Smelly heads

You know that stench you get below decks when you return to your boat after a few days away? It is, more often than not, down to the sea toilet.

Most marine toilets are flushed with raw water from sea, lake or river. This flushing water contains living organisms and it’s the demise of these little devils in the pipe work that begins the downward spiral; the resultant bacteria generate that awful sulphurous gas smell which you suck into the boat when you pump. The pipework itself can become contaminated so that no amount of flushing will get rid of the smell.

At one time I handled maintenance for a fleet of charter boats and keeping the heads sweet was a big headache. I was persuaded that a major contributor to the odour was the fact that the translucent sanitation hoses let in sunlight which hastened the demise of the bugs and, thereby, the creation of the bacteria which caused the smell. I wrapped all my pipes in silver foil as a defence but found no real improvement and ended up changing all the pipes at the beginning of each season, and still had to deploy an array of disinfectants on a regular basis.

When I moved onto my boat full time and set off on my three-year modest odyssey the problem was greatly alleviated by frequent and regular flushing. Unless you live aboard you simply can’t keep up the necessary flow.

The only boat of the seven I’ve owned not to suffer the odours was my GB32 trawler which had a fresh water flushing system and in-line deodorizer. But on a long-distance cruising boat you simply can’t afford to flush freshwater down the bog, it’s way too precious for that.

VHF transmission range

For VHF communication the most significant factor in establishing range is your antenna’s height above sea level. This assumes, of course, your system consists of a good antenna with the right size cabling and a properly functioning radio or AIS unit.

Think of radio range as your radio horizon plus the radio horizon of the station you are communicating with. Radio horizon is an invisible circle around your boat, the perimeter of which is the distance to which the radio signal from your antenna will reach. The station with which you are communicating will have its own circle, the extent of which will depend on its antenna’s height above sea level. When the two circles meet you can communicate. This is your range. So, your communicating range varies, depending upon the radio horizon of the station with which you are communicating.

Your radio horizon in nautical miles is 1.4 x root of antenna height in feet above SL. For example, if your antenna is at the masthead, 49 feet above sea level, your radio horizon will be 1.4 x 7 = 9.8 nm. If you are communicating with an identical boat, your combined range will be twice this figure, about 20 miles. However, if you are communicating with the QE2 where her antenna is nearly 200 feet above sea level, her radio horizon will be about 20 miles so you’ll be able to communicate at closer to 30 miles.

Coastguard stations have powerful transmitters located high up on headlands and have large radio horizons. An antenna at 900 feet above sea level would have a range of 1.4 x 30 = 42 miles, so you could communicate at about 50 miles.

Clearly, the ideal location for your VHF antenna is as high as you can get it and, on a sailing boat, that means the masthead. Nowadays you’ll probably be using AIS and radio so the masthead location can create a problem – how to locate two antennas far enough apart so they don’t interfere with each other. If you can get the antennas over 0.75 meters apart, they should function fine. Some experts say they need to be more than 1m apart but anecdotal evidence seems to suggest the 0.75m figure is good enough. If you can’t get this degree of separation your choices come down to using an active splitter or mounting one of the antennas (AIS) at the next highest location – mizzen mast, radar-arch/pole or the pushpit.

Having a second antenna is a wise choice because it means you aren’t interrupting AIS data when using the radio and the second antenna provides redundancy. Arrange the cabling so that either antenna can be connected to either radio or AIS. Carry an SO239/BNC adapter if the input to your AIS is BNC. Your radio is always PL259.

If you have a combined radio/AIS it will usually be equipped with a splitter – be sure to use a full range VHF antenna, 156 to 163 MHz, so as not to compromise reception.

Fair winds!

Masthead LED Navigation Lights

Masthead LED navigation lights – tri-colour, anchor, a combination of the two – make perfect sense for sailboats. Ultra-low power consumption and long life are the main attractions.

Those advantages are obvious, but what else should you expect from your masthead lights? Rugged reliability, for one thing. We shouldn’t underestimate the vibration and brutal motion at the masthead in a seaway and your navigation light has to cope with all that. So, super-solid construction and a strong fixing system should be on the list.

A reliable photoelectric cell to switch the light on at dusk and when daylight fades in storms and fog, and off again when normal light conditions return, is a big advantage. Also, a tall light as opposed to a squat profile ensures the light won’t be masked from some angles by the mast upon which it’s mounted. If you use a lamp like a hockey puck, it might be a good idea to elevate it somehow.

Another factor, a big issue with LEDs, is interference with VHF radio and AIS reception. When you switch on your masthead light you don’t want to hear crackling on the radio and you don’t want your AIS information to go walkabout. You’ll want a guarantee from the manufacturer that this won’t happen. In my role as a Metz VHF antenna system provider, I’ve been banging on about this for years. Navigation lights and antennas share a tight spot at the top of the mast and they must be compatible. As recently as August 2018 the US Coastguard was warning about the proliferation of difficult or failed VHF radio communications as a direct result of LED interference. It is the voltage regulating circuit that’s the culprit and even expensive LEDs may have the sort of buck regulator that oscillates at a frequency which blocks VHF transmissions. Check yours!

LED navigation lights are a great innovation for the sailor, providing excellent performance and miserly power consumption. There are many brands on the market, be sure to choose wisely.

1 December 2018: Salty John has now concluded a deal with OPTOLAMP to stock their range of LED masthead navigation lights. These excellent lights tick all the boxes. Have a look at for more details. Should be in stock by Christmas. Now in stock.

Metz VHF antenna – a thing of beauty.

The superb Metz Manta VHF antenna is a thing of beauty and durability. It also gives exceptional performance. What makes it so special is the precision-wound, heavy-duty coil housed within that stainless-steel can, and the way the coil is properly supported so it doesn’t distort when heat builds during transmission. The coil is sealed with epoxy and has a lifetime warranty. The 34” whip is stainless-steel, of course.

The Metz Manta is used by the US Coastguard, UK lowland Search and Rescue organisations, many charter fleets, several boat manufacturers, and the round-the-world Clipper fleet. And by many, many thousands of individuals – it’s been in continuous manufacture since 1977.

The Metz comes with a stainless L-bracket. Other mounting options include the Metz quick release rail mount and there’s an adapter available so it can be mounted on any 1”, 14 tpi, threaded mount.

Put the Metz Manta together with marine quality coaxial cable of the correct size, use top class connectors and your antenna system will extract the maximum performance from your VHF radio and AIS system.

Get your Metz antenna and accessories from, the UK and European distributors.

Designing a bilge-pump system for your boat


The Problem

You’re bilge pump system has to handle two situations – pumping out the normal accumulations of water from stern gland, condensation and minor leakage, and pumping out a large influx of water in an emergency.

The most likely causes of a catastrophic leak in a displacement boat are:

  1. The loss of a seacock – either the hose becomes detached or the seacock itself breaks off the through hull.
  2. Loss of a through hull transducer.
  3. A disintegrating drive shaft stuffing box or stern gland.
  4. An overheating engine which melts the exhaust system components and pumps water into the bilge.

Holes in the hull caused by grounding or collision, and flooding by waves could be any size; it’s unrealistic to design for such freak occurrences.

Simple fact: A 1½” hole (such as an open seacock) located 2’ below the waterline will let in around 60 US gallons (230 litres) per minute. That’s 3,600 gallons per hour. That water weighs nearly 30,000 lbs. If you were so inclined you could calculate the amount of water your boat could accommodate before she sank. It isn’t many hours for the size of boat most of us sail.

So, ideally, you need an emergency bilge pump system to handle around 4,000 gallons (15,000 litres) per hour. You also need a supplementary system to keep the bilge dry.

Types of pump and how to drive them.

We can power our bilge pumps in three ways:

Mechanically, off the engine.

Electrically, from the batteries.

Manually, by a crewmember.

Think about these options a little. To drive the pump mechanically the engine must be running; to drive the pump electrically there must be juice in the batteries; to drive the pump manually a crewmember must be available.

To cover all contingencies the bilge pump system will need to be a combination of pump types.

Capacity ratings

Now, before we select the appropriate pumps, let’s consider the pump capacity rating. I’m going to try and make this as simple as possible because not everyone wants to plough through charts and graphs and extrapolations to calculate the precise capability of a bilge pump.

An electric pump with a rated capacity of 2,000 gallons per hour will only do this if there is no hose connected and the batteries are bulging with volts. But in real life the pump has to lift the water out of the bilge and push it uphill to a discharge point. Furthermore, it has to push this water through a pipe, and various bends and probably a seacock. This combination of the uphill battle and the resistance in the system is known as the pressure head and it must be applied to the pump’s rated capacity to get the real-world capacity.

My rule of thumb for calculating pressure head in a typical 25’ to 45’boat installation is to measure the height from the pump to the highest point of the pipe run and double this figure to give total pressure head. So, if you want a pump to move 2000 gph vertically 5’ your total pressure head is 10’ Now look at, for instance, a Rule 2000 electric pump which has an open flow rating of 2000gph and apply the 10’ pressure head on the manufacturers chart; you will find that this pump does a little under half of the open flow rating at this pressure head.

So, my second, and simpler, rule of thumb is – down rate electric pump capacity to 40% of rated capacity. And be aware that this requires the batteries to be fully charged; depleted batteries and dodgy wiring will further degrade performance.

Your 2000 gph pump will actually handle around 800 gph.

Mechanical and manual pumps usually give the capacity at a particular pressure head so their selection is less confusing, but the rule about total pressure head stands.

The biggest manual pumps, such as the Edson 30, will pump one gallon per stroke and the Whale Henderson Mark 5 about half that rate. Although some manufacturers give pump capacity at hugely optimistic pumping rates, (70 strokes per minute, for instance), 30 strokes per minute is hard work; if you can manage that you’ll get 1800 gallons per hour from the Edson. These are physically large pumps and can be challenging to house on a small boat. Lower capacity pumps take up less room.

Types of pump.

Every boat should have at least one manual bilge pump. Manual pumps are diaphragm pumps and the best type are double acting – they pump on both forward and backward strokes of the handle. Think about its location and how easy it will be to operate in an emergency. A long handle that can be operated in a standing position is best; kneeling in the cockpit is less good. Do what you can.

Electric pumps are, most often, of the submersible, centrifugal type. Such a pump would form the basis of your non-emergency maintenance system – to keep your bilge dry under normal conditions. Equipped with a level switch it will cycle on and off as needed to keep nuisance water from building up. Float switches are notoriously unreliable so check them frequently; electronic switches with no moving parts, such as the Water Witch, are usually a better choice.

You may wish to add a second, higher capacity pump as an emergency pump and it should be designed to come on if the smaller pump isn’t coping. It should have a level switch located higher in the bilge than the maintenance pump. This switch should operate an audio/visual alarm to tell the crew it has operated. You must be able to override the automatic function and force the pump to run if the switch fails.

If your boat can accommodate it the best of all pumps is a mechanical clutch pump, belt driven off the engine. A Jabsco Series 51270 engine driven pump will handle 4,100 gph at 10’ total pressure head but is physically large and nearly impossible to house on smaller boats.

Your engine already has a pump on it, the cooling water pump, and some advocate that this be plumbed in such a way that by switching a valve it will draw its water from the bilge instead of outside. I’m very sceptical of this advice – the engine pump doesn’t move an awful lot of water, and I’d hate to be jeopardising my engines cooling system when I already have an emergency on my hands.

So, to sum up: A typical bilge water management system will comprise a 12v submersible pump to handle normal seepage, one or two larger electric pumps to handle larger influxes and a manual bilge pump to supplement the electric pumps or replace them when the batteries are flat. An engine driven pump would be a very desirable addition.

Oh, and a baling bucket is a vital component of any leak management system.

Installation considerations.

It will be clear from the discussion of pump capacity that keeping the total pressure head as low as possible is important. The pump in the bilge should be located as close to being vertically in line with the discharge hole as is feasible so that the length of horizontal run is minimised. The maximum lift height will be determined by the distance between the pump outlet and the discharge point, or the top of any loop, vented or otherwise, in the line. Sharp bends should be avoided. The pipe should have smooth interior walls. You’re trying to make it as easy as possibly for the pump to move the water – don’t put obstacles in its way.

You’ll want the bilge pump discharge hose to be well above the heeled waterline. If you can’t achieve this you’ll need to consider a vented loop. Try hard to avoid that need.

Consider installing your electric pumps and their switches on a common base; I use a piece of Plexiglas. If your bilge is very deep you can attach a handle or lanyard to this base plate to allow you to lift the whole assembly within reach for maintenance and repair.


OK, those are my thoughts on bilge pump systems, but let me say right now that I have never had a boat in which the bilge pump system could evacuate 4,000 gph. In smaller boats it’s just impractical to achieve this capacity, as you may have gathered from the above. Top priority, therefore, is to avoid a situation that would require such a capacity:

Prevention and preparation.

Minimise the number of holes in your boat. Use a manifold or seachest where appropriate to combine several functions into one seacock. Use suitable seacocks – bronze, stainless or Marelon. Use quality hose and double clamp it. Maintain your seacocks, engine stuffing box and rudder bearings scrupulously and regularly.

You have to be able to get to all your seacocks easily and quickly even when they’re underwater. At each seacock you must have a soft wood or rubber bung of the appropriate size. Tie it to the seacock with a lanyard. Have a contingency plan for stemming the flow from a hull breach, stuffing box failure, displaced rudder or other catastrophe. Keep your cockpit drains clear and, if your boat doesn’t have a bridge-deck (companionway sill) keep the lower companionway hatch board in place if there’s a chance of shipping a wave.

It’s a good idea to have an exhaust temperature monitor on your exhaust pipe. A melted exhaust pipe will allow the engine to pump its raw cooling water into the boat. Melting of exhaust components can occur before the normal engine block temperature alarm sounds.

Note: In the forgoing discussion I’ve used US gallons and (litres) because that’s what most pumps are rated in and it saves me making conversions. If you want figures in Imperial gallons multiply the US gallon figure by 0.83 or divide the litre figure by 4.5.

Storm preparation – keep it simple

On a small boat in really heavy weather the only thing most of us want to do is lie in our bunk wishing it would all go away. If you’re seasick it must be ten times worse.

Going on deck to take action to secure the survival of the boat is a frightening proposition. It’s easy at this point to convince yourself that you should wait until it’s a bit calmer before putting in that reef, or hoisting the storm jib, or securing the dinghy which is beginning to come loose in its chocks. Of course you can’t succumb to that inner voice; you have to put on the harness and lifejacket, get yourself out into the maelstrom and get the job done.

If you’ve never been there you can’t imagine just how hard it is to operate under the conditions you’re likely to find on deck: The banshee wail in the rigging, the constant deluge of spray and solid water, the violent motion threatening to hurl you overboard. Even the strongest crew can become exhausted in a frighteningly short time.

One hand for the boat and one for yourself is the rule, although for much of the time it’s two hands for you and that leaves none for the boat which is why it’s so terribly hard to perform tasks that seemed so simple when it was calm.

This is why my mantra is simplicity in all things. That huge sea anchor with a complex bridle of rope and chain which you bought for just this occasion is going to defeat your attempts to deploy it, unless you have a large, strong and un-seasick crew. Even putting in the third or fourth reef with your single line reefing system with miles and miles of line is going to be a challenge if you’ve left it a bit late.

In my experience, if conditions are such that you can successfully deploy drogues, sea anchors and the like you probably don’t need them. By the time conditions are bad enough that you might benefit from such devices you’ll probably be unable to deploy them successfully without the possibility of damage to the boat or the crew. Heaving-to or running off will be your best tactics.

So, analyse your systems again and ask yourself how easy it’s going to be to get the boat snugged down and safe when the going gets tough. Can you get the sail plan sorted quickly and efficiently? Can you heave-to? Can you secure the helm? Is there any chance of items lashed on deck coming loose?

If you plan ahead and prepare the boat for bad weather before it arrives you probably can lay snuggly, and smugly, in your bunk until the storm passes. Assuming your lee cloths are properly designed and tested, of course, and your lockers have good catches and the floorboards are screwed down. And, vitally, you’ve given yourself enough sea room.