2012-01-13T13:00:35-05:00

I well remember the first boat that I built. Twelve foot long and bright orange I constructed it when I was still at high school. Looking back now it was pretty rough but I had a lot of fun with that boat and it obviously made an big impression on me as I have built several boats for my own use since. That first boat was built from a set of plans; constructed of plywood and solid lumber I recall transferring the shapes to the expensive plywood and other parts took up an extraordinary amount of time if only I had started with a kit things would have been so much easier.
Building from a kit makes so much sense. All the parts are cut out for you, often on a computer controlled machine so you know that are going to fit and providing that you can follow some fairly simple instructions I believe that almost anyone can build an acceptable craft. The last boat that I built was from a kit supplied by Chesapeake Light Craft. Just about everything came with the kit except the paint and varnish, which you supply along with several weekends and evenings to build it. CLC kits like many other kit boats are built from marine plywood which is glued together with epoxy resin, the pre cut panels are initially temporarily stitched together with copper wires the seams glued with resin which when dry allows the stitches to be withdrawn and the boat finished off.
Building a kit makes an ideal winter project and lest you think that there is a huge time commitment I spent 40 hours building the Eastport pram from opening the box to completion, I then spent another 40 hours or so sanding, varnishing and painting. What is not mentioned in the plans is the satisfaction that you get from building your own boat and until you have actually done it it can be hard to describe; a smug feeling that you have actually constructed a craft with your own hands that is denied to most boat owners.
Apart from the kit itself you need space in which to build which for small dinghy or kayak can be a single car garage. You will also need a few basic woodworking tools and the motivation to see the job through which is where the kit comes into its own. Because all the parts are cut out for you can begin actually assembling the boat on the first day right out of the box, which means that good progress can be made the first weekend. I personally know of many builders who have started with a kayak and ended up building a much larger boat. Having been bitten by the boat building bug they seem to enjoy the building almost as much as the boating. I strongly believe that almost anyone can build a kit boat, it makes a great winter project to build either alone or with the family, many kids love to help and the speed of building means that they won't get bored. If I have one final tip and that is to not take on a project that is too large, there are some truly impressive kits for boats of 30 feet long and more and this is a major undertaking likely to take several years to complete. If you have never built a boat and are not sure if you will enjoy the challenge start small and if you like it you can always progress to something bigger for a next project.
Choosing which design to build is almost half the fun and now that there is the internet searching for a suitable design is much easier than years ago when one would have to send off a stamped addressed envelope and wait with anticipation for the brochure to drop onto the door mat. A very pleasant evening can now be spent instead looking at the various web sites and dreaming of the voyages and trips that you will take in your new craft. I well remember that a few sketches and photos stapled to the wall kept me motivated when I had had a gut full of sanding.

Costs vary with the boat that you build and who supplies the kit. Taking my Eastport pram as an example the cost is just under $1000 including shipping to which as I mentioned you will have to add the cost of paint and varnish. If that is out of your price range then a small kayak would be a little cheaper.

Santorum's Dark Cloud for Boaters

2012-01-06T11:41:46-05:00

I don’t often get political with OnBoard, but up here in NH a few days before the primary it’s hard to avoid. With Rick Santorum’s Iowa boost, he’s moved on to the Granite State with an extra million in his pocket but here’s a little tidbit for all my boater friends worth noting.

The National Weather Service Duties Act of 2005 was a legislative proposal he sponsored in April 2005 to prohibit the National Weather Service from publishing weather data (except in case of severe weather alerts) to the public when private-sector entities, perform the same function commercially. Funny thing is..surprise, surprise .. AccuWeather, the commercial weather company is based in Santorum’s PA district and their head honcho, Joel Myers is a constituent and a campaign contributor.

Of course, this has implications for boaters as it would mean that the free information via the NOAA website and such like would no longer be free. Although this bill was sponsored in 2005 and to many may be seen as dead in the water there is a good chance that it could resurface if Santorum gets to the White House. Boaters are not the only ones who should be concerned both commercial and recreational pilots have expressed deep dismay and in fact were somewhat more vocal than many boaters back in 2005.

Granted, his bill never made it out of committee, but it does give us an indication of his sentiment.

Holy crap

2012-01-04T21:14:11-05:00

This looks harmless enough does it not? It is the drain, there are two port and starboard on the swim platform of a well known boat manufacturer. All looks good from above but when you look underneath you see this..............

A hole is simply bored through the swim platform with a hole saw and the plastic drain cover screwed in from the top with the merest bit of 4200 under the flange. That brown looking material that you see in the picture is the wood core completely unsealed where it has absorbed water not only from the inevitable water that drains through from above but also from sea water splashing up from under the boat. I find it beyond belief that this manufacturer makes no attempt to even seal the balsa core at all. This boat was almost brand new but serious delamination has already taken hold and will eventually cost the boat owner hundreds if not thousands to put right. It would be so easy to have a solid fiberglass plug molded into the swim platform when the boat was built so that when the hole was bored it would be going through solid glass thus avoiding problems and costs for the owner later. With quality control like this the builder does not deserve to stay in business.

Comfortable cruising

2012-01-02T21:08:37-05:00

Happy New Year. Here's to a relaxing years boating.