On Board with Mark Corke

Phil Bolger

It is with much regret that I announce the death of boat designer Phil Bolger at the age of 81. Bolger died last Sunday the 23rd of May at his home in Gloucester MA. Boilger committed suicide by shooting himself in the garden of the home that he shared with long time partner Susanne Altenburger with whom he is pictured above. Bolger was best known for his eccentric designs and easy to build boats including the brick which could be built entirely from three 4 by 8 sheet of plywood. His most famous design was of the Surprise a 20 gun frigate that was featured in the Film master and Commander starring Russell Crowe.

I met him once and was taken aback at his modesty and how self effacing he was. He firmly believed in cheap eco friendly boats and at the time of his death had been working on some fuel efficient inshore fishing craft. You can read more about some of his designs by clicking here. 

So long Phil we miss you already.

Bristol, England

I am writing this from a friends house in Bristol, England. This is for me a brief stop off on the way down to see my mother who has not been well but my layover in Bristol has given me the chance to revisit old haunts that I have not been to for over 25 years since I lived and worked here while at the BBC. The shot above is a portion of what remains of what was once a thriving working water front. To the left is the remains of some of the warehouses now turned into trendy shops and restaurants, but in a former life were used as bonded storage for tobacco products much of which was imported from Virginia in the USA which at the time when much of Bristol was being developed was a still a colony. This area is known as the watershed and would have been filled with sailing ships all the way up to the tower block that you can see in the distance. Sadly much of Bristol was severely damaged or destroyed by German bombers during the second world war but the although many of the former shore side buildings have gone it is still an interesting place to walk around. Rich in maritime history Bristol is home to the SS Great Britain one of Brunel's finest achievements and the ship that laid the first transatlantic telegraph cable. While I am over on this side of the pond I plan on visiting some boat builders so with any luck I shall have some photos to share of that with you in a day or two.

Honda 60hp outboard

I've liked Honda outboards for a long time ever since I used to operate a launch with a 90 h model strapped to the back. It was quiet and powerful and started first time every time, the block is based on the Honda FIT car which although not available in the USA is very popular in other parts of the world.
Honda have just announced the new 60 hp model which looks like a winner too. I can't wait to take one out for a spin. I've asked the folks at Honda and as soon as a test model becomes available I'll bring you a review. Unlike the 90 the engine in the 60 hp model is three cylinder 1 liter block and apparently has something called the BLAST system. The BLAST technology advances the BF60's ignition spark timing to within one degree of the knock limit during "hammer down" acceleration, dramatically improving acceleration according to Honda. The Engine Control Module (ECM) also steps in to increase injector timing, creating a more potent air/fuel mixture. The resulting boost in available torque at low RPM contributes to a strong holeshot to get the boat up on plane quickly. The ignition spark timing is appropriately adjusted under slower throttle advancement, ensuring a leaner air/fuel mix and class-leading fuel efficiency. Available in either long or standard shaft variants it is also comes with the option of tiller steering shown above or remote operation for wheel steered boats.

The BF60 also has a trolling setting which can be set in 50 rpm increments from 750 to 1000 rpm which I suspect may appeal to fishermen. Additionally there is also a 22 amp alternator which should keep the batteries topped up and allow plenty in reserve for running electronics

The Honda also comes with a five year non diminishing warranty so they obviously expect the engine to have few problems in the service department. I've seen a few pictures with the 'hood off' as it were and from as far as it is possible to see all the major serviceable items look easy to get at. I'll bring you further details in due course but I am thinking that this engine could be a good bet for the skiff I am going to be building.

Changing a water pump impeller

Changing a water pump impeller is normally a straightforward job that every voyager should be able to tackle.  Impeller pumps are far more common than you might imagine and are used for everything aboard from bilge pumps to shower pump and freshwater wash down. Generally they can be relied upon to work without incident for many months or even years but that does not mean they are maintenance free. In my view one of the most important of these pumps is that used for raw water cooling on the inboard engine. Should this pump fail or work at less than full capacity overheating will result and damage result to the engine. I am sure that I am not the only one who has a quick peek over the transom after starting the engine to make sure that water is being ejected with the exhaust. All engines differ but if you get used to a quick visual check each time the engine is fired up you will soon spot if something is amiss; reduced water flow or a dry throaty exhaust note is a sure sign that something is amiss. I must confess that I like to change my raw water impeller every winter no matter how little I may have used the boat during the season. Largely a preventive maintenance issue I then can relax knowing that when the boat goes back into the water the water pump is in tiptop condition. Often water pumps are left for too long before being serviced and are apt to fail at the most critical times just when you need the engine the most.

Here’s how to do it.

This is a typical set up which in this case is a Yanmar 3GM engine with the raw water pump driven by a belt from the from end of the crankshaft. All engines vary to some extent and some pumps are driven by gears or pinion shaft in which case they are bolted directly to the engine block.

Depending on the engine/pump configuration it can often be easier to remove the pump from the engine to change the impeller. One important caveat here and that is to shut off the water at the seacock especially if the water pump is lower than the water level as the siphon action can flood the boat. Undo the pipe clamps after removing the securing nuts and bolts pull the pump clear.

Old is new again

    I got this photo the other day as part of a press release. Apparently it is being marketed as some 'new' mooring aid, the rubber balls on a bit of rope roll up and down the piling with the rising and falling tide keeping the boat pulled in to the dock. Now call me old fashioned but these are simply parrel beads made from rubber rather than wood but parrel beads the are. Parrel beads have been around for hundreds of years so this is nothing new simply a new take on an old idea. Apparently the beads cost $50 but I do have to ask myself why you would need them especially in the situation shown in the picture as the dock rides up and down with the tide and the boat can just be tied up to the dock cleats.

Vacuum bagging

I guess I must not be the only one who has thought of this but I have been having ideas about using a domestic kitchen vacuum bagger for small glue up jobs. I've done a trawl through pages on the internet and I can find no one else who has thought of using one of these $75 vacuum sealers for boat building. Well OK you could not use it to bag a whole boat but I could see distinct possibilities for one of these units for small jobs. The bags it seems come in a roll and although there are limitations to the width dictated by the machine the length is determined by where you cut the strip off to make the bag. Epoxy won't stick to the inside of the bag and unlike the large vacuum pump that I have in the workshop won't have to be run all night just to glue up some small component. I should think that it would be great for small laminating jobs, for instance sticking some veneer to a bit of ply or I could see that it would even be possible with a little imagination to rig something up to make small fiber glass panels that were smooth on both sides. It should be a simple matter of putting a layer of gel coat on both inside faces of the bag slipping in the requisite number of presaturated layers of cloth, sucking out the air and then opening it up a few hours later. I'd have to trim the panel to size of course but it just might work.

What is Plywood?

I've had a few e mails asking about which plywood to use for certain projects, specifically from readers of On Board wanting to know if it is OK to use cheap plywood from the local home store for structural parts inside their boats. Basically this is not a good idea so what follows is a  basic introduction to plywood, specifically in relation to those types most applicable to boat work.

Plywood is made of an odd number of thin layers of wood (plies) stacked at right angles to each other. The contact surfaces are coated with glue, and the plies are then bonded into panels under heat and pressure. The sum of the parts makes a panel whose strength is less directional and less prone to splitting than solid wood; a plywood panel is dimensionally stable and largely unaffected by changes in the ambient atmosphere. The most common panel size is 4 feet by 8 feet, though larger panels, up to 5 feet wide and 12 feet long, are available. Complex shapes can be cut that would be impossible with natural timber.

Plywood varies greatly in price and quality, and generally you get what you pay for. The cheapest interior-grade ply is made from poorer-quality wood; there may be voids in the intermediate layers, and the exterior surfaces are often of poor quality and must be painted. Luckily, standards and grade stamps on panels make choosing the right plywood for DIY boat projects a little easier.

There are U.S. standards for Douglas fir and American-hardwood plywoods, while tropical-hardwood plywoods imported into the U.S. usually conform to British Standard BS 1088 or comparable European standards. BS 1088 is the most common and has stringent codes. For instance: “Plywood shall be made from untreated tropical hardwood veneers having a suitable level of resistance to fungal attack, with a bond of WBP (weather and boil proof) glue quality between the plies. Bonding shall be with a phenolic formaldehyde WBP adhesive to BS EN 314-2 class 3. Finally, the veneers may be rotary or slice cut. The method of cutting is at the option of the manufacturer unless otherwise specified.

“Face veneers shall present a solid surface, free from open defects. They shall be free from knots, other than pin knots, of which there shall be no more than 6 in any area 30 cm square, and not more than an average of 2 per 30 cm square. Veneers showing compression failure shall be excluded. Occasional discoloration is permissible.”

Plywood that’s claimed to meet a marine standard has to be suitable for the purpose. These are minimum standards, however, and some plywood exceeds them. Still, it pays to be vigilant when buying plywood. If possible, visit the supplier and check out the stock before you buy. This is especially important if you plan to varnish the plywood. Discoloration is possible (but unlikely) due to water staining. Color variation is usually not an issue if all components are to be cut from the same sheet, but different sheets can have marked color differences.

Although it may be tempting to use a non-marine-grade ply for some jobs, this often proves to be false economy. Boats live in a harsh environment, and cheaper ply may not be as strong, it may have interior voids, the glue may not be waterproof, and delamination may occur, necessitating costly repairs.

If you do an Internet search, you’ll find a host of vendors of marine plywood. Prices for a 4-foot-by-8-foot sheet range from about $70 to $150 for 1/4 ( plywood to $140 to $330 for 3/4 ( Okoume and Sapele plywood; Sapele is the more expensive.

Okoume (Gaboon) is an African hardwood. The mature trees are tall and straight and free of knots; they have large-diameter trunks. Okoume ranges in color from a brown to salmon pink, takes finishes well, and may be either painted or varnished. While Okoume is often the first choice when it comes to marine plywood because of its light weight, it is not particularly strong and is rated as non durable. It must be thoroughly sealed, usually with epoxy resin, if it will be exposed to water.

Sapele, also from Africa, is moderately resistant to decay and almost 50 percent heavier than Okoume. In the U.S., Douglas fir, a moderately rot-resistant softwood, is used for plywood. Douglas-fir plywood is usually used for structural applications since it is difficult to finish. Painting can raise the grain, and small face checks (surface flaws) can lead to early failure. When a cosmetic finish is required, MDO (Medium Density Overlay) plywood—where the panel is overlaid with resin-treated paper—provides an excellent surface for paint.

More-decorative veneers than the common plywood species may be used for the face veneer if the plywood is to be varnished, with tropical hardwoods or Douglas fir used for the core plies. Teak and mahogany are perennial favorites for the surface, but plywood is also available with other face veneers; ash and cherry are currently popular.

Plywood plays an important part in today’s fiberglass boats. It is often used for bulkheads, doors and drawers, cabin soles, and bunk tops. The inherent stiffness of plywood panels makes them ideal for bulkheads that will be subjected to significant structural loads.

I have built several boats from plywood and find it an almost perfect material for the amateur woodworker. A hull can be quickly built from large panels, so the boat takes shape fast, and it can be completely encapsulated with epoxy resin. Epoxy is also a perfect adhesive for joining the panels together, making the boat very stiff and robust. One of the popular ways of building a boat especially for the DIYer is the stitch and tape method. This involves temporarily stitching precut plywood hull panels together with copper or wire ties and then glassing over the joints with epoxy and glass tape. The technique was pioneered by Barry Bucknall, who used it with great success in designing the Mirror Dinghy; now boats of up to 50 feet and over can be built this way. One of the firms that have been very popular in bringing this method of construction to a mass market in recent years has been Chesapeake Light Craft who offer a vast range of small boats. Another is Sam Devlin who offers complete boats and plans to 50 feet in length using this method.

There are several things you cannot do with plywood; most important, you cannot bend it in two directions at once, so making compound curves is impossible. In addition, plywood will ultimately rot if left exposed to the weather. More-expensive grades will hold up longer and generally be more resilient, but eventually all plywood will fail if not properly sealed with paint and varnish or other surface coatings.

Power One

    Cleaners for removing rust have tended to have a large amount of oxalic acid as there main active ingredient. Although this gets rid of rust it is also prone to eat into the underlying material. Additionally oxalic acid is not very pleasant to handle, you need to wear rubber gloves and if you get any into a small cut on your hands it hurts like hell.
    I was recently sent a sample of this Power One product which has none of the noxious smells and does not hurt if it gets on your hands. I tried it on a variety of surfaces and I must say that it did work better than I initially anticipated. The instructions on the bottle say that it is safe for use on virtually any surface, even carpet it won't hurt fiberglass or paint  and my tests appear to bear this out. I also accidentally splashed some onto some bronze fittings and the green surface patina seemed to come off with just a wipe of a rag which could speed up the polishing process if you are into such things.

  It was less effective at removing rust from sail cloth, although there was a noticeable improvement in the before and after condition of the sails. I actually took a bunch of photos which I was going to post here but I left the camera in the truck at the boatyard so you will have to wait for those.

    A liter bottle costs 15.95 but should last a long time especially if you only use it for spot cleaning. I'm going to keep it on the boat this year and add it to the cleaning supplies box where I am sure that it will come in  very handy.

    Basically a good product that can be recommended. Power One works as advertised without the harsh chemicals associated with many of the other cleaners which although may clean your boat are just as likely to blister the paint too!

Replacing through hull fittings

     As someone who has built boats and worked in boatyards one of the jobs that I was most nervous about when I started out was installing through hulls. Get it right and every thing’s OK. Get it wrong and the boat could sink. According to a recent report by insurance companies almost half of boats that sink at their slips can be attributed to faulty skin fittings. The words skin fittings and through hulls are often used interchangeably although it could be argued that a through hull is a pipe that penetrates the hull whereas a skin fitting might be a transducer for a log or depth sounder. Whatever you call them replacing a transducer or other skin fitting is all done in the same way. Replacing through hulls is straightforward providing a thorough methodical approach is adopted. The hardest part of the operation is often getting the old one out.

After removing any internal fixtures such as hoses and sea cocks remove the back nut from inside the boat. These are often large so require either a large wrench or channel lock pliers to get a decent grip. If the nut does not unscrew but instead the whole fitting starts to rotate get a helper on the outside of the boat to hold the through hull either with a stepped through hull wrench or by jamming a set of pliers or other suitable tool into the opening. These same tools can be used to unscrew the fitting as soon as the nut is removed. Sometimes the mastic bond is so strong that the fitting refuses to budge, gently warming a bronze skin fitting with a hot air gun is often sufficient to soften the mastic and enable it to be withdrawn but be careful of damaging the laminate though. As a last resort you may have to cut it away with a hacksaw but use caution not to cut into the hull.

With the fitting finally removed clean off all dust dirt grease and traces of old bedding compounds. All through hulls should always be installed with a backing block on the inside of the hull, often of plywood if there are signs of rot or delamination it must be replaced. Have a trial run at fitting the new through hull in position, as some holes may need enlarging if swapping from one manufacturer to another.

If the flange of the fitting fits sweetly against the exterior of the hull withdraw it then run a generous bead of sealant around the flange and about an inch up the threads. Boatlife and 3M are just a couple of the manufacturers of suitable mastic sealants but don’t be tempted to use 3M’S 5200 which although an excellent product will glue the skin fitting in and make it almost impossible to remove at a later date should this be required.

Have a helper hold the fitting in place while you go onto the inside of the boat, bed down the backing block with some additional mastic and tighten down the back nut.

Scrape off any excess sealant that has oozed out before finally cleaning up with a suitable solvent; denatured alcohol works well. Finally reattach sea cocks and pipe work to the skin fitting before relaunching. As soon as the boat goes back into the water check for leaks and subsequently every few hours after that until you are confident that all is well.

Belt tightening

    There has been a lot of talk in the papers and on TV lately about belt tightening. Well this bit of belt tightening won't cost you a penny. I'm talking about fan belts and drive belts on the engine.

    Yesterday I took a 33 foot sail boat out for a sea trial with the new owner, it was the last thing to do before the boat was handed over from the old owner. I had surveyed the boat some time ago and had requested that a few things be addressed before the boat was relaunched. One  of these was to replace the raw water intake hose amongst other things. While I was checking that this had been done before putting out to sea I also checked over the engine to make sure that everything is as it ought to be which thankfully it was. I always check the belt tensions on motors, you would be surprised how often they are either too tight or too loose. A belt that it too tight will put undue strain on the bearing for the alternator and any pumps which it might be operating in addition to wearing out the belt in short order. On the other hand a belt that is too loose may not drive the alternator at all especially if the electrical demand is high and there is a lot of drag from the windings. A loose belt will also wear out faster as it tends to slip and skid making a high pitched squeal. Ideally there should be about a half inch to three quarter deflection in the longest run of the belt which in the case of this small Yanmar 2GM engine happens to be between the crankshaft and alternator pulleys. As you can see from the picture you can check the deflection with a moderate amount of pressure from your index finger. If the belt needs dusting then the bolt on the alternator quadrant can be loosened and the alternator body moved in or out until the belt is at the correct tension then the bolt retightend.

SAFETY TIP

To make sure that the engine cannot be started while you are working on belts and other things remove the ignition key and place it into your pocket, also make sure that the electric master switch is set to off.
 When you have finished your engine checks turn on the main isolator and replace the ignition key.
Going through this routine will ensure that another crew member will not try to start the engine when you have your fingers and hands in the way.