On Board with Mark Corke

Shurhold Polisher test

2009-11-11T15:28:42-05:00

I've been testing the Surhold dual action polisher these last few days and I must say that I am impressed. For $150 dollars the cost of this tool is a lot less than the cost of a polisher that the pros may use, the Makita for instance. But at first glance the Surhold seems to work well enough and the cost makesit an affordable tool for the DIY boat owner who only has one boat, wants to buff it up a couple of times a year and get good looking results.

The full report and a video will follow in the next post which hopefully will be tomorrow.

Skin fitting thoughts

2009-11-05T20:39:40-05:00

I surveyed a Sabre 42 yesterday and while down in the engine room I noticed that all the sea cocks were labeled. That makes my job that much easier but I am sure that the labels were not there on the off chance that a surveyor might happen to come aboard. But I did get to thinking how sensible it is and wishing more builders would routinely label through hulls and sea cocks. Especially when one considers how many skin fittings and sea cocks there are on the average boat.

If the boat has a couple of air conditioning units, saltwater wash down, engine and generator intakes plus all the other sanitation fittings and so forth then a 40 foot boat may well have 15 or 16 holes below the water line.

It was also good to see some softwood plugs which in an emergency can be hammered into a failed skin fitting to prevent the boat from flooding although a plug of the correct dimensions should be secured adjacent to the skin fitting rather than just hung up on the windshield washer reservoir as shown above. You are going to be in a panic if you need a plug and remembering where you left it is not the place to be when the water is flooding in.

Stitch and tape construction

2009-11-02T19:50:34-05:00

So called stitch and tape construction is now widely used in all sorts of boats from those that are built from plywood as I have shown here to those that may be built of more exotic materials. As it's name implies the ply panels are at first joined together with temporary wire stitches the inside, joints are then made with epoxy then after the epoxy has set the stitches are removed before the exterior joints are made with epoxy and glass cloth.

Below is the sequence of events for those that are interested in constructing a boat using the stitch and tape method. The picture show a small boat that I was building for my son but the technique will be similar in all cases except that the plywood may be thicker and the epoxy joint will be larger to thus spread the load across a larger area more effectively. I have personally built a number of boats using the stitch and tape method which produces a boat which is both very stiff and strong. One word of caution would not go amiss here and that is to check the boat dimensions carefully before applying epoxy to any joint. If a boat is wired up out of square or in other words with a twist in it once the epoxy sets up the twist will be there for evermore and the boat could be useless.

1 Mark up the planks to be joined. Clamp them both back to back so that you can drill through both of them at the same time. I was using 6mm ply so I measured in about half an inch from the edge to prevent the stitches from tearing out.

2. Spacings will depend on the amount of bend and tension that the plank will be subjected to. I set mine at 6 inch centers and this will be good for most applications, you can always add more if you find that you need them once you start the actual wiring together of the panels.

3. Drill for the wire stitches. The drill diameter should be just slightly larger than the wire gauge that you are using which in my case was a sixteenth.

4. With all the holes drilled open out the panels. Precut some lengths of copper wire and prebend them into a large u shape, then feed them through from what will be the inside surface of the boat.

5. Twist them loosely together on the outside with the pliers. Leave them fairly loose, you can always snug them up a little later. Drill a few more holes and add extra wires if you feel that what you have is insufficient to hold the panels to the correct shape.

6. Continue wiring all the panels together. This was small dinghy so I was able to wire the entire boat together before I even thought about breaking out the epoxy. This is a fun part too as the boat starts to take shape very swiftly. As the boat was small I was able to hold each panel myself as I wired the boat together. Had the boat been any larger then a helper would have been useful; one to hold and adjust the panel up or down as required and another person to do the actual wiring up.

7. The wiring up almost complete. Note the temporary spacer to hold the beam of the boat to the correct dimension.

8 With the wiring complete it is time to mix up some thickened epoxy, I used wood flour, and spread it into the inside joints. Neatness pays here and will save hours of final sanding if you are careful. After spreading on the thickened epoxy smooth it out with a shaped stick like a tongue depressor or the back of a plastic spoon. Larger craft will have fillets that are much larger than these shown here and for that you will need to make a consequently larger spreader and smoothing tool.

9 This is how the finished joint should look, neat and well executed.

10 After leaving the epoxy to set up overnight you can remove all the staples. Most if not all should pull out with a set of pliers but if they are at all reluctant to come out then heat them with a soldering iron. This has the effect of softening the epoxy a tiny bit and allows the wire to be withdrawn.

The boat is now essentially a one piece monocoque structure but there is still a lot of work to do, the outside joints have to be made and the fiberglass reinforcement added. I'll be covering these steps in part two.

Flashlight fetish

2009-10-29T22:27:25-04:00

I've always like flashlights ever since my dad got me on for Christmas when I was a small boy. As I recall it was a cheap affair but the best thing was that it had different colored shades that flipped in front of the lens to change color of the projected beam. I took it to bed that first night and read under the covers with it. The thing was that I must have fallen asleep and left it on for in the morning the batteries were dead.

Things have moved on a bit since those days some 45 years ago and although I still have a fascination for flashlights I tend not to fall asleep reading under the covers with them any more , but if i did I could do far worse than to do it using one of the new Maglite flashlights with an LED 'bulb'. The light output is fantastic and best of all the new models have a 25% setting meaning that the light is reduced to one quarter of full power and in this mode will work for literally days on one set of batteries; probably enough to polish off War and Peace under the bed clothes!

I use mine for surveys and other assorted tasks aboard and although I have used it almost every day for the past year or so it has worked faultlessly apart from the time I thought it was broken and took it apart and rebuilt it only to find that I had put the batteries in back to front ... oops.

Maglites come in a variety of sizes but all are made form aircraft grade aluminum apparently and come with a lifetime warranty but don't drop them over the side of the boat, the warranty won't cover that!

Winter preparations

2009-10-26T18:52:38-04:00

I've spent a good portion of the day getting Mallard ready to go into the barn for the long winter ahead. Part of that entails changing the oil and filters so that the engine will sit with fresh in it oil during the cold weather. Although it is very tempting to simply roll the boat into the shed or cover with shrink wrapping and then forget about it all until the spring recommissioning it is always best to service the engine before the boat is laid up for any length of time.

Engine oil holds impurities in suspension and sucking out the oil removes these. One of the main contaminants is sulphur and if left stagnant in the oil will combine with condensation which forms within a cold engine and turn into sulphuric acid and thus begin eating away at your very expensive motor from the insides out.

As an aide memoir as to when I actually changed the oil I like to write the date on the filter then as the next service interval approaches I will not be trying to wrack my brain as to when the oil and filter was actually swapped.

Although I have a check list that I work through each end of season there are some things that do have to be done before the boat goes back into the water. After winterizing the boat I therefore attach a note as shown over the ignition switch so that the engine cannot be started without removing the label and running through the essentials that absolutely have to be done.

By way of an explanation of the things shown on the list above.

The raw water pump has been removed for inspection and replacement but has been left out for the winter so that the vanes will not take up a 'set' or deflection from which they may take some time to recover.

Although the filters have been changed in the fuel line, bugs and algae can grow so I like to change these once more before putting the boat back into the water and firing up the engine. Algae in the fuel can clog lines and injectors and cause all sorts of problems, new filters will avoid this malady.

Checking the oil levels is self explanatory and should be done each time the engine is operated anyhow.

I like to stuff a rag into the air intake to prevent spiders and other critters from nesting there. if the engine is started without removing the rag it will get sucked into the engine and cause a ton of damage.

I like to change the anode in the engine at least once per year, but mine was not too badly eroded this year and after inspection has some life left in it so I put it back. I have a new one on order and as soon as it comes in I will replace it although in my case it is not critical to do this immediately.

Boat hauling

2009-10-22T21:11:30-04:00

It was a sad day today as mallard was hauled from the water for to begin her winter sojourn back in the barn. It seems like only yesterday that I was splashing her with anticipation of the coming season afloat which alas has passed me by all too swiftly.

One of the first things to do when the boat comes out of the water is to pressure wash the bottom as soon as possible. I know I have said it before but it pays to wash the bottom without delay. Waiting until tomorrow makes the job much much harder. The little critters will have set like concrete and those that would have washed off without incident just after hauling the boat will now require the use of a scraper and about 3 times the length of time with the pressure washer to get the old girl cleaned up.

I don't have a fancy pressure washer just a modest electric model that works well enough. Not as powerful perhaps as a gas powered model that pumps out 2600 psi but good enough for removing the nasty stuff while it's still soft.

DIY Boat Owner Magazine

2009-10-20T09:18:50-04:00

DIY Boat Owner magazine which many On Board readers will be familiar with has been sold to Madmariner.com the on line boating resource site. The magazine was originally started by Jan Mundy and her husband Steve Kalman in 1995 before being sold to Boat US in 2006 who in turn have sold it to Glen Justice the owner of Mad Mariner.

As before DIY Boat Owner will continue to be published quarterly although at the time of writing this I am unsure as to whether Jan Mundy is to stay on as editor. The first issue to be published by the new owners will be available next month and it will be interesting to see what sort of changes if any will be incorporated.

The magazine is currently available through subscription and in some West marine stores.

Magneto ignition tip

2009-10-14T20:12:49-04:00

Now have to admit that i have something of a soft spot for the old British Seagull outboards. I've owned one for getting close on to forty years and although it's smelly and noisy I love it. Simple in the extreme, they take a hell of beating and still run, or they should.

Seagulls like many early outboards and other utility motors of that era had magneto ignition which works great most of the time but a problem can occur where you fail to get a spark at the plug. Assuming that the lead and plug is good you may wonder if the magneto itself is at fault and need replacement. The answer is - perhaps, but a good tip before you throw out the old motor or replace the expensive magneto is to crank the engine in reverse which often restores the properties of the magneto and brings back the HT spark.

With the Seagull this is simply a matter or removing the plug so there is no compression and the engine turns over easily, wrapping the cord around the flywheel in the opposite direction and pulling.

My Seagull had sat idle for a couple of years and there was no spark whatsoever but a couple of pulls in the wrong direction and al was back to normal with a great big fat powerful spark. This tip works for other motors with magneto ignition also although you may have to rig up some other method of rotating the engine in reverse, a battery powered drill springs to mind as the ideal for such trickery.

Speed transducer replacement

2009-10-10T22:15:34-04:00

If you have one of the paddle wheel speed transducers like the one shown above then you will know how easily they can get clogged up with weed. Made by Airmar who supply transducers to Raymarine, B and G, Lowrance and just about all the other manufacturers of marine electronics these transducers are very common. They work fine after the annual haul out and service but even the smallest little critter or section of weed can effect the reading or stop the paddle wheel from going around at all. Considering that the log is one of the most useful and essential bits of navigational kit aboard it is frustrating to say the least when it packs up working.

Now thankfully there is an answer and that is to install the replacement Airmar CS4500 sensor which as I understand it is a direct replacement for the removable center section of the existing transducer. This means that the old paddle wheel can be removed and the CS4500 slipped in it's place and once wired up will mean that you or I will be back in action in a jiffy. Because Airmar transducers are made to be serviced from the inside of the boat even when afloat then the paddle wheel can be swapped out for the new unit even while the boat is in the water thus saving the expense of a haul out.

Unlike the paddle wheel log the new unit has no moving parts and measures the speed of particles in the water moving past the transducer face. It does this twice every second so an instantaneous readout is virtually guaranteed.

Best of all the new transducer has nothing to hang up on any weeds and so it looks like I might be able to go a whole season without having to clean off the paddle wheel every time I go out on the boat.

For full details on the CS4500 you can click Download CS4500 to view a PDF.

Shrink wrap ventilaton

2009-10-06T12:20:34-04:00

In my last post I mentioned the need for ventilation for shrink wrapped boats. Without it mold will develop and it will not do the boat any good whatsoever. Think of a shrink wrapped boat as a big sealed in green house. As the sun warms the cover it causes any moisture under the cover to be absorbed into the atmosphere then as the sun goes down and the cover cools the still warm air condenses on the inside of the shrink wrap and drips back onto the boat. As it is impossible to shrink wrap a boat without trapping some moisture inside a good amount of ventilation will defeat this condense/drip cycle and allow the air to reach equilibrium thus mitigating problems to a large extent.

At the time that the boat is shrink wrapped it makes a lot of sense therefore to incorporate some sort of ventilation. Costing just $6 a piece these wind cup forced ventilation systems from Dr Shrink could solve many problems. Attached to the outside of the cover these cups which drive a small fan on the inside and duct air through the cover should go a long way to preventing moisture problems. For areas where there is a lot of sun but little to no wind solar powered versions are available.